[cfe-commits] r171912 - in /cfe/trunk: include/clang/Basic/DiagnosticSemaKinds.td lib/Sema/SemaExpr.cpp test/SemaObjCXX/capturing-flexible-array-in-block.mm

[jahanian]

On Jan 8, 2013, at 3:29 PM, Eli Friedman <eli.friedman at gmail.com> wrote:

> On Tue, Jan 8, 2013 at 3:17 PM, Fariborz Jahanian <fjahanian at apple.com> wrote:
>> Author: fjahanian
>> Date: Tue Jan  8 17:17:51 2013
>> New Revision: 171912
>> 
>> URL: http://llvm.org/viewvc/llvm-project?rev=171912&view=rev
>> Log:
>> objectiveC blocks: It is impractical to capture
>> struct variables with flexiable array members in
>> blocks (and lambdas). Issue error instead of
>> crashing in IRGen. // rdar://12655829
>> 
>> Added:
>>    cfe/trunk/test/SemaObjCXX/capturing-flexible-array-in-block.mm
>> Modified:
>>    cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
>>    cfe/trunk/lib/Sema/SemaExpr.cpp
>> 
>> Modified: cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td?rev=171912&r1=171911&r2=171912&view=diff
>> ==============================================================================
>> --- cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td (original)
>> +++ cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td Tue Jan  8 17:17:51 2013
>> @@ -4224,6 +4224,9 @@
>> def err_ref_non_value : Error<"%0 does not refer to a value">;
>> def err_ref_vm_type : Error<
>>   "cannot refer to declaration with a variably modified type inside block">;
>> +def err_ref_flexarray_type : Error<
>> +  "cannot refer to declaration of structure variable with flexible array member "
>> +  "inside block">;
>> def err_ref_array_type : Error<
>>   "cannot refer to declaration with an array type inside block">;
>> def err_property_not_found : Error<
>> @@ -4609,6 +4612,9 @@
>>   def err_lambda_capture_vm_type : Error<
>>     "variable %0 with variably modified type cannot be captured in "
>>     "a lambda expression">;
>> +  def err_lambda_capture_flexarray_type : Error<
>> +    "variable %0 with flexible array member cannot be captured in "
>> +    "a lambda expression">;
>>   def err_lambda_impcap : Error<
>>     "variable %0 cannot be implicitly captured in a lambda with no "
>>     "capture-default specified">;
>> 
>> Modified: cfe/trunk/lib/Sema/SemaExpr.cpp
>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaExpr.cpp?rev=171912&r1=171911&r2=171912&view=diff
>> ==============================================================================
>> --- cfe/trunk/lib/Sema/SemaExpr.cpp (original)
>> +++ cfe/trunk/lib/Sema/SemaExpr.cpp Tue Jan  8 17:17:51 2013
>> @@ -10759,7 +10759,22 @@
>>       }
>>       return true;
>>     }
>> -
>> +    // Prohibit prohibit structs with flexisble array members too.
>> +    // We cannot capture what is in the tail end of the struct.
>> +    if (const RecordType *VTTy = Var->getType()->getAs<RecordType>()) {
>> +      if (VTTy->getDecl()->hasFlexibleArrayMember()) {
>> +        if (BuildAndDiagnose) {
>> +          if (IsBlock)
>> +            Diag(Loc, diag::err_ref_flexarray_type);
>> +          else
>> +            Diag(Loc, diag::err_lambda_capture_flexarray_type)
>> +              << Var->getDeclName();
>> +          Diag(Var->getLocation(), diag::note_previous_decl)
>> +            << Var->getDeclName();
>> +        }
>> +        return true;
>> +      }
>> +    }
>>     // Lambdas are not allowed to capture __block variables; they don't
>>     // support the expected semantics.
>>     if (IsLambda && HasBlocksAttr) {
>> 
>> Added: cfe/trunk/test/SemaObjCXX/capturing-flexible-array-in-block.mm
>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaObjCXX/capturing-flexible-array-in-block.mm?rev=171912&view=auto
>> ==============================================================================
>> --- cfe/trunk/test/SemaObjCXX/capturing-flexible-array-in-block.mm (added)
>> +++ cfe/trunk/test/SemaObjCXX/capturing-flexible-array-in-block.mm Tue Jan  8 17:17:51 2013
>> @@ -0,0 +1,9 @@
>> +// RUN: %clang_cc1 -fsyntax-only -fblocks -verify -std=c++11 %s
>> +// rdar://12655829
>> +
>> +void f() {
>> +  struct { int x; int y[]; } a; // expected-note 2 {{'a' declared here}}
>> +  ^{return a.x;}(); // expected-error {{cannot refer to declaration of structure variable with flexible array member inside block}}
>> +
>> +  [] {return a.x;}(); // expected-error {{variable 'a' with flexible array member cannot be captured in a lambda expression}}
>> +}
> 
> We can do whatever we want with blocks, but the C++11 standard doesn't
> allow us to reject this construct for lambda expressions.
> 

Fair enough. I take it out. 
- Fariborz

> -Eli