go/buildutil: TagsFlag provides a flag.Value for setting build.Context.BuildTags from -tags flag.

Add -tags flag to oracle, ssadump, callgraph, gomvpkg, gorename, eg.

Change-Id: I4a818501b2331c4ea589caca37a3ad9d381dc8af
Reviewed-on: https://go-review.googlesource.com/9172
Reviewed-by: David Crawshaw <crawshaw@golang.org>

cmd/callgraph/main.go

@@ -30,6 +30,7 @@ import (
 	"runtime"
 	"text/template"
 
+	"golang.org/x/tools/go/buildutil"
 	"golang.org/x/tools/go/callgraph"
 	"golang.org/x/tools/go/callgraph/cha"
 	"golang.org/x/tools/go/callgraph/rta"
@@ -50,6 +51,10 @@ var formatFlag = flag.String("format",
 	"{{.Caller}}\t--{{.Dynamic}}-{{.Line}}:{{.Column}}-->\t{{.Callee}}",
 	"A template expression specifying how to format an edge")
 
+func init() {
+	flag.Var((*buildutil.TagsFlag)(&build.Default.BuildTags), "tags", buildutil.TagsFlagDoc)
+}
+
 const Usage = `callgraph: display the the call graph of a Go program.
 
 Usage:

cmd/eg/eg.go

@@ -6,6 +6,7 @@ package main // import "golang.org/x/tools/cmd/eg"
 import (
 	"flag"
 	"fmt"
+	"go/build"
 	"go/parser"
 	"go/printer"
 	"go/token"
@@ -13,6 +14,7 @@ import (
 	"os/exec"
 	"strings"
 
+	"golang.org/x/tools/go/buildutil"
 	"golang.org/x/tools/go/loader"
 	"golang.org/x/tools/refactor/eg"
 )
@@ -26,6 +28,10 @@ var (
 	verboseFlag    = flag.Bool("v", false, "show verbose matcher diagnostics")
 )
 
+func init() {
+	flag.Var((*buildutil.TagsFlag)(&build.Default.BuildTags), "tags", buildutil.TagsFlagDoc)
+}
+
 const usage = `eg: an example-based refactoring tool.
 
 Usage: eg -t template.go [-w] [-transitive] <args>...

cmd/gomvpkg/main.go

@@ -12,6 +12,7 @@ import (
 	"go/build"
 	"os"
 
+	"golang.org/x/tools/go/buildutil"
 	"golang.org/x/tools/refactor/rename"
 )
 
@@ -22,6 +23,10 @@ var (
 	helpFlag     = flag.Bool("help", false, "show usage message")
 )
 
+func init() {
+	flag.Var((*buildutil.TagsFlag)(&build.Default.BuildTags), "tags", buildutil.TagsFlagDoc)
+}
+
 const Usage = `gomvpkg: moves a package, updating import declarations
 
 Usage:

cmd/gorename/main.go

@@ -14,6 +14,7 @@ import (
 	"os"
 	"runtime"
 
+	"golang.org/x/tools/go/buildutil"
 	"golang.org/x/tools/refactor/rename"
 )
 
@@ -25,6 +26,7 @@ var (
 )
 
 func init() {
+	flag.Var((*buildutil.TagsFlag)(&build.Default.BuildTags), "tags", buildutil.TagsFlagDoc)
 	flag.BoolVar(&rename.Force, "force", false, "proceed, even if conflicts were reported")
 	flag.BoolVar(&rename.DryRun, "dryrun", false, "show the change, but do not apply it")
 	flag.BoolVar(&rename.Verbose, "v", false, "print verbose information")

cmd/oracle/main.go

@@ -23,6 +23,7 @@ import (
 	"runtime"
 	"runtime/pprof"
 
+	"golang.org/x/tools/go/buildutil"
 	"golang.org/x/tools/go/loader"
 	"golang.org/x/tools/oracle"
 )
@@ -38,6 +39,10 @@ var formatFlag = flag.String("format", "plain", "Output format.  One of {plain,j
 
 var reflectFlag = flag.Bool("reflect", false, "Analyze reflection soundly (slow).")
 
+func init() {
+	flag.Var((*buildutil.TagsFlag)(&build.Default.BuildTags), "tags", buildutil.TagsFlagDoc)
+}
+
 const useHelp = "Run 'oracle -help' for more information.\n"
 
 const helpMessage = `Go source code oracle.

cmd/ssadump/main.go

@@ -13,6 +13,7 @@ import (
 	"runtime"
 	"runtime/pprof"
 
+	"golang.org/x/tools/go/buildutil"
 	"golang.org/x/tools/go/loader"
 	"golang.org/x/tools/go/ssa"
 	"golang.org/x/tools/go/ssa/interp"
@@ -39,7 +40,7 @@ Usage: ssadump [<flag> ...] <args> ...
 Use -help flag to display options.
 
 Examples:
-% ssadump -build=FP -importbin hello.go  # quickly dump SSA form of a single package
+% ssadump -build=F hello.go              # dump SSA form of a single package
 % ssadump -run -interp=T hello.go        # interpret a program, with tracing
 % ssadump -run -test unicode -- -test.v  # interpret the unicode package's tests, verbosely
 ` + loader.FromArgsUsage +
@@ -53,6 +54,8 @@ if set, it runs the tests of each package.
 var cpuprofile = flag.String("cpuprofile", "", "write cpu profile to file")
 
 func init() {
+	flag.Var((*buildutil.TagsFlag)(&build.Default.BuildTags), "tags", buildutil.TagsFlagDoc)
+
 	// If $GOMAXPROCS isn't set, use the full capacity of the machine.
 	// For small machines, use at least 4 threads.
 	if os.Getenv("GOMAXPROCS") == "" {
@@ -76,8 +79,8 @@ func doMain() error {
 	args := flag.Args()
 
 	conf := loader.Config{Build: &build.Default}
-	// TODO(adonovan): make go/types choose its default Sizes from
-	// build.Default or a specified *build.Context.
+
+	// Choose types.Sizes from conf.Build.
 	var wordSize int64 = 8
 	switch conf.Build.GOARCH {
 	case "386", "arm":

go/buildutil/tags.go

@@ -0,0 +1,73 @@
+package buildutil
+
+// This logic was copied from stringsFlag from $GOROOT/src/cmd/go/build.go.
+
+import "fmt"
+
+const TagsFlagDoc = `'tag list'\ta list of build tags to consider satisfied during the build.
+For more information about build tags, see the description of
+build constraints in the documentation for the go/build package`
+
+// TagsFlag is an implementation of the flag.Value interface that parses
+// a flag value in the same manner as go build's -tags flag and
+// populates a []string slice.
+//
+// See $GOROOT/src/go/build/doc.go for description of build tags.
+// See $GOROOT/src/cmd/go/doc.go for description of 'go build -tags' flag.
+//
+// Example:
+//	flag.Var((*buildutil.TagsFlag)(&build.Default.BuildTags), "tags", buildutil.TagsDoc)
+type TagsFlag []string
+
+func (v *TagsFlag) Set(s string) error {
+	var err error
+	*v, err = splitQuotedFields(s)
+	if *v == nil {
+		*v = []string{}
+	}
+	return err
+}
+
+func splitQuotedFields(s string) ([]string, error) {
+	// Split fields allowing '' or "" around elements.
+	// Quotes further inside the string do not count.
+	var f []string
+	for len(s) > 0 {
+		for len(s) > 0 && isSpaceByte(s[0]) {
+			s = s[1:]
+		}
+		if len(s) == 0 {
+			break
+		}
+		// Accepted quoted string. No unescaping inside.
+		if s[0] == '"' || s[0] == '\'' {
+			quote := s[0]
+			s = s[1:]
+			i := 0
+			for i < len(s) && s[i] != quote {
+				i++
+			}
+			if i >= len(s) {
+				return nil, fmt.Errorf("unterminated %c string", quote)
+			}
+			f = append(f, s[:i])
+			s = s[i+1:]
+			continue
+		}
+		i := 0
+		for i < len(s) && !isSpaceByte(s[i]) {
+			i++
+		}
+		f = append(f, s[:i])
+		s = s[i:]
+	}
+	return f, nil
+}
+
+func (v *TagsFlag) String() string {
+	return "<tagsFlag>"
+}
+
+func isSpaceByte(c byte) bool {
+	return c == ' ' || c == '\t' || c == '\n' || c == '\r'
+}

go/buildutil/tags_test.go

@@ -0,0 +1,28 @@
+package buildutil_test
+
+import (
+	"flag"
+	"go/build"
+	"reflect"
+	"testing"
+
+	"golang.org/x/tools/go/buildutil"
+)
+
+func TestTags(t *testing.T) {
+	f := flag.NewFlagSet("TestTags", flag.PanicOnError)
+	var ctxt build.Context
+	f.Var((*buildutil.TagsFlag)(&ctxt.BuildTags), "tags", buildutil.TagsFlagDoc)
+	f.Parse([]string{"-tags", ` 'one'"two"	'three "four"'`, "rest"})
+
+	// BuildTags
+	want := []string{"one", "two", "three \"four\""}
+	if !reflect.DeepEqual(ctxt.BuildTags, want) {
+		t.Errorf("BuildTags = %q, want %q", ctxt.BuildTags, want)
+	}
+
+	// Args()
+	if want := []string{"rest"}; !reflect.DeepEqual(f.Args(), want) {
+		t.Errorf("f.Args() = %q, want %q", f.Args(), want)
+	}
+}