[PATCH] Don't suppress warning about dllimport on non-functions and variables

[Hans Wennborg]

Hi krememek, rnk,

This warning suppression in MS extensions mode was added by Ted in r96722.

It's true that MSVC doesn't warn about dllimport when applied to e.g. a typedef, but that applies to dllexport too. I would like us to be consistent between the two attributes, and I think the right thing to do is to warn. Ted: is there still a need to suppress this warning? (If yes, I'd like to make it consistent and suppress the warning for dllexport too).

http://reviews.llvm.org/D3832

Files:
  include/clang/Basic/Attr.td
  lib/Sema/SemaDeclAttr.cpp
  test/Rewriter/dllimport-typedef.c

Index: include/clang/Basic/Attr.td
===================================================================
--- include/clang/Basic/Attr.td
+++ include/clang/Basic/Attr.td
@@ -1653,8 +1653,7 @@
 
 def DLLImport : InheritableAttr, TargetSpecificAttr<TargetWindows> {
   let Spellings = [Declspec<"dllimport">, GCC<"dllimport">];
-  // Technically, the subjects for DllImport are Function and Var, but there is
-  // custom semantic handling required when MicrosoftExt is true.
+  let Subjects = SubjectList<[Function, Var]>;
   let Documentation = [Undocumented];
 }
 
Index: lib/Sema/SemaDeclAttr.cpp
===================================================================
--- lib/Sema/SemaDeclAttr.cpp
+++ lib/Sema/SemaDeclAttr.cpp
@@ -3836,18 +3836,6 @@
 }
 
 static void handleDLLImportAttr(Sema &S, Decl *D, const AttributeList &Attr) {
-  // Attribute can be applied only to functions or variables.
-  FunctionDecl *FD = dyn_cast<FunctionDecl>(D);
-  if (!FD && !isa<VarDecl>(D)) {
-    // Apparently Visual C++ thinks it is okay to not emit a warning
-    // in this case, so only emit a warning when -fms-extensions is not
-    // specified.
-    if (!S.getLangOpts().MicrosoftExt)
-      S.Diag(Attr.getLoc(), diag::warn_attribute_wrong_decl_type)
-        << Attr.getName() << ExpectedVariableOrFunction;
-    return;
-  }
-
   unsigned Index = Attr.getAttributeSpellingListIndex();
   DLLImportAttr *NewAttr = S.mergeDLLImportAttr(D, Attr.getRange(), Index);
   if (NewAttr)
Index: test/Rewriter/dllimport-typedef.c
===================================================================
--- test/Rewriter/dllimport-typedef.c
+++ /dev/null
@@ -1,17 +0,0 @@
-// RUN: not %clang_cc1 -triple i686-pc-win32 -fms-extensions -fsyntax-only %s 2>&1 | FileCheck -check-prefix=CHECK-NEG %s
-// RUN: not %clang_cc1 -triple i686-pc-win32 -fsyntax-only %s 2>&1 | FileCheck -check-prefix=CHECK-POS %s
-
-// Do not report an error with including dllimport in the typedef when -fms-extensions is specified.
-// Addresses <rdar://problem/7653870>.
-typedef __declspec(dllimport) int CB(void);
-
-// This function is added just to trigger a diagnostic.  This way we can test how many
-// diagnostics we expect.
-void bar() { return 1; }
-
-// CHECK-NEG: error: void function 'bar' should not return a value
-// CHECK-NEG: {{^}}1 error generated
-// CHECK-POS: warning: 'dllimport' attribute only applies to variables and functions
-// CHECK-POS: error: void function 'bar' should not return a value
-// CHECK-POS: 1 warning and 1 error generated
-
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