[dev.regabi] go/types: add support for language version checking

This is a port of CL 289509 to go/types. It differs from that CL in
codes added to errors, to fit the new factoring of check_test.go, and to
allow go/types to import regexp in deps_test.go

For #31793

Change-Id: Ia9e4c7f5aac1493001189184227c2ebc79a76e77
Reviewed-on: https://go-review.googlesource.com/c/go/+/291317
Trust: Robert Findley <rfindley@google.com>
Run-TryBot: Robert Findley <rfindley@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>

1 files changed, 29 insertions, 7 deletions

diff --git a/src/go/types/check_test.go b/src/go/types/check_test.go
index 7292f7bcb2..ca7d926ca9 100644
--- a/src/go/types/check_test.go
+++ b/src/go/types/check_test.go
@@ -47,7 +47,8 @@ import (
 var (
 	haltOnError = flag.Bool("halt", false, "halt on error")
 	listErrors  = flag.Bool("errlist", false, "list errors")
-	testFiles   = flag.String("files", "", "space-separated list of test files")
+	testFiles   = flag.String("files", "", "comma-separated list of test files")
+	goVersion   = flag.String("lang", "", "Go language version (e.g. \"go1.12\"")
 )
 
 var fset = token.NewFileSet()
@@ -188,7 +189,21 @@ func eliminate(t *testing.T, errmap map[string][]string, errlist []error) {
 	}
 }
 
-func checkFiles(t *testing.T, filenames []string, srcs [][]byte) {
+// goVersionRx matches a Go version string using '_', e.g. "go1_12".
+var goVersionRx = regexp.MustCompile(`^go[1-9][0-9]*_(0|[1-9][0-9]*)$`)
+
+// asGoVersion returns a regular Go language version string
+// if s is a Go version string using '_' rather than '.' to
+// separate the major and minor version numbers (e.g. "go1_12").
+// Otherwise it returns the empty string.
+func asGoVersion(s string) string {
+	if goVersionRx.MatchString(s) {
+		return strings.Replace(s, "_", ".", 1)
+	}
+	return ""
+}
+
+func checkFiles(t *testing.T, goVersion string, filenames []string, srcs [][]byte) {
 	if len(filenames) == 0 {
 		t.Fatal("no source files")
 	}
@@ -201,6 +216,11 @@ func checkFiles(t *testing.T, filenames []string, srcs [][]byte) {
 		pkgName = files[0].Name.Name
 	}
 
+	// if no Go version is given, consider the package name
+	if goVersion == "" {
+		goVersion = asGoVersion(pkgName)
+	}
+
 	if *listErrors && len(errlist) > 0 {
 		t.Errorf("--- %s:", pkgName)
 		for _, err := range errlist {
@@ -210,6 +230,7 @@ func checkFiles(t *testing.T, filenames []string, srcs [][]byte) {
 
 	// typecheck and collect typechecker errors
 	var conf Config
+	conf.GoVersion = goVersion
 
 	// special case for importC.src
 	if len(filenames) == 1 {
@@ -267,19 +288,20 @@ func checkFiles(t *testing.T, filenames []string, srcs [][]byte) {
 }
 
 // TestCheck is for manual testing of selected input files, provided with -files.
+// The accepted Go language version can be controlled with the -lang flag.
 func TestCheck(t *testing.T) {
 	if *testFiles == "" {
 		return
 	}
 	testenv.MustHaveGoBuild(t)
 	DefPredeclaredTestFuncs()
-	testPkg(t, strings.Split(*testFiles, " "))
+	testPkg(t, strings.Split(*testFiles, ","), *goVersion)
 }
 
 func TestLongConstants(t *testing.T) {
 	format := "package longconst\n\nconst _ = %s\nconst _ = %s // ERROR excessively long constant"
 	src := fmt.Sprintf(format, strings.Repeat("1", 9999), strings.Repeat("1", 10001))
-	checkFiles(t, []string{"longconst.go"}, [][]byte{[]byte(src)})
+	checkFiles(t, "", []string{"longconst.go"}, [][]byte{[]byte(src)})
 }
 
 func TestTestdata(t *testing.T)  { DefPredeclaredTestFuncs(); testDir(t, "testdata") }
@@ -312,12 +334,12 @@ func testDir(t *testing.T, dir string) {
 			filenames = []string{path}
 		}
 		t.Run(filepath.Base(path), func(t *testing.T) {
-			testPkg(t, filenames)
+			testPkg(t, filenames, "")
 		})
 	}
 }
 
-func testPkg(t *testing.T, filenames []string) {
+func testPkg(t *testing.T, filenames []string, goVersion string) {
 	srcs := make([][]byte, len(filenames))
 	for i, filename := range filenames {
 		src, err := os.ReadFile(filename)
@@ -326,5 +348,5 @@ func testPkg(t *testing.T, filenames []string) {
 		}
 		srcs[i] = src
 	}
-	checkFiles(t, filenames, srcs)
+	checkFiles(t, goVersion, filenames, srcs)
 }