[cfe-dev] pragma float_control(push) or (pop)

[Aaron Ballman via cfe-dev]

On Wed, Jul 28, 2021 at 12:46 PM James Y Knight via cfe-dev
<cfe-dev at lists.llvm.org> wrote:
>
> I suspect this is just a bug and the code meant to say (untested):
>
> diff --git clang/lib/Sema/SemaAttr.cpp clang/lib/Sema/SemaAttr.cpp
>
> index fe8f02f02368..2277e08d9b05 100644
>
> --- clang/lib/Sema/SemaAttr.cpp
>
> +++ clang/lib/Sema/SemaAttr.cpp
>
> @@ -475,7 +475,7 @@ void Sema::ActOnPragmaFloatControl(SourceLocation Loc,
>
>                                     PragmaFloatControlKind Value) {
>
>    FPOptionsOverride NewFPFeatures = CurFPFeatureOverrides();
>
>    if ((Action == PSK_Push_Set || Action == PSK_Push || Action == PSK_Pop) &&
>
> -      !(CurContext->isTranslationUnit()) && !CurContext->isNamespace()) {
>
> +      !CurContext->getRedeclContext()->isFileContext()) {
>
>      // Push and pop can only occur at file or namespace scope.
>
>      Diag(Loc, diag::err_pragma_fc_pp_scope);
>
>      return;

Oh, good suggestion James! I'll change what I did in
https://reviews.llvm.org/rGb0ef3d8f666fa6008abb09340b73d9340d442569 to
use this approach instead.

~Aaron

>
>
> On Wed, Jul 28, 2021 at 12:47 AM Smith, Kevin B via cfe-dev <cfe-dev at lists.llvm.org> wrote:
>>
>> I was a little surprised by this behavior.  I was trying to write a header file that would use file scope pragma float_control(push) and pragma float_control(pop) and ran into this error.  It seems like this makes these pragmas pretty difficult to be effectively used.
>>
>>
>>
>> Thank you,
>>
>> Kevin Smith
>>
>>
>>
>> $ clang bad.cpp
>>
>> bad.cpp:2:9: error: '#pragma float_control push/pop' can only appear at file scope or namespace scope
>>
>> #pragma float_control(push)
>>
>>         ^
>>
>> bad.cpp:9:9: error: '#pragma float_control push/pop' can only appear at file scope or namespace scope
>>
>> #pragma float_control(pop)
>>
>>         ^
>>
>> 2 errors generated.
>>
>>
>>
>> $ cat bad.cpp
>>
>> extern "C++" {
>>
>> #pragma float_control(push)
>>
>> #pragma clang fp reassociate(off)
>>
>>
>>
>>   float my_silly_func(float a, float b) {
>>
>>     return (a + b) - b;
>>
>>   }
>>
>>
>>
>> #pragma float_control(pop)
>>
>> }
>>
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>
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