cmd/gotype: re-introduce gotype command at traditional location

Except for the added comment in the beginning and the removal of
the 'ignore' build tag, there is no difference between gotype.go
and the original.

Fixes golang/go#19516.

Change-Id: Ie1ab9aced6e650573c2cdce0c165af1e1094213f
Reviewed-on: https://go-review.googlesource.com/38132
Reviewed-by: Alan Donovan <adonovan@google.com>

cmd/gotype/gotype.go

@@ -0,0 +1,338 @@
+// 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.
+
+// gotype.go is a 1:1 copy of the original source maintained in
+// $GOROOT/src/go/types/gotype.go.
+//
+// This copy is here for the sole purpose of satisfying existing
+// references to this location, and for making gotype accessible
+// via 'go get'.
+//
+// Do NOT make changes to this version as they will not be maintained
+// (and possibly overwritten). Any changes should be made to the original.
+
+/*
+The gotype command, like the front-end of a Go compiler, parses and
+type-checks a single Go package. Errors are reported if the analysis
+fails; otherwise gotype is quiet (unless -v is set).
+
+Without a list of paths, gotype reads from standard input, which
+must provide a single Go source file defining a complete package.
+
+With a single directory argument, gotype checks the Go files in
+that directory, comprising a single package. Use -t to include the
+(in-package) _test.go files. Use -x to type check only external
+test files.
+
+Otherwise, each path must be the filename of a Go file belonging
+to the same package.
+
+Imports are processed by importing directly from the source of
+imported packages (default), or by importing from compiled and
+installed packages (by setting -c to the respective compiler).
+
+The -c flag must be set to a compiler ("gc", "gccgo") when type-
+checking packages containing imports with relative import paths
+(import "./mypkg") because the source importer cannot know which
+files to include for such packages.
+
+Usage:
+	gotype [flags] [path...]
+
+The flags are:
+	-t
+		include local test files in a directory (ignored if -x is provided)
+	-x
+		consider only external test files in a directory
+	-e
+		report all errors (not just the first 10)
+	-v
+		verbose mode
+	-c
+		compiler used for installed packages (gc, gccgo, or source); default: source
+
+Flags controlling additional output:
+	-ast
+		print AST (forces -seq)
+	-trace
+		print parse trace (forces -seq)
+	-comments
+		parse comments (ignored unless -ast or -trace is provided)
+
+Examples:
+
+To check the files a.go, b.go, and c.go:
+
+	gotype a.go b.go c.go
+
+To check an entire package including (in-package) tests in the directory dir and print the processed files:
+
+	gotype -t -v dir
+
+To check the external test package (if any) in the current directory, based on installed packages compiled with
+cmd/compile:
+
+	gotype -c=gc -x .
+
+To verify the output of a pipe:
+
+	echo "package foo" | gotype
+
+*/
+package main
+
+import (
+	"flag"
+	"fmt"
+	"go/ast"
+	"go/build"
+	"go/importer"
+	"go/parser"
+	"go/scanner"
+	"go/token"
+	"go/types"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"sync"
+	"time"
+)
+
+var (
+	// main operation modes
+	testFiles  = flag.Bool("t", false, "include in-package test files in a directory")
+	xtestFiles = flag.Bool("x", false, "consider only external test files in a directory")
+	allErrors  = flag.Bool("e", false, "report all errors, not just the first 10")
+	verbose    = flag.Bool("v", false, "verbose mode")
+	compiler   = flag.String("c", "source", "compiler used for installed packages (gc, gccgo, or source)")
+
+	// additional output control
+	printAST      = flag.Bool("ast", false, "print AST (forces -seq)")
+	printTrace    = flag.Bool("trace", false, "print parse trace (forces -seq)")
+	parseComments = flag.Bool("comments", false, "parse comments (ignored unless -ast or -trace is provided)")
+)
+
+var (
+	fset       = token.NewFileSet()
+	errorCount = 0
+	sequential = false
+	parserMode parser.Mode
+)
+
+func initParserMode() {
+	if *allErrors {
+		parserMode |= parser.AllErrors
+	}
+	if *printAST {
+		sequential = true
+	}
+	if *printTrace {
+		parserMode |= parser.Trace
+		sequential = true
+	}
+	if *parseComments && (*printAST || *printTrace) {
+		parserMode |= parser.ParseComments
+	}
+}
+
+const usageString = `usage: gotype [flags] [path ...]
+
+The gotype command, like the front-end of a Go compiler, parses and
+type-checks a single Go package. Errors are reported if the analysis
+fails; otherwise gotype is quiet (unless -v is set).
+
+Without a list of paths, gotype reads from standard input, which
+must provide a single Go source file defining a complete package.
+
+With a single directory argument, gotype checks the Go files in
+that directory, comprising a single package. Use -t to include the
+(in-package) _test.go files. Use -x to type check only external
+test files.
+
+Otherwise, each path must be the filename of a Go file belonging
+to the same package.
+
+Imports are processed by importing directly from the source of
+imported packages (default), or by importing from compiled and
+installed packages (by setting -c to the respective compiler).
+
+The -c flag must be set to a compiler ("gc", "gccgo") when type-
+checking packages containing imports with relative import paths
+(import "./mypkg") because the source importer cannot know which
+files to include for such packages.
+`
+
+func usage() {
+	fmt.Fprintln(os.Stderr, usageString)
+	flag.PrintDefaults()
+	os.Exit(2)
+}
+
+func report(err error) {
+	scanner.PrintError(os.Stderr, err)
+	if list, ok := err.(scanner.ErrorList); ok {
+		errorCount += len(list)
+		return
+	}
+	errorCount++
+}
+
+// parse may be called concurrently
+func parse(filename string, src interface{}) (*ast.File, error) {
+	if *verbose {
+		fmt.Println(filename)
+	}
+	file, err := parser.ParseFile(fset, filename, src, parserMode) // ok to access fset concurrently
+	if *printAST {
+		ast.Print(fset, file)
+	}
+	return file, err
+}
+
+func parseStdin() (*ast.File, error) {
+	src, err := ioutil.ReadAll(os.Stdin)
+	if err != nil {
+		return nil, err
+	}
+	return parse("<standard input>", src)
+}
+
+func parseFiles(dir string, filenames []string) ([]*ast.File, error) {
+	files := make([]*ast.File, len(filenames))
+	errors := make([]error, len(filenames))
+
+	var wg sync.WaitGroup
+	for i, filename := range filenames {
+		wg.Add(1)
+		go func(i int, filepath string) {
+			defer wg.Done()
+			files[i], errors[i] = parse(filepath, nil)
+		}(i, filepath.Join(dir, filename))
+		if sequential {
+			wg.Wait()
+		}
+	}
+	wg.Wait()
+
+	// if there are errors, return the first one for deterministic results
+	for _, err := range errors {
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	return files, nil
+}
+
+func parseDir(dir string) ([]*ast.File, error) {
+	ctxt := build.Default
+	pkginfo, err := ctxt.ImportDir(dir, 0)
+	if _, nogo := err.(*build.NoGoError); err != nil && !nogo {
+		return nil, err
+	}
+
+	if *xtestFiles {
+		return parseFiles(dir, pkginfo.XTestGoFiles)
+	}
+
+	filenames := append(pkginfo.GoFiles, pkginfo.CgoFiles...)
+	if *testFiles {
+		filenames = append(filenames, pkginfo.TestGoFiles...)
+	}
+	return parseFiles(dir, filenames)
+}
+
+func getPkgFiles(args []string) ([]*ast.File, error) {
+	if len(args) == 0 {
+		// stdin
+		file, err := parseStdin()
+		if err != nil {
+			return nil, err
+		}
+		return []*ast.File{file}, nil
+	}
+
+	if len(args) == 1 {
+		// possibly a directory
+		path := args[0]
+		info, err := os.Stat(path)
+		if err != nil {
+			return nil, err
+		}
+		if info.IsDir() {
+			return parseDir(path)
+		}
+	}
+
+	// list of files
+	return parseFiles("", args)
+}
+
+func checkPkgFiles(files []*ast.File) {
+	type bailout struct{}
+
+	// if checkPkgFiles is called multiple times, set up conf only once
+	conf := types.Config{
+		FakeImportC: true,
+		Error: func(err error) {
+			if !*allErrors && errorCount >= 10 {
+				panic(bailout{})
+			}
+			report(err)
+		},
+		Importer: importer.For(*compiler, nil),
+		Sizes:    types.SizesFor(build.Default.Compiler, build.Default.GOARCH),
+	}
+
+	defer func() {
+		switch p := recover().(type) {
+		case nil, bailout:
+			// normal return or early exit
+		default:
+			// re-panic
+			panic(p)
+		}
+	}()
+
+	const path = "pkg" // any non-empty string will do for now
+	conf.Check(path, fset, files, nil)
+}
+
+func printStats(d time.Duration) {
+	fileCount := 0
+	lineCount := 0
+	fset.Iterate(func(f *token.File) bool {
+		fileCount++
+		lineCount += f.LineCount()
+		return true
+	})
+
+	fmt.Printf(
+		"%s (%d files, %d lines, %d lines/s)\n",
+		d, fileCount, lineCount, int64(float64(lineCount)/d.Seconds()),
+	)
+}
+
+func main() {
+	flag.Usage = usage
+	flag.Parse()
+	initParserMode()
+
+	start := time.Now()
+
+	files, err := getPkgFiles(flag.Args())
+	if err != nil {
+		report(err)
+		os.Exit(2)
+	}
+
+	checkPkgFiles(files)
+	if errorCount > 0 {
+		os.Exit(2)
+	}
+
+	if *verbose {
+		printStats(time.Since(start))
+	}
+}