[clang-tidy] Make format style customizable

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". 

Reviewers: Prazek, aaron.ballman, hokein, alexfh

Subscribers: cfe-commits, malcolm.parsons

Tags: #clang-tools-extra

Differential Revision: https://reviews.llvm.org/D27142

llvm-svn: 288258

clang-tools-extra/clang-tidy/ClangTidy.cpp

@@ -88,13 +88,13 @@ private:
 
 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);
   }
@@ -196,8 +196,7 @@ public:
           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);
@@ -248,6 +247,7 @@ private:
   unsigned TotalFixes;
   unsigned AppliedFixes;
   unsigned WarningsAsErrors;
+  StringRef FormatStyle;
 };
 
 class ClangTidyASTConsumer : public MultiplexConsumer {
@@ -538,8 +538,8 @@ runClangTidy(std::unique_ptr<ClangTidyOptionsProvider> OptionsProvider,
 }
 
 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();

clang-tools-extra/clang-tidy/ClangTidy.h

@@ -235,9 +235,10 @@ runClangTidy(std::unique_ptr<ClangTidyOptionsProvider> OptionsProvider,
 // 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.
+/// Errors containing fixes are automatically applied and reformatted. If no
+/// clang-format configuration file is found, the given \P FormatStyle is used.
 void handleErrors(const std::vector<ClangTidyError> &Errors, bool Fix,
-                  unsigned &WarningsAsErrorsCount);
+                  StringRef FormatStyle, unsigned &WarningsAsErrorsCount);
 
 /// \brief Serializes replacements into YAML and writes them to the specified
 /// output stream.

clang-tools-extra/clang-tidy/tool/ClangTidyMain.cpp

@@ -49,9 +49,9 @@ Configuration files:
 
 )");
 
-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 '-'
@@ -120,6 +120,13 @@ 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.
@@ -386,7 +393,8 @@ static int clangTidyMain(int argc, const char **argv) {
   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;

clang-tools-extra/docs/clang-tidy/index.rst

@@ -179,6 +179,9 @@ An overview of all the command-line options:
                                    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