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Re: Please help me understand va_alist
From: |
Bruno Haible |
Subject: |
Re: Please help me understand va_alist |
Date: |
Thu, 06 Feb 2020 18:24:58 +0100 |
User-agent: |
KMail/5.1.3 (Linux/4.4.0-171-generic; KDE/5.18.0; x86_64; ; ) |
> I think the man is a bit confusing because va_start_type or va_arg_type
> functions are defined in the source as va_arg_int(LIST) and using
> va_arg_type(alist[, arg_type]) in the manual seems to suggest that it
> expect an additional parameter?
The additional parameter exists only for struct types. For elementary
and pointer types there is no need to have it.
> Anyway, I still have an issue wrt va_start_type. I don't fully
> understand the purpose of _type in the va_start macro since it
> doesn't seem to return anything.
It needs to match the va_return_.... invocation.
The implementation would be more complicated if the return type
was not already known when the va_start_... is invoked.
> ps: if it's any useful, I'm using the ffcall library from Debian (oldstable)
> that appears to be v1.10
I really suggest to use the newest release, 2.2. It produces fewer warnings,
has much improved portability, and has all known bugs fixed.
Bruno