[clang-tidy] Allow access to the SourceManager in clang-tidy checks

[nicovank]

Summary

I am writing a prototype check that needs source file and line numbers to map code to external data. As far as I know, the only way to achieve that is to expose the SourceManager which is so far only used to emit diagnostics.

Test Plan:
On a blank new check, MatchedDecl->getBeginLoc().dump(Context->getSourceManager()); does properly show the matched declaration's origin filename and line number.

[gribozavr2]

Could you provide more context? There seems to be plenty of ways to access the SourceManager from a ClangTidy check, for example, see clang-tools-extra/clang-tidy/readability/ElseAfterReturnCheck.cpp

[nicovank]

Thanks! Looks like registerPPCallbacks might be what I am looking for, I was not aware of it. I will mark this as planning changes temporarily, then abandon if solved.

[nicovank]

Looks like registerPPCallbacks / Result.Context->getSourceManager() gives me the information I need. Thank you @gribozavr2 for your help!

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

shouldSuppressDiagnostic(DiagnosticsEngine::Level DiagLevel,
                            SmallVectorImpl<tooling::Diagnostic> &NoLintErrors,
                            bool AllowIO = true, bool EnableNoLintBlocks = true);
 
   /// Sets the \c SourceManager of the used \c DiagnosticsEngine.
   ///
   /// This is called from the \c ClangTidyCheck base class.
   void setSourceManager(SourceManager *SourceMgr);
 
+  /// Gets the \c SourceManager from the used \c DiagnosticsEngine.
+  SourceManager &getSourceManager();
+
   /// Should be called when starting to process new translation unit.
   void setCurrentFile(StringRef File);
 
   /// Returns the main file name of the current translation unit.
   StringRef getCurrentFile() const { return CurrentFile; }
 
   /// Sets ASTContext for the current translation unit.
   void setASTContext(ASTContext *Context);

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

bool ClangTidyContext::shouldSuppressDiagnostic(
   return NoLintHandler.shouldSuppress(DiagLevel, Info, CheckName, NoLintErrors,
                                       AllowIO, EnableNoLintBlocks);
 }
 
 void ClangTidyContext::setSourceManager(SourceManager *SourceMgr) {
   DiagEngine->setSourceManager(SourceMgr);
 }
 
+SourceManager &ClangTidyContext::getSourceManager() {
+  return DiagEngine->getSourceManager();
+}
+
 void ClangTidyContext::setCurrentFile(StringRef File) {
   CurrentFile = std::string(File);
   CurrentOptions = getOptionsForFile(CurrentFile);
   CheckFilter = std::make_unique<CachedGlobList>(*getOptions().Checks);
   WarningAsErrorFilter =
       std::make_unique<CachedGlobList>(*getOptions().WarningsAsErrors);
 }