[clang-format] Add DiagHandler parameter to format::getStyle() (#91317)

It allows to control of error output for the function.

Closes #94205.

---------

Co-authored-by: Owen Pan <[email protected]>

Author: pointhex

clang/include/clang/Format/Format.h

@@ -5387,10 +5387,11 @@ extern const char *DefaultFallbackStyle;
 /// \returns FormatStyle as specified by ``StyleName``. If ``StyleName`` is
 /// "file" and no file is found, returns ``FallbackStyle``. If no style could be
 /// determined, returns an Error.
-Expected<FormatStyle> getStyle(StringRef StyleName, StringRef FileName,
-                               StringRef FallbackStyle, StringRef Code = "",
-                               llvm::vfs::FileSystem *FS = nullptr,
-                               bool AllowUnknownOptions = false);
+Expected<FormatStyle>
+getStyle(StringRef StyleName, StringRef FileName, StringRef FallbackStyle,
+         StringRef Code = "", llvm::vfs::FileSystem *FS = nullptr,
+         bool AllowUnknownOptions = false,
+         llvm::SourceMgr::DiagHandlerTy DiagHandler = nullptr);
 
 // Guesses the language from the ``FileName`` and ``Code`` to be formatted.
 // Defaults to FormatStyle::LK_Cpp.

clang/lib/Format/Format.cpp

@@ -3946,20 +3946,24 @@ const char *DefaultFallbackStyle = "LLVM";
 
 llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>>
 loadAndParseConfigFile(StringRef ConfigFile, llvm::vfs::FileSystem *FS,
-                       FormatStyle *Style, bool AllowUnknownOptions) {
+                       FormatStyle *Style, bool AllowUnknownOptions,
+                       llvm::SourceMgr::DiagHandlerTy DiagHandler) {
   llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>> Text =
       FS->getBufferForFile(ConfigFile.str());
   if (auto EC = Text.getError())
     return EC;
-  if (auto EC = parseConfiguration(*Text.get(), Style, AllowUnknownOptions))
+  if (auto EC = parseConfiguration(*Text.get(), Style, AllowUnknownOptions,
+                                   DiagHandler)) {
     return EC;
+  }
   return Text;
 }
 
 Expected<FormatStyle> getStyle(StringRef StyleName, StringRef FileName,
                                StringRef FallbackStyleName, StringRef Code,
                                llvm::vfs::FileSystem *FS,
-                               bool AllowUnknownOptions) {
+                               bool AllowUnknownOptions,
+                               llvm::SourceMgr::DiagHandlerTy DiagHandler) {
   FormatStyle Style = getLLVMStyle(guessLanguage(FileName, Code));
   FormatStyle FallbackStyle = getNoStyle();
   if (!getPredefinedStyle(FallbackStyleName, Style.Language, &FallbackStyle))
@@ -3972,7 +3976,7 @@ Expected<FormatStyle> getStyle(StringRef StyleName, StringRef FileName,
     StringRef Source = "<command-line>";
     if (std::error_code ec =
             parseConfiguration(llvm::MemoryBufferRef(StyleName, Source), &Style,
-                               AllowUnknownOptions)) {
+                               AllowUnknownOptions, DiagHandler)) {
       return make_string_error("Error parsing -style: " + ec.message());
     }
 
@@ -3992,7 +3996,8 @@ Expected<FormatStyle> getStyle(StringRef StyleName, StringRef FileName,
       StyleName.starts_with_insensitive("file:")) {
     auto ConfigFile = StyleName.substr(5);
     llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>> Text =
-        loadAndParseConfigFile(ConfigFile, FS, &Style, AllowUnknownOptions);
+        loadAndParseConfigFile(ConfigFile, FS, &Style, AllowUnknownOptions,
+                               DiagHandler);
     if (auto EC = Text.getError()) {
       return make_string_error("Error reading " + ConfigFile + ": " +
                                EC.message());
@@ -4031,8 +4036,9 @@ Expected<FormatStyle> getStyle(StringRef StyleName, StringRef FileName,
 
   auto applyChildFormatTexts = [&](FormatStyle *Style) {
     for (const auto &MemBuf : llvm::reverse(ChildFormatTextToApply)) {
-      auto EC = parseConfiguration(*MemBuf, Style, AllowUnknownOptions,
-                                   dropDiagnosticHandler);
+      auto EC =
+          parseConfiguration(*MemBuf, Style, AllowUnknownOptions,
+                             DiagHandler ? DiagHandler : dropDiagnosticHandler);
       // It was already correctly parsed.
       assert(!EC);
       static_cast<void>(EC);
@@ -4066,7 +4072,8 @@ Expected<FormatStyle> getStyle(StringRef StyleName, StringRef FileName,
       }
 
       llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>> Text =
-          loadAndParseConfigFile(ConfigFile, FS, &Style, AllowUnknownOptions);
+          loadAndParseConfigFile(ConfigFile, FS, &Style, AllowUnknownOptions,
+                                 DiagHandler);
       if (auto EC = Text.getError()) {
         if (EC != ParseError::Unsuitable) {
           return make_string_error("Error reading " + ConfigFile + ": " +

clang/unittests/Format/ConfigParseTest.cpp

@@ -1452,6 +1452,27 @@ TEST(ConfigParseTest, GetStyleOfSpecificFile) {
   ASSERT_EQ(*Style, getGoogleStyle());
 }
 
+TEST(ConfigParseTest, GetStyleOutput) {
+  llvm::vfs::InMemoryFileSystem FS;
+
+  // Don't suppress output.
+  testing::internal::CaptureStderr();
+  auto Style = getStyle("{invalid_key=invalid_value}", "a.h", "LLVM", "", &FS,
+                        /*AllowUnknownOptions=*/true);
+  auto Output = testing::internal::GetCapturedStderr();
+  ASSERT_TRUE((bool)Style);
+  ASSERT_FALSE(Output.empty());
+
+  // Suppress stderr.
+  testing::internal::CaptureStderr();
+  Style = getStyle("{invalid_key=invalid_value}", "a.h", "LLVM", "", &FS,
+                   /*AllowUnknownOptions=*/true,
+                   [](const llvm::SMDiagnostic &, void *) {});
+  Output = testing::internal::GetCapturedStderr();
+  ASSERT_TRUE((bool)Style);
+  ASSERT_TRUE(Output.empty());
+}
+
 } // namespace
 } // namespace format
 } // namespace clang