[clang] 877859a - [clang] Handle __declspec() attributes in using

[Tobias Hieta via cfe-commits]

Author: Tobias Hieta
Date: 2023-02-13T15:43:08+01:00
New Revision: 877859a09bda29fe9a7f1a9016b06cf80661a032

URL: https://github.com/llvm/llvm-project/commit/877859a09bda29fe9a7f1a9016b06cf80661a032
DIFF: https://github.com/llvm/llvm-project/commit/877859a09bda29fe9a7f1a9016b06cf80661a032.diff

LOG: [clang] Handle __declspec() attributes in using

This patch fixes so that declspec attributes are forwarded
to the alias declaration.

Before this patch this would assert:

class Test { int a; };
using AlignedTest = __declspec(align(16)) const Test;
static_assert(alignof(AlignedTest) == 16, "error");

But afterwards it behaves the same as MSVC does and doesn't
assert.

Fixes: llvm/llvm-project#60513

Reviewed By: aaron.ballman

Differential Revision: https://reviews.llvm.org/D143632

Added: 
    clang/test/SemaCXX/using-declspec.cpp

Modified: 
    clang/docs/ReleaseNotes.rst
    clang/lib/Parse/ParseDecl.cpp

Removed: 
    


################################################################################
diff  --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 4fef5f883655..06f0bdcc796d 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -109,6 +109,10 @@ to be worn by functions containing buffer operations that could cause out of
 bounds memory accesses. It emits warnings at call sites to such functions when
 the flag ``-Wunsafe-buffer-usage`` is enabled.
 
+``__declspec`` attributes can now be used together with the using keyword. Before
+the attributes on ``__declspec`` was ignored, while now it will be forwarded to the
+point where the alias is used.
+
 Windows Support
 ---------------
 

diff  --git a/clang/lib/Parse/ParseDecl.cpp b/clang/lib/Parse/ParseDecl.cpp
index 96c25ba0c853..d32f26b9c32e 100644
--- a/clang/lib/Parse/ParseDecl.cpp
+++ b/clang/lib/Parse/ParseDecl.cpp
@@ -56,6 +56,18 @@ TypeResult Parser::ParseTypeName(SourceRange *Range, DeclaratorContext Context,
   if (OwnedType)
     *OwnedType = DS.isTypeSpecOwned() ? DS.getRepAsDecl() : nullptr;
 
+  // Move declspec attributes to ParsedAttributes
+  if (Attrs) {
+    llvm::SmallVector<ParsedAttr *, 1> ToBeMoved;
+    for (ParsedAttr &AL : DS.getAttributes()) {
+      if (AL.isDeclspecAttribute())
+        ToBeMoved.push_back(&AL);
+    }
+
+    for (ParsedAttr *AL : ToBeMoved)
+      Attrs->takeOneFrom(DS.getAttributes(), AL);
+  }
+
   // Parse the abstract-declarator, if present.
   Declarator DeclaratorInfo(DS, ParsedAttributesView::none(), Context);
   ParseDeclarator(DeclaratorInfo);

diff  --git a/clang/test/SemaCXX/using-declspec.cpp b/clang/test/SemaCXX/using-declspec.cpp
new file mode 100644
index 000000000000..a903bc93c9b4
--- /dev/null
+++ b/clang/test/SemaCXX/using-declspec.cpp
@@ -0,0 +1,19 @@
+// RUN: %clang_cc1 -fms-compatibility -fsyntax-only -verify %s
+
+// This should ignore the alignment and issue a warning about
+// align not being used
+auto func() -> __declspec(align(16)) int; // expected-warning{{attribute ignored when parsing type}}
+static_assert(alignof(decltype(func())) == alignof(int));
+
+// The following should NOT assert since alignment should
+// follow the type
+struct Test { int a; };
+using AlignedTest = __declspec(align(16)) const Test;
+static_assert(alignof(AlignedTest) == 16, "error");
+
+// Same here, no declaration to shift to
+int i = (__declspec(align(16))int)12; // expected-warning{{attribute ignored when parsing type}}
+
+// But there is a declaration here!
+typedef __declspec(align(16)) int Foo;
+static_assert(alignof(Foo) == 16);