[cfe-dev] invalid bits size for WrittenBuiltinSpecs::Type

[Reid Kleckner via cfe-dev]

Patch to catch this bug if you're curious: https://reviews.llvm.org/D30923

On Mon, Mar 13, 2017 at 4:29 PM, Vladimir Voskresensky via cfe-dev <
cfe-dev at lists.llvm.org> wrote:

>
>
> On 14.03.2017 00:33, Reid Kleckner via cfe-dev wrote:
>
> I think this is something the compiler should catch. I'm writing a
> generalized warning in clang for it right now.
>
> Yes, I agree. In fact, this is how I got here myself. I ran test
>
> ${LLVM_SRC}/llvm/tools/clang/test/Lexer/cxx1z-trigraphs.cpp
>
> using Clank (the Java port of CLang)
> https://eurollvm2017.sched.com/event/9wDw/clank-java-
> port-of-cc-compiler-frontend
>  and got Java-assert that reducing from enumerator to 5 bits doesn't fit
> for TST_error value :-)
>
> Please, send me the changeset when you are done with compiler warning.
>
> Thanks!
> Vladimir.
>
>
>
> On Mon, Mar 13, 2017 at 12:57 PM, Vladimir Voskresensky via cfe-dev <
> <cfe-dev at lists.llvm.org>cfe-dev at lists.llvm.org> wrote:
>
>> Reid,
>>
>> May be it's worth to have the same assert for
>> clang::DeclSpec::TypeSpecType?
>>
>> Thanks,
>> Vladimir.
>>
>>
>> On 13.03.2017 21:59, Reid Kleckner via cfe-dev wrote:
>>
>> Thanks, fixed in r297654.
>>
>> On Mon, Mar 13, 2017 at 10:35 AM, Vladimir Voskresensky via cfe-dev <
>> cfe-dev at lists.llvm.org> wrote:
>>
>>> Hello Clang Developers,
>>>
>>> in file clang/Basic/Specifiers.h there is
>>>    struct clang::WrittenBuiltinSpecs {
>>>      /*DeclSpec::TST*/ unsigned Type  : 5; // << must be *6*
>>> ....
>>>   };
>>>
>>> "Type" field must be 6 to match DeclSpec::TST which is the same as enum
>>> TypeSpecifierType
>>> which has
>>>  TST_error // erroneous type
>>> with value 43 which can not be kept in 5 bits field.
>>>
>>> as a correct example you can see that
>>> clang::DeclSpec::TypeSpecType field is 6 bits
>>>
>>> So, we corrupt values  during save in clang::DeclSpec::SaveWrittenBuiltinSpecs
>>> for all after TST_image1d_t.
>>> Btw, due to this TST_error is changed to TST_float128....
>>>
>>> Hope it helps,
>>> Vladimir.
>>> _______________________________________________
>>> cfe-dev mailing list
>>> cfe-dev at lists.llvm.org
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>>>
>>
>>
>>
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