Revert "Disallow -warnings-as-errors in tidy_flags"

This reverts commit 2d481842b1.

Reason for revert: b/235569235#comment4

Change-Id: I5c87b1d5a1bdf0bad7f436c397688fe3fc20d04e

cc/tidy.go

@@ -188,14 +188,31 @@ func (tidy *tidyFeature) flags(ctx ModuleContext, flags Flags) Flags {
 	tidyChecks = tidyChecks + ",-cert-err33-c"
 	flags.TidyFlags = append(flags.TidyFlags, tidyChecks)
 
-	// Embedding -warnings-as-errors in tidy_flags is error-prone.
+	if ctx.Config().IsEnvTrue("WITH_TIDY") {
-	// It should be replaced with the tidy_checks_as_errors list.
+		// WITH_TIDY=1 enables clang-tidy globally. There could be many unexpected
-	for _, s := range flags.TidyFlags {
+		// warnings from new checks and many local tidy_checks_as_errors and
-		if strings.Contains(s, "-warnings-as-errors=") {
+		// -warnings-as-errors can break a global build.
-			ctx.PropertyErrorf("tidy_flags", "should not contain -warnings-as-errors, use tidy_checks_as_errors instead")
+		// So allow all clang-tidy warnings.
+		inserted := false
+		for i, s := range flags.TidyFlags {
+			if strings.Contains(s, "-warnings-as-errors=") {
+				// clang-tidy accepts only one -warnings-as-errors
+				// replace the old one
+				re := regexp.MustCompile(`'?-?-warnings-as-errors=[^ ]* *`)
+				newFlag := re.ReplaceAllString(s, "")
+				if newFlag == "" {
+					flags.TidyFlags[i] = "-warnings-as-errors=-*"
+				} else {
+					flags.TidyFlags[i] = newFlag + " -warnings-as-errors=-*"
+				}
+				inserted = true
+				break
+			}
 		}
-	}
+		if !inserted {
-	if len(tidy.Properties.Tidy_checks_as_errors) > 0 {
+			flags.TidyFlags = append(flags.TidyFlags, "-warnings-as-errors=-*")
+		}
+	} else if len(tidy.Properties.Tidy_checks_as_errors) > 0 {
 		tidyChecksAsErrors := "-warnings-as-errors=" + strings.Join(esc(ctx, "tidy_checks_as_errors", tidy.Properties.Tidy_checks_as_errors), ",")
 		flags.TidyFlags = append(flags.TidyFlags, tidyChecksAsErrors)
 	}

cc/tidy_test.go

@@ -22,76 +22,6 @@ import (
 	"android/soong/android"
 )
 
-func TestTidyFlagsWarningsAsErrors(t *testing.T) {
-	// The "tidy_flags" property should not contain -warnings-as-errors.
-	testCases := []struct {
-		libName, bp string
-		errorMsg    string   // a negative test; must have error message
-		flags       []string // must have substrings in tidyFlags
-		noFlags     []string // must not have substrings in tidyFlags
-	}{
-		{
-			"libfoo1",
-			`cc_library_shared { // no warnings-as-errors, good tidy_flags
-			  name: "libfoo1",
-			  srcs: ["foo.c"],
-              tidy_flags: ["-header-filter=dir1/"],
-		    }`,
-			"",
-			[]string{"-header-filter=dir1/"},
-			[]string{"-warnings-as-errors"},
-		},
-		{
-			"libfoo2",
-			`cc_library_shared { // good use of tidy_checks_as_errors
-			  name: "libfoo2",
-			  srcs: ["foo.c"],
-			  tidy_checks_as_errors: ["xyz-*", "abc"],
-              tidy_flags: ["-header-filter=dir2/"],
-		    }`,
-			"",
-			[]string{"-header-filter=dir2/", "-warnings-as-errors='xyz-*',abc"},
-			[]string{},
-		},
-		{
-			"libfoo3",
-			`cc_library_shared { // bad use of -warnings-as-errors in tidy_flags
-			  name: "libfoo3",
-			  srcs: ["foo.c"],
-              tidy_flags: [
-                "-header-filters=.*",
-			    "-warnings-as-errors=xyz-*",
-              ],
-		    }`,
-			`module "libfoo3" .*: tidy_flags: should not contain -warnings-as-errors,` +
-				` use tidy_checks_as_errors instead`,
-			[]string{},
-			[]string{},
-		},
-	}
-	for _, test := range testCases {
-		if test.errorMsg != "" {
-			testCcError(t, test.errorMsg, test.bp)
-			continue
-		}
-		variant := "android_arm64_armv8-a_shared"
-		ctx := testCc(t, test.bp)
-		t.Run("caseTidyFlags", func(t *testing.T) {
-			flags := ctx.ModuleForTests(test.libName, variant).Rule("clangTidy").Args["tidyFlags"]
-			for _, flag := range test.flags {
-				if !strings.Contains(flags, flag) {
-					t.Errorf("tidyFlags for %s does not contain %s.", test.libName, flag)
-				}
-			}
-			for _, flag := range test.noFlags {
-				if strings.Contains(flags, flag) {
-					t.Errorf("tidyFlags for %s should not contain %s.", test.libName, flag)
-				}
-			}
-		})
-	}
-}
-
 func TestTidyChecks(t *testing.T) {
 	// The "tidy_checks" property defines additional checks appended
 	// to global default. But there are some checks disabled after