Deduplicate clang-tidy error messages by file, offset and message.

[alexfh]

Summary

Peter, I guess, this can help you in testing your check.

[alexfh]

Addressed review comments.

[alexfh]

Addressed all review comments ;)

[alexfh]

Changed the comparator implementation to use std::tie.

[klimek]

lg

clang-tidy/ClangTidyDiagnosticConsumer.cpp

 ///    http://clang.llvm.org/docs/HowToSetupToolingForLLVM.html
 ///  for details on setting it up with LLVM source tree.
 ///
 //===----------------------------------------------------------------------===//
 
 #include "ClangTidyDiagnosticConsumer.h"
 #include "llvm/ADT/SmallString.h"
 
+#include <set>
+#include <tuple>
+
 namespace clang {
 namespace tidy {
 
 ClangTidyMessage::ClangTidyMessage(StringRef Message) : Message(Message) {}
 
 ClangTidyMessage::ClangTidyMessage(StringRef Message,
                                    const SourceManager &Sources,
                                    SourceLocation Loc)
void ClangTidyDiagnosticConsumer::HandleDiagnostic(
 
   // Let argument parsing-related warnings through.
   if (!Info.getLocation().isValid() ||
       !Diags->getSourceManager().isInSystemHeader(Info.getLocation())) {
     LastErrorRelatesToUserCode = true;
   }
 }
 
+struct LessClangTidyError {
+  bool operator()(const ClangTidyError *LHS, const ClangTidyError *RHS) const {
+    const ClangTidyMessage &M1 = LHS->Message;
+    const ClangTidyMessage &M2 = RHS->Message;
+
+    return std::tie(M1.FilePath, M1.FileOffset, M1.Message) <
+           std::tie(M2.FilePath, M2.FileOffset, M2.Message);
+  }
+};
+
 // Flushes the internal diagnostics buffer to the ClangTidyContext.
 void ClangTidyDiagnosticConsumer::finish() {
   finalizeLastError();
-  for (const ClangTidyError &Error : Errors)
+  std::set<const ClangTidyError*, LessClangTidyError> UniqueErrors;
+  for (const ClangTidyError &Error : Errors) {
+    if (UniqueErrors.insert(&Error).second)
       Context.storeError(Error);
+  }
   Errors.clear();
 }
 
 void ClangTidyDiagnosticConsumer::addFixes(const Diagnostic &Info,
                                            ClangTidyError &Error) {
   if (!Info.hasSourceManager())
     return;
   SourceManager &Sources = Info.getSourceManager();

test/clang-tidy/deduplication.cpp

+// RUN: clang-tidy -checks=google-explicit-constructor %s -- | FileCheck %s
+
+template<typename T>
+class A { A(T); };
+// CHECK: :[[@LINE-1]]:11: warning: Single-argument constructors must be explicit [google-explicit-constructor]
+// CHECK-NOT: warning:
+
+
+void f() {
+  A<int> a;
+  A<double> b;
+}