r318796 - The offsetof macro is intended to work with subobjects rather than simple identifiers designating a member, making the -Wextended-offsetof diagnostic obsolete as this construct is not an extension. Implements WG14 DR496.

[Aaron Ballman via cfe-commits]

Author: aaronballman
Date: Tue Nov 21 11:25:38 2017
New Revision: 318796

URL: http://llvm.org/viewvc/llvm-project?rev=318796&view=rev
Log:
The offsetof macro is intended to work with subobjects rather than simple 
identifiers designating a member, making the -Wextended-offsetof diagnostic 
obsolete as this construct is not an extension. Implements WG14 DR496.

Modified:
    cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
    cfe/trunk/lib/Sema/SemaExpr.cpp
    cfe/trunk/test/CXX/drs/dr4xx.cpp

Modified: cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
URL: 
http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td?rev=318796&r1=318795&r2=318796&view=diff
==============================================================================
--- cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td (original)
+++ cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td Tue Nov 21 11:25:38 
2017
@@ -5546,9 +5546,6 @@ def err_offsetof_incomplete_type : Error
 def err_offsetof_record_type : Error<
   "offsetof requires struct, union, or class type, %0 invalid">;
 def err_offsetof_array_type : Error<"offsetof requires array type, %0 
invalid">;
-def ext_offsetof_extended_field_designator : Extension<
-  "using extended field designator is an extension">,
-  InGroup<DiagGroup<"extended-offsetof">>;
 def ext_offsetof_non_pod_type : ExtWarn<"offset of on non-POD type %0">,
   InGroup<InvalidOffsetof>;
 def ext_offsetof_non_standardlayout_type : ExtWarn<

Modified: cfe/trunk/lib/Sema/SemaExpr.cpp
URL: 
http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaExpr.cpp?rev=318796&r1=318795&r2=318796&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/SemaExpr.cpp (original)
+++ cfe/trunk/lib/Sema/SemaExpr.cpp Tue Nov 21 11:25:38 2017
@@ -12588,15 +12588,7 @@ ExprResult Sema::BuildBuiltinOffsetOf(So
       && RequireCompleteType(BuiltinLoc, ArgTy,
                              diag::err_offsetof_incomplete_type, TypeRange))
     return ExprError();
-  
-  // offsetof with non-identifier designators (e.g. "offsetof(x, a.b[c])") are 
a
-  // GCC extension, diagnose them.
-  // FIXME: This diagnostic isn't actually visible because the location is in
-  // a system header!
-  if (Components.size() != 1)
-    Diag(BuiltinLoc, diag::ext_offsetof_extended_field_designator)
-      << SourceRange(Components[1].LocStart, Components.back().LocEnd);
-  
+
   bool DidWarnAboutNonPOD = false;
   QualType CurrentType = ArgTy;
   SmallVector<OffsetOfNode, 4> Comps;

Modified: cfe/trunk/test/CXX/drs/dr4xx.cpp
URL: 
http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CXX/drs/dr4xx.cpp?rev=318796&r1=318795&r2=318796&view=diff
==============================================================================
--- cfe/trunk/test/CXX/drs/dr4xx.cpp (original)
+++ cfe/trunk/test/CXX/drs/dr4xx.cpp Tue Nov 21 11:25:38 2017
@@ -593,10 +593,10 @@ namespace dr447 { // dr447: yes
     U<__builtin_offsetof(A, n)>::type a;
     U<__builtin_offsetof(T, n)>::type b; // expected-error +{{}} 
expected-warning 0+{{}}
     // as an extension, we allow the member-designator to include array indices
-    g(__builtin_offsetof(A, a[0])).h<int>(); // expected-error {{extension}}
-    g(__builtin_offsetof(A, a[N])).h<int>(); // expected-error {{extension}}
-    U<__builtin_offsetof(A, a[0])>::type c; // expected-error {{extension}}
-    U<__builtin_offsetof(A, a[N])>::type d; // expected-error {{extension}} 
expected-error +{{}} expected-warning 0+{{}}
+    g(__builtin_offsetof(A, a[0])).h<int>();
+    g(__builtin_offsetof(A, a[N])).h<int>();
+    U<__builtin_offsetof(A, a[0])>::type c;
+    U<__builtin_offsetof(A, a[N])>::type d; // expected-error +{{}} 
expected-warning 0+{{}}
   }
 }
 


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