compiler_wrapper: add -clang-tidy-flag support

This CL adds support for specifying compiler flags that're meant to be
passed only to clang-tidy. This allows for easier local experimentation
with clang-tidy by users.

BUG=chromium:982944
TEST=`WITH_TIDY=1 emerge-amd64-generic biod` with custom cflags; cq+1
     on crrev.com/c/2308774

Change-Id: I654559d14a78ade4920fe37757fb5b249a997290
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/toolchain-utils/+/2309152
Reviewed-by: Caroline Tice <cmtice@chromium.org>
Tested-by: George Burgess <gbiv@chromium.org>

3 files changed, 115 insertions, 48 deletions

diff --git a/compiler_wrapper/clang_tidy_flag.go b/compiler_wrapper/clang_tidy_flag.go
index edbbb412..2d97ddd3 100644
--- a/compiler_wrapper/clang_tidy_flag.go
+++ b/compiler_wrapper/clang_tidy_flag.go
@@ -21,10 +21,20 @@ const (
 	tidyModeTricium
 )
 
-func processClangTidyFlags(builder *commandBuilder) (cSrcFile string, mode useTidyMode) {
+func processClangTidyFlags(builder *commandBuilder) (cSrcFile string, clangTidyFlags []string, mode useTidyMode) {
+	builder.transformArgs(func(arg builderArg) string {
+		const prefix = "-clang-tidy-flag="
+		if !strings.HasPrefix(arg.value, prefix) {
+			return arg.value
+		}
+
+		clangTidyFlags = append(clangTidyFlags, arg.value[len(prefix):])
+		return ""
+	})
+
 	withTidy, _ := builder.env.getenv("WITH_TIDY")
 	if withTidy == "" {
-		return "", tidyModeNone
+		return "", clangTidyFlags, tidyModeNone
 	}
 	srcFileSuffixes := []string{
 		".c",
@@ -51,7 +61,7 @@ func processClangTidyFlags(builder *commandBuilder) (cSrcFile string, mode useTi
 	}
 
 	if cSrcFile == "" {
-		return "", tidyModeNone
+		return "", clangTidyFlags, tidyModeNone
 	}
 
 	if withTidy == "tricium" {
@@ -65,7 +75,7 @@ func processClangTidyFlags(builder *commandBuilder) (cSrcFile string, mode useTi
 	} else {
 		mode = tidyModeAll
 	}
-	return cSrcFile, mode
+	return cSrcFile, clangTidyFlags, mode
 }
 
 func calcClangTidyInvocation(env env, clangCmd *command, cSrcFile string, tidyFlags ...string) (*command, error) {
@@ -85,7 +95,7 @@ func calcClangTidyInvocation(env env, clangCmd *command, cSrcFile string, tidyFl
 	}, nil
 }
 
-func runClangTidyForTricium(env env, clangCmd *command, cSrcFile, fixesDir string) error {
+func runClangTidyForTricium(env env, clangCmd *command, cSrcFile, fixesDir string, extraTidyFlags []string) error {
 	if err := os.MkdirAll(fixesDir, 0777); err != nil {
 		return fmt.Errorf("creating fixes directory at %q: %v", fixesDir, err)
 	}
@@ -103,7 +113,8 @@ func runClangTidyForTricium(env env, clangCmd *command, cSrcFile, fixesDir strin
 
 	// FIXME(gbiv): Remove `-checks=*` when testing is complete; we should defer to .clang-tidy
 	// files, which are both more expressive and more approachable than `-checks=*`.
-	clangTidyCmd, err := calcClangTidyInvocation(env, clangCmd, cSrcFile, "-checks=*", "--export-fixes="+fixesFilePath)
+	extraTidyFlags = append(extraTidyFlags, "-checks=*", "--export-fixes="+fixesFilePath)
+	clangTidyCmd, err := calcClangTidyInvocation(env, clangCmd, cSrcFile, extraTidyFlags...)
 	if err != nil {
 		return fmt.Errorf("calculating tidy invocation: %v", err)
 	}
@@ -149,9 +160,9 @@ func runClangTidyForTricium(env env, clangCmd *command, cSrcFile, fixesDir strin
 	return nil
 }
 
-func runClangTidy(env env, clangCmd *command, cSrcFile string) error {
-	clangTidyCmd, err := calcClangTidyInvocation(env, clangCmd, cSrcFile, "-checks="+
-		strings.Join([]string{
+func runClangTidy(env env, clangCmd *command, cSrcFile string, extraTidyFlags []string) error {
+	extraTidyFlags = append(extraTidyFlags,
+		"-checks="+strings.Join([]string{
 			"*",
 			"-bugprone-narrowing-conversions",
 			"-cppcoreguidelines-*",
@@ -165,6 +176,7 @@ func runClangTidy(env env, clangCmd *command, cSrcFile string) error {
 			"-modernize-*",
 			"-readability-*",
 		}, ","))
+	clangTidyCmd, err := calcClangTidyInvocation(env, clangCmd, cSrcFile, extraTidyFlags...)
 	if err != nil {
 		return fmt.Errorf("calculating clang-tidy invocation: %v", err)
 	}
diff --git a/compiler_wrapper/clang_tidy_flag_test.go b/compiler_wrapper/clang_tidy_flag_test.go
index d45d1bdd..54159cdc 100644
--- a/compiler_wrapper/clang_tidy_flag_test.go
+++ b/compiler_wrapper/clang_tidy_flag_test.go
@@ -333,6 +333,59 @@ func TestTriciumClangTidySkipsProtobufFiles(t *testing.T) {
 	})
 }
 
+func testClangTidyFiltersClangTidySpecificFlagsWithPresetEnv(t *testing.T, ctx *testContext) {
+	addedFlag := "--some_clang_tidy=flag"
+	ctx.cmdMock = func(cmd *command, stdin io.Reader, stdout io.Writer, stderr io.Writer) error {
+		switch ctx.cmdCount {
+		case 1:
+			if err := verifyPath(cmd, "usr/bin/clang"); err != nil {
+				t.Error(err)
+			} else if err := verifyArgCount(cmd, 0, addedFlag); err != nil {
+				t.Error(err)
+			}
+			return nil
+		case 2:
+			if err := verifyPath(cmd, "usr/bin/clang-tidy"); err != nil {
+				t.Error(err)
+			} else if verifyArgCount(cmd, 1, addedFlag); err != nil {
+				t.Error(err)
+			}
+			return nil
+		default:
+			return nil
+		}
+	}
+	cmd := ctx.must(callCompiler(ctx, ctx.cfg, ctx.newCommand(clangX86_64, mainCc, "-clang-tidy-flag="+addedFlag)))
+	if ctx.cmdCount != 3 {
+		t.Errorf("expected 3 calls. Got: %d", ctx.cmdCount)
+	}
+	if err := verifyPath(cmd, "usr/bin/clang"); err != nil {
+		t.Error(err)
+	}
+}
+
+func TestClangTidyFiltersClangTidySpecificFlagsForTricium(t *testing.T) {
+	withClangTidyTestContext(t, func(ctx *testContext) {
+		ctx.env = []string{"WITH_TIDY=tricium"}
+		testClangTidyFiltersClangTidySpecificFlagsWithPresetEnv(t, ctx)
+	})
+}
+
+func TestClangTidyFiltersClangTidySpecificFlags(t *testing.T) {
+	withClangTidyTestContext(t, func(ctx *testContext) {
+		testClangTidyFiltersClangTidySpecificFlagsWithPresetEnv(t, ctx)
+	})
+}
+
+func TestClangTidyFlagsAreFilteredFromGccInvocations(t *testing.T) {
+	withTestContext(t, func(ctx *testContext) {
+		cmd := ctx.must(callCompiler(ctx, ctx.cfg, ctx.newCommand(gccX86_64, mainCc, "-clang-tidy-flag=--foo")))
+		if err := verifyArgCount(cmd, 0, ".*--foo.*"); err != nil {
+			t.Error(err)
+		}
+	})
+}
+
 func withClangTidyTestContext(t *testing.T, work func(ctx *testContext)) {
 	withTestContext(t, func(ctx *testContext) {
 		ctx.env = []string{"WITH_TIDY=1"}
diff --git a/compiler_wrapper/compiler_wrapper.go b/compiler_wrapper/compiler_wrapper.go
index 14de210a..a5d35a2c 100644
--- a/compiler_wrapper/compiler_wrapper.go
+++ b/compiler_wrapper/compiler_wrapper.go
@@ -89,53 +89,55 @@ func callCompilerInternal(env env, cfg *config, inputCmd *command) (exitCode int
 		default:
 			return 0, newErrorwithSourceLocf("unsupported compiler: %s", mainBuilder.target.compiler)
 		}
-	} else if mainBuilder.target.compilerType == clangType {
-		cSrcFile, tidyMode := processClangTidyFlags(mainBuilder)
-		err := prepareClangCommand(mainBuilder)
-		if err != nil {
-			return 0, err
-		}
-		allowCCache := true
-		if tidyMode != tidyModeNone {
-			allowCCache = false
-			clangCmdWithoutGomaAndCCache := mainBuilder.build()
-			var err error
-			switch tidyMode {
-			case tidyModeTricium:
-				if cfg.triciumNitsDir == "" {
-					return 0, newErrorwithSourceLocf("tricium linting was requested, but no nits directory is configured")
-				}
-				err = runClangTidyForTricium(env, clangCmdWithoutGomaAndCCache, cSrcFile, cfg.triciumNitsDir)
-			case tidyModeAll:
-				err = runClangTidy(env, clangCmdWithoutGomaAndCCache, cSrcFile)
-			default:
-				panic(fmt.Sprintf("Unknown tidy mode: %v", tidyMode))
-			}
-
+	} else {
+		cSrcFile, tidyFlags, tidyMode := processClangTidyFlags(mainBuilder)
+		if mainBuilder.target.compilerType == clangType {
+			err := prepareClangCommand(mainBuilder)
 			if err != nil {
 				return 0, err
 			}
-		}
-		if err := processGomaCCacheFlags(allowCCache, mainBuilder); err != nil {
-			return 0, err
-		}
-		compilerCmd = mainBuilder.build()
-	} else {
-		if clangSyntax {
-			allowCCache := false
-			clangCmd, err := calcClangCommand(allowCCache, mainBuilder.clone())
-			if err != nil {
+			allowCCache := true
+			if tidyMode != tidyModeNone {
+				allowCCache = false
+				clangCmdWithoutGomaAndCCache := mainBuilder.build()
+				var err error
+				switch tidyMode {
+				case tidyModeTricium:
+					if cfg.triciumNitsDir == "" {
+						return 0, newErrorwithSourceLocf("tricium linting was requested, but no nits directory is configured")
+					}
+					err = runClangTidyForTricium(env, clangCmdWithoutGomaAndCCache, cSrcFile, cfg.triciumNitsDir, tidyFlags)
+				case tidyModeAll:
+					err = runClangTidy(env, clangCmdWithoutGomaAndCCache, cSrcFile, tidyFlags)
+				default:
+					panic(fmt.Sprintf("Unknown tidy mode: %v", tidyMode))
+				}
+
+				if err != nil {
+					return 0, err
+				}
+			}
+			if err := processGomaCCacheFlags(allowCCache, mainBuilder); err != nil {
 				return 0, err
 			}
-			gccCmd, err := calcGccCommand(mainBuilder)
+			compilerCmd = mainBuilder.build()
+		} else {
+			if clangSyntax {
+				allowCCache := false
+				clangCmd, err := calcClangCommand(allowCCache, mainBuilder.clone())
+				if err != nil {
+					return 0, err
+				}
+				gccCmd, err := calcGccCommand(mainBuilder)
+				if err != nil {
+					return 0, err
+				}
+				return checkClangSyntax(env, clangCmd, gccCmd)
+			}
+			compilerCmd, err = calcGccCommand(mainBuilder)
 			if err != nil {
 				return 0, err
 			}
-			return checkClangSyntax(env, clangCmd, gccCmd)
-		}
-		compilerCmd, err = calcGccCommand(mainBuilder)
-		if err != nil {
-			return 0, err
 		}
 	}
 	rusageLogfileName := getRusageLogFilename(env)