[Issue 24414] ImportC: undefined identifier `__builtin_clz`

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=24414

Alex Bryan <abryanbugzilla at proton.me> changed:

           What    |Removed                     |Added
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                 CC|                            |abryanbugzilla at proton.me

--- Comment #1 from Alex Bryan <abryanbugzilla at proton.me> ---
I've ran into this issue before and worked around it by putting this in a D
file:

module util;
// for C files built with import C that try to use GCC/clang builtin that
importC does not provide

extern(C) int __builtin_clz(int v)    
{    
    return clz(v);    
}    

// count leading zeros.    
int clz(uint v) pure nothrow @nogc @safe    
in(v != 0)    
{    
    import core.bitop : bsr;    
    return 31 - bsr(v);    
}


and putting
__import util
at the top of the C file

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