[clang-tidy] Make format style customizable

[JDevlieghere]

Summary

I came across an outstanding FIXME to make the format style customizable. Inspired by the include fixer, I added an new option -style to configure the fallback style in case no clang-format configuration file is found. The default remains "llvm".

[JDevlieghere]

• Fixed typo and formatting in ClangTidy.h

[malcolm.parsons]

Always subscribe cfe-commits.

[alexfh]

LG. Thanks!

clang-tidy/ClangTidy.h

runClangTidy(std::unique_ptr<ClangTidyOptionsProvider> OptionsProvider,
              ArrayRef<std::string> InputFiles,
              std::vector<ClangTidyError> *Errors,
              ProfileData *Profile = nullptr);
 
 // FIXME: This interface will need to be significantly extended to be useful.
 // FIXME: Implement confidence levels for displaying/fixing errors.
 //
 /// \brief Displays the found \p Errors to the users. If \p Fix is true, \p
-/// Errors containing fixes are automatically applied.
-void handleErrors(const std::vector<ClangTidyError> &Errors, bool Fix,
+/// Errors containing fixes are automatically applied and reformatted. If no
+/// clang-format configuration file the given \P FormatStyle is used.
+void handleErrors(const std::vector<ClangTidyError> &Errors, bool Fix, StringRef FormatStyle,
                   unsigned &WarningsAsErrorsCount);
 
 /// \brief Serializes replacements into YAML and writes them to the specified
 /// output stream.
 void exportReplacements(const std::vector<ClangTidyError> &Errors,
                         raw_ostream &OS);
 
 } // end namespace tidy
 } // end namespace clang
 
 #endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_CLANGTIDY_H

clang-tidy/ClangTidy.cpp

public:
   bool supportsCrossFileDiagnostics() const override { return true; }
 
 private:
   ClangTidyContext &Context;
 };
 
 class ErrorReporter {
 public:
-  ErrorReporter(bool ApplyFixes)
+  ErrorReporter(bool ApplyFixes, StringRef FormatStyle)
       : Files(FileSystemOptions()), DiagOpts(new DiagnosticOptions()),
         DiagPrinter(new TextDiagnosticPrinter(llvm::outs(), &*DiagOpts)),
         Diags(IntrusiveRefCntPtr<DiagnosticIDs>(new DiagnosticIDs), &*DiagOpts,
               DiagPrinter),
         SourceMgr(Diags, Files), ApplyFixes(ApplyFixes), TotalFixes(0),
-        AppliedFixes(0), WarningsAsErrors(0) {
+        AppliedFixes(0), WarningsAsErrors(0), FormatStyle(FormatStyle) {
     DiagOpts->ShowColors = llvm::sys::Process::StandardOutHasColors();
     DiagPrinter->BeginSourceFile(LangOpts);
   }
 
   SourceManager &getSourceManager() { return SourceMgr; }
 
   void reportDiagnostic(const ClangTidyError &Error) {
     const ClangTidyMessage &Message = Error.Message;
if (ApplyFixes && TotalFixes > 0) {
             SourceMgr.getFileManager().getBufferForFile(File);
         if (!Buffer) {
           llvm::errs() << "Can't get buffer for file " << File << ": "
                        << Buffer.getError().message() << "\n";
           // FIXME: Maybe don't apply fixes for other files as well.
           continue;
         }
         StringRef Code = Buffer.get()->getBuffer();
-        // FIXME: Make the style customizable.
-        format::FormatStyle Style = format::getStyle("file", File, "LLVM");
+        format::FormatStyle Style = format::getStyle("file", File, FormatStyle);
         llvm::Expected<Replacements> CleanReplacements =
             format::cleanupAroundReplacements(Code, FileAndReplacements.second,
                                               Style);
         if (!CleanReplacements) {
           llvm::errs() << llvm::toString(CleanReplacements.takeError()) << "\n";
           continue;
         }
         if (!tooling::applyAllReplacements(CleanReplacements.get(), Rewrite)) {
private:
   DiagnosticConsumer *DiagPrinter;
   DiagnosticsEngine Diags;
   SourceManager SourceMgr;
   llvm::StringMap<Replacements> FileReplacements;
   bool ApplyFixes;
   unsigned TotalFixes;
   unsigned AppliedFixes;
   unsigned WarningsAsErrors;
+  StringRef FormatStyle;
 };
 
 class ClangTidyASTConsumer : public MultiplexConsumer {
 public:
   ClangTidyASTConsumer(std::vector<std::unique_ptr<ASTConsumer>> Consumers,
                        std::unique_ptr<ast_matchers::MatchFinder> Finder,
                        std::vector<std::unique_ptr<ClangTidyCheck>> Checks)
       : MultiplexConsumer(std::move(Consumers)), Finder(std::move(Finder)),
runClangTidy(std::unique_ptr<ClangTidyOptionsProvider> OptionsProvider,
 
   ActionFactory Factory(Context);
   Tool.run(&Factory);
   *Errors = Context.getErrors();
   return Context.getStats();
 }
 
 void handleErrors(const std::vector<ClangTidyError> &Errors, bool Fix,
-                  unsigned &WarningsAsErrorsCount) {
-  ErrorReporter Reporter(Fix);
+                  StringRef FormatStyle, unsigned &WarningsAsErrorsCount) {
+  ErrorReporter Reporter(Fix, FormatStyle);
   vfs::FileSystem &FileSystem =
       *Reporter.getSourceManager().getFileManager().getVirtualFileSystem();
   auto InitialWorkingDir = FileSystem.getCurrentWorkingDirectory();
   if (!InitialWorkingDir)
     llvm::report_fatal_error("Cannot get current working path.");
 
   for (const ClangTidyError &Error : Errors) {
     if (!Error.BuildDirectory.empty()) {

clang-tidy/tool/ClangTidyMain.cpp

configuration can be inspected using -dump-config:
     User:            user
     CheckOptions:
       - key:             some-check.SomeOption
         value:           'some value'
     ...
 
 )");
 
-const char DefaultChecks[] =  // Enable these checks by default:
-    "clang-diagnostic-*,"     //   * compiler diagnostics
-    "clang-analyzer-*";       //   * Static Analyzer checks
+const char DefaultChecks[] = // Enable these checks by default:
+    "clang-diagnostic-*,"    //   * compiler diagnostics
+    "clang-analyzer-*";      //   * Static Analyzer checks
 
 static cl::opt<std::string> Checks("checks", cl::desc(R"(
 Comma-separated list of globs with optional '-'
 prefix. Globs are processed in order of
 appearance in the list. Globs without '-'
 prefix add checks with matching names to the
 set, globs with the '-' prefix remove checks
 with matching names from the set of enabled

 static cl::opt<bool> FixErrors("fix-errors", cl::desc(R"(
 Apply suggested fixes even if compilation
 errors were found. If compiler errors have
 attached fix-its, clang-tidy will apply them as
 well.
 )"),
                                cl::init(false), cl::cat(ClangTidyCategory));
 
+static cl::opt<std::string> FormatStyle("style", cl::desc(R"(
+Fallback style for reformatting after inserting fixes
+if there is no clang-format config file found.
+)"),
+                                        cl::init("llvm"),
+                                        cl::cat(ClangTidyCategory));
+
 static cl::opt<bool> ListChecks("list-checks", cl::desc(R"(
 List all enabled checks and exit. Use with
 -checks=* to list all available checks.
 )"),
                                 cl::init(false), cl::cat(ClangTidyCategory));
 
 static cl::opt<bool> ExplainConfig("explain-config", cl::desc(R"(
 For each enabled check explains, where it is
bool FoundErrors =
         return E.DiagLevel == ClangTidyError::Error;
       }) != Errors.end();
 
   const bool DisableFixes = Fix && FoundErrors && !FixErrors;
 
   unsigned WErrorCount = 0;
 
   // -fix-errors implies -fix.
-  handleErrors(Errors, (FixErrors || Fix) && !DisableFixes, WErrorCount);
+  handleErrors(Errors, (FixErrors || Fix) && !DisableFixes, FormatStyle,
+               WErrorCount);
 
   if (!ExportFixes.empty() && !Errors.empty()) {
     std::error_code EC;
     llvm::raw_fd_ostream OS(ExportFixes, EC, llvm::sys::fs::F_None);
     if (EC) {
       llvm::errs() << "Error opening output file: " << EC.message() << '\n';
       return 1;
     }

docs/clang-tidy/index.rst

-line-filter=<string>        -
                                      [
                                        {"name":"file1.cpp","lines":[[1,3],[5,7]]},
                                        {"name":"file2.h"}
                                      ]
     -list-checks                 - 
                                    List all enabled checks and exit. Use with
                                    -checks=* to list all available checks.
     -p=<string>                  - Build path
+    -style=<string>              -
+                                   Fallback style for reformatting after inserting fixes
+                                   if there is no clang-format config file found.
     -system-headers              - Display the errors from system headers.
     -warnings-as-errors=<string> - 
                                    Upgrades warnings to errors. Same format as
                                    '-checks'.
                                    This option's value is appended to the value of
                                    the 'WarningsAsErrors' option in .clang-tidy
                                    file, if any.