Re: [build, ada] Allow Solaris bootstrap with C++ (PR bootstrap/49794)

[Rainer Orth <ro at CeBiTec dot Uni-Bielefeld dot DE>]

Arnaud,

>> * Similarly to IRIX 6, there was a mismatch in ada/init.c for the type
>>   of the signal handler installed with sigaction.  g++ also doesn't like
>>   arithmetic on void * ;-)
>
> I'm a bit puzzled as to why the C compiler isn't complaining, and what
> error message the C++ compiler is generating, can you clarify?

I'd removed the previous build before copying the exact error message.
Here's what I get without the init.c change:

/vol/gcc/src/hg/trunk/local/gcc/ada/init.c: In function 'void __gnat_install_handler()':
/vol/gcc/src/hg/trunk/local/gcc/ada/init.c:1049:20: error: invalid conversion from 'void (*)(int, siginfo_t*, void*) {aka void (*)(int, siginfo*, void*)}' to 'void (*)(int)' [-fpermissive]

which is correct.  <sys/signal.h> has

/*
 * The signal handler routine can have either one or three arguments.
 * Existing C code has used either form so not specifing the arguments
 * neatly finesses the problem.  C++ doesn't accept this.  To C++
 * "(*sa_handler)()" indicates a routine with no arguments (ANSI C would
 * specify this as "(*sa_handler)(void)").  One or the other form must be
 * used for C++ and the only logical choice is "(*sa_handler)(int)" to allow
 * the SIG_* defines to work.  "(*sa_sigaction)(int, siginfo_t *, void *)"
 * can be used for the three argument form.
 */

/*
 * Note: storage overlap by sa_handler and sa_sigaction
 */
struct sigaction {
        int sa_flags;
        union {
#ifdef  __cplusplus
                void (*_handler)(int);
#else
                void (*_handler)();
#endif
#if defined(__EXTENSIONS__) || defined(_KERNEL) || \
        (!defined(_STRICT_STDC) && !defined(__XOPEN_OR_POSIX)) || \
        (_POSIX_C_SOURCE > 2) || defined(_XPG4_2)
                void (*_sigaction)(int, siginfo_t *, void *);
#endif
        }       _funcptr;
        sigset_t sa_mask;
#ifndef _LP64
        int sa_resv[2];
#endif
};
#define sa_handler      _funcptr._handler
#define sa_sigaction    _funcptr._sigaction

> Why is the code accepted by the C compiler in the first place?

... which explains why the C compiler accepts the code as is.

	Rainer

-- 
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Rainer Orth, Center for Biotechnology, Bielefeld University