[PATCH] D90042: [clang-tidy] performance-unnecessary-copy-initialization: Check for const reference arguments that are replaced template parameter type.

[Felix Berger via Phabricator via cfe-commits]

flx created this revision.
flx added reviewers: aaron.ballman, gribozavr2.
Herald added subscribers: cfe-commits, xazax.hun.
Herald added a project: clang.
flx requested review of this revision.

This fixes false positive cases where a non-const reference is passed to a
std::function but interpreted as a const reference.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D90042

Files:
  clang-tools-extra/clang-tidy/utils/DeclRefExprUtils.cpp
  clang-tools-extra/test/clang-tidy/checkers/performance-unnecessary-copy-initialization.cpp


Index: clang-tools-extra/test/clang-tidy/checkers/performance-unnecessary-copy-initialization.cpp
===================================================================
--- clang-tools-extra/test/clang-tidy/checkers/performance-unnecessary-copy-initialization.cpp
+++ clang-tools-extra/test/clang-tidy/checkers/performance-unnecessary-copy-initialization.cpp
@@ -1,4 +1,4 @@
-// RUN: %check_clang_tidy %s performance-unnecessary-copy-initialization %t
+// RUN: %check_clang_tidy -std=c++17 %s performance-unnecessary-copy-initialization %t
 
 struct ExpensiveToCopyType {
   ExpensiveToCopyType();
@@ -411,12 +411,12 @@
 
 template <class>
 class function;
-template <class R, class... Args>
-class function<R(Args...)> {
+template <class R, class... ArgTypes>
+class function<R(ArgTypes...)> {
 public:
   function();
-  function(const function &other);
-  R operator()(Args &&...args) const;
+  function(const function &Other);
+  R operator()(ArgTypes &&...Args) const;
 };
 
 } // namespace __1
@@ -460,3 +460,19 @@
 }
 
 } // namespace fake
+
+void positiveInvokedOnStdFunction(
+    std::function<void(const ExpensiveToCopyType &)> Update,
+    const ExpensiveToCopyType Orig) {
+  auto Copy = Orig.reference();
+  // CHECK-MESSAGES: [[@LINE-1]]:8: warning: the variable 'Copy' is copy-constructed from a const reference
+  // CHECK-FIXES: const auto& Copy = Orig.reference();
+  Update(Copy);
+}
+
+void negativeInvokedOnStdFunction(
+    std::function<void(ExpensiveToCopyType &)> Update,
+    const ExpensiveToCopyType Orig) {
+  auto Copy = Orig.reference();
+  Update(Copy);
+}
Index: clang-tools-extra/clang-tidy/utils/DeclRefExprUtils.cpp
===================================================================
--- clang-tools-extra/clang-tidy/utils/DeclRefExprUtils.cpp
+++ clang-tools-extra/clang-tidy/utils/DeclRefExprUtils.cpp
@@ -57,11 +57,15 @@
       Stmt, Context);
   SmallPtrSet<const DeclRefExpr *, 16> DeclRefs;
   extractNodesByIdTo(Matches, "declRef", DeclRefs);
-  auto ConstReferenceOrValue =
-      qualType(anyOf(referenceType(pointee(qualType(isConstQualified()))),
-                     unless(anyOf(referenceType(), pointerType()))));
+  auto ConstReferenceOrValue = qualType(
+      anyOf(referenceType(pointee(qualType(isConstQualified()))),
+            unless(anyOf(referenceType(),
+                         pointerType() /*, substTemplateTypeParmType()*/))));
+  auto ConstReferenceOrValueOrReplaced = qualType(anyOf(
+      ConstReferenceOrValue,
+      substTemplateTypeParmType(hasReplacementType(ConstReferenceOrValue))));
   auto UsedAsConstRefOrValueArg = forEachArgumentWithParam(
-      DeclRefToVar, parmVarDecl(hasType(ConstReferenceOrValue)));
+      DeclRefToVar, parmVarDecl(hasType(ConstReferenceOrValueOrReplaced)));
   Matches = match(findAll(callExpr(UsedAsConstRefOrValueArg)), Stmt, Context);
   extractNodesByIdTo(Matches, "declRef", DeclRefs);
   Matches =


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