Add OutputPath.ReplaceExtension()

Add a helper method that returns a new OutputPath with the
extension replaced.

Test: paths_test.go
Change-Id: I7f93b3475031a19b53652022740488373a1b7d97

android/paths.go

@@ -697,6 +697,16 @@ func (p OutputPath) Join(ctx PathContext, paths ...string) OutputPath {
 	return p.withRel(path)
 }
 
+// ReplaceExtension creates a new OutputPath with the extension replaced with ext.
+func (p OutputPath) ReplaceExtension(ctx PathContext, ext string) OutputPath {
+	if strings.Contains(ext, "/") {
+		reportPathErrorf(ctx, "extension %q cannot contain /", ext)
+	}
+	ret := PathForOutput(ctx, pathtools.ReplaceExtension(p.path, ext))
+	ret.rel = p.rel
+	return ret
+}
+
 // PathForIntermediates returns an OutputPath representing the top-level
 // intermediates directory.
 func PathForIntermediates(ctx PathContext, paths ...string) OutputPath {

android/paths_test.go

@@ -691,3 +691,15 @@ func TestPathForSource(t *testing.T) {
 		})
 	}
 }
+
+func ExampleOutputPath_ReplaceExtension() {
+	ctx := &configErrorWrapper{
+		config: TestConfig("out", nil),
+	}
+	p := PathForOutput(ctx, "system/framework/boot.art")
+	p2 := p.ReplaceExtension(ctx, "oat")
+	fmt.Println(p, p2)
+
+	// Output:
+	// out/system/framework/boot.art out/system/framework/boot.oat
+}