Split into a MS and Itanium attribute

Author: amykhuang

clang/include/clang/Basic/Attr.td

@@ -1799,11 +1799,22 @@ def ArmMveStrictPolymorphism : TypeAttr, TargetSpecificAttr<TargetARM> {
 }
 
 def NoUniqueAddress : InheritableAttr {
-  let Spellings = [CXX11<"", "no_unique_address", 201803>,
-                   CXX11<"msvc", "no_unique_address", 201803>];
-  let Accessors = [Accessor<"isStandard", [CXX11<"", "no_unique_address", 201803>]>,
-                   Accessor<"isMSVC", [CXX11<"msvc", "no_unique_address", 201803>]>];
   let Subjects = SubjectList<[NonBitField], ErrorDiag>;
+  // No spellings because instances of this attribute are created by
+  // MSNoUniqueAddress and ItaniumNoUniqueAddress
+  let Spellings = [];
+  let Documentation = [NoUniqueAddressDocs];
+}
+
+def MSNoUniqueAddress : InheritableAttr, TargetSpecificAttr<TargetMicrosoftCXXABI> {
+  let Subjects = SubjectList<[NonBitField], ErrorDiag>;
+  let Spellings = [CXX11<"msvc", "no_unique_address", 201803>];
+  let Documentation = [NoUniqueAddressDocs];
+}
+
+def ItaniumNoUniqueAddress : InheritableAttr, TargetSpecificAttr<TargetItaniumCXXABI> {
+  let Subjects = SubjectList<[NonBitField], ErrorDiag>;
+  let Spellings = [CXX11<"", "no_unique_address", 201803>];
   let Documentation = [NoUniqueAddressDocs];
 }
 

clang/lib/Parse/ParseDeclCXX.cpp

@@ -4364,7 +4364,8 @@ static bool IsBuiltInOrStandardCXX11Attribute(IdentifierInfo *AttrName,
   case ParsedAttr::AT_Deprecated:
   case ParsedAttr::AT_FallThrough:
   case ParsedAttr::AT_CXX11NoReturn:
-  case ParsedAttr::AT_NoUniqueAddress:
+  case ParsedAttr::AT_MSNoUniqueAddress:
+  case ParsedAttr::AT_ItaniumNoUniqueAddress:
   case ParsedAttr::AT_Likely:
   case ParsedAttr::AT_Unlikely:
     return true;

clang/lib/Sema/SemaDeclAttr.cpp

@@ -8372,14 +8372,6 @@ static void handleNoMergeAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
 }
 
 static void handleNoUniqueAddressAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
-  NoUniqueAddressAttr TmpAttr(S.Context, AL);
-  if (S.getLangOpts().MSVCCompat && TmpAttr.isStandard()) {
-    S.Diag(AL.getLoc(), diag::warn_attribute_ignored) << AL;
-    return;
-  } else if (TmpAttr.isMSVC()) {
-    S.Diag(AL.getLoc(), diag::warn_attribute_ignored) << AL;
-    return;
-  }
   D->addAttr(NoUniqueAddressAttr::Create(S.Context, AL));
 }
 
@@ -9288,7 +9280,10 @@ ProcessDeclAttribute(Sema &S, Scope *scope, Decl *D, const ParsedAttr &AL,
   case ParsedAttr::AT_NoMerge:
     handleNoMergeAttr(S, D, AL);
     break;
-  case ParsedAttr::AT_NoUniqueAddress:
+  case ParsedAttr::AT_MSNoUniqueAddress:
+    handleNoUniqueAddressAttr(S, D, AL);
+    break;
+  case ParsedAttr::AT_ItaniumNoUniqueAddress:
     handleNoUniqueAddressAttr(S, D, AL);
     break;
 

clang/test/Preprocessor/has_attribute.cpp

@@ -43,6 +43,7 @@ CXX11(fallthrough)
 CXX11(likely)
 CXX11(maybe_unused)
 CXX11(no_unique_address)
+CXX11(msvc::no_unique_address)
 CXX11(nodiscard)
 CXX11(noreturn)
 CXX11(unlikely)
@@ -55,7 +56,9 @@ CXX11(unlikely)
 // CHECK: likely: 201803L
 // CHECK: maybe_unused: 201603L
 // ITANIUM: no_unique_address: 201803L
-// WINDOWS: no_unique_address: 201803L 
+// WINDOWS: no_unique_address: 0 
+// ITANIUM: msvc::no_unique_address: 0
+// WINDOWS: msvc::no_unique_address: 201803L
 // CHECK: nodiscard: 201907L
 // CHECK: noreturn: 200809L
 // CHECK: unlikely: 201803L

clang/test/SemaCXX/cxx2a-ms-no-unique-address.cpp

@@ -0,0 +1,19 @@
+// RUN: %clang_cc1 -std=c++2a %s -verify=unsupported -triple x86_64-linux-gnu
+// RUN: %clang_cc1 -std=c++2a %s -verify -triple x86_64-windows -fms-compatibility
+
+[[msvc::no_unique_address]] int a; // expected-error {{only applies to non-bit-field non-static data members}} unsupported-warning {{unknown}}
+[[msvc::no_unique_address]] void f(); // expected-error {{only applies to non-bit-field non-static data members}} unsupported-warning {{unknown}}
+struct [[msvc::no_unique_address]] S { // expected-error {{only applies to non-bit-field non-static data members}} unsupported-warning {{unknown}}
+  [[msvc::no_unique_address]] int a; // unsupported-warning {{unknown}}
+  [[msvc::no_unique_address]] void f(); // expected-error {{only applies to non-bit-field non-static data members}} unsupported-warning {{unknown}}
+  [[msvc::no_unique_address]] static int sa;// expected-error {{only applies to non-bit-field non-static data members}} unsupported-warning {{unknown}}
+  [[msvc::no_unique_address]] static void sf(); // expected-error {{only applies to non-bit-field non-static data members}} unsupported-warning {{unknown}}
+  [[msvc::no_unique_address]] int b : 3; // expected-error {{only applies to non-bit-field non-static data members}} unsupported-warning {{unknown}}
+
+  [[msvc::no_unique_address, msvc::no_unique_address]] int duplicated; // ok
+  // unsupported-warning@-1 2{{unknown}}
+  [[msvc::no_unique_address]] [[msvc::no_unique_address]] int duplicated2; // unsupported-warning 2{{unknown}}
+  [[msvc::no_unique_address()]] int arglist; // expected-error {{cannot have an argument list}} unsupported-warning {{unknown}}
+
+  int [[msvc::no_unique_address]] c; // expected-error {{cannot be applied to types}} unsupported-error {{cannot be applied to types}}
+};

clang/test/SemaCXX/cxx2a-no-unique-address.cpp

@@ -1,5 +1,5 @@
 // RUN: %clang_cc1 -std=c++2a %s -verify -triple x86_64-linux-gnu
-// RUN: %clang_cc1 -std=c++2a %s -verify -triple x86_64-windows
+// RUN: %clang_cc1 -std=c++2a %s -verify=unsupported -triple x86_64-windows
 
 [[no_unique_address]] int a; // expected-error {{only applies to non-bit-field non-static data members}} unsupported-warning {{unknown}}
 [[no_unique_address]] void f(); // expected-error {{only applies to non-bit-field non-static data members}} unsupported-warning {{unknown}}