[cfe-dev] clang::Qualifiers::TQ flags are not in sync with DeclSpec::TQ flags

[John McCall via cfe-dev]

> On Aug 9, 2017, at 4:51 PM, Vladimir Voskresensky via cfe-dev <cfe-dev at lists.llvm.org> wrote:
> Ping,
> 
> Could someone comment, please, if clang::Qualifiers::TQ intentionally reduces number of flags from 5 to 3?

It is not intentional, no.  We do not represent _Atomic as an ordinary qualifier in the AST, so I think this might accidentally be okay there.  Offhand, I don't think we want to support either of those qualifiers as an array index type qualifier unless the C spec absolutely demands it.

John.

> 
> Thanks,
> Vladimir.
> 
> On 07.08.2017 16:06, Vladimir Voskresensky via cfe-dev wrote:
>> Hello,
>> 
>> clang::Qualifiers::TQ has 3 flags and CVRMask mask. Also it has the note:
>> // NOTE: These flags must be kept in sync with DeclSpec::TQ.
>> 
>> But
>> DeclSpec::TQ has 5 flags (so  TQ_unaligned = 8, TQ_atomic = 16 are missed in clang::Qualifiers::TQ)
>> 
>> This inconsistency can be found by debugging test llvm/tools/clang/test/Sema/MicrosoftExtensions.c on the last declaration:
>> void test_unaligned2(int x[__unaligned 4]) {}
>> 
>> Array type is created incorrectly here, because '__unaligned' is lost in the ArrayType constructor at line:
>> ArrayTypeBits.IndexTypeQuals = tq;
>> tq has value 8 (TQ_unaligned) while IndexTypeQuals is declared to use ":3" bits only, so IndexTypeQuals is zero after assign.
>> 
>> Usually TQ fields are 5 bits (see i.e. DeclSpec::TypeQualifiers), so
>> declaration Type::ArrayTypeBitfields::IndexTypeQuals must be fixed as well
>> 
>> Hope it helps,
>> Vladimir.
>> 
>> 
>> 
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