r179035 - <rdar://problem/13540921> Cope with deduced 'auto' in a C++11 for-range loop that is actually an Objective-C fast enumeration loop.

[Erik Verbruggen]

Pardon my ignorance, but why a warning? Or to rephrase it: why could this be problematic at all to fail with -Werror?

-- Erik


On 8 apr. 2013, at 20:25, Douglas Gregor <dgregor at apple.com> wrote:

> Author: dgregor
> Date: Mon Apr  8 13:25:02 2013
> New Revision: 179035
> 
> URL: http://llvm.org/viewvc/llvm-project?rev=179035&view=rev
> Log:
> <rdar://problem/13540921> Cope with deduced 'auto' in a C++11 for-range loop that is actually an Objective-C fast enumeration loop.
> 
> Modified:
>    cfe/trunk/lib/Sema/SemaStmt.cpp
>    cfe/trunk/test/SemaObjCXX/foreach.mm
> 
> Modified: cfe/trunk/lib/Sema/SemaStmt.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaStmt.cpp?rev=179035&r1=179034&r2=179035&view=diff
> ==============================================================================
> --- cfe/trunk/lib/Sema/SemaStmt.cpp (original)
> +++ cfe/trunk/lib/Sema/SemaStmt.cpp Mon Apr  8 13:25:02 2013
> @@ -1570,6 +1570,33 @@ Sema::ActOnObjCForCollectionStmt(SourceL
>       if (!D->hasLocalStorage())
>         return StmtError(Diag(D->getLocation(),
>                               diag::err_non_variable_decl_in_for));
> +
> +      // If the type contained 'auto', deduce the 'auto' to 'id'.
> +      if (FirstType->getContainedAutoType()) {
> +        TypeSourceInfo *DeducedType = 0;
> +        OpaqueValueExpr OpaqueId(D->getLocation(), Context.getObjCIdType(),
> +                                 VK_RValue);
> +        Expr *DeducedInit = &OpaqueId;
> +        if (DeduceAutoType(D->getTypeSourceInfo(), DeducedInit, DeducedType)
> +              == DAR_Failed) {
> +          DiagnoseAutoDeductionFailure(D, DeducedInit);
> +        }
> +        if (!DeducedType) {
> +          D->setInvalidDecl();
> +          return StmtError();
> +        }
> +
> +        D->setTypeSourceInfo(DeducedType);
> +        D->setType(DeducedType->getType());
> +        FirstType = DeducedType->getType();
> +
> +        if (ActiveTemplateInstantiations.empty()) {
> +          SourceLocation Loc = DeducedType->getTypeLoc().getBeginLoc();
> +          Diag(Loc, diag::warn_auto_var_is_id)
> +            << D->getDeclName();
> +        }
> +      }
> +
>     } else {
>       Expr *FirstE = cast<Expr>(First);
>       if (!FirstE->isTypeDependent() && !FirstE->isLValue())
> 
> Modified: cfe/trunk/test/SemaObjCXX/foreach.mm
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaObjCXX/foreach.mm?rev=179035&r1=179034&r2=179035&view=diff
> ==============================================================================
> --- cfe/trunk/test/SemaObjCXX/foreach.mm (original)
> +++ cfe/trunk/test/SemaObjCXX/foreach.mm Mon Apr  8 13:25:02 2013
> @@ -12,6 +12,8 @@ void f(NSArray *a) {
>                  // expected-warning {{expression result unused}}
> 
>   for (id thisKey : keys);
> +
> +  for (auto thisKey : keys) { } // expected-warning{{'auto' deduced as 'id' in declaration of 'thisKey'}}
> }
> 
> /* // rdar://9072298 */
> 
> 
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