[PATCH] D21936: [clang-tidy] UnnecessaryValueParamCheck - only warn for virtual methods

[Felix Berger via cfe-commits]

flx created this revision.
flx added reviewers: alexfh, sbenza.
flx added a subscriber: cfe-commits.
flx set the repository for this revision to rL LLVM.

As changing virtual methods could break method overrides disable applying the fix and just warn.

Repository:
  rL LLVM

http://reviews.llvm.org/D21936

Files:
  clang-tidy/performance/UnnecessaryValueParamCheck.cpp
  test/clang-tidy/performance-unnecessary-value-param.cpp

Index: test/clang-tidy/performance-unnecessary-value-param.cpp
===================================================================
--- test/clang-tidy/performance-unnecessary-value-param.cpp
+++ test/clang-tidy/performance-unnecessary-value-param.cpp
@@ -224,3 +224,16 @@
   ExpensiveToCopyType B;
   B = A;
 }
+
+struct VirtualMethodWarningOnly {
+  virtual void methodWithExpensiveValueParam(ExpensiveToCopyType T) {}
+  // CHECK-MESSAGES: [[@LINE-1]]:66: warning: the parameter 'T' is copied
+  // CHECK-FIXES: virtual void methodWithExpensiveValueParam(ExpensiveToCopyType T) {}
+  virtual ~VirtualMethodWarningOnly() {}
+};
+
+struct PositiveNonVirualMethod {
+  void method(const ExpensiveToCopyType T) {}
+  // CHECK-MESSAGES: [[@LINE-1]]:41: warning: the const qualified parameter 'T' is copied
+  // CHECK-FIXES: void method(const ExpensiveToCopyType& T) {}
+};
Index: clang-tidy/performance/UnnecessaryValueParamCheck.cpp
===================================================================
--- clang-tidy/performance/UnnecessaryValueParamCheck.cpp
+++ clang-tidy/performance/UnnecessaryValueParamCheck.cpp
@@ -118,8 +118,10 @@
                               "invocation but only used as a const reference; "
                               "consider making it a const reference")
       << paramNameOrIndex(Param->getName(), Index);
-  // Do not propose fixes in macros since we cannot place them correctly.
-  if (Param->getLocStart().isMacroID())
+  // Do not propose fixes in macros since we cannot place them correctly, or if
+  // function is virtual as it might break overrides.
+  const auto *Method = llvm::dyn_cast<CXXMethodDecl>(Function);
+  if (Param->getLocStart().isMacroID() || (Method && Method->isVirtual()))
     return;
   for (const auto *FunctionDecl = Function; FunctionDecl != nullptr;
        FunctionDecl = FunctionDecl->getPreviousDecl()) {


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