[cfe-dev] How to disable the generation of TypedefDecl for __builtin_va_list

[Chengnian Sun via cfe-dev]

Thanks, David.

The clang::Decl::isImplicit solves my problem.



On Mon, Feb 22, 2016 at 4:37 PM, David Majnemer <david.majnemer at gmail.com>
wrote:

> You are missing a typdef which would provide the definition of va_list.
> Because va_list is not defined, we parse 'va_list' in the function
> parameter as a parameter name.  Via the C rules, we implicitly give it type
> int.
>
>
> On Mon, Feb 22, 2016 at 4:29 PM, Chengnian Sun <chengniansun at gmail.com>
> wrote:
>
>> Thank you for letting me know this API. However, I have another problem:
>> when I have the forward declaration of vprintf (produced by the
>> preprocessor), the clang AST will assign the type int to va_list.  Is it a
>> correct way to use prettyprint to dump code from AST?
>>
>>
>> =======================================
>>
>> bash-3.2$ cat t1.c
>>
>> int vprintf(const char * restrict, va_list) __attribute__((__format__
>> (__printf__, 1, 0)));
>>
>> bash-3.2$ clang -Xclang -ast-dump -w -fsyntax-only t1.c
>>
>> *TranslationUnitDecl* 0x10382dcc0 <<invalid sloc>> <invalid sloc>
>>
>> |-*TypedefDecl* 0x10382e1c0 <<invalid sloc>> <invalid sloc> implicit*
>> __int128_t* '__int128'
>>
>> |-*TypedefDecl* 0x10382e220 <<invalid sloc>> <invalid sloc> implicit*
>> __uint128_t* 'unsigned __int128'
>>
>> |-*TypedefDecl* 0x10382e5b0 <<invalid sloc>> <invalid sloc> implicit*
>> __builtin_va_list* '__va_list_tag [1]'
>>
>> |-*FunctionDecl* 0x10382e910 <t1.c:1:5> col:5 implicit* vprintf* 'int
>> (const char *, __va_list_tag *)' extern
>>
>> | |-*ParmVarDecl* 0x103871400 <<invalid sloc>> <invalid sloc> 'const
>> char *'
>>
>> | |-*ParmVarDecl* 0x103871460 <<invalid sloc>> <invalid sloc> '__va_list_tag
>> *'
>>
>> | `-*FormatAttr* 0x1038714d0 <col:5> Implicit printf 1 0
>>
>> `-*FunctionDecl* 0x103871520 prev 0x10382e910 <col:1, col:90> col:5*
>> vprintf* 'int (const char *restrict, int)'
>>
>>   |-*ParmVarDecl* 0x10382e640 <col:13, col:24> col:34 'const char
>> *restrict'
>>
>>   |-*ParmVarDecl* 0x10382e6b0 <col:36> col:36* va_list* 'int'
>>
>>   `-*FormatAttr* 0x1038715e0 <col:60, col:88> printf 1 0
>>
>> On Mon, Feb 22, 2016 at 4:01 PM, David Majnemer <david.majnemer at gmail.com
>> > wrote:
>>
>>>
>>>
>>> On Mon, Feb 22, 2016 at 3:46 PM, Chengnian Sun via cfe-dev <
>>> cfe-dev at lists.llvm.org> wrote:
>>>
>>>> I want to randomly remove the variable declaration "a" or "b" from the
>>>> source file. There are two ways to do this.
>>>>     1) I can pretty print the VarDecl of "a" and "b". However, these
>>>> three builtin typedefs mentioned above make the modified source file not
>>>> compilable, as the _builtin_va_list is not defined.
>>>>
>>>
>>> Why not skip things marked as implicit (clang::Decl::isImplicit) ?
>>>
>>>
>>>>     2) I can use rewriter to change the source file. However, as both
>>>> "a" and "b" are declared in one statement, removing either of them makes
>>>> the deletion complex.
>>>>
>>>> I think another way to do this is to separate the statement "int a, b;"
>>>> into "int a; int b". Any existing functionality in clang to do this?
>>>>
>>>> Thank you. Any advice is appreciated.
>>>>
>>>>
>>>>
>>>> On Mon, Feb 22, 2016 at 3:30 PM, Meador Inge <meadori at gmail.com> wrote:
>>>>
>>>>> On Mon, Feb 22, 2016 at 11:15 AM, Chengnian Sun via cfe-dev <
>>>>> cfe-dev at lists.llvm.org> wrote:
>>>>>
>>>>> Hi,
>>>>>>
>>>>>> I found out that for the following code (only containing two variable
>>>>>> declarations), clang will generate three internal typedef declarations. Is
>>>>>> there any way to disable the generation of the three typedef?
>>>>>>
>>>>>
>>>>> Not that I know of.  What problem are you trying to solve by disabling
>>>>> them?
>>>>>
>>>>> -- Meador
>>>>>
>>>>
>>>>
>>>>
>>>> --
>>>> Best Regards.
>>>>
>>>> Chengnian SUN.
>>>>
>>>> _______________________________________________
>>>> cfe-dev mailing list
>>>> cfe-dev at lists.llvm.org
>>>> http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev
>>>>
>>>>
>>>
>>
>>
>> --
>> Best Regards.
>>
>> Chengnian SUN.
>>
>
>


-- 
Best Regards.

Chengnian SUN.
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