Fix ASTContext::typesAreCompatible to allow for int/enum compatibility (C99 6.7.2.2p4).

Fix Sema::MergeFunctionDecl to allow for function type compatibility (by using the predicate on ASTContext). Function types don't have to be identical to be compatible...

llvm-svn: 45784

clang/AST/ASTContext.cpp

@@ -1618,15 +1618,23 @@ bool ASTContext::typesAreCompatible(QualType lhs, QualType rhs) {
   if (rcanon->getTypeClass() == Type::Reference)
     rcanon = cast<ReferenceType>(rcanon)->getReferenceeType();
   
-  // If the canonical type classes don't match, they can't be compatible
+  // If the canonical type classes don't match...
   if (lcanon->getTypeClass() != rcanon->getTypeClass()) {
     // For Objective-C, it is possible for two types to be compatible
     // when their classes don't match (when dealing with "id"). If either type
     // is an interface, we defer to objcTypesAreCompatible(). 
     if (lcanon->isObjCInterfaceType() || rcanon->isObjCInterfaceType())
       return objcTypesAreCompatible(lcanon, rcanon);
+	  
+	// C99 6.7.2.2p4: Each enumerated type shall be compatible with char,
+	// a signed integer type, or an unsigned integer type.
+	if ((lcanon->isEnumeralType() && rcanon->isIntegralType()) ||
+	    (rcanon->isEnumeralType() && lcanon->isIntegralType()))
+	  return true;
+	  
     return false;
   }
+  // The canonical type classes match.
   switch (lcanon->getTypeClass()) {
     case Type::Pointer:
       return pointerTypesAreCompatible(lcanon, rcanon);

clang/Sema/SemaDecl.cpp

@@ -245,7 +245,9 @@ FunctionDecl *Sema::MergeFunctionDecl(FunctionDecl *New, ScopedDecl *OldD) {
     if (OldQType.getTypePtr()->getTypeClass() == Type::FunctionNoProto && 
         Old->getResultType() == New->getResultType())
       return New;
-    if (OldQType == NewQType)
+    // Function types need to be compatible, not identical. This handles
+    // duplicate function decls like "void f(int); void f(enum X);" properly.
+    if (Context.functionTypesAreCompatible(OldQType, NewQType))
       return New;
   }
 

clang/test/Sema/predefined-function.c

@@ -1,5 +1,9 @@
 // RUN: clang -fsyntax-only -verify -pedantic %s
- 
+
+char *funk(int format);
+enum Test {A=-1};
+char *funk(enum Test x);
+
 int foo();
 int foo()
 {