[Sema] Create a separate group for incompatible function pointer warning

Give incompatible function pointer warning its own diagnostic group
but still leave it as a subgroup of incompatible-pointer-types. This is in
preparation to promote -Wincompatible-function-pointer-types to error on
darwin.

Differential Revision: https://reviews.llvm.org/D22248

rdar://problem/12907612

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@275907 91177308-0d34-0410-b5e6-96231b3b80d8

include/clang/Basic/DiagnosticGroups.td

@@ -225,9 +225,12 @@ def GNUIncludeNext : DiagGroup<"gnu-include-next">;
 def IncompatibleMSStruct : DiagGroup<"incompatible-ms-struct">;
 def IncompatiblePointerTypesDiscardsQualifiers 
   : DiagGroup<"incompatible-pointer-types-discards-qualifiers">;
+def IncompatibleFunctionPointerTypes
+  : DiagGroup<"incompatible-function-pointer-types">;
 def IncompatiblePointerTypes
   : DiagGroup<"incompatible-pointer-types",
-    [IncompatiblePointerTypesDiscardsQualifiers]>;
+    [IncompatiblePointerTypesDiscardsQualifiers,
+     IncompatibleFunctionPointerTypes]>;
 def IncompleteUmbrella : DiagGroup<"incomplete-umbrella">;
 def NonModularIncludeInFrameworkModule
   : DiagGroup<"non-modular-include-in-framework-module">;

include/clang/Basic/DiagnosticSemaKinds.td

@@ -6351,6 +6351,24 @@ def ext_typecheck_convert_incompatible_pointer : ExtWarn<
   "; remove *|"
   "; remove &}3">,
   InGroup<IncompatiblePointerTypes>;
+def ext_typecheck_convert_incompatible_function_pointer : ExtWarn<
+  "incompatible function pointer types "
+  "%select{%diff{assigning to $ from $|assigning to different types}0,1"
+  "|%diff{passing $ to parameter of type $|"
+  "passing to parameter of different type}0,1"
+  "|%diff{returning $ from a function with result type $|"
+  "returning from function with different return type}0,1"
+  "|%diff{converting $ to type $|converting between types}0,1"
+  "|%diff{initializing $ with an expression of type $|"
+  "initializing with expression of different type}0,1"
+  "|%diff{sending $ to parameter of type $|"
+  "sending to parameter of different type}0,1"
+  "|%diff{casting $ to type $|casting between types}0,1}2"
+  "%select{|; dereference with *|"
+  "; take the address with &|"
+  "; remove *|"
+  "; remove &}3">,
+  InGroup<IncompatibleFunctionPointerTypes>;
 def ext_typecheck_convert_discards_qualifiers : ExtWarn<
   "%select{%diff{assigning to $ from $|assigning to different types}0,1"
   "|%diff{passing $ to parameter of type $|"

lib/Sema/SemaExpr.cpp

@@ -12423,10 +12423,14 @@ bool Sema::DiagnoseAssignmentResult(AssignConvertType ConvTy,
     MayHaveConvFixit = true;
     break;
   case IncompatiblePointer:
-      DiagKind =
-        (Action == AA_Passing_CFAudited ?
-          diag::err_arc_typecheck_convert_incompatible_pointer :
-          diag::ext_typecheck_convert_incompatible_pointer);
+    if (Action == AA_Passing_CFAudited)
+      DiagKind = diag::err_arc_typecheck_convert_incompatible_pointer;
+    else if (SrcType->isFunctionPointerType() &&
+             DstType->isFunctionPointerType())
+      DiagKind = diag::ext_typecheck_convert_incompatible_function_pointer;
+    else
+      DiagKind = diag::ext_typecheck_convert_incompatible_pointer;
+
     CheckInferredResultType = DstType->isObjCObjectPointerType() &&
       SrcType->isObjCObjectPointerType();
     if (Hint.isNull() && !CheckInferredResultType) {

test/Sema/incompatible-function-pointer-types.c

@@ -0,0 +1,14 @@
+// RUN: %clang_cc1 -fsyntax-only %s -Wincompatible-pointer-types -verify
+// RUN: %clang_cc1 -fsyntax-only %s -Wincompatible-function-pointer-types -verify
+
+// This test ensures that the subgroup of -Wincompatible-pointer-types warnings
+// that concern function pointers can be promoted (or not promoted) to an error
+// *separately* from the other -Wincompatible-pointer-type warnings.
+typedef int (*MyFnTyA)(int *, char *);
+
+int bar(char *a, int *b) { return 0; }
+int foo(MyFnTyA x) { return 0; } // expected-note {{passing argument to parameter 'x' here}}
+
+void baz() {
+  foo(&bar); // expected-warning {{incompatible function pointer types passing 'int (*)(char *, int *)' to parameter of type 'MyFnTyA' (aka 'int (*)(int *, char *)')}}
+}

test/Sema/initialize-noreturn.c

@@ -8,7 +8,7 @@ void foo(void);
 void foo_noret(void)  __attribute__((noreturn));
 
 void test() {
-  Fn_noret fn2 = &foo; // expected-warning {{incompatible pointer types initializing 'Fn_noret'}}
+  Fn_noret fn2 = &foo; // expected-warning {{incompatible function pointer types initializing 'Fn_noret'}}
   Fn_noret fn3 = &foo_noret; 
   Fn_ret fn4 = &foo_noret; 
   Fn_ret fn5 = &foo;

test/Sema/overloadable.c

@@ -109,7 +109,7 @@ void fn_type_conversions() {
   void (*ambiguous)(int *) = &foo; // expected-error{{initializing 'void (*)(int *)' with an expression of incompatible type '<overloaded function type>'}} expected-note@105{{candidate function}} expected-note@106{{candidate function}}
   void *vp_ambiguous = &foo; // expected-error{{initializing 'void *' with an expression of incompatible type '<overloaded function type>'}} expected-note@105{{candidate function}} expected-note@106{{candidate function}}
 
-  void (*specific1)(int *) = (void (*)(void *))&foo; // expected-warning{{incompatible pointer types initializing 'void (*)(int *)' with an expression of type 'void (*)(void *)'}}
+  void (*specific1)(int *) = (void (*)(void *))&foo; // expected-warning{{incompatible function pointer types initializing 'void (*)(int *)' with an expression of type 'void (*)(void *)'}}
   void *specific2 = (void (*)(void *))&foo;
 
   void disabled(void *c) __attribute__((overloadable, enable_if(0, "")));