tsdb: test for leaks (#7566)

Signed-off-by: Julien Pivotto <roidelapluie@inuits.eu>

go.mod

@@ -64,6 +64,7 @@ require (
 	github.com/uber/jaeger-lib v2.2.0+incompatible
 	go.mongodb.org/mongo-driver v1.3.2 // indirect
 	go.uber.org/atomic v1.6.0 // indirect
+	go.uber.org/goleak v1.0.0
 	golang.org/x/net v0.0.0-20200707034311-ab3426394381
 	golang.org/x/oauth2 v0.0.0-20200107190931-bf48bf16ab8d
 	golang.org/x/sync v0.0.0-20200625203802-6e8e738ad208

go.sum

@@ -760,6 +760,8 @@ go.uber.org/atomic v1.3.2/go.mod h1:gD2HeocX3+yG+ygLZcrzQJaqmWj9AIm7n08wl/qW/PE=
 go.uber.org/atomic v1.5.0/go.mod h1:sABNBOSYdrvTF6hTgEIbc7YasKWGhgEQZyfxyTvoXHQ=
 go.uber.org/atomic v1.6.0 h1:Ezj3JGmsOnG1MoRWQkPBsKLe9DwWD9QeXzTRzzldNVk=
 go.uber.org/atomic v1.6.0/go.mod h1:sABNBOSYdrvTF6hTgEIbc7YasKWGhgEQZyfxyTvoXHQ=
+go.uber.org/goleak v1.0.0 h1:qsup4IcBdlmsnGfqyLl4Ntn3C2XCCuKAE7DwHpScyUo=
+go.uber.org/goleak v1.0.0/go.mod h1:8a7PlsEVH3e/a/GLqe5IIrQx6GzcnRmZEufDUTk4A7A=
 go.uber.org/multierr v1.1.0/go.mod h1:wR5kodmAFQ0UK8QlbwjlSNy0Z68gJhDJUG5sjR94q/0=
 go.uber.org/multierr v1.3.0/go.mod h1:VgVr7evmIr6uPjLBxg28wmKNXyqE9akIJ5XnfpiKl+4=
 go.uber.org/tools v0.0.0-20190618225709-2cfd321de3ee/go.mod h1:vJERXedbb3MVM5f9Ejo0C68/HhF8uaILCdgjnY+goOA=
@@ -971,6 +973,7 @@ golang.org/x/tools v0.0.0-20190911174233-4f2ddba30aff/go.mod h1:b+2E5dAYhXwXZwtn
 golang.org/x/tools v0.0.0-20191012152004-8de300cfc20a/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
 golang.org/x/tools v0.0.0-20191029041327-9cc4af7d6b2c/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
 golang.org/x/tools v0.0.0-20191029190741-b9c20aec41a5/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
+golang.org/x/tools v0.0.0-20191108193012-7d206e10da11/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
 golang.org/x/tools v0.0.0-20191113191852-77e3bb0ad9e7/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
 golang.org/x/tools v0.0.0-20191115202509-3a792d9c32b2/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
 golang.org/x/tools v0.0.0-20191119224855-298f0cb1881e/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=

tsdb/db_test.go

@@ -46,8 +46,13 @@ import (
 	"github.com/prometheus/prometheus/tsdb/tsdbutil"
 	"github.com/prometheus/prometheus/tsdb/wal"
 	"github.com/prometheus/prometheus/util/testutil"
+	"go.uber.org/goleak"
 )
 
+func TestMain(m *testing.M) {
+	goleak.VerifyTestMain(m)
+}
+
 func openTestDB(t testing.TB, opts *Options, rngs []int64) (db *DB, close func()) {
 	tmpdir, err := ioutil.TempDir("", "test")
 	testutil.Ok(t, err)

tsdb/index/index_test.go

@@ -30,8 +30,13 @@ import (
 	"github.com/prometheus/prometheus/tsdb/chunks"
 	"github.com/prometheus/prometheus/tsdb/encoding"
 	"github.com/prometheus/prometheus/util/testutil"
+	"go.uber.org/goleak"
 )
 
+func TestMain(m *testing.M) {
+	goleak.VerifyTestMain(m)
+}
+
 type series struct {
 	l      labels.Labels
 	chunks []chunks.Meta

tsdb/tombstones/tombstones_test.go

@@ -24,8 +24,13 @@ import (
 
 	"github.com/go-kit/kit/log"
 	"github.com/prometheus/prometheus/util/testutil"
+	"go.uber.org/goleak"
 )
 
+func TestMain(m *testing.M) {
+	goleak.VerifyTestMain(m)
+}
+
 func TestWriteAndReadbackTombstones(t *testing.T) {
 	tmpdir, _ := ioutil.TempDir("", "test")
 	defer func() {

tsdb/wal/wal_test.go

@@ -24,11 +24,16 @@ import (
 	"testing"
 
 	"github.com/prometheus/prometheus/tsdb/fileutil"
+	"go.uber.org/goleak"
 
 	client_testutil "github.com/prometheus/client_golang/prometheus/testutil"
 	"github.com/prometheus/prometheus/util/testutil"
 )
 
+func TestMain(m *testing.M) {
+	goleak.VerifyTestMain(m)
+}
+
 // TestWALRepair_ReadingError ensures that a repair is run for an error
 // when reading a record.
 func TestWALRepair_ReadingError(t *testing.T) {

tsdb/wal/watcher_test.go

@@ -14,7 +14,6 @@ package wal
 
 import (
 	"fmt"
-	"github.com/go-kit/kit/log"
 	"io/ioutil"
 	"math/rand"
 	"os"
@@ -23,6 +22,8 @@ import (
 	"testing"
 	"time"
 
+	"github.com/go-kit/kit/log"
+
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/prometheus/pkg/labels"
 	"github.com/prometheus/prometheus/tsdb/record"

tsdb/wal_test.go

@@ -93,6 +93,7 @@ func TestSegmentWAL_Truncate(t *testing.T) {
 
 	w, err := OpenSegmentWAL(dir, nil, 0, nil)
 	testutil.Ok(t, err)
+	defer func(wal *SegmentWAL) { testutil.Ok(t, wal.Close()) }(w)
 	w.segmentSize = 10000
 
 	for i := 0; i < numMetrics; i += batch {
@@ -143,6 +144,7 @@ func TestSegmentWAL_Truncate(t *testing.T) {
 	// The same again with a new WAL.
 	w, err = OpenSegmentWAL(dir, nil, 0, nil)
 	testutil.Ok(t, err)
+	defer func(wal *SegmentWAL) { testutil.Ok(t, wal.Close()) }(w)
 
 	var readSeries []record.RefSeries
 	r := w.Reader()
@@ -283,6 +285,7 @@ func TestWALRestoreCorrupted_invalidSegment(t *testing.T) {
 
 	wal, err := OpenSegmentWAL(dir, nil, 0, nil)
 	testutil.Ok(t, err)
+	defer func(wal *SegmentWAL) { testutil.Ok(t, wal.Close()) }(wal)
 
 	_, err = wal.createSegmentFile(filepath.Join(dir, "000000"))
 	testutil.Ok(t, err)
@@ -299,8 +302,9 @@ func TestWALRestoreCorrupted_invalidSegment(t *testing.T) {
 
 	testutil.Ok(t, wal.Close())
 
-	_, err = OpenSegmentWAL(dir, log.NewLogfmtLogger(os.Stderr), 0, nil)
+	wal, err = OpenSegmentWAL(dir, log.NewLogfmtLogger(os.Stderr), 0, nil)
 	testutil.Ok(t, err)
+	defer func(wal *SegmentWAL) { testutil.Ok(t, wal.Close()) }(wal)
 
 	files, err := ioutil.ReadDir(dir)
 	testutil.Ok(t, err)
@@ -386,6 +390,7 @@ func TestWALRestoreCorrupted(t *testing.T) {
 
 			w, err := OpenSegmentWAL(dir, nil, 0, nil)
 			testutil.Ok(t, err)
+			defer func(wal *SegmentWAL) { testutil.Ok(t, wal.Close()) }(w)
 
 			testutil.Ok(t, w.LogSamples([]record.RefSample{{T: 1, V: 2}}))
 			testutil.Ok(t, w.LogSamples([]record.RefSample{{T: 2, V: 3}}))
@@ -416,6 +421,7 @@ func TestWALRestoreCorrupted(t *testing.T) {
 
 			w2, err := OpenSegmentWAL(dir, logger, 0, nil)
 			testutil.Ok(t, err)
+			defer func(wal *SegmentWAL) { testutil.Ok(t, wal.Close()) }(w2)
 
 			r := w2.Reader()
 
@@ -443,6 +449,7 @@ func TestWALRestoreCorrupted(t *testing.T) {
 			// is truncated.
 			w3, err := OpenSegmentWAL(dir, logger, 0, nil)
 			testutil.Ok(t, err)
+			defer func(wal *SegmentWAL) { testutil.Ok(t, wal.Close()) }(w3)
 
 			r = w3.Reader()
 

vendor/go.uber.org/goleak/.gitignore

@@ -0,0 +1,5 @@
+vendor/
+/bin
+/lint.log
+/cover.out
+/cover.html

vendor/go.uber.org/goleak/.travis.yml

@@ -0,0 +1,24 @@
+sudo: false
+language: go
+go_import_path: go.uber.org/goleak
+
+env:
+  global:
+    - GO111MODULE=on
+
+matrix:
+  include:
+  - go: 1.12.x
+  - go: 1.13.x
+    env: LINT=1
+
+install:
+  - make install
+
+script:
+  - test -z "$LINT" || make lint
+  - make test
+
+after_success:
+  - make cover
+  - bash <(curl -s https://codecov.io/bash)

vendor/go.uber.org/goleak/CHANGELOG.md

@@ -0,0 +1,17 @@
+# Changelog
+All notable changes to this project will be documented in this file.
+
+The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/)
+and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html).
+
+## [1.0.0]
+### Changed
+- Migrate to Go modules.
+
+### Fixed
+- Ignore trace related goroutines that cause false positives with -trace.
+
+## 0.10.0
+- Initial release.
+
+[1.0.0]: https://github.com/uber-go/goleak/compare/v0.10.0...v1.0.0

vendor/go.uber.org/goleak/LICENSE

@@ -0,0 +1,21 @@
+The MIT License (MIT)
+
+Copyright (c) 2018 Uber Technologies, Inc.
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.

vendor/go.uber.org/goleak/Makefile

@@ -0,0 +1,41 @@
+export GOBIN ?= $(shell pwd)/bin
+
+GOLINT = $(GOBIN)/golint
+
+GO_FILES := $(shell \
+	find . '(' -path '*/.*' -o -path './vendor' ')' -prune \
+	-o -name '*.go' -print | cut -b3-)
+
+.PHONY: build
+build:
+	go build ./...
+
+.PHONY: install
+install:
+	go mod download
+
+.PHONY: test
+test:
+	go test -v -race ./...
+	go test -v -trace=/dev/null .
+
+.PHONY: cover
+cover:
+	go test -race -coverprofile=cover.out -coverpkg=./... ./...
+	go tool cover -html=cover.out -o cover.html
+
+$(GOLINT):
+	go install golang.org/x/lint/golint
+
+.PHONY: lint
+lint: $(GOLINT)
+	@rm -rf lint.log
+	@echo "Checking formatting..."
+	@gofmt -d -s $(GO_FILES) 2>&1 | tee lint.log
+	@echo "Checking vet..."
+	@go vet ./... 2>&1 | tee -a lint.log
+	@echo "Checking lint..."
+	@$(GOLINT) ./... 2>&1 | tee -a lint.log
+	@echo "Checking for unresolved FIXMEs..."
+	@git grep -i fixme | grep -v -e '^vendor/' -e '^Makefile' | tee -a lint.log
+	@[ ! -s lint.log ]

vendor/go.uber.org/goleak/README.md

@@ -0,0 +1,70 @@
+# goleak [![GoDoc][doc-img]][doc] [![Build Status][ci-img]][ci] [![Coverage Status][cov-img]][cov]
+
+Goroutine leak detector to help avoid Goroutine leaks.
+
+## Development Status: Alpha
+
+goleak is still in development, and APIs are still in flux.
+
+## Installation
+
+You can use `go get` to get the latest version:
+
+`go get -u go.uber.org/goleak`
+
+`goleak` also supports semver releases. It is compatible with Go 1.5+.
+
+## Quick Start
+
+To verify that there are no unexpected goroutines running at the end of a test:
+
+```go
+func TestA(t *testing.T) {
+	defer goleak.VerifyNone(t)
+
+	// test logic here.
+}
+```
+
+Instead of checking for leaks at the end of every test, `goleak` can also be run
+at the end of every test package by creating a `TestMain` function for your
+package:
+
+```go
+func TestMain(m *testing.M) {
+	goleak.VerifyTestMain(m)
+}
+```
+
+## Determine Source of Package Leaks
+
+When verifying leaks using `TestMain`, the leak test is only run once after all tests
+have been run. This is typically enough to ensure there's no goroutines leaked from
+tests, but when there are leaks, it's hard to determine which test is causing them.
+
+You can use the following bash script to determine the source of the failing test:
+
+```sh
+# Create a test binary which will be used to run each test individually
+$ go test -c -o tests
+
+# Run each test individually, printing "." for successful tests, or the test name
+# for failing tests.
+$ for test in $(go test -list . | grep "^Test"); do ./tests -test.run "^$test\$" &>/dev/null && echo -n "." || echo "\n$test failed"; done
+```
+
+This will only print names of failing tests which can be investigated individually. E.g.,
+
+```
+.....
+TestLeakyTest failed
+.......
+```
+
+
+[doc-img]: https://godoc.org/go.uber.org/goleak?status.svg
+[doc]: https://godoc.org/go.uber.org/goleak
+[ci-img]: https://travis-ci.com/uber-go/goleak.svg?branch=master
+[ci]: https://travis-ci.com/uber-go/goleak
+[cov-img]: https://codecov.io/gh/uber-go/goleak/branch/master/graph/badge.svg
+[cov]: https://codecov.io/gh/uber-go/goleak

vendor/go.uber.org/goleak/doc.go

@@ -0,0 +1,22 @@
+// Copyright (c) 2018 Uber Technologies, Inc.
+
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+// Package goleak is a Goroutine leak detector.
+package goleak // import "go.uber.org/goleak"

vendor/go.uber.org/goleak/glide.yaml

@@ -0,0 +1,8 @@
+package: go.uber.org/goleak
+import: []
+testImport:
+- package: github.com/stretchr/testify
+  version: ^1.1.4
+  subpackages:
+  - assert
+  - require

vendor/go.uber.org/goleak/go.mod

@@ -0,0 +1,11 @@
+module go.uber.org/goleak
+
+go 1.13
+
+require (
+	github.com/kr/pretty v0.1.0 // indirect
+	github.com/stretchr/testify v1.4.0
+	golang.org/x/lint v0.0.0-20190930215403-16217165b5de
+	golang.org/x/tools v0.0.0-20191108193012-7d206e10da11 // indirect
+	gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127 // indirect
+)

vendor/go.uber.org/goleak/go.sum

@@ -0,0 +1,30 @@
+github.com/davecgh/go-spew v1.1.0 h1:ZDRjVQ15GmhC3fiQ8ni8+OwkZQO4DARzQgrnXU1Liz8=
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/kr/pretty v0.1.0 h1:L/CwN0zerZDmRFUapSPitk6f+Q3+0za1rQkzVuMiMFI=
+github.com/kr/pretty v0.1.0/go.mod h1:dAy3ld7l9f0ibDNOQOHHMYYIIbhfbHSm3C4ZsoJORNo=
+github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
+github.com/kr/text v0.1.0 h1:45sCR5RtlFHMR4UwH9sdQ5TC8v0qDQCHnXt+kaKSTVE=
+github.com/kr/text v0.1.0/go.mod h1:4Jbv+DJW3UT/LiOwJeYQe1efqtUx/iVham/4vfdArNI=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/testify v1.4.0 h1:2E4SXV/wtOkTonXsotYi4li6zVWxYlZuYNCXe9XRJyk=
+github.com/stretchr/testify v1.4.0/go.mod h1:j7eGeouHqKxXV5pUuKE4zz7dFj8WfuZ+81PSLYec5m4=
+golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
+golang.org/x/lint v0.0.0-20190930215403-16217165b5de h1:5hukYrvBGR8/eNkX5mdUezrA6JiaEZDtJb9Ei+1LlBs=
+golang.org/x/lint v0.0.0-20190930215403-16217165b5de/go.mod h1:6SW0HCj/g11FgYtHlgUYUwCkIfeOF89ocIRzGO/8vkc=
+golang.org/x/net v0.0.0-20190311183353-d8887717615a/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
+golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
+golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
+golang.org/x/tools v0.0.0-20190311212946-11955173bddd/go.mod h1:LCzVGOaR6xXOjkQ3onu1FJEFr0SW1gC7cKk1uF8kGRs=
+golang.org/x/tools v0.0.0-20191108193012-7d206e10da11 h1:Yq9t9jnGoR+dBuitxdo9l6Q7xh/zOyNnYUtDKaQ3x0E=
+golang.org/x/tools v0.0.0-20191108193012-7d206e10da11/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
+golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127 h1:qIbj1fsPNlZgppZ+VLlY7N33q108Sa+fhmuc+sWQYwY=
+gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v2 v2.2.2 h1:ZCJp+EgiOT7lHqUV2J862kp8Qj64Jo6az82+3Td9dZw=
+gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=

vendor/go.uber.org/goleak/internal/stack/stacks.go

@@ -0,0 +1,155 @@
+// Copyright (c) 2017 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package stack
+
+import (
+	"bufio"
+	"bytes"
+	"fmt"
+	"io"
+	"runtime"
+	"strconv"
+	"strings"
+)
+
+const _defaultBufferSize = 64 * 1024 // 64 KiB
+
+// Stack represents a single Goroutine's stack.
+type Stack struct {
+	id            int
+	state         string
+	firstFunction string
+	fullStack     *bytes.Buffer
+}
+
+// ID returns the goroutine ID.
+func (s Stack) ID() int {
+	return s.id
+}
+
+// State returns the Goroutine's state.
+func (s Stack) State() string {
+	return s.state
+}
+
+// Full returns the full stack trace for this goroutine.
+func (s Stack) Full() string {
+	return s.fullStack.String()
+}
+
+// FirstFunction returns the name of the first function on the stack.
+func (s Stack) FirstFunction() string {
+	return s.firstFunction
+}
+
+func (s Stack) String() string {
+	return fmt.Sprintf(
+		"Goroutine %v in state %v, with %v on top of the stack:\n%s",
+		s.id, s.state, s.firstFunction, s.Full())
+}
+
+func getStacks(all bool) []Stack {
+	var stacks []Stack
+
+	var curStack *Stack
+	stackReader := bufio.NewReader(bytes.NewReader(getStackBuffer(all)))
+	for {
+		line, err := stackReader.ReadString('\n')
+		if err == io.EOF {
+			break
+		}
+		if err != nil {
+			// We're reading using bytes.NewReader which should never fail.
+			panic("bufio.NewReader failed on a fixed string")
+		}
+
+		// If we see the goroutine header, start a new stack.
+		isFirstLine := false
+		if strings.HasPrefix(line, "goroutine ") {
+			// flush any previous stack
+			if curStack != nil {
+				stacks = append(stacks, *curStack)
+			}
+			id, goState := parseGoStackHeader(line)
+			curStack = &Stack{
+				id:        id,
+				state:     goState,
+				fullStack: &bytes.Buffer{},
+			}
+			isFirstLine = true
+		}
+		curStack.fullStack.WriteString(line)
+		if !isFirstLine && curStack.firstFunction == "" {
+			curStack.firstFunction = parseFirstFunc(line)
+		}
+	}
+
+	if curStack != nil {
+		stacks = append(stacks, *curStack)
+	}
+	return stacks
+}
+
+// All returns the stacks for all running goroutines.
+func All() []Stack {
+	return getStacks(true)
+}
+
+// Current returns the stack for the current goroutine.
+func Current() Stack {
+	return getStacks(false)[0]
+}
+
+func getStackBuffer(all bool) []byte {
+	for i := _defaultBufferSize; ; i *= 2 {
+		buf := make([]byte, i)
+		if n := runtime.Stack(buf, all); n < i {
+			return buf[:n]
+		}
+	}
+}
+
+func parseFirstFunc(line string) string {
+	line = strings.TrimSpace(line)
+	if idx := strings.LastIndex(line, "("); idx > 0 {
+		return line[:idx]
+	}
+	panic(fmt.Sprintf("function calls missing parents: %q", line))
+}
+
+// parseGoStackHeader parses a stack header that looks like:
+// goroutine 643 [runnable]:\n
+// And returns the goroutine ID, and the state.
+func parseGoStackHeader(line string) (goroutineID int, state string) {
+	line = strings.TrimSuffix(line, ":\n")
+	parts := strings.SplitN(line, " ", 3)
+	if len(parts) != 3 {
+		panic(fmt.Sprintf("unexpected stack header format: %q", line))
+	}
+
+	id, err := strconv.Atoi(parts[1])
+	if err != nil {
+		panic(fmt.Sprintf("failed to parse goroutine ID: %v in line %q", parts[1], line))
+	}
+
+	state = strings.TrimSuffix(strings.TrimPrefix(parts[2], "["), "]")
+	return id, state
+}

vendor/go.uber.org/goleak/leaks.go

@@ -0,0 +1,80 @@
+// Copyright (c) 2017 Uber Technologies, Inc.
+
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package goleak
+
+import (
+	"fmt"
+
+	"go.uber.org/goleak/internal/stack"
+)
+
+// TestingT is the minimal subset of testing.TB that we use.
+type TestingT interface {
+	Error(...interface{})
+}
+
+// filterStacks will filter any stacks excluded by the given opts.
+// filterStacks modifies the passed in stacks slice.
+func filterStacks(stacks []stack.Stack, skipID int, opts *opts) []stack.Stack {
+	filtered := stacks[:0]
+	for _, stack := range stacks {
+		// Always skip the running goroutine.
+		if stack.ID() == skipID {
+			continue
+		}
+		// Run any default or user-specified filters.
+		if opts.filter(stack) {
+			continue
+		}
+		filtered = append(filtered, stack)
+	}
+	return filtered
+}
+
+// Find looks for extra goroutines, and returns a descriptive error if
+// any are found.
+func Find(options ...Option) error {
+	cur := stack.Current().ID()
+
+	opts := buildOpts(options...)
+	var stacks []stack.Stack
+	retry := true
+	for i := 0; retry; i++ {
+		stacks = filterStacks(stack.All(), cur, opts)
+
+		if len(stacks) == 0 {
+			return nil
+		}
+		retry = opts.retry(i)
+	}
+
+	return fmt.Errorf("found unexpected goroutines:\n%s", stacks)
+}
+
+// VerifyNone marks the given TestingT as failed if any extra goroutines are
+// found by Find. This is a helper method to make it easier to integrate in
+// tests by doing:
+// 	defer VerifyNone(t)
+func VerifyNone(t TestingT, options ...Option) {
+	if err := Find(options...); err != nil {
+		t.Error(err)
+	}
+}

vendor/go.uber.org/goleak/options.go

@@ -0,0 +1,152 @@
+// Copyright (c) 2017 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package goleak
+
+import (
+	"strings"
+	"time"
+
+	"go.uber.org/goleak/internal/stack"
+)
+
+// Option lets users specify custom verifications.
+type Option interface {
+	apply(*opts)
+}
+
+// We retry up to 20 times if we can't find the goroutine that
+// we are looking for. In between each attempt, we will sleep for
+// a short while to let any running goroutines complete.
+const _defaultRetries = 20
+
+type opts struct {
+	filters    []func(stack.Stack) bool
+	maxRetries int
+	maxSleep   time.Duration
+}
+
+// optionFunc lets us easily write options without a custom type.
+type optionFunc func(*opts)
+
+func (f optionFunc) apply(opts *opts) { f(opts) }
+
+// IgnoreTopFunction ignores any goroutines where the specified function
+// is at the top of the stack. The function name should be fully qualified,
+// e.g., go.uber.org/goleak.IgnoreTopFunction
+func IgnoreTopFunction(f string) Option {
+	return addFilter(func(s stack.Stack) bool {
+		return s.FirstFunction() == f
+	})
+}
+
+func maxSleep(d time.Duration) Option {
+	return optionFunc(func(opts *opts) {
+		opts.maxSleep = d
+	})
+}
+
+func addFilter(f func(stack.Stack) bool) Option {
+	return optionFunc(func(opts *opts) {
+		opts.filters = append(opts.filters, f)
+	})
+}
+
+func buildOpts(options ...Option) *opts {
+	opts := &opts{
+		maxRetries: _defaultRetries,
+		maxSleep:   100 * time.Millisecond,
+	}
+	opts.filters = append(opts.filters,
+		isTestStack,
+		isSyscallStack,
+		isStdLibStack,
+		isTraceStack,
+	)
+	for _, option := range options {
+		option.apply(opts)
+	}
+	return opts
+}
+
+func (vo *opts) filter(s stack.Stack) bool {
+	for _, filter := range vo.filters {
+		if filter(s) {
+			return true
+		}
+	}
+	return false
+}
+
+func (vo *opts) retry(i int) bool {
+	if i >= vo.maxRetries {
+		return false
+	}
+
+	d := time.Duration(int(time.Microsecond) << uint(i))
+	if d > vo.maxSleep {
+		d = vo.maxSleep
+	}
+	time.Sleep(d)
+	return true
+}
+
+// isTestStack is a default filter installed to automatically skip goroutines
+// that the testing package runs while the user's tests are running.
+func isTestStack(s stack.Stack) bool {
+	// Until go1.7, the main goroutine ran RunTests, which started
+	// the test in a separate goroutine and waited for that test goroutine
+	// to end by waiting on a channel.
+	// Since go1.7, a separate goroutine is started to wait for signals.
+	// T.Parallel is for parallel tests, which are blocked until all serial
+	// tests have run with T.Parallel at the top of the stack.
+	switch s.FirstFunction() {
+	case "testing.RunTests", "testing.(*T).Run", "testing.(*T).Parallel":
+		// In pre1.7 and post-1.7, background goroutines started by the testing
+		// package are blocked waiting on a channel.
+		return strings.HasPrefix(s.State(), "chan receive")
+	}
+	return false
+}
+
+func isSyscallStack(s stack.Stack) bool {
+	// Typically runs in the background when code uses CGo:
+	// https://github.com/golang/go/issues/16714
+	return s.FirstFunction() == "runtime.goexit" && strings.HasPrefix(s.State(), "syscall")
+}
+
+func isStdLibStack(s stack.Stack) bool {
+	// Importing os/signal starts a background goroutine.
+	// The name of the function at the top has changed between versions.
+	if f := s.FirstFunction(); f == "os/signal.signal_recv" || f == "os/signal.loop" {
+		return true
+	}
+
+	// Using signal.Notify will start a runtime goroutine.
+	return strings.Contains(s.Full(), "runtime.ensureSigM")
+}
+
+func isTraceStack(s stack.Stack) bool {
+	if f := s.FirstFunction(); f != "runtime.goparkunlock" {
+		return false
+	}
+
+	return strings.Contains(s.Full(), "runtime.ReadTrace")
+}

vendor/go.uber.org/goleak/testmain.go

@@ -0,0 +1,63 @@
+// Copyright (c) 2017 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package goleak
+
+import (
+	"fmt"
+	"io"
+	"os"
+)
+
+// Variables for stubbing in unit tests.
+var (
+	_osExit             = os.Exit
+	_osStderr io.Writer = os.Stderr
+)
+
+// TestingM is the minimal subset of testing.M that we use.
+type TestingM interface {
+	Run() int
+}
+
+// VerifyTestMain can be used in a TestMain function for package tests to
+// verify that there were no goroutine leaks.
+// To use it, your TestMain function should look like:
+//
+//  func TestMain(m *testing.M) {
+//    goleak.VerifyTestMain(m)
+//  }
+//
+// See https://golang.org/pkg/testing/#hdr-Main for more details.
+//
+// This will run all tests as per normal, and if they were successful, look
+// for any goroutine leaks and fail the tests if any leaks were found.
+func VerifyTestMain(m TestingM, options ...Option) {
+	exitCode := m.Run()
+
+	if exitCode == 0 {
+		if err := Find(options...); err != nil {
+			fmt.Fprintf(_osStderr, "goleak: Errors on successful test run: %v\n", err)
+			exitCode = 1
+		}
+	}
+
+	_osExit(exitCode)
+}

vendor/go.uber.org/goleak/tools.go

@@ -0,0 +1,28 @@
+// Copyright (c) 2019 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+// +build tools
+
+package goleak
+
+import (
+	// Tools we use during development.
+	_ "golang.org/x/lint/golint"
+)

vendor/golang.org/x/lint/.travis.yml

@@ -0,0 +1,19 @@
+sudo: false
+language: go
+go:
+  - 1.10.x
+  - 1.11.x
+  - master
+
+go_import_path: golang.org/x/lint
+
+install:
+  - go get -t -v ./...
+
+script:
+  - go test -v -race ./...
+
+matrix:
+  allow_failures:
+    - go: master
+  fast_finish: true

vendor/golang.org/x/lint/CONTRIBUTING.md

@@ -0,0 +1,15 @@
+# Contributing to Golint
+
+## Before filing an issue:
+
+### Are you having trouble building golint?
+
+Check you have the latest version of its dependencies. Run
+```
+go get -u golang.org/x/lint/golint
+```
+If you still have problems, consider searching for existing issues before filing a new issue.
+
+## Before sending a pull request:
+
+Have you understood the purpose of golint? Make sure to carefully read `README`.

vendor/golang.org/x/lint/LICENSE

@@ -0,0 +1,27 @@
+Copyright (c) 2013 The Go Authors. All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+   * Redistributions of source code must retain the above copyright
+notice, this list of conditions and the following disclaimer.
+   * Redistributions in binary form must reproduce the above
+copyright notice, this list of conditions and the following disclaimer
+in the documentation and/or other materials provided with the
+distribution.
+   * Neither the name of Google Inc. nor the names of its
+contributors may be used to endorse or promote products derived from
+this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

vendor/golang.org/x/lint/README.md

@@ -0,0 +1,88 @@
+Golint is a linter for Go source code.
+
+[![Build Status](https://travis-ci.org/golang/lint.svg?branch=master)](https://travis-ci.org/golang/lint)
+
+## Installation
+
+Golint requires a
+[supported release of Go](https://golang.org/doc/devel/release.html#policy).
+
+    go get -u golang.org/x/lint/golint
+
+To find out where `golint` was installed you can run `go list -f {{.Target}} golang.org/x/lint/golint`. For `golint` to be used globally add that directory to the `$PATH` environment setting.
+
+## Usage
+
+Invoke `golint` with one or more filenames, directories, or packages named
+by its import path. Golint uses the same
+[import path syntax](https://golang.org/cmd/go/#hdr-Import_path_syntax) as
+the `go` command and therefore
+also supports relative import paths like `./...`. Additionally the `...`
+wildcard can be used as suffix on relative and absolute file paths to recurse
+into them.
+
+The output of this tool is a list of suggestions in Vim quickfix format,
+which is accepted by lots of different editors.
+
+## Purpose
+
+Golint differs from gofmt. Gofmt reformats Go source code, whereas
+golint prints out style mistakes.
+
+Golint differs from govet. Govet is concerned with correctness, whereas
+golint is concerned with coding style. Golint is in use at Google, and it
+seeks to match the accepted style of the open source Go project.
+
+The suggestions made by golint are exactly that: suggestions.
+Golint is not perfect, and has both false positives and false negatives.
+Do not treat its output as a gold standard. We will not be adding pragmas
+or other knobs to suppress specific warnings, so do not expect or require
+code to be completely "lint-free".
+In short, this tool is not, and will never be, trustworthy enough for its
+suggestions to be enforced automatically, for example as part of a build process.
+Golint makes suggestions for many of the mechanically checkable items listed in
+[Effective Go](https://golang.org/doc/effective_go.html) and the
+[CodeReviewComments wiki page](https://golang.org/wiki/CodeReviewComments).
+
+## Scope
+
+Golint is meant to carry out the stylistic conventions put forth in
+[Effective Go](https://golang.org/doc/effective_go.html) and
+[CodeReviewComments](https://golang.org/wiki/CodeReviewComments).
+Changes that are not aligned with those documents will not be considered.
+
+## Contributions
+
+Contributions to this project are welcome provided they are [in scope](#scope),
+though please send mail before starting work on anything major.
+Contributors retain their copyright, so we need you to fill out
+[a short form](https://developers.google.com/open-source/cla/individual)
+before we can accept your contribution.
+
+## Vim
+
+Add this to your ~/.vimrc:
+
+    set rtp+=$GOPATH/src/golang.org/x/lint/misc/vim
+
+If you have multiple entries in your GOPATH, replace `$GOPATH` with the right value.
+
+Running `:Lint` will run golint on the current file and populate the quickfix list.
+
+Optionally, add this to your `~/.vimrc` to automatically run `golint` on `:w`
+
+    autocmd BufWritePost,FileWritePost *.go execute 'Lint' | cwindow
+
+
+## Emacs
+
+Add this to your `.emacs` file:
+
+    (add-to-list 'load-path (concat (getenv "GOPATH")  "/src/golang.org/x/lint/misc/emacs/"))
+    (require 'golint)
+
+If you have multiple entries in your GOPATH, replace `$GOPATH` with the right value.
+
+Running M-x golint will run golint on the current file.
+
+For more usage, see [Compilation-Mode](http://www.gnu.org/software/emacs/manual/html_node/emacs/Compilation-Mode.html).

vendor/golang.org/x/lint/go.mod

@@ -0,0 +1,5 @@
+module golang.org/x/lint
+
+go 1.11
+
+require golang.org/x/tools v0.0.0-20200130002326-2f3ba24bd6e7

vendor/golang.org/x/lint/go.sum

@@ -0,0 +1,12 @@
+golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
+golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
+golang.org/x/mod v0.1.1-0.20191105210325-c90efee705ee/go.mod h1:QqPTAvyqsEbceGzBzNggFXnrqF1CaUcvgkdR5Ot7KZg=
+golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
+golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
+golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
+golang.org/x/tools v0.0.0-20200130002326-2f3ba24bd6e7 h1:EBZoQjiKKPaLbPrbpssUfuHtwM6KV/vb4U85g/cigFY=
+golang.org/x/tools v0.0.0-20200130002326-2f3ba24bd6e7/go.mod h1:TB2adYChydJhpapKDTa4BR/hXlZSLoq2Wpct/0txZ28=
+golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=

vendor/golang.org/x/lint/golint/golint.go

@@ -0,0 +1,159 @@
+// Copyright (c) 2013 The Go Authors. All rights reserved.
+//
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file or at
+// https://developers.google.com/open-source/licenses/bsd.
+
+// golint lints the Go source files named on its command line.
+package main
+
+import (
+	"flag"
+	"fmt"
+	"go/build"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"golang.org/x/lint"
+)
+
+var (
+	minConfidence = flag.Float64("min_confidence", 0.8, "minimum confidence of a problem to print it")
+	setExitStatus = flag.Bool("set_exit_status", false, "set exit status to 1 if any issues are found")
+	suggestions   int
+)
+
+func usage() {
+	fmt.Fprintf(os.Stderr, "Usage of %s:\n", os.Args[0])
+	fmt.Fprintf(os.Stderr, "\tgolint [flags] # runs on package in current directory\n")
+	fmt.Fprintf(os.Stderr, "\tgolint [flags] [packages]\n")
+	fmt.Fprintf(os.Stderr, "\tgolint [flags] [directories] # where a '/...' suffix includes all sub-directories\n")
+	fmt.Fprintf(os.Stderr, "\tgolint [flags] [files] # all must belong to a single package\n")
+	fmt.Fprintf(os.Stderr, "Flags:\n")
+	flag.PrintDefaults()
+}
+
+func main() {
+	flag.Usage = usage
+	flag.Parse()
+
+	if flag.NArg() == 0 {
+		lintDir(".")
+	} else {
+		// dirsRun, filesRun, and pkgsRun indicate whether golint is applied to
+		// directory, file or package targets. The distinction affects which
+		// checks are run. It is no valid to mix target types.
+		var dirsRun, filesRun, pkgsRun int
+		var args []string
+		for _, arg := range flag.Args() {
+			if strings.HasSuffix(arg, "/...") && isDir(arg[:len(arg)-len("/...")]) {
+				dirsRun = 1
+				for _, dirname := range allPackagesInFS(arg) {
+					args = append(args, dirname)
+				}
+			} else if isDir(arg) {
+				dirsRun = 1
+				args = append(args, arg)
+			} else if exists(arg) {
+				filesRun = 1
+				args = append(args, arg)
+			} else {
+				pkgsRun = 1
+				args = append(args, arg)
+			}
+		}
+
+		if dirsRun+filesRun+pkgsRun != 1 {
+			usage()
+			os.Exit(2)
+		}
+		switch {
+		case dirsRun == 1:
+			for _, dir := range args {
+				lintDir(dir)
+			}
+		case filesRun == 1:
+			lintFiles(args...)
+		case pkgsRun == 1:
+			for _, pkg := range importPaths(args) {
+				lintPackage(pkg)
+			}
+		}
+	}
+
+	if *setExitStatus && suggestions > 0 {
+		fmt.Fprintf(os.Stderr, "Found %d lint suggestions; failing.\n", suggestions)
+		os.Exit(1)
+	}
+}
+
+func isDir(filename string) bool {
+	fi, err := os.Stat(filename)
+	return err == nil && fi.IsDir()
+}
+
+func exists(filename string) bool {
+	_, err := os.Stat(filename)
+	return err == nil
+}
+
+func lintFiles(filenames ...string) {
+	files := make(map[string][]byte)
+	for _, filename := range filenames {
+		src, err := ioutil.ReadFile(filename)
+		if err != nil {
+			fmt.Fprintln(os.Stderr, err)
+			continue
+		}
+		files[filename] = src
+	}
+
+	l := new(lint.Linter)
+	ps, err := l.LintFiles(files)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "%v\n", err)
+		return
+	}
+	for _, p := range ps {
+		if p.Confidence >= *minConfidence {
+			fmt.Printf("%v: %s\n", p.Position, p.Text)
+			suggestions++
+		}
+	}
+}
+
+func lintDir(dirname string) {
+	pkg, err := build.ImportDir(dirname, 0)
+	lintImportedPackage(pkg, err)
+}
+
+func lintPackage(pkgname string) {
+	pkg, err := build.Import(pkgname, ".", 0)
+	lintImportedPackage(pkg, err)
+}
+
+func lintImportedPackage(pkg *build.Package, err error) {
+	if err != nil {
+		if _, nogo := err.(*build.NoGoError); nogo {
+			// Don't complain if the failure is due to no Go source files.
+			return
+		}
+		fmt.Fprintln(os.Stderr, err)
+		return
+	}
+
+	var files []string
+	files = append(files, pkg.GoFiles...)
+	files = append(files, pkg.CgoFiles...)
+	files = append(files, pkg.TestGoFiles...)
+	if pkg.Dir != "." {
+		for i, f := range files {
+			files[i] = filepath.Join(pkg.Dir, f)
+		}
+	}
+	// TODO(dsymonds): Do foo_test too (pkg.XTestGoFiles)
+
+	lintFiles(files...)
+}

vendor/golang.org/x/lint/golint/import.go

@@ -0,0 +1,309 @@
+package main
+
+/*
+
+This file holds a direct copy of the import path matching code of
+https://github.com/golang/go/blob/master/src/cmd/go/main.go. It can be
+replaced when https://golang.org/issue/8768 is resolved.
+
+It has been updated to follow upstream changes in a few ways.
+
+*/
+
+import (
+	"fmt"
+	"go/build"
+	"log"
+	"os"
+	"path"
+	"path/filepath"
+	"regexp"
+	"runtime"
+	"strings"
+)
+
+var (
+	buildContext = build.Default
+	goroot       = filepath.Clean(runtime.GOROOT())
+	gorootSrc    = filepath.Join(goroot, "src")
+)
+
+// importPathsNoDotExpansion returns the import paths to use for the given
+// command line, but it does no ... expansion.
+func importPathsNoDotExpansion(args []string) []string {
+	if len(args) == 0 {
+		return []string{"."}
+	}
+	var out []string
+	for _, a := range args {
+		// Arguments are supposed to be import paths, but
+		// as a courtesy to Windows developers, rewrite \ to /
+		// in command-line arguments.  Handles .\... and so on.
+		if filepath.Separator == '\\' {
+			a = strings.Replace(a, `\`, `/`, -1)
+		}
+
+		// Put argument in canonical form, but preserve leading ./.
+		if strings.HasPrefix(a, "./") {
+			a = "./" + path.Clean(a)
+			if a == "./." {
+				a = "."
+			}
+		} else {
+			a = path.Clean(a)
+		}
+		if a == "all" || a == "std" {
+			out = append(out, allPackages(a)...)
+			continue
+		}
+		out = append(out, a)
+	}
+	return out
+}
+
+// importPaths returns the import paths to use for the given command line.
+func importPaths(args []string) []string {
+	args = importPathsNoDotExpansion(args)
+	var out []string
+	for _, a := range args {
+		if strings.Contains(a, "...") {
+			if build.IsLocalImport(a) {
+				out = append(out, allPackagesInFS(a)...)
+			} else {
+				out = append(out, allPackages(a)...)
+			}
+			continue
+		}
+		out = append(out, a)
+	}
+	return out
+}
+
+// matchPattern(pattern)(name) reports whether
+// name matches pattern.  Pattern is a limited glob
+// pattern in which '...' means 'any string' and there
+// is no other special syntax.
+func matchPattern(pattern string) func(name string) bool {
+	re := regexp.QuoteMeta(pattern)
+	re = strings.Replace(re, `\.\.\.`, `.*`, -1)
+	// Special case: foo/... matches foo too.
+	if strings.HasSuffix(re, `/.*`) {
+		re = re[:len(re)-len(`/.*`)] + `(/.*)?`
+	}
+	reg := regexp.MustCompile(`^` + re + `$`)
+	return func(name string) bool {
+		return reg.MatchString(name)
+	}
+}
+
+// hasPathPrefix reports whether the path s begins with the
+// elements in prefix.
+func hasPathPrefix(s, prefix string) bool {
+	switch {
+	default:
+		return false
+	case len(s) == len(prefix):
+		return s == prefix
+	case len(s) > len(prefix):
+		if prefix != "" && prefix[len(prefix)-1] == '/' {
+			return strings.HasPrefix(s, prefix)
+		}
+		return s[len(prefix)] == '/' && s[:len(prefix)] == prefix
+	}
+}
+
+// treeCanMatchPattern(pattern)(name) reports whether
+// name or children of name can possibly match pattern.
+// Pattern is the same limited glob accepted by matchPattern.
+func treeCanMatchPattern(pattern string) func(name string) bool {
+	wildCard := false
+	if i := strings.Index(pattern, "..."); i >= 0 {
+		wildCard = true
+		pattern = pattern[:i]
+	}
+	return func(name string) bool {
+		return len(name) <= len(pattern) && hasPathPrefix(pattern, name) ||
+			wildCard && strings.HasPrefix(name, pattern)
+	}
+}
+
+// allPackages returns all the packages that can be found
+// under the $GOPATH directories and $GOROOT matching pattern.
+// The pattern is either "all" (all packages), "std" (standard packages)
+// or a path including "...".
+func allPackages(pattern string) []string {
+	pkgs := matchPackages(pattern)
+	if len(pkgs) == 0 {
+		fmt.Fprintf(os.Stderr, "warning: %q matched no packages\n", pattern)
+	}
+	return pkgs
+}
+
+func matchPackages(pattern string) []string {
+	match := func(string) bool { return true }
+	treeCanMatch := func(string) bool { return true }
+	if pattern != "all" && pattern != "std" {
+		match = matchPattern(pattern)
+		treeCanMatch = treeCanMatchPattern(pattern)
+	}
+
+	have := map[string]bool{
+		"builtin": true, // ignore pseudo-package that exists only for documentation
+	}
+	if !buildContext.CgoEnabled {
+		have["runtime/cgo"] = true // ignore during walk
+	}
+	var pkgs []string
+
+	// Commands
+	cmd := filepath.Join(goroot, "src/cmd") + string(filepath.Separator)
+	filepath.Walk(cmd, func(path string, fi os.FileInfo, err error) error {
+		if err != nil || !fi.IsDir() || path == cmd {
+			return nil
+		}
+		name := path[len(cmd):]
+		if !treeCanMatch(name) {
+			return filepath.SkipDir
+		}
+		// Commands are all in cmd/, not in subdirectories.
+		if strings.Contains(name, string(filepath.Separator)) {
+			return filepath.SkipDir
+		}
+
+		// We use, e.g., cmd/gofmt as the pseudo import path for gofmt.
+		name = "cmd/" + name
+		if have[name] {
+			return nil
+		}
+		have[name] = true
+		if !match(name) {
+			return nil
+		}
+		_, err = buildContext.ImportDir(path, 0)
+		if err != nil {
+			if _, noGo := err.(*build.NoGoError); !noGo {
+				log.Print(err)
+			}
+			return nil
+		}
+		pkgs = append(pkgs, name)
+		return nil
+	})
+
+	for _, src := range buildContext.SrcDirs() {
+		if (pattern == "std" || pattern == "cmd") && src != gorootSrc {
+			continue
+		}
+		src = filepath.Clean(src) + string(filepath.Separator)
+		root := src
+		if pattern == "cmd" {
+			root += "cmd" + string(filepath.Separator)
+		}
+		filepath.Walk(root, func(path string, fi os.FileInfo, err error) error {
+			if err != nil || !fi.IsDir() || path == src {
+				return nil
+			}
+
+			// Avoid .foo, _foo, and testdata directory trees.
+			_, elem := filepath.Split(path)
+			if strings.HasPrefix(elem, ".") || strings.HasPrefix(elem, "_") || elem == "testdata" {
+				return filepath.SkipDir
+			}
+
+			name := filepath.ToSlash(path[len(src):])
+			if pattern == "std" && (strings.Contains(name, ".") || name == "cmd") {
+				// The name "std" is only the standard library.
+				// If the name is cmd, it's the root of the command tree.
+				return filepath.SkipDir
+			}
+			if !treeCanMatch(name) {
+				return filepath.SkipDir
+			}
+			if have[name] {
+				return nil
+			}
+			have[name] = true
+			if !match(name) {
+				return nil
+			}
+			_, err = buildContext.ImportDir(path, 0)
+			if err != nil {
+				if _, noGo := err.(*build.NoGoError); noGo {
+					return nil
+				}
+			}
+			pkgs = append(pkgs, name)
+			return nil
+		})
+	}
+	return pkgs
+}
+
+// allPackagesInFS is like allPackages but is passed a pattern
+// beginning ./ or ../, meaning it should scan the tree rooted
+// at the given directory.  There are ... in the pattern too.
+func allPackagesInFS(pattern string) []string {
+	pkgs := matchPackagesInFS(pattern)
+	if len(pkgs) == 0 {
+		fmt.Fprintf(os.Stderr, "warning: %q matched no packages\n", pattern)
+	}
+	return pkgs
+}
+
+func matchPackagesInFS(pattern string) []string {
+	// Find directory to begin the scan.
+	// Could be smarter but this one optimization
+	// is enough for now, since ... is usually at the
+	// end of a path.
+	i := strings.Index(pattern, "...")
+	dir, _ := path.Split(pattern[:i])
+
+	// pattern begins with ./ or ../.
+	// path.Clean will discard the ./ but not the ../.
+	// We need to preserve the ./ for pattern matching
+	// and in the returned import paths.
+	prefix := ""
+	if strings.HasPrefix(pattern, "./") {
+		prefix = "./"
+	}
+	match := matchPattern(pattern)
+
+	var pkgs []string
+	filepath.Walk(dir, func(path string, fi os.FileInfo, err error) error {
+		if err != nil || !fi.IsDir() {
+			return nil
+		}
+		if path == dir {
+			// filepath.Walk starts at dir and recurses. For the recursive case,
+			// the path is the result of filepath.Join, which calls filepath.Clean.
+			// The initial case is not Cleaned, though, so we do this explicitly.
+			//
+			// This converts a path like "./io/" to "io". Without this step, running
+			// "cd $GOROOT/src/pkg; go list ./io/..." would incorrectly skip the io
+			// package, because prepending the prefix "./" to the unclean path would
+			// result in "././io", and match("././io") returns false.
+			path = filepath.Clean(path)
+		}
+
+		// Avoid .foo, _foo, and testdata directory trees, but do not avoid "." or "..".
+		_, elem := filepath.Split(path)
+		dot := strings.HasPrefix(elem, ".") && elem != "." && elem != ".."
+		if dot || strings.HasPrefix(elem, "_") || elem == "testdata" {
+			return filepath.SkipDir
+		}
+
+		name := prefix + filepath.ToSlash(path)
+		if !match(name) {
+			return nil
+		}
+		if _, err = build.ImportDir(path, 0); err != nil {
+			if _, noGo := err.(*build.NoGoError); !noGo {
+				log.Print(err)
+			}
+			return nil
+		}
+		pkgs = append(pkgs, name)
+		return nil
+	})
+	return pkgs
+}

vendor/golang.org/x/lint/golint/importcomment.go

@@ -0,0 +1,13 @@
+// Copyright (c) 2018 The Go Authors. All rights reserved.
+//
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file or at
+// https://developers.google.com/open-source/licenses/bsd.
+
+// +build go1.12
+
+// Require use of the correct import path only for Go 1.12+ users, so
+// any breakages coincide with people updating their CI configs or
+// whatnot.
+
+package main // import "golang.org/x/lint/golint"

vendor/golang.org/x/tools/go/gcexportdata/gcexportdata.go

@@ -0,0 +1,109 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package gcexportdata provides functions for locating, reading, and
+// writing export data files containing type information produced by the
+// gc compiler.  This package supports go1.7 export data format and all
+// later versions.
+//
+// Although it might seem convenient for this package to live alongside
+// go/types in the standard library, this would cause version skew
+// problems for developer tools that use it, since they must be able to
+// consume the outputs of the gc compiler both before and after a Go
+// update such as from Go 1.7 to Go 1.8.  Because this package lives in
+// golang.org/x/tools, sites can update their version of this repo some
+// time before the Go 1.8 release and rebuild and redeploy their
+// developer tools, which will then be able to consume both Go 1.7 and
+// Go 1.8 export data files, so they will work before and after the
+// Go update. (See discussion at https://golang.org/issue/15651.)
+//
+package gcexportdata // import "golang.org/x/tools/go/gcexportdata"
+
+import (
+	"bufio"
+	"bytes"
+	"fmt"
+	"go/token"
+	"go/types"
+	"io"
+	"io/ioutil"
+
+	"golang.org/x/tools/go/internal/gcimporter"
+)
+
+// Find returns the name of an object (.o) or archive (.a) file
+// containing type information for the specified import path,
+// using the workspace layout conventions of go/build.
+// If no file was found, an empty filename is returned.
+//
+// A relative srcDir is interpreted relative to the current working directory.
+//
+// Find also returns the package's resolved (canonical) import path,
+// reflecting the effects of srcDir and vendoring on importPath.
+func Find(importPath, srcDir string) (filename, path string) {
+	return gcimporter.FindPkg(importPath, srcDir)
+}
+
+// NewReader returns a reader for the export data section of an object
+// (.o) or archive (.a) file read from r.  The new reader may provide
+// additional trailing data beyond the end of the export data.
+func NewReader(r io.Reader) (io.Reader, error) {
+	buf := bufio.NewReader(r)
+	_, err := gcimporter.FindExportData(buf)
+	// If we ever switch to a zip-like archive format with the ToC
+	// at the end, we can return the correct portion of export data,
+	// but for now we must return the entire rest of the file.
+	return buf, err
+}
+
+// Read reads export data from in, decodes it, and returns type
+// information for the package.
+// The package name is specified by path.
+// File position information is added to fset.
+//
+// Read may inspect and add to the imports map to ensure that references
+// within the export data to other packages are consistent.  The caller
+// must ensure that imports[path] does not exist, or exists but is
+// incomplete (see types.Package.Complete), and Read inserts the
+// resulting package into this map entry.
+//
+// On return, the state of the reader is undefined.
+func Read(in io.Reader, fset *token.FileSet, imports map[string]*types.Package, path string) (*types.Package, error) {
+	data, err := ioutil.ReadAll(in)
+	if err != nil {
+		return nil, fmt.Errorf("reading export data for %q: %v", path, err)
+	}
+
+	if bytes.HasPrefix(data, []byte("!<arch>")) {
+		return nil, fmt.Errorf("can't read export data for %q directly from an archive file (call gcexportdata.NewReader first to extract export data)", path)
+	}
+
+	// The App Engine Go runtime v1.6 uses the old export data format.
+	// TODO(adonovan): delete once v1.7 has been around for a while.
+	if bytes.HasPrefix(data, []byte("package ")) {
+		return gcimporter.ImportData(imports, path, path, bytes.NewReader(data))
+	}
+
+	// The indexed export format starts with an 'i'; the older
+	// binary export format starts with a 'c', 'd', or 'v'
+	// (from "version"). Select appropriate importer.
+	if len(data) > 0 && data[0] == 'i' {
+		_, pkg, err := gcimporter.IImportData(fset, imports, data[1:], path)
+		return pkg, err
+	}
+
+	_, pkg, err := gcimporter.BImportData(fset, imports, data, path)
+	return pkg, err
+}
+
+// Write writes encoded type information for the specified package to out.
+// The FileSet provides file position information for named objects.
+func Write(out io.Writer, fset *token.FileSet, pkg *types.Package) error {
+	b, err := gcimporter.IExportData(fset, pkg)
+	if err != nil {
+		return err
+	}
+	_, err = out.Write(b)
+	return err
+}

vendor/golang.org/x/tools/go/gcexportdata/importer.go

@@ -0,0 +1,73 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package gcexportdata
+
+import (
+	"fmt"
+	"go/token"
+	"go/types"
+	"os"
+)
+
+// NewImporter returns a new instance of the types.Importer interface
+// that reads type information from export data files written by gc.
+// The Importer also satisfies types.ImporterFrom.
+//
+// Export data files are located using "go build" workspace conventions
+// and the build.Default context.
+//
+// Use this importer instead of go/importer.For("gc", ...) to avoid the
+// version-skew problems described in the documentation of this package,
+// or to control the FileSet or access the imports map populated during
+// package loading.
+//
+func NewImporter(fset *token.FileSet, imports map[string]*types.Package) types.ImporterFrom {
+	return importer{fset, imports}
+}
+
+type importer struct {
+	fset    *token.FileSet
+	imports map[string]*types.Package
+}
+
+func (imp importer) Import(importPath string) (*types.Package, error) {
+	return imp.ImportFrom(importPath, "", 0)
+}
+
+func (imp importer) ImportFrom(importPath, srcDir string, mode types.ImportMode) (_ *types.Package, err error) {
+	filename, path := Find(importPath, srcDir)
+	if filename == "" {
+		if importPath == "unsafe" {
+			// Even for unsafe, call Find first in case
+			// the package was vendored.
+			return types.Unsafe, nil
+		}
+		return nil, fmt.Errorf("can't find import: %s", importPath)
+	}
+
+	if pkg, ok := imp.imports[path]; ok && pkg.Complete() {
+		return pkg, nil // cache hit
+	}
+
+	// open file
+	f, err := os.Open(filename)
+	if err != nil {
+		return nil, err
+	}
+	defer func() {
+		f.Close()
+		if err != nil {
+			// add file name to error
+			err = fmt.Errorf("reading export data: %s: %v", filename, err)
+		}
+	}()
+
+	r, err := NewReader(f)
+	if err != nil {
+		return nil, err
+	}
+
+	return Read(r, imp.fset, imp.imports, path)
+}

vendor/golang.org/x/tools/go/internal/gcimporter/bexport.go

@@ -0,0 +1,852 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Binary package export.
+// This file was derived from $GOROOT/src/cmd/compile/internal/gc/bexport.go;
+// see that file for specification of the format.
+
+package gcimporter
+
+import (
+	"bytes"
+	"encoding/binary"
+	"fmt"
+	"go/ast"
+	"go/constant"
+	"go/token"
+	"go/types"
+	"math"
+	"math/big"
+	"sort"
+	"strings"
+)
+
+// If debugFormat is set, each integer and string value is preceded by a marker
+// and position information in the encoding. This mechanism permits an importer
+// to recognize immediately when it is out of sync. The importer recognizes this
+// mode automatically (i.e., it can import export data produced with debugging
+// support even if debugFormat is not set at the time of import). This mode will
+// lead to massively larger export data (by a factor of 2 to 3) and should only
+// be enabled during development and debugging.
+//
+// NOTE: This flag is the first flag to enable if importing dies because of
+// (suspected) format errors, and whenever a change is made to the format.
+const debugFormat = false // default: false
+
+// If trace is set, debugging output is printed to std out.
+const trace = false // default: false
+
+// Current export format version. Increase with each format change.
+// Note: The latest binary (non-indexed) export format is at version 6.
+//       This exporter is still at level 4, but it doesn't matter since
+//       the binary importer can handle older versions just fine.
+// 6: package height (CL 105038) -- NOT IMPLEMENTED HERE
+// 5: improved position encoding efficiency (issue 20080, CL 41619) -- NOT IMPLEMEMTED HERE
+// 4: type name objects support type aliases, uses aliasTag
+// 3: Go1.8 encoding (same as version 2, aliasTag defined but never used)
+// 2: removed unused bool in ODCL export (compiler only)
+// 1: header format change (more regular), export package for _ struct fields
+// 0: Go1.7 encoding
+const exportVersion = 4
+
+// trackAllTypes enables cycle tracking for all types, not just named
+// types. The existing compiler invariants assume that unnamed types
+// that are not completely set up are not used, or else there are spurious
+// errors.
+// If disabled, only named types are tracked, possibly leading to slightly
+// less efficient encoding in rare cases. It also prevents the export of
+// some corner-case type declarations (but those are not handled correctly
+// with with the textual export format either).
+// TODO(gri) enable and remove once issues caused by it are fixed
+const trackAllTypes = false
+
+type exporter struct {
+	fset *token.FileSet
+	out  bytes.Buffer
+
+	// object -> index maps, indexed in order of serialization
+	strIndex map[string]int
+	pkgIndex map[*types.Package]int
+	typIndex map[types.Type]int
+
+	// position encoding
+	posInfoFormat bool
+	prevFile      string
+	prevLine      int
+
+	// debugging support
+	written int // bytes written
+	indent  int // for trace
+}
+
+// internalError represents an error generated inside this package.
+type internalError string
+
+func (e internalError) Error() string { return "gcimporter: " + string(e) }
+
+func internalErrorf(format string, args ...interface{}) error {
+	return internalError(fmt.Sprintf(format, args...))
+}
+
+// BExportData returns binary export data for pkg.
+// If no file set is provided, position info will be missing.
+func BExportData(fset *token.FileSet, pkg *types.Package) (b []byte, err error) {
+	defer func() {
+		if e := recover(); e != nil {
+			if ierr, ok := e.(internalError); ok {
+				err = ierr
+				return
+			}
+			// Not an internal error; panic again.
+			panic(e)
+		}
+	}()
+
+	p := exporter{
+		fset:          fset,
+		strIndex:      map[string]int{"": 0}, // empty string is mapped to 0
+		pkgIndex:      make(map[*types.Package]int),
+		typIndex:      make(map[types.Type]int),
+		posInfoFormat: true, // TODO(gri) might become a flag, eventually
+	}
+
+	// write version info
+	// The version string must start with "version %d" where %d is the version
+	// number. Additional debugging information may follow after a blank; that
+	// text is ignored by the importer.
+	p.rawStringln(fmt.Sprintf("version %d", exportVersion))
+	var debug string
+	if debugFormat {
+		debug = "debug"
+	}
+	p.rawStringln(debug) // cannot use p.bool since it's affected by debugFormat; also want to see this clearly
+	p.bool(trackAllTypes)
+	p.bool(p.posInfoFormat)
+
+	// --- generic export data ---
+
+	// populate type map with predeclared "known" types
+	for index, typ := range predeclared() {
+		p.typIndex[typ] = index
+	}
+	if len(p.typIndex) != len(predeclared()) {
+		return nil, internalError("duplicate entries in type map?")
+	}
+
+	// write package data
+	p.pkg(pkg, true)
+	if trace {
+		p.tracef("\n")
+	}
+
+	// write objects
+	objcount := 0
+	scope := pkg.Scope()
+	for _, name := range scope.Names() {
+		if !ast.IsExported(name) {
+			continue
+		}
+		if trace {
+			p.tracef("\n")
+		}
+		p.obj(scope.Lookup(name))
+		objcount++
+	}
+
+	// indicate end of list
+	if trace {
+		p.tracef("\n")
+	}
+	p.tag(endTag)
+
+	// for self-verification only (redundant)
+	p.int(objcount)
+
+	if trace {
+		p.tracef("\n")
+	}
+
+	// --- end of export data ---
+
+	return p.out.Bytes(), nil
+}
+
+func (p *exporter) pkg(pkg *types.Package, emptypath bool) {
+	if pkg == nil {
+		panic(internalError("unexpected nil pkg"))
+	}
+
+	// if we saw the package before, write its index (>= 0)
+	if i, ok := p.pkgIndex[pkg]; ok {
+		p.index('P', i)
+		return
+	}
+
+	// otherwise, remember the package, write the package tag (< 0) and package data
+	if trace {
+		p.tracef("P%d = { ", len(p.pkgIndex))
+		defer p.tracef("} ")
+	}
+	p.pkgIndex[pkg] = len(p.pkgIndex)
+
+	p.tag(packageTag)
+	p.string(pkg.Name())
+	if emptypath {
+		p.string("")
+	} else {
+		p.string(pkg.Path())
+	}
+}
+
+func (p *exporter) obj(obj types.Object) {
+	switch obj := obj.(type) {
+	case *types.Const:
+		p.tag(constTag)
+		p.pos(obj)
+		p.qualifiedName(obj)
+		p.typ(obj.Type())
+		p.value(obj.Val())
+
+	case *types.TypeName:
+		if obj.IsAlias() {
+			p.tag(aliasTag)
+			p.pos(obj)
+			p.qualifiedName(obj)
+		} else {
+			p.tag(typeTag)
+		}
+		p.typ(obj.Type())
+
+	case *types.Var:
+		p.tag(varTag)
+		p.pos(obj)
+		p.qualifiedName(obj)
+		p.typ(obj.Type())
+
+	case *types.Func:
+		p.tag(funcTag)
+		p.pos(obj)
+		p.qualifiedName(obj)
+		sig := obj.Type().(*types.Signature)
+		p.paramList(sig.Params(), sig.Variadic())
+		p.paramList(sig.Results(), false)
+
+	default:
+		panic(internalErrorf("unexpected object %v (%T)", obj, obj))
+	}
+}
+
+func (p *exporter) pos(obj types.Object) {
+	if !p.posInfoFormat {
+		return
+	}
+
+	file, line := p.fileLine(obj)
+	if file == p.prevFile {
+		// common case: write line delta
+		// delta == 0 means different file or no line change
+		delta := line - p.prevLine
+		p.int(delta)
+		if delta == 0 {
+			p.int(-1) // -1 means no file change
+		}
+	} else {
+		// different file
+		p.int(0)
+		// Encode filename as length of common prefix with previous
+		// filename, followed by (possibly empty) suffix. Filenames
+		// frequently share path prefixes, so this can save a lot
+		// of space and make export data size less dependent on file
+		// path length. The suffix is unlikely to be empty because
+		// file names tend to end in ".go".
+		n := commonPrefixLen(p.prevFile, file)
+		p.int(n)           // n >= 0
+		p.string(file[n:]) // write suffix only
+		p.prevFile = file
+		p.int(line)
+	}
+	p.prevLine = line
+}
+
+func (p *exporter) fileLine(obj types.Object) (file string, line int) {
+	if p.fset != nil {
+		pos := p.fset.Position(obj.Pos())
+		file = pos.Filename
+		line = pos.Line
+	}
+	return
+}
+
+func commonPrefixLen(a, b string) int {
+	if len(a) > len(b) {
+		a, b = b, a
+	}
+	// len(a) <= len(b)
+	i := 0
+	for i < len(a) && a[i] == b[i] {
+		i++
+	}
+	return i
+}
+
+func (p *exporter) qualifiedName(obj types.Object) {
+	p.string(obj.Name())
+	p.pkg(obj.Pkg(), false)
+}
+
+func (p *exporter) typ(t types.Type) {
+	if t == nil {
+		panic(internalError("nil type"))
+	}
+
+	// Possible optimization: Anonymous pointer types *T where
+	// T is a named type are common. We could canonicalize all
+	// such types *T to a single type PT = *T. This would lead
+	// to at most one *T entry in typIndex, and all future *T's
+	// would be encoded as the respective index directly. Would
+	// save 1 byte (pointerTag) per *T and reduce the typIndex
+	// size (at the cost of a canonicalization map). We can do
+	// this later, without encoding format change.
+
+	// if we saw the type before, write its index (>= 0)
+	if i, ok := p.typIndex[t]; ok {
+		p.index('T', i)
+		return
+	}
+
+	// otherwise, remember the type, write the type tag (< 0) and type data
+	if trackAllTypes {
+		if trace {
+			p.tracef("T%d = {>\n", len(p.typIndex))
+			defer p.tracef("<\n} ")
+		}
+		p.typIndex[t] = len(p.typIndex)
+	}
+
+	switch t := t.(type) {
+	case *types.Named:
+		if !trackAllTypes {
+			// if we don't track all types, track named types now
+			p.typIndex[t] = len(p.typIndex)
+		}
+
+		p.tag(namedTag)
+		p.pos(t.Obj())
+		p.qualifiedName(t.Obj())
+		p.typ(t.Underlying())
+		if !types.IsInterface(t) {
+			p.assocMethods(t)
+		}
+
+	case *types.Array:
+		p.tag(arrayTag)
+		p.int64(t.Len())
+		p.typ(t.Elem())
+
+	case *types.Slice:
+		p.tag(sliceTag)
+		p.typ(t.Elem())
+
+	case *dddSlice:
+		p.tag(dddTag)
+		p.typ(t.elem)
+
+	case *types.Struct:
+		p.tag(structTag)
+		p.fieldList(t)
+
+	case *types.Pointer:
+		p.tag(pointerTag)
+		p.typ(t.Elem())
+
+	case *types.Signature:
+		p.tag(signatureTag)
+		p.paramList(t.Params(), t.Variadic())
+		p.paramList(t.Results(), false)
+
+	case *types.Interface:
+		p.tag(interfaceTag)
+		p.iface(t)
+
+	case *types.Map:
+		p.tag(mapTag)
+		p.typ(t.Key())
+		p.typ(t.Elem())
+
+	case *types.Chan:
+		p.tag(chanTag)
+		p.int(int(3 - t.Dir())) // hack
+		p.typ(t.Elem())
+
+	default:
+		panic(internalErrorf("unexpected type %T: %s", t, t))
+	}
+}
+
+func (p *exporter) assocMethods(named *types.Named) {
+	// Sort methods (for determinism).
+	var methods []*types.Func
+	for i := 0; i < named.NumMethods(); i++ {
+		methods = append(methods, named.Method(i))
+	}
+	sort.Sort(methodsByName(methods))
+
+	p.int(len(methods))
+
+	if trace && methods != nil {
+		p.tracef("associated methods {>\n")
+	}
+
+	for i, m := range methods {
+		if trace && i > 0 {
+			p.tracef("\n")
+		}
+
+		p.pos(m)
+		name := m.Name()
+		p.string(name)
+		if !exported(name) {
+			p.pkg(m.Pkg(), false)
+		}
+
+		sig := m.Type().(*types.Signature)
+		p.paramList(types.NewTuple(sig.Recv()), false)
+		p.paramList(sig.Params(), sig.Variadic())
+		p.paramList(sig.Results(), false)
+		p.int(0) // dummy value for go:nointerface pragma - ignored by importer
+	}
+
+	if trace && methods != nil {
+		p.tracef("<\n} ")
+	}
+}
+
+type methodsByName []*types.Func
+
+func (x methodsByName) Len() int           { return len(x) }
+func (x methodsByName) Swap(i, j int)      { x[i], x[j] = x[j], x[i] }
+func (x methodsByName) Less(i, j int) bool { return x[i].Name() < x[j].Name() }
+
+func (p *exporter) fieldList(t *types.Struct) {
+	if trace && t.NumFields() > 0 {
+		p.tracef("fields {>\n")
+		defer p.tracef("<\n} ")
+	}
+
+	p.int(t.NumFields())
+	for i := 0; i < t.NumFields(); i++ {
+		if trace && i > 0 {
+			p.tracef("\n")
+		}
+		p.field(t.Field(i))
+		p.string(t.Tag(i))
+	}
+}
+
+func (p *exporter) field(f *types.Var) {
+	if !f.IsField() {
+		panic(internalError("field expected"))
+	}
+
+	p.pos(f)
+	p.fieldName(f)
+	p.typ(f.Type())
+}
+
+func (p *exporter) iface(t *types.Interface) {
+	// TODO(gri): enable importer to load embedded interfaces,
+	// then emit Embeddeds and ExplicitMethods separately here.
+	p.int(0)
+
+	n := t.NumMethods()
+	if trace && n > 0 {
+		p.tracef("methods {>\n")
+		defer p.tracef("<\n} ")
+	}
+	p.int(n)
+	for i := 0; i < n; i++ {
+		if trace && i > 0 {
+			p.tracef("\n")
+		}
+		p.method(t.Method(i))
+	}
+}
+
+func (p *exporter) method(m *types.Func) {
+	sig := m.Type().(*types.Signature)
+	if sig.Recv() == nil {
+		panic(internalError("method expected"))
+	}
+
+	p.pos(m)
+	p.string(m.Name())
+	if m.Name() != "_" && !ast.IsExported(m.Name()) {
+		p.pkg(m.Pkg(), false)
+	}
+
+	// interface method; no need to encode receiver.
+	p.paramList(sig.Params(), sig.Variadic())
+	p.paramList(sig.Results(), false)
+}
+
+func (p *exporter) fieldName(f *types.Var) {
+	name := f.Name()
+
+	if f.Anonymous() {
+		// anonymous field - we distinguish between 3 cases:
+		// 1) field name matches base type name and is exported
+		// 2) field name matches base type name and is not exported
+		// 3) field name doesn't match base type name (alias name)
+		bname := basetypeName(f.Type())
+		if name == bname {
+			if ast.IsExported(name) {
+				name = "" // 1) we don't need to know the field name or package
+			} else {
+				name = "?" // 2) use unexported name "?" to force package export
+			}
+		} else {
+			// 3) indicate alias and export name as is
+			// (this requires an extra "@" but this is a rare case)
+			p.string("@")
+		}
+	}
+
+	p.string(name)
+	if name != "" && !ast.IsExported(name) {
+		p.pkg(f.Pkg(), false)
+	}
+}
+
+func basetypeName(typ types.Type) string {
+	switch typ := deref(typ).(type) {
+	case *types.Basic:
+		return typ.Name()
+	case *types.Named:
+		return typ.Obj().Name()
+	default:
+		return "" // unnamed type
+	}
+}
+
+func (p *exporter) paramList(params *types.Tuple, variadic bool) {
+	// use negative length to indicate unnamed parameters
+	// (look at the first parameter only since either all
+	// names are present or all are absent)
+	n := params.Len()
+	if n > 0 && params.At(0).Name() == "" {
+		n = -n
+	}
+	p.int(n)
+	for i := 0; i < params.Len(); i++ {
+		q := params.At(i)
+		t := q.Type()
+		if variadic && i == params.Len()-1 {
+			t = &dddSlice{t.(*types.Slice).Elem()}
+		}
+		p.typ(t)
+		if n > 0 {
+			name := q.Name()
+			p.string(name)
+			if name != "_" {
+				p.pkg(q.Pkg(), false)
+			}
+		}
+		p.string("") // no compiler-specific info
+	}
+}
+
+func (p *exporter) value(x constant.Value) {
+	if trace {
+		p.tracef("= ")
+	}
+
+	switch x.Kind() {
+	case constant.Bool:
+		tag := falseTag
+		if constant.BoolVal(x) {
+			tag = trueTag
+		}
+		p.tag(tag)
+
+	case constant.Int:
+		if v, exact := constant.Int64Val(x); exact {
+			// common case: x fits into an int64 - use compact encoding
+			p.tag(int64Tag)
+			p.int64(v)
+			return
+		}
+		// uncommon case: large x - use float encoding
+		// (powers of 2 will be encoded efficiently with exponent)
+		p.tag(floatTag)
+		p.float(constant.ToFloat(x))
+
+	case constant.Float:
+		p.tag(floatTag)
+		p.float(x)
+
+	case constant.Complex:
+		p.tag(complexTag)
+		p.float(constant.Real(x))
+		p.float(constant.Imag(x))
+
+	case constant.String:
+		p.tag(stringTag)
+		p.string(constant.StringVal(x))
+
+	case constant.Unknown:
+		// package contains type errors
+		p.tag(unknownTag)
+
+	default:
+		panic(internalErrorf("unexpected value %v (%T)", x, x))
+	}
+}
+
+func (p *exporter) float(x constant.Value) {
+	if x.Kind() != constant.Float {
+		panic(internalErrorf("unexpected constant %v, want float", x))
+	}
+	// extract sign (there is no -0)
+	sign := constant.Sign(x)
+	if sign == 0 {
+		// x == 0
+		p.int(0)
+		return
+	}
+	// x != 0
+
+	var f big.Float
+	if v, exact := constant.Float64Val(x); exact {
+		// float64
+		f.SetFloat64(v)
+	} else if num, denom := constant.Num(x), constant.Denom(x); num.Kind() == constant.Int {
+		// TODO(gri): add big.Rat accessor to constant.Value.
+		r := valueToRat(num)
+		f.SetRat(r.Quo(r, valueToRat(denom)))
+	} else {
+		// Value too large to represent as a fraction => inaccessible.
+		// TODO(gri): add big.Float accessor to constant.Value.
+		f.SetFloat64(math.MaxFloat64) // FIXME
+	}
+
+	// extract exponent such that 0.5 <= m < 1.0
+	var m big.Float
+	exp := f.MantExp(&m)
+
+	// extract mantissa as *big.Int
+	// - set exponent large enough so mant satisfies mant.IsInt()
+	// - get *big.Int from mant
+	m.SetMantExp(&m, int(m.MinPrec()))
+	mant, acc := m.Int(nil)
+	if acc != big.Exact {
+		panic(internalError("internal error"))
+	}
+
+	p.int(sign)
+	p.int(exp)
+	p.string(string(mant.Bytes()))
+}
+
+func valueToRat(x constant.Value) *big.Rat {
+	// Convert little-endian to big-endian.
+	// I can't believe this is necessary.
+	bytes := constant.Bytes(x)
+	for i := 0; i < len(bytes)/2; i++ {
+		bytes[i], bytes[len(bytes)-1-i] = bytes[len(bytes)-1-i], bytes[i]
+	}
+	return new(big.Rat).SetInt(new(big.Int).SetBytes(bytes))
+}
+
+func (p *exporter) bool(b bool) bool {
+	if trace {
+		p.tracef("[")
+		defer p.tracef("= %v] ", b)
+	}
+
+	x := 0
+	if b {
+		x = 1
+	}
+	p.int(x)
+	return b
+}
+
+// ----------------------------------------------------------------------------
+// Low-level encoders
+
+func (p *exporter) index(marker byte, index int) {
+	if index < 0 {
+		panic(internalError("invalid index < 0"))
+	}
+	if debugFormat {
+		p.marker('t')
+	}
+	if trace {
+		p.tracef("%c%d ", marker, index)
+	}
+	p.rawInt64(int64(index))
+}
+
+func (p *exporter) tag(tag int) {
+	if tag >= 0 {
+		panic(internalError("invalid tag >= 0"))
+	}
+	if debugFormat {
+		p.marker('t')
+	}
+	if trace {
+		p.tracef("%s ", tagString[-tag])
+	}
+	p.rawInt64(int64(tag))
+}
+
+func (p *exporter) int(x int) {
+	p.int64(int64(x))
+}
+
+func (p *exporter) int64(x int64) {
+	if debugFormat {
+		p.marker('i')
+	}
+	if trace {
+		p.tracef("%d ", x)
+	}
+	p.rawInt64(x)
+}
+
+func (p *exporter) string(s string) {
+	if debugFormat {
+		p.marker('s')
+	}
+	if trace {
+		p.tracef("%q ", s)
+	}
+	// if we saw the string before, write its index (>= 0)
+	// (the empty string is mapped to 0)
+	if i, ok := p.strIndex[s]; ok {
+		p.rawInt64(int64(i))
+		return
+	}
+	// otherwise, remember string and write its negative length and bytes
+	p.strIndex[s] = len(p.strIndex)
+	p.rawInt64(-int64(len(s)))
+	for i := 0; i < len(s); i++ {
+		p.rawByte(s[i])
+	}
+}
+
+// marker emits a marker byte and position information which makes
+// it easy for a reader to detect if it is "out of sync". Used for
+// debugFormat format only.
+func (p *exporter) marker(m byte) {
+	p.rawByte(m)
+	// Enable this for help tracking down the location
+	// of an incorrect marker when running in debugFormat.
+	if false && trace {
+		p.tracef("#%d ", p.written)
+	}
+	p.rawInt64(int64(p.written))
+}
+
+// rawInt64 should only be used by low-level encoders.
+func (p *exporter) rawInt64(x int64) {
+	var tmp [binary.MaxVarintLen64]byte
+	n := binary.PutVarint(tmp[:], x)
+	for i := 0; i < n; i++ {
+		p.rawByte(tmp[i])
+	}
+}
+
+// rawStringln should only be used to emit the initial version string.
+func (p *exporter) rawStringln(s string) {
+	for i := 0; i < len(s); i++ {
+		p.rawByte(s[i])
+	}
+	p.rawByte('\n')
+}
+
+// rawByte is the bottleneck interface to write to p.out.
+// rawByte escapes b as follows (any encoding does that
+// hides '$'):
+//
+//	'$'  => '|' 'S'
+//	'|'  => '|' '|'
+//
+// Necessary so other tools can find the end of the
+// export data by searching for "$$".
+// rawByte should only be used by low-level encoders.
+func (p *exporter) rawByte(b byte) {
+	switch b {
+	case '$':
+		// write '$' as '|' 'S'
+		b = 'S'
+		fallthrough
+	case '|':
+		// write '|' as '|' '|'
+		p.out.WriteByte('|')
+		p.written++
+	}
+	p.out.WriteByte(b)
+	p.written++
+}
+
+// tracef is like fmt.Printf but it rewrites the format string
+// to take care of indentation.
+func (p *exporter) tracef(format string, args ...interface{}) {
+	if strings.ContainsAny(format, "<>\n") {
+		var buf bytes.Buffer
+		for i := 0; i < len(format); i++ {
+			// no need to deal with runes
+			ch := format[i]
+			switch ch {
+			case '>':
+				p.indent++
+				continue
+			case '<':
+				p.indent--
+				continue
+			}
+			buf.WriteByte(ch)
+			if ch == '\n' {
+				for j := p.indent; j > 0; j-- {
+					buf.WriteString(".  ")
+				}
+			}
+		}
+		format = buf.String()
+	}
+	fmt.Printf(format, args...)
+}
+
+// Debugging support.
+// (tagString is only used when tracing is enabled)
+var tagString = [...]string{
+	// Packages
+	-packageTag: "package",
+
+	// Types
+	-namedTag:     "named type",
+	-arrayTag:     "array",
+	-sliceTag:     "slice",
+	-dddTag:       "ddd",
+	-structTag:    "struct",
+	-pointerTag:   "pointer",
+	-signatureTag: "signature",
+	-interfaceTag: "interface",
+	-mapTag:       "map",
+	-chanTag:      "chan",
+
+	// Values
+	-falseTag:    "false",
+	-trueTag:     "true",
+	-int64Tag:    "int64",
+	-floatTag:    "float",
+	-fractionTag: "fraction",
+	-complexTag:  "complex",
+	-stringTag:   "string",
+	-unknownTag:  "unknown",
+
+	// Type aliases
+	-aliasTag: "alias",
+}

vendor/golang.org/x/tools/go/internal/gcimporter/exportdata.go

@@ -0,0 +1,93 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// This file is a copy of $GOROOT/src/go/internal/gcimporter/exportdata.go.
+
+// This file implements FindExportData.
+
+package gcimporter
+
+import (
+	"bufio"
+	"fmt"
+	"io"
+	"strconv"
+	"strings"
+)
+
+func readGopackHeader(r *bufio.Reader) (name string, size int, err error) {
+	// See $GOROOT/include/ar.h.
+	hdr := make([]byte, 16+12+6+6+8+10+2)
+	_, err = io.ReadFull(r, hdr)
+	if err != nil {
+		return
+	}
+	// leave for debugging
+	if false {
+		fmt.Printf("header: %s", hdr)
+	}
+	s := strings.TrimSpace(string(hdr[16+12+6+6+8:][:10]))
+	size, err = strconv.Atoi(s)
+	if err != nil || hdr[len(hdr)-2] != '`' || hdr[len(hdr)-1] != '\n' {
+		err = fmt.Errorf("invalid archive header")
+		return
+	}
+	name = strings.TrimSpace(string(hdr[:16]))
+	return
+}
+
+// FindExportData positions the reader r at the beginning of the
+// export data section of an underlying GC-created object/archive
+// file by reading from it. The reader must be positioned at the
+// start of the file before calling this function. The hdr result
+// is the string before the export data, either "$$" or "$$B".
+//
+func FindExportData(r *bufio.Reader) (hdr string, err error) {
+	// Read first line to make sure this is an object file.
+	line, err := r.ReadSlice('\n')
+	if err != nil {
+		err = fmt.Errorf("can't find export data (%v)", err)
+		return
+	}
+
+	if string(line) == "!<arch>\n" {
+		// Archive file. Scan to __.PKGDEF.
+		var name string
+		if name, _, err = readGopackHeader(r); err != nil {
+			return
+		}
+
+		// First entry should be __.PKGDEF.
+		if name != "__.PKGDEF" {
+			err = fmt.Errorf("go archive is missing __.PKGDEF")
+			return
+		}
+
+		// Read first line of __.PKGDEF data, so that line
+		// is once again the first line of the input.
+		if line, err = r.ReadSlice('\n'); err != nil {
+			err = fmt.Errorf("can't find export data (%v)", err)
+			return
+		}
+	}
+
+	// Now at __.PKGDEF in archive or still at beginning of file.
+	// Either way, line should begin with "go object ".
+	if !strings.HasPrefix(string(line), "go object ") {
+		err = fmt.Errorf("not a Go object file")
+		return
+	}
+
+	// Skip over object header to export data.
+	// Begins after first line starting with $$.
+	for line[0] != '$' {
+		if line, err = r.ReadSlice('\n'); err != nil {
+			err = fmt.Errorf("can't find export data (%v)", err)
+			return
+		}
+	}
+	hdr = string(line)
+
+	return
+}

vendor/golang.org/x/tools/go/internal/gcimporter/iexport.go

@@ -0,0 +1,739 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Indexed binary package export.
+// This file was derived from $GOROOT/src/cmd/compile/internal/gc/iexport.go;
+// see that file for specification of the format.
+
+package gcimporter
+
+import (
+	"bytes"
+	"encoding/binary"
+	"go/ast"
+	"go/constant"
+	"go/token"
+	"go/types"
+	"io"
+	"math/big"
+	"reflect"
+	"sort"
+)
+
+// Current indexed export format version. Increase with each format change.
+// 0: Go1.11 encoding
+const iexportVersion = 0
+
+// IExportData returns the binary export data for pkg.
+//
+// If no file set is provided, position info will be missing.
+// The package path of the top-level package will not be recorded,
+// so that calls to IImportData can override with a provided package path.
+func IExportData(fset *token.FileSet, pkg *types.Package) (b []byte, err error) {
+	defer func() {
+		if e := recover(); e != nil {
+			if ierr, ok := e.(internalError); ok {
+				err = ierr
+				return
+			}
+			// Not an internal error; panic again.
+			panic(e)
+		}
+	}()
+
+	p := iexporter{
+		out:         bytes.NewBuffer(nil),
+		fset:        fset,
+		allPkgs:     map[*types.Package]bool{},
+		stringIndex: map[string]uint64{},
+		declIndex:   map[types.Object]uint64{},
+		typIndex:    map[types.Type]uint64{},
+		localpkg:    pkg,
+	}
+
+	for i, pt := range predeclared() {
+		p.typIndex[pt] = uint64(i)
+	}
+	if len(p.typIndex) > predeclReserved {
+		panic(internalErrorf("too many predeclared types: %d > %d", len(p.typIndex), predeclReserved))
+	}
+
+	// Initialize work queue with exported declarations.
+	scope := pkg.Scope()
+	for _, name := range scope.Names() {
+		if ast.IsExported(name) {
+			p.pushDecl(scope.Lookup(name))
+		}
+	}
+
+	// Loop until no more work.
+	for !p.declTodo.empty() {
+		p.doDecl(p.declTodo.popHead())
+	}
+
+	// Append indices to data0 section.
+	dataLen := uint64(p.data0.Len())
+	w := p.newWriter()
+	w.writeIndex(p.declIndex)
+	w.flush()
+
+	// Assemble header.
+	var hdr intWriter
+	hdr.WriteByte('i')
+	hdr.uint64(iexportVersion)
+	hdr.uint64(uint64(p.strings.Len()))
+	hdr.uint64(dataLen)
+
+	// Flush output.
+	io.Copy(p.out, &hdr)
+	io.Copy(p.out, &p.strings)
+	io.Copy(p.out, &p.data0)
+
+	return p.out.Bytes(), nil
+}
+
+// writeIndex writes out an object index. mainIndex indicates whether
+// we're writing out the main index, which is also read by
+// non-compiler tools and includes a complete package description
+// (i.e., name and height).
+func (w *exportWriter) writeIndex(index map[types.Object]uint64) {
+	// Build a map from packages to objects from that package.
+	pkgObjs := map[*types.Package][]types.Object{}
+
+	// For the main index, make sure to include every package that
+	// we reference, even if we're not exporting (or reexporting)
+	// any symbols from it.
+	pkgObjs[w.p.localpkg] = nil
+	for pkg := range w.p.allPkgs {
+		pkgObjs[pkg] = nil
+	}
+
+	for obj := range index {
+		pkgObjs[obj.Pkg()] = append(pkgObjs[obj.Pkg()], obj)
+	}
+
+	var pkgs []*types.Package
+	for pkg, objs := range pkgObjs {
+		pkgs = append(pkgs, pkg)
+
+		sort.Slice(objs, func(i, j int) bool {
+			return objs[i].Name() < objs[j].Name()
+		})
+	}
+
+	sort.Slice(pkgs, func(i, j int) bool {
+		return w.exportPath(pkgs[i]) < w.exportPath(pkgs[j])
+	})
+
+	w.uint64(uint64(len(pkgs)))
+	for _, pkg := range pkgs {
+		w.string(w.exportPath(pkg))
+		w.string(pkg.Name())
+		w.uint64(uint64(0)) // package height is not needed for go/types
+
+		objs := pkgObjs[pkg]
+		w.uint64(uint64(len(objs)))
+		for _, obj := range objs {
+			w.string(obj.Name())
+			w.uint64(index[obj])
+		}
+	}
+}
+
+type iexporter struct {
+	fset *token.FileSet
+	out  *bytes.Buffer
+
+	localpkg *types.Package
+
+	// allPkgs tracks all packages that have been referenced by
+	// the export data, so we can ensure to include them in the
+	// main index.
+	allPkgs map[*types.Package]bool
+
+	declTodo objQueue
+
+	strings     intWriter
+	stringIndex map[string]uint64
+
+	data0     intWriter
+	declIndex map[types.Object]uint64
+	typIndex  map[types.Type]uint64
+}
+
+// stringOff returns the offset of s within the string section.
+// If not already present, it's added to the end.
+func (p *iexporter) stringOff(s string) uint64 {
+	off, ok := p.stringIndex[s]
+	if !ok {
+		off = uint64(p.strings.Len())
+		p.stringIndex[s] = off
+
+		p.strings.uint64(uint64(len(s)))
+		p.strings.WriteString(s)
+	}
+	return off
+}
+
+// pushDecl adds n to the declaration work queue, if not already present.
+func (p *iexporter) pushDecl(obj types.Object) {
+	// Package unsafe is known to the compiler and predeclared.
+	assert(obj.Pkg() != types.Unsafe)
+
+	if _, ok := p.declIndex[obj]; ok {
+		return
+	}
+
+	p.declIndex[obj] = ^uint64(0) // mark n present in work queue
+	p.declTodo.pushTail(obj)
+}
+
+// exportWriter handles writing out individual data section chunks.
+type exportWriter struct {
+	p *iexporter
+
+	data     intWriter
+	currPkg  *types.Package
+	prevFile string
+	prevLine int64
+}
+
+func (w *exportWriter) exportPath(pkg *types.Package) string {
+	if pkg == w.p.localpkg {
+		return ""
+	}
+	return pkg.Path()
+}
+
+func (p *iexporter) doDecl(obj types.Object) {
+	w := p.newWriter()
+	w.setPkg(obj.Pkg(), false)
+
+	switch obj := obj.(type) {
+	case *types.Var:
+		w.tag('V')
+		w.pos(obj.Pos())
+		w.typ(obj.Type(), obj.Pkg())
+
+	case *types.Func:
+		sig, _ := obj.Type().(*types.Signature)
+		if sig.Recv() != nil {
+			panic(internalErrorf("unexpected method: %v", sig))
+		}
+		w.tag('F')
+		w.pos(obj.Pos())
+		w.signature(sig)
+
+	case *types.Const:
+		w.tag('C')
+		w.pos(obj.Pos())
+		w.value(obj.Type(), obj.Val())
+
+	case *types.TypeName:
+		if obj.IsAlias() {
+			w.tag('A')
+			w.pos(obj.Pos())
+			w.typ(obj.Type(), obj.Pkg())
+			break
+		}
+
+		// Defined type.
+		w.tag('T')
+		w.pos(obj.Pos())
+
+		underlying := obj.Type().Underlying()
+		w.typ(underlying, obj.Pkg())
+
+		t := obj.Type()
+		if types.IsInterface(t) {
+			break
+		}
+
+		named, ok := t.(*types.Named)
+		if !ok {
+			panic(internalErrorf("%s is not a defined type", t))
+		}
+
+		n := named.NumMethods()
+		w.uint64(uint64(n))
+		for i := 0; i < n; i++ {
+			m := named.Method(i)
+			w.pos(m.Pos())
+			w.string(m.Name())
+			sig, _ := m.Type().(*types.Signature)
+			w.param(sig.Recv())
+			w.signature(sig)
+		}
+
+	default:
+		panic(internalErrorf("unexpected object: %v", obj))
+	}
+
+	p.declIndex[obj] = w.flush()
+}
+
+func (w *exportWriter) tag(tag byte) {
+	w.data.WriteByte(tag)
+}
+
+func (w *exportWriter) pos(pos token.Pos) {
+	if w.p.fset == nil {
+		w.int64(0)
+		return
+	}
+
+	p := w.p.fset.Position(pos)
+	file := p.Filename
+	line := int64(p.Line)
+
+	// When file is the same as the last position (common case),
+	// we can save a few bytes by delta encoding just the line
+	// number.
+	//
+	// Note: Because data objects may be read out of order (or not
+	// at all), we can only apply delta encoding within a single
+	// object. This is handled implicitly by tracking prevFile and
+	// prevLine as fields of exportWriter.
+
+	if file == w.prevFile {
+		delta := line - w.prevLine
+		w.int64(delta)
+		if delta == deltaNewFile {
+			w.int64(-1)
+		}
+	} else {
+		w.int64(deltaNewFile)
+		w.int64(line) // line >= 0
+		w.string(file)
+		w.prevFile = file
+	}
+	w.prevLine = line
+}
+
+func (w *exportWriter) pkg(pkg *types.Package) {
+	// Ensure any referenced packages are declared in the main index.
+	w.p.allPkgs[pkg] = true
+
+	w.string(w.exportPath(pkg))
+}
+
+func (w *exportWriter) qualifiedIdent(obj types.Object) {
+	// Ensure any referenced declarations are written out too.
+	w.p.pushDecl(obj)
+
+	w.string(obj.Name())
+	w.pkg(obj.Pkg())
+}
+
+func (w *exportWriter) typ(t types.Type, pkg *types.Package) {
+	w.data.uint64(w.p.typOff(t, pkg))
+}
+
+func (p *iexporter) newWriter() *exportWriter {
+	return &exportWriter{p: p}
+}
+
+func (w *exportWriter) flush() uint64 {
+	off := uint64(w.p.data0.Len())
+	io.Copy(&w.p.data0, &w.data)
+	return off
+}
+
+func (p *iexporter) typOff(t types.Type, pkg *types.Package) uint64 {
+	off, ok := p.typIndex[t]
+	if !ok {
+		w := p.newWriter()
+		w.doTyp(t, pkg)
+		off = predeclReserved + w.flush()
+		p.typIndex[t] = off
+	}
+	return off
+}
+
+func (w *exportWriter) startType(k itag) {
+	w.data.uint64(uint64(k))
+}
+
+func (w *exportWriter) doTyp(t types.Type, pkg *types.Package) {
+	switch t := t.(type) {
+	case *types.Named:
+		w.startType(definedType)
+		w.qualifiedIdent(t.Obj())
+
+	case *types.Pointer:
+		w.startType(pointerType)
+		w.typ(t.Elem(), pkg)
+
+	case *types.Slice:
+		w.startType(sliceType)
+		w.typ(t.Elem(), pkg)
+
+	case *types.Array:
+		w.startType(arrayType)
+		w.uint64(uint64(t.Len()))
+		w.typ(t.Elem(), pkg)
+
+	case *types.Chan:
+		w.startType(chanType)
+		// 1 RecvOnly; 2 SendOnly; 3 SendRecv
+		var dir uint64
+		switch t.Dir() {
+		case types.RecvOnly:
+			dir = 1
+		case types.SendOnly:
+			dir = 2
+		case types.SendRecv:
+			dir = 3
+		}
+		w.uint64(dir)
+		w.typ(t.Elem(), pkg)
+
+	case *types.Map:
+		w.startType(mapType)
+		w.typ(t.Key(), pkg)
+		w.typ(t.Elem(), pkg)
+
+	case *types.Signature:
+		w.startType(signatureType)
+		w.setPkg(pkg, true)
+		w.signature(t)
+
+	case *types.Struct:
+		w.startType(structType)
+		w.setPkg(pkg, true)
+
+		n := t.NumFields()
+		w.uint64(uint64(n))
+		for i := 0; i < n; i++ {
+			f := t.Field(i)
+			w.pos(f.Pos())
+			w.string(f.Name())
+			w.typ(f.Type(), pkg)
+			w.bool(f.Anonymous())
+			w.string(t.Tag(i)) // note (or tag)
+		}
+
+	case *types.Interface:
+		w.startType(interfaceType)
+		w.setPkg(pkg, true)
+
+		n := t.NumEmbeddeds()
+		w.uint64(uint64(n))
+		for i := 0; i < n; i++ {
+			f := t.Embedded(i)
+			w.pos(f.Obj().Pos())
+			w.typ(f.Obj().Type(), f.Obj().Pkg())
+		}
+
+		n = t.NumExplicitMethods()
+		w.uint64(uint64(n))
+		for i := 0; i < n; i++ {
+			m := t.ExplicitMethod(i)
+			w.pos(m.Pos())
+			w.string(m.Name())
+			sig, _ := m.Type().(*types.Signature)
+			w.signature(sig)
+		}
+
+	default:
+		panic(internalErrorf("unexpected type: %v, %v", t, reflect.TypeOf(t)))
+	}
+}
+
+func (w *exportWriter) setPkg(pkg *types.Package, write bool) {
+	if write {
+		w.pkg(pkg)
+	}
+
+	w.currPkg = pkg
+}
+
+func (w *exportWriter) signature(sig *types.Signature) {
+	w.paramList(sig.Params())
+	w.paramList(sig.Results())
+	if sig.Params().Len() > 0 {
+		w.bool(sig.Variadic())
+	}
+}
+
+func (w *exportWriter) paramList(tup *types.Tuple) {
+	n := tup.Len()
+	w.uint64(uint64(n))
+	for i := 0; i < n; i++ {
+		w.param(tup.At(i))
+	}
+}
+
+func (w *exportWriter) param(obj types.Object) {
+	w.pos(obj.Pos())
+	w.localIdent(obj)
+	w.typ(obj.Type(), obj.Pkg())
+}
+
+func (w *exportWriter) value(typ types.Type, v constant.Value) {
+	w.typ(typ, nil)
+
+	switch v.Kind() {
+	case constant.Bool:
+		w.bool(constant.BoolVal(v))
+	case constant.Int:
+		var i big.Int
+		if i64, exact := constant.Int64Val(v); exact {
+			i.SetInt64(i64)
+		} else if ui64, exact := constant.Uint64Val(v); exact {
+			i.SetUint64(ui64)
+		} else {
+			i.SetString(v.ExactString(), 10)
+		}
+		w.mpint(&i, typ)
+	case constant.Float:
+		f := constantToFloat(v)
+		w.mpfloat(f, typ)
+	case constant.Complex:
+		w.mpfloat(constantToFloat(constant.Real(v)), typ)
+		w.mpfloat(constantToFloat(constant.Imag(v)), typ)
+	case constant.String:
+		w.string(constant.StringVal(v))
+	case constant.Unknown:
+		// package contains type errors
+	default:
+		panic(internalErrorf("unexpected value %v (%T)", v, v))
+	}
+}
+
+// constantToFloat converts a constant.Value with kind constant.Float to a
+// big.Float.
+func constantToFloat(x constant.Value) *big.Float {
+	assert(x.Kind() == constant.Float)
+	// Use the same floating-point precision (512) as cmd/compile
+	// (see Mpprec in cmd/compile/internal/gc/mpfloat.go).
+	const mpprec = 512
+	var f big.Float
+	f.SetPrec(mpprec)
+	if v, exact := constant.Float64Val(x); exact {
+		// float64
+		f.SetFloat64(v)
+	} else if num, denom := constant.Num(x), constant.Denom(x); num.Kind() == constant.Int {
+		// TODO(gri): add big.Rat accessor to constant.Value.
+		n := valueToRat(num)
+		d := valueToRat(denom)
+		f.SetRat(n.Quo(n, d))
+	} else {
+		// Value too large to represent as a fraction => inaccessible.
+		// TODO(gri): add big.Float accessor to constant.Value.
+		_, ok := f.SetString(x.ExactString())
+		assert(ok)
+	}
+	return &f
+}
+
+// mpint exports a multi-precision integer.
+//
+// For unsigned types, small values are written out as a single
+// byte. Larger values are written out as a length-prefixed big-endian
+// byte string, where the length prefix is encoded as its complement.
+// For example, bytes 0, 1, and 2 directly represent the integer
+// values 0, 1, and 2; while bytes 255, 254, and 253 indicate a 1-,
+// 2-, and 3-byte big-endian string follow.
+//
+// Encoding for signed types use the same general approach as for
+// unsigned types, except small values use zig-zag encoding and the
+// bottom bit of length prefix byte for large values is reserved as a
+// sign bit.
+//
+// The exact boundary between small and large encodings varies
+// according to the maximum number of bytes needed to encode a value
+// of type typ. As a special case, 8-bit types are always encoded as a
+// single byte.
+//
+// TODO(mdempsky): Is this level of complexity really worthwhile?
+func (w *exportWriter) mpint(x *big.Int, typ types.Type) {
+	basic, ok := typ.Underlying().(*types.Basic)
+	if !ok {
+		panic(internalErrorf("unexpected type %v (%T)", typ.Underlying(), typ.Underlying()))
+	}
+
+	signed, maxBytes := intSize(basic)
+
+	negative := x.Sign() < 0
+	if !signed && negative {
+		panic(internalErrorf("negative unsigned integer; type %v, value %v", typ, x))
+	}
+
+	b := x.Bytes()
+	if len(b) > 0 && b[0] == 0 {
+		panic(internalErrorf("leading zeros"))
+	}
+	if uint(len(b)) > maxBytes {
+		panic(internalErrorf("bad mpint length: %d > %d (type %v, value %v)", len(b), maxBytes, typ, x))
+	}
+
+	maxSmall := 256 - maxBytes
+	if signed {
+		maxSmall = 256 - 2*maxBytes
+	}
+	if maxBytes == 1 {
+		maxSmall = 256
+	}
+
+	// Check if x can use small value encoding.
+	if len(b) <= 1 {
+		var ux uint
+		if len(b) == 1 {
+			ux = uint(b[0])
+		}
+		if signed {
+			ux <<= 1
+			if negative {
+				ux--
+			}
+		}
+		if ux < maxSmall {
+			w.data.WriteByte(byte(ux))
+			return
+		}
+	}
+
+	n := 256 - uint(len(b))
+	if signed {
+		n = 256 - 2*uint(len(b))
+		if negative {
+			n |= 1
+		}
+	}
+	if n < maxSmall || n >= 256 {
+		panic(internalErrorf("encoding mistake: %d, %v, %v => %d", len(b), signed, negative, n))
+	}
+
+	w.data.WriteByte(byte(n))
+	w.data.Write(b)
+}
+
+// mpfloat exports a multi-precision floating point number.
+//
+// The number's value is decomposed into mantissa × 2**exponent, where
+// mantissa is an integer. The value is written out as mantissa (as a
+// multi-precision integer) and then the exponent, except exponent is
+// omitted if mantissa is zero.
+func (w *exportWriter) mpfloat(f *big.Float, typ types.Type) {
+	if f.IsInf() {
+		panic("infinite constant")
+	}
+
+	// Break into f = mant × 2**exp, with 0.5 <= mant < 1.
+	var mant big.Float
+	exp := int64(f.MantExp(&mant))
+
+	// Scale so that mant is an integer.
+	prec := mant.MinPrec()
+	mant.SetMantExp(&mant, int(prec))
+	exp -= int64(prec)
+
+	manti, acc := mant.Int(nil)
+	if acc != big.Exact {
+		panic(internalErrorf("mantissa scaling failed for %f (%s)", f, acc))
+	}
+	w.mpint(manti, typ)
+	if manti.Sign() != 0 {
+		w.int64(exp)
+	}
+}
+
+func (w *exportWriter) bool(b bool) bool {
+	var x uint64
+	if b {
+		x = 1
+	}
+	w.uint64(x)
+	return b
+}
+
+func (w *exportWriter) int64(x int64)   { w.data.int64(x) }
+func (w *exportWriter) uint64(x uint64) { w.data.uint64(x) }
+func (w *exportWriter) string(s string) { w.uint64(w.p.stringOff(s)) }
+
+func (w *exportWriter) localIdent(obj types.Object) {
+	// Anonymous parameters.
+	if obj == nil {
+		w.string("")
+		return
+	}
+
+	name := obj.Name()
+	if name == "_" {
+		w.string("_")
+		return
+	}
+
+	w.string(name)
+}
+
+type intWriter struct {
+	bytes.Buffer
+}
+
+func (w *intWriter) int64(x int64) {
+	var buf [binary.MaxVarintLen64]byte
+	n := binary.PutVarint(buf[:], x)
+	w.Write(buf[:n])
+}
+
+func (w *intWriter) uint64(x uint64) {
+	var buf [binary.MaxVarintLen64]byte
+	n := binary.PutUvarint(buf[:], x)
+	w.Write(buf[:n])
+}
+
+func assert(cond bool) {
+	if !cond {
+		panic("internal error: assertion failed")
+	}
+}
+
+// The below is copied from go/src/cmd/compile/internal/gc/syntax.go.
+
+// objQueue is a FIFO queue of types.Object. The zero value of objQueue is
+// a ready-to-use empty queue.
+type objQueue struct {
+	ring       []types.Object
+	head, tail int
+}
+
+// empty returns true if q contains no Nodes.
+func (q *objQueue) empty() bool {
+	return q.head == q.tail
+}
+
+// pushTail appends n to the tail of the queue.
+func (q *objQueue) pushTail(obj types.Object) {
+	if len(q.ring) == 0 {
+		q.ring = make([]types.Object, 16)
+	} else if q.head+len(q.ring) == q.tail {
+		// Grow the ring.
+		nring := make([]types.Object, len(q.ring)*2)
+		// Copy the old elements.
+		part := q.ring[q.head%len(q.ring):]
+		if q.tail-q.head <= len(part) {
+			part = part[:q.tail-q.head]
+			copy(nring, part)
+		} else {
+			pos := copy(nring, part)
+			copy(nring[pos:], q.ring[:q.tail%len(q.ring)])
+		}
+		q.ring, q.head, q.tail = nring, 0, q.tail-q.head
+	}
+
+	q.ring[q.tail%len(q.ring)] = obj
+	q.tail++
+}
+
+// popHead pops a node from the head of the queue. It panics if q is empty.
+func (q *objQueue) popHead() types.Object {
+	if q.empty() {
+		panic("dequeue empty")
+	}
+	obj := q.ring[q.head%len(q.ring)]
+	q.head++
+	return obj
+}

vendor/golang.org/x/tools/go/internal/gcimporter/iimport.go

@@ -0,0 +1,630 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Indexed package import.
+// See cmd/compile/internal/gc/iexport.go for the export data format.
+
+// This file is a copy of $GOROOT/src/go/internal/gcimporter/iimport.go.
+
+package gcimporter
+
+import (
+	"bytes"
+	"encoding/binary"
+	"fmt"
+	"go/constant"
+	"go/token"
+	"go/types"
+	"io"
+	"sort"
+)
+
+type intReader struct {
+	*bytes.Reader
+	path string
+}
+
+func (r *intReader) int64() int64 {
+	i, err := binary.ReadVarint(r.Reader)
+	if err != nil {
+		errorf("import %q: read varint error: %v", r.path, err)
+	}
+	return i
+}
+
+func (r *intReader) uint64() uint64 {
+	i, err := binary.ReadUvarint(r.Reader)
+	if err != nil {
+		errorf("import %q: read varint error: %v", r.path, err)
+	}
+	return i
+}
+
+const predeclReserved = 32
+
+type itag uint64
+
+const (
+	// Types
+	definedType itag = iota
+	pointerType
+	sliceType
+	arrayType
+	chanType
+	mapType
+	signatureType
+	structType
+	interfaceType
+)
+
+// IImportData imports a package from the serialized package data
+// and returns the number of bytes consumed and a reference to the package.
+// If the export data version is not recognized or the format is otherwise
+// compromised, an error is returned.
+func IImportData(fset *token.FileSet, imports map[string]*types.Package, data []byte, path string) (_ int, pkg *types.Package, err error) {
+	const currentVersion = 1
+	version := int64(-1)
+	defer func() {
+		if e := recover(); e != nil {
+			if version > currentVersion {
+				err = fmt.Errorf("cannot import %q (%v), export data is newer version - update tool", path, e)
+			} else {
+				err = fmt.Errorf("cannot import %q (%v), possibly version skew - reinstall package", path, e)
+			}
+		}
+	}()
+
+	r := &intReader{bytes.NewReader(data), path}
+
+	version = int64(r.uint64())
+	switch version {
+	case currentVersion, 0:
+	default:
+		errorf("unknown iexport format version %d", version)
+	}
+
+	sLen := int64(r.uint64())
+	dLen := int64(r.uint64())
+
+	whence, _ := r.Seek(0, io.SeekCurrent)
+	stringData := data[whence : whence+sLen]
+	declData := data[whence+sLen : whence+sLen+dLen]
+	r.Seek(sLen+dLen, io.SeekCurrent)
+
+	p := iimporter{
+		ipath:   path,
+		version: int(version),
+
+		stringData:  stringData,
+		stringCache: make(map[uint64]string),
+		pkgCache:    make(map[uint64]*types.Package),
+
+		declData: declData,
+		pkgIndex: make(map[*types.Package]map[string]uint64),
+		typCache: make(map[uint64]types.Type),
+
+		fake: fakeFileSet{
+			fset:  fset,
+			files: make(map[string]*token.File),
+		},
+	}
+
+	for i, pt := range predeclared() {
+		p.typCache[uint64(i)] = pt
+	}
+
+	pkgList := make([]*types.Package, r.uint64())
+	for i := range pkgList {
+		pkgPathOff := r.uint64()
+		pkgPath := p.stringAt(pkgPathOff)
+		pkgName := p.stringAt(r.uint64())
+		_ = r.uint64() // package height; unused by go/types
+
+		if pkgPath == "" {
+			pkgPath = path
+		}
+		pkg := imports[pkgPath]
+		if pkg == nil {
+			pkg = types.NewPackage(pkgPath, pkgName)
+			imports[pkgPath] = pkg
+		} else if pkg.Name() != pkgName {
+			errorf("conflicting names %s and %s for package %q", pkg.Name(), pkgName, path)
+		}
+
+		p.pkgCache[pkgPathOff] = pkg
+
+		nameIndex := make(map[string]uint64)
+		for nSyms := r.uint64(); nSyms > 0; nSyms-- {
+			name := p.stringAt(r.uint64())
+			nameIndex[name] = r.uint64()
+		}
+
+		p.pkgIndex[pkg] = nameIndex
+		pkgList[i] = pkg
+	}
+	if len(pkgList) == 0 {
+		errorf("no packages found for %s", path)
+		panic("unreachable")
+	}
+	p.ipkg = pkgList[0]
+	names := make([]string, 0, len(p.pkgIndex[p.ipkg]))
+	for name := range p.pkgIndex[p.ipkg] {
+		names = append(names, name)
+	}
+	sort.Strings(names)
+	for _, name := range names {
+		p.doDecl(p.ipkg, name)
+	}
+
+	for _, typ := range p.interfaceList {
+		typ.Complete()
+	}
+
+	// record all referenced packages as imports
+	list := append(([]*types.Package)(nil), pkgList[1:]...)
+	sort.Sort(byPath(list))
+	p.ipkg.SetImports(list)
+
+	// package was imported completely and without errors
+	p.ipkg.MarkComplete()
+
+	consumed, _ := r.Seek(0, io.SeekCurrent)
+	return int(consumed), p.ipkg, nil
+}
+
+type iimporter struct {
+	ipath   string
+	ipkg    *types.Package
+	version int
+
+	stringData  []byte
+	stringCache map[uint64]string
+	pkgCache    map[uint64]*types.Package
+
+	declData []byte
+	pkgIndex map[*types.Package]map[string]uint64
+	typCache map[uint64]types.Type
+
+	fake          fakeFileSet
+	interfaceList []*types.Interface
+}
+
+func (p *iimporter) doDecl(pkg *types.Package, name string) {
+	// See if we've already imported this declaration.
+	if obj := pkg.Scope().Lookup(name); obj != nil {
+		return
+	}
+
+	off, ok := p.pkgIndex[pkg][name]
+	if !ok {
+		errorf("%v.%v not in index", pkg, name)
+	}
+
+	r := &importReader{p: p, currPkg: pkg}
+	r.declReader.Reset(p.declData[off:])
+
+	r.obj(name)
+}
+
+func (p *iimporter) stringAt(off uint64) string {
+	if s, ok := p.stringCache[off]; ok {
+		return s
+	}
+
+	slen, n := binary.Uvarint(p.stringData[off:])
+	if n <= 0 {
+		errorf("varint failed")
+	}
+	spos := off + uint64(n)
+	s := string(p.stringData[spos : spos+slen])
+	p.stringCache[off] = s
+	return s
+}
+
+func (p *iimporter) pkgAt(off uint64) *types.Package {
+	if pkg, ok := p.pkgCache[off]; ok {
+		return pkg
+	}
+	path := p.stringAt(off)
+	if path == p.ipath {
+		return p.ipkg
+	}
+	errorf("missing package %q in %q", path, p.ipath)
+	return nil
+}
+
+func (p *iimporter) typAt(off uint64, base *types.Named) types.Type {
+	if t, ok := p.typCache[off]; ok && (base == nil || !isInterface(t)) {
+		return t
+	}
+
+	if off < predeclReserved {
+		errorf("predeclared type missing from cache: %v", off)
+	}
+
+	r := &importReader{p: p}
+	r.declReader.Reset(p.declData[off-predeclReserved:])
+	t := r.doType(base)
+
+	if base == nil || !isInterface(t) {
+		p.typCache[off] = t
+	}
+	return t
+}
+
+type importReader struct {
+	p          *iimporter
+	declReader bytes.Reader
+	currPkg    *types.Package
+	prevFile   string
+	prevLine   int64
+	prevColumn int64
+}
+
+func (r *importReader) obj(name string) {
+	tag := r.byte()
+	pos := r.pos()
+
+	switch tag {
+	case 'A':
+		typ := r.typ()
+
+		r.declare(types.NewTypeName(pos, r.currPkg, name, typ))
+
+	case 'C':
+		typ, val := r.value()
+
+		r.declare(types.NewConst(pos, r.currPkg, name, typ, val))
+
+	case 'F':
+		sig := r.signature(nil)
+
+		r.declare(types.NewFunc(pos, r.currPkg, name, sig))
+
+	case 'T':
+		// Types can be recursive. We need to setup a stub
+		// declaration before recursing.
+		obj := types.NewTypeName(pos, r.currPkg, name, nil)
+		named := types.NewNamed(obj, nil, nil)
+		r.declare(obj)
+
+		underlying := r.p.typAt(r.uint64(), named).Underlying()
+		named.SetUnderlying(underlying)
+
+		if !isInterface(underlying) {
+			for n := r.uint64(); n > 0; n-- {
+				mpos := r.pos()
+				mname := r.ident()
+				recv := r.param()
+				msig := r.signature(recv)
+
+				named.AddMethod(types.NewFunc(mpos, r.currPkg, mname, msig))
+			}
+		}
+
+	case 'V':
+		typ := r.typ()
+
+		r.declare(types.NewVar(pos, r.currPkg, name, typ))
+
+	default:
+		errorf("unexpected tag: %v", tag)
+	}
+}
+
+func (r *importReader) declare(obj types.Object) {
+	obj.Pkg().Scope().Insert(obj)
+}
+
+func (r *importReader) value() (typ types.Type, val constant.Value) {
+	typ = r.typ()
+
+	switch b := typ.Underlying().(*types.Basic); b.Info() & types.IsConstType {
+	case types.IsBoolean:
+		val = constant.MakeBool(r.bool())
+
+	case types.IsString:
+		val = constant.MakeString(r.string())
+
+	case types.IsInteger:
+		val = r.mpint(b)
+
+	case types.IsFloat:
+		val = r.mpfloat(b)
+
+	case types.IsComplex:
+		re := r.mpfloat(b)
+		im := r.mpfloat(b)
+		val = constant.BinaryOp(re, token.ADD, constant.MakeImag(im))
+
+	default:
+		if b.Kind() == types.Invalid {
+			val = constant.MakeUnknown()
+			return
+		}
+		errorf("unexpected type %v", typ) // panics
+		panic("unreachable")
+	}
+
+	return
+}
+
+func intSize(b *types.Basic) (signed bool, maxBytes uint) {
+	if (b.Info() & types.IsUntyped) != 0 {
+		return true, 64
+	}
+
+	switch b.Kind() {
+	case types.Float32, types.Complex64:
+		return true, 3
+	case types.Float64, types.Complex128:
+		return true, 7
+	}
+
+	signed = (b.Info() & types.IsUnsigned) == 0
+	switch b.Kind() {
+	case types.Int8, types.Uint8:
+		maxBytes = 1
+	case types.Int16, types.Uint16:
+		maxBytes = 2
+	case types.Int32, types.Uint32:
+		maxBytes = 4
+	default:
+		maxBytes = 8
+	}
+
+	return
+}
+
+func (r *importReader) mpint(b *types.Basic) constant.Value {
+	signed, maxBytes := intSize(b)
+
+	maxSmall := 256 - maxBytes
+	if signed {
+		maxSmall = 256 - 2*maxBytes
+	}
+	if maxBytes == 1 {
+		maxSmall = 256
+	}
+
+	n, _ := r.declReader.ReadByte()
+	if uint(n) < maxSmall {
+		v := int64(n)
+		if signed {
+			v >>= 1
+			if n&1 != 0 {
+				v = ^v
+			}
+		}
+		return constant.MakeInt64(v)
+	}
+
+	v := -n
+	if signed {
+		v = -(n &^ 1) >> 1
+	}
+	if v < 1 || uint(v) > maxBytes {
+		errorf("weird decoding: %v, %v => %v", n, signed, v)
+	}
+
+	buf := make([]byte, v)
+	io.ReadFull(&r.declReader, buf)
+
+	// convert to little endian
+	// TODO(gri) go/constant should have a more direct conversion function
+	//           (e.g., once it supports a big.Float based implementation)
+	for i, j := 0, len(buf)-1; i < j; i, j = i+1, j-1 {
+		buf[i], buf[j] = buf[j], buf[i]
+	}
+
+	x := constant.MakeFromBytes(buf)
+	if signed && n&1 != 0 {
+		x = constant.UnaryOp(token.SUB, x, 0)
+	}
+	return x
+}
+
+func (r *importReader) mpfloat(b *types.Basic) constant.Value {
+	x := r.mpint(b)
+	if constant.Sign(x) == 0 {
+		return x
+	}
+
+	exp := r.int64()
+	switch {
+	case exp > 0:
+		x = constant.Shift(x, token.SHL, uint(exp))
+	case exp < 0:
+		d := constant.Shift(constant.MakeInt64(1), token.SHL, uint(-exp))
+		x = constant.BinaryOp(x, token.QUO, d)
+	}
+	return x
+}
+
+func (r *importReader) ident() string {
+	return r.string()
+}
+
+func (r *importReader) qualifiedIdent() (*types.Package, string) {
+	name := r.string()
+	pkg := r.pkg()
+	return pkg, name
+}
+
+func (r *importReader) pos() token.Pos {
+	if r.p.version >= 1 {
+		r.posv1()
+	} else {
+		r.posv0()
+	}
+
+	if r.prevFile == "" && r.prevLine == 0 && r.prevColumn == 0 {
+		return token.NoPos
+	}
+	return r.p.fake.pos(r.prevFile, int(r.prevLine), int(r.prevColumn))
+}
+
+func (r *importReader) posv0() {
+	delta := r.int64()
+	if delta != deltaNewFile {
+		r.prevLine += delta
+	} else if l := r.int64(); l == -1 {
+		r.prevLine += deltaNewFile
+	} else {
+		r.prevFile = r.string()
+		r.prevLine = l
+	}
+}
+
+func (r *importReader) posv1() {
+	delta := r.int64()
+	r.prevColumn += delta >> 1
+	if delta&1 != 0 {
+		delta = r.int64()
+		r.prevLine += delta >> 1
+		if delta&1 != 0 {
+			r.prevFile = r.string()
+		}
+	}
+}
+
+func (r *importReader) typ() types.Type {
+	return r.p.typAt(r.uint64(), nil)
+}
+
+func isInterface(t types.Type) bool {
+	_, ok := t.(*types.Interface)
+	return ok
+}
+
+func (r *importReader) pkg() *types.Package { return r.p.pkgAt(r.uint64()) }
+func (r *importReader) string() string      { return r.p.stringAt(r.uint64()) }
+
+func (r *importReader) doType(base *types.Named) types.Type {
+	switch k := r.kind(); k {
+	default:
+		errorf("unexpected kind tag in %q: %v", r.p.ipath, k)
+		return nil
+
+	case definedType:
+		pkg, name := r.qualifiedIdent()
+		r.p.doDecl(pkg, name)
+		return pkg.Scope().Lookup(name).(*types.TypeName).Type()
+	case pointerType:
+		return types.NewPointer(r.typ())
+	case sliceType:
+		return types.NewSlice(r.typ())
+	case arrayType:
+		n := r.uint64()
+		return types.NewArray(r.typ(), int64(n))
+	case chanType:
+		dir := chanDir(int(r.uint64()))
+		return types.NewChan(dir, r.typ())
+	case mapType:
+		return types.NewMap(r.typ(), r.typ())
+	case signatureType:
+		r.currPkg = r.pkg()
+		return r.signature(nil)
+
+	case structType:
+		r.currPkg = r.pkg()
+
+		fields := make([]*types.Var, r.uint64())
+		tags := make([]string, len(fields))
+		for i := range fields {
+			fpos := r.pos()
+			fname := r.ident()
+			ftyp := r.typ()
+			emb := r.bool()
+			tag := r.string()
+
+			fields[i] = types.NewField(fpos, r.currPkg, fname, ftyp, emb)
+			tags[i] = tag
+		}
+		return types.NewStruct(fields, tags)
+
+	case interfaceType:
+		r.currPkg = r.pkg()
+
+		embeddeds := make([]types.Type, r.uint64())
+		for i := range embeddeds {
+			_ = r.pos()
+			embeddeds[i] = r.typ()
+		}
+
+		methods := make([]*types.Func, r.uint64())
+		for i := range methods {
+			mpos := r.pos()
+			mname := r.ident()
+
+			// TODO(mdempsky): Matches bimport.go, but I
+			// don't agree with this.
+			var recv *types.Var
+			if base != nil {
+				recv = types.NewVar(token.NoPos, r.currPkg, "", base)
+			}
+
+			msig := r.signature(recv)
+			methods[i] = types.NewFunc(mpos, r.currPkg, mname, msig)
+		}
+
+		typ := newInterface(methods, embeddeds)
+		r.p.interfaceList = append(r.p.interfaceList, typ)
+		return typ
+	}
+}
+
+func (r *importReader) kind() itag {
+	return itag(r.uint64())
+}
+
+func (r *importReader) signature(recv *types.Var) *types.Signature {
+	params := r.paramList()
+	results := r.paramList()
+	variadic := params.Len() > 0 && r.bool()
+	return types.NewSignature(recv, params, results, variadic)
+}
+
+func (r *importReader) paramList() *types.Tuple {
+	xs := make([]*types.Var, r.uint64())
+	for i := range xs {
+		xs[i] = r.param()
+	}
+	return types.NewTuple(xs...)
+}
+
+func (r *importReader) param() *types.Var {
+	pos := r.pos()
+	name := r.ident()
+	typ := r.typ()
+	return types.NewParam(pos, r.currPkg, name, typ)
+}
+
+func (r *importReader) bool() bool {
+	return r.uint64() != 0
+}
+
+func (r *importReader) int64() int64 {
+	n, err := binary.ReadVarint(&r.declReader)
+	if err != nil {
+		errorf("readVarint: %v", err)
+	}
+	return n
+}
+
+func (r *importReader) uint64() uint64 {
+	n, err := binary.ReadUvarint(&r.declReader)
+	if err != nil {
+		errorf("readUvarint: %v", err)
+	}
+	return n
+}
+
+func (r *importReader) byte() byte {
+	x, err := r.declReader.ReadByte()
+	if err != nil {
+		errorf("declReader.ReadByte: %v", err)
+	}
+	return x
+}

vendor/golang.org/x/tools/go/internal/gcimporter/newInterface10.go

@@ -0,0 +1,21 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build !go1.11
+
+package gcimporter
+
+import "go/types"
+
+func newInterface(methods []*types.Func, embeddeds []types.Type) *types.Interface {
+	named := make([]*types.Named, len(embeddeds))
+	for i, e := range embeddeds {
+		var ok bool
+		named[i], ok = e.(*types.Named)
+		if !ok {
+			panic("embedding of non-defined interfaces in interfaces is not supported before Go 1.11")
+		}
+	}
+	return types.NewInterface(methods, named)
+}

vendor/golang.org/x/tools/go/internal/gcimporter/newInterface11.go

@@ -0,0 +1,13 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build go1.11
+
+package gcimporter
+
+import "go/types"
+
+func newInterface(methods []*types.Func, embeddeds []types.Type) *types.Interface {
+	return types.NewInterfaceType(methods, embeddeds)
+}

vendor/modules.txt

@@ -408,10 +408,16 @@ go.opencensus.io/trace/propagation
 go.opencensus.io/trace/tracestate
 # go.uber.org/atomic v1.6.0
 go.uber.org/atomic
+# go.uber.org/goleak v1.0.0
+go.uber.org/goleak
+go.uber.org/goleak/internal/stack
 # golang.org/x/crypto v0.0.0-20200622213623-75b288015ac9
 golang.org/x/crypto/ed25519
 golang.org/x/crypto/ed25519/internal/edwards25519
 golang.org/x/crypto/ssh/terminal
+# golang.org/x/lint v0.0.0-20200302205851-738671d3881b
+golang.org/x/lint
+golang.org/x/lint/golint
 # golang.org/x/mod v0.3.0
 golang.org/x/mod/module
 golang.org/x/mod/semver
@@ -455,6 +461,8 @@ golang.org/x/time/rate
 # golang.org/x/tools v0.0.0-20200710042808-f1c4188a97a1
 golang.org/x/tools/cmd/goimports
 golang.org/x/tools/go/ast/astutil
+golang.org/x/tools/go/gcexportdata
+golang.org/x/tools/go/internal/gcimporter
 golang.org/x/tools/internal/event
 golang.org/x/tools/internal/event/core
 golang.org/x/tools/internal/event/keys