Re: Does boost have an assert that works nicely with constexpr evaluation, and if not should we add one?

From: David P. Riedel (driedel_at_[hidden])
Date: 2021-08-25 18:39:21

On 8/21/21 11:54 AM, Peter Dimov via Boost wrote:
> Ivan Matek wrote:
> 
>> As you may know assert does not play nicely with constexpr evaluation.
> 
> It does. https://www.godbolt.org/z/KhPja6cEs
> 
> 
> 
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What am I missing here?

I click the above link and see the code

If I compile with gcc x86-64 trunk, I get the following:

> source>: In function 'int main()':
> <source>:12:21: error: non-constant condition for static assertion
>    12 |     static_assert(5 == func(9,1));
>       |                   ~~^~~~~~~~~~~~
> In file included from /opt/compiler-explorer/gcc-trunk-20210825/include/c++/12.0.0/cassert:44,
>                  from <source>:2:
> <source>:12:28:   in 'constexpr' expansion of 'func(9, 1)'
> <source>:6:5: error: call to non-'constexpr' function 'void __assert_fail(const char*, const char*, unsigned int, const char*)'
>     6 |     assert(a<b);
>       |     ^~~~~~
> /usr/include/assert.h:69:13: note: 'void __assert_fail(const char*, const char*, unsigned int, const char*)' declared here
>    69 | extern void __assert_fail (const char *__assertion, const char *__file,
>       |             ^~~~~~~~~~~~~
> Compiler returned: 1

Thanks