[PATCH] D57032: [SemaCXX] Param diagnostic matches overload logic

[Brian Gesiak via Phabricator via cfe-commits]

modocache created this revision.
modocache added a reviewer: rsmith.

Given the following test program:

  class C {
  public:
    int A(int a, int& b);
  };
  
  int C::A(const int a, int b) {
    return a * b;
  }

Clang would produce an error message that correctly diagnosed the
redeclaration of `C::A` to not match the original declaration (the
parameters to the two declarations do not match -- the original takes an
`int &` as its 2nd parameter, but the redeclaration takes an `int`). However,
it also produced a note diagnostic that inaccurately pointed to the
first parameter, claiming that `const int` in the redeclaration did not
match the unqualified `int` in the original. The diagnostic is
misleading because it has nothing to do with why the program does not
compile.

The logic for checking for a function overload, in
`Sema::FunctionParamTypesAreEqual`, discards cv-qualifiers before
checking whether the types are equal. Do the same when producing the
overload diagnostic.


Repository:
  rC Clang

https://reviews.llvm.org/D57032

Files:
  lib/Sema/SemaDecl.cpp
  test/SemaCXX/function-redecl.cpp


Index: test/SemaCXX/function-redecl.cpp
===================================================================
--- test/SemaCXX/function-redecl.cpp
+++ test/SemaCXX/function-redecl.cpp
@@ -125,3 +125,9 @@
 }
 void Foo::beEvil() {} // expected-error {{out-of-line definition of 'beEvil' does not match any declaration in namespace 'redecl_typo::Foo'; did you mean 'BeEvil'?}}
 }
+
+struct CVQualFun {
+  void func(int a, int &b); // expected-note {{type of 2nd parameter of member declaration does not match definition ('int &' vs 'int')}}
+};
+
+void CVQualFun::func(const int a, int b) {} // expected-error {{out-of-line definition of 'func' does not match any declaration in 'CVQualFun'}}
Index: lib/Sema/SemaDecl.cpp
===================================================================
--- lib/Sema/SemaDecl.cpp
+++ lib/Sema/SemaDecl.cpp
@@ -5089,7 +5089,8 @@
     QualType DefParamTy = Definition->getParamDecl(Idx)->getType();
 
     // The parameter types are identical
-    if (Context.hasSameType(DefParamTy, DeclParamTy))
+    if (Context.hasSameType(DefParamTy.getUnqualifiedType(),
+                            DeclParamTy.getUnqualifiedType()))
       continue;
 
     QualType DeclParamBaseTy = getCoreType(DeclParamTy);


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