[PATCH] D78444: Perform ActOnConversionDeclarator after looking for any virtual functions it overrides

[Ronald Wampler via Phabricator via cfe-commits]

rdwampler created this revision.
rdwampler added reviewers: saar.raz, aaron.ballman, doug.gregor, rsmith.
rdwampler added a project: clang.
Herald added subscribers: cfe-commits, dexonsmith.

This allows for suppressing warnings about the conversion function never being called if it overrides a virtual function in a base class.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D78444

Files:
  clang/lib/Sema/SemaDecl.cpp
  clang/lib/Sema/SemaDeclCXX.cpp
  clang/test/SemaCXX/conversion-function.cpp


Index: clang/test/SemaCXX/conversion-function.cpp
===================================================================
--- clang/test/SemaCXX/conversion-function.cpp
+++ clang/test/SemaCXX/conversion-function.cpp
@@ -62,6 +62,27 @@
   operator const B(); // expected-warning{{conversion function converting 'B' to itself will never be used}}
 };
 
+class DerivedB;
+
+class BaseA {
+public:
+  virtual operator BaseA&() = 0; //OK. Virtual function 
+  virtual operator DerivedB&() = 0; //OK. Virtual function
+  virtual operator const void() = 0; //OK. Virtual function
+};
+
+class DerivedB : public BaseA {
+#if __cplusplus >= 201103L
+    operator BaseA&() override; //OK. Overrides virtual function in BaseA
+    operator DerivedB&() override; //OK. Overrides virtual function BaseA
+    operator const void() override; //OK. Overrides virtual function BaseA
+#else
+    virtual operator BaseA&(); //OK. Overrides virtual function in BaseA
+    virtual operator DerivedB&(); //OK. Overrides virtual function BaseA
+    virtual operator const void(); //OK. Overrides virtual function BaseA
+#endif
+};
+
 // This used to crash Clang.
 struct Flip;
 struct Flop {
Index: clang/lib/Sema/SemaDeclCXX.cpp
===================================================================
--- clang/lib/Sema/SemaDeclCXX.cpp
+++ clang/lib/Sema/SemaDeclCXX.cpp
@@ -10486,15 +10486,12 @@
 
   // Make sure we aren't redeclaring the conversion function.
   QualType ConvType = Context.getCanonicalType(Conversion->getConversionType());
-
   // C++ [class.conv.fct]p1:
   //   [...] A conversion function is never used to convert a
   //   (possibly cv-qualified) object to the (possibly cv-qualified)
   //   same object type (or a reference to it), to a (possibly
   //   cv-qualified) base class of that type (or a reference to it),
   //   or to (possibly cv-qualified) void.
-  // FIXME: Suppress this warning if the conversion function ends up being a
-  // virtual function that overrides a virtual function in a base class.
   QualType ClassType
     = Context.getCanonicalType(Context.getTypeDeclType(ClassDecl));
   if (const ReferenceType *ConvTypeRef = ConvType->getAs<ReferenceType>())
@@ -10502,6 +10499,8 @@
   if (Conversion->getTemplateSpecializationKind() != TSK_Undeclared &&
       Conversion->getTemplateSpecializationKind() != TSK_ExplicitSpecialization)
     /* Suppress diagnostics for instantiations. */;
+  else if(Conversion->isVirtual())
+    /*Suppress diagnostics if the function is virtual*/;
   else if (ConvType->isRecordType()) {
     ConvType = Context.getCanonicalType(ConvType).getUnqualifiedType();
     if (ConvType == ClassType)
Index: clang/lib/Sema/SemaDecl.cpp
===================================================================
--- clang/lib/Sema/SemaDecl.cpp
+++ clang/lib/Sema/SemaDecl.cpp
@@ -10713,9 +10713,6 @@
           return Redeclaration;
         }
       }
-    } else if (CXXConversionDecl *Conversion
-               = dyn_cast<CXXConversionDecl>(NewFD)) {
-      ActOnConversionDeclarator(Conversion);
     } else if (auto *Guide = dyn_cast<CXXDeductionGuideDecl>(NewFD)) {
       if (auto *TD = Guide->getDescribedFunctionTemplate())
         CheckDeductionGuideTemplate(TD);
@@ -10743,6 +10740,9 @@
       if (Method->isStatic())
         checkThisInStaticMemberFunctionType(Method);
     }
+    
+    if (CXXConversionDecl *Conversion = dyn_cast<CXXConversionDecl>(NewFD))
+          ActOnConversionDeclarator(Conversion);
 
     // Extra checking for C++ overloaded operators (C++ [over.oper]).
     if (NewFD->isOverloadedOperator() &&


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