[core.stdc.math] everything is pure

[thewilsonator]

Everything in core.stdc.math so use an attribute at the top.

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[thewilsonator]

Thanks, fixed.

[ibuclaw]

I don't think you can say that everything is pure when most alter errno.

[Geod24]

For ref: https://en.cppreference.com/w/cpp/numeric/math/math_errhandling

[ibuclaw]

For your reference:

echo "module gcc.builtins;" | gdc -fsyntax-only -x d -Hf /dev/stdout - | less

Functions that are not intrinsically pure (because they store into memory).

• frexp{f,l}
• gamma{f,l}
• gamma_r{f,l}
• lgamma{f,l}
• lgamma_r{f,l}
• modf{f,l}
• remquo{f,l}
• sincos{f,l}

[n8sh]

I think #2045 doesn't leave anything in core.stdc.math that can be marked pure unless the definition of pure is changed to allow changes to errno. IIRC Walter Bright has toyed with that idea in the past.

[Geod24]

unless the definition of pure is changed to allow changes to errno

I really hope we don't go in that direction. Logical pure would be as useful as logical const.

[ibuclaw]

unless the definition of pure is changed to allow changes to errno

I really hope we don't go in that direction. Logical pure would be as useful as logical const.

Well pure+errno is the main reason why we do things ourselves in std.math over just forwarding to libm.

[RazvanN7]

Closing as per:

I think #2045 doesn't leave anything in core.stdc.math that can be marked pure unless the definition of pure is changed to allow changes to errno. IIRC Walter Bright has toyed with that idea in the past.