C inlines that are also builtins.
Sergey Organov
sorganov@gmail.com
Mon Nov 9 19:40:00 GMT 2015
Martin Sebor <msebor@gmail.com> writes:
> On 11/09/2015 05:57 AM, Sergey Organov wrote:
>> Hello,
>>
>> GCC, when compiling C code, seems to always generate out-of-line copy of
>> any [C99] inline function that also happens to be a GCC builtin,
>> resulting in link errors (see a test-case below). According to C99
>> standard, an out-of-line copy of a function should only be instantiated
>> in those compilation unit(s) where the function is also declared
>> 'extern'.
>>
>> Apparently, all builtin functions implicitly get 'extern' declaration that
>> forces out-of-line copy of inline function in every compilation unit.
>>
>> Is it a bug of feature? If the latter, what is the way for a library to
>> provide generic inline functions that might happen to be GCC builtins?
>
> Depending on the -std= option, GCC can generate a copy of an inline
> function (regardless of whether or not the function also has a builtin
> form) in each translation unit that defines it. To avoid multiple
> definition errors, define inline functions in C headers as static.
>
> The following page explains how GCC treats the inline specifier
> in each of the standard mode:
>
> https://gcc.gnu.org/onlinedocs/gcc/Inline.html
The point is that for builtin functions it apparently does it wrong.
-- Sergey.
More information about the Gcc-help
mailing list