cgo: make file path work for windows

R=golang-dev, mattn.jp, adg
CC=golang-dev
https://golang.org/cl/4634043

src/cmd/cgo/gcc.go

@@ -697,7 +697,7 @@ func (p *Package) gccMachine() []string {
 	return nil
 }
 
-const gccTmp = "_obj/_cgo_.o"
+var gccTmp = objDir + "_cgo_.o"
 
 // gccCmd returns the gcc command line to use for compiling
 // the input.

src/cmd/cgo/main.go

@@ -18,6 +18,7 @@ import (
 	"go/token"
 	"io"
 	"os"
+	"path/filepath"
 	"reflect"
 	"strings"
 )
@@ -228,7 +229,7 @@ func main() {
 		}
 		pkg := f.Package
 		if dir := os.Getenv("CGOPKGPATH"); dir != "" {
-			pkg = dir + "/" + pkg
+			pkg = filepath.Join(dir, pkg)
 		}
 		p.PackagePath = pkg
 		p.writeOutput(f, input)

src/cmd/cgo/out.go

@@ -14,17 +14,20 @@ import (
 	"go/printer"
 	"go/token"
 	"os"
+	"path/filepath"
 	"strings"
 )
 
+var objDir = "_obj" + string(filepath.Separator)
+
 // writeDefs creates output files to be compiled by 6g, 6c, and gcc.
 // (The comments here say 6g and 6c but the code applies to the 8 and 5 tools too.)
 func (p *Package) writeDefs() {
-	fgo2 := creat("_obj/_cgo_gotypes.go")
-	fc := creat("_obj/_cgo_defun.c")
-	fm := creat("_obj/_cgo_main.c")
+	fgo2 := creat(objDir + "_cgo_gotypes.go")
+	fc := creat(objDir + "_cgo_defun.c")
+	fm := creat(objDir + "_cgo_main.c")
 
-	fflg := creat("_obj/_cgo_flags")
+	fflg := creat(objDir + "_cgo_flags")
 	for k, v := range p.CgoFlags {
 		fmt.Fprintf(fflg, "_CGO_%s=%s\n", k, v)
 	}
@@ -285,8 +288,8 @@ func (p *Package) writeOutput(f *File, srcfile string) {
 		base = base[0 : len(base)-3]
 	}
 	base = strings.Map(slashToUnderscore, base)
-	fgo1 := creat("_obj/" + base + ".cgo1.go")
-	fgcc := creat("_obj/" + base + ".cgo2.c")
+	fgo1 := creat(objDir + base + ".cgo1.go")
+	fgcc := creat(objDir + base + ".cgo2.c")
 
 	p.GoFiles = append(p.GoFiles, base+".cgo1.go")
 	p.GccFiles = append(p.GccFiles, base+".cgo2.c")
@@ -361,7 +364,7 @@ func (p *Package) writeOutputFunc(fgcc *os.File, n *Name) {
 // Write out the various stubs we need to support functions exported
 // from Go so that they are callable from C.
 func (p *Package) writeExports(fgo2, fc, fm *os.File) {
-	fgcc := creat("_obj/_cgo_export.c")
+	fgcc := creat(objDir + "_cgo_export.c")
 	fgcch := creat("_cgo_export.h")
 
 	fmt.Fprintf(fgcch, "/* Created by cgo - DO NOT EDIT. */\n")

src/cmd/cgo/util.go

@@ -103,7 +103,7 @@ func creat(name string) *os.File {
 }
 
 func slashToUnderscore(c int) int {
-	if c == '/' {
+	if c == '/' || c == '\\' || c == ':' {
 		c = '_'
 	}
 	return c