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Re: AC_PROG_CC_C99 macro description is too vague / ambiguous


From: Ralf Wildenhues
Subject: Re: AC_PROG_CC_C99 macro description is too vague / ambiguous
Date: Tue, 21 Apr 2009 23:04:14 +0200
User-agent: Mutt/1.5.18 (2008-05-17)

* Vincent Lefevre wrote on Wed, Mar 25, 2009 at 12:39:51AM CET:
> The documentation of AC_PROG_CC_C99 is rather vague:
> 
>  -- Macro: AC_PROG_CC_C99
>      If the C compiler is not in C99 mode by default, try to add an
>      option to output variable `CC' to make it so.
[...]
> It is not clear whether GNU extensions are allowed or not. Even though
> one may think that it is natural to keep the GNU extensions, gcc has
> -std=c99 for strict ISO C99 (as opposed to gnu99 for the GNU dialect),
> so that one can easily mix up "C99 mode" above and "c99 language" from
> gcc. The macro description should avoid this possible confusion.

OK?

Thanks,
Ralf

    Improve description of AC_PROG_CC_C89 and AC_PROG_CC_C99.
    
    * doc/autoconf.texi (C Compiler): Document that AC_PROG_CC_C89
    and AC_PROG_CC_C99 prefer extended over strict conformance modes.
    Report by Vincent Lefevre.

diff --git a/doc/autoconf.texi b/doc/autoconf.texi
index ea71eb4..15f4e41 100644
--- a/doc/autoconf.texi
+++ b/doc/autoconf.texi
@@ -6810,7 +6810,8 @@ set to accept Standard C; if not, the shell variable
 If the C compiler is not in @acronym{ANSI} C89 (@acronym{ISO} C90) mode by
 default, try to add an option to output variable @code{CC} to make it
 so.  This macro tries various options that select @acronym{ANSI} C89 on
-some system or another.  It considers the compiler to be in
+some system or another, preferring extended functionality modes over
+strict conformance modes.  It considers the compiler to be in
 @acronym{ANSI} C89 mode if it handles function prototypes correctly.
 
 After calling this macro you can check whether the C compiler has been
@@ -6824,7 +6825,8 @@ This macro is called automatically by @code{AC_PROG_CC}.
 @acindex{PROG_CC_C99}
 If the C compiler is not in C99 mode by default, try to add an
 option to output variable @code{CC} to make it so.  This macro tries
-various options that select C99 on some system or another.  It
+various options that select C99 on some system or another, preferring
+extended functionality modes over strict conformance modes.  It
 considers the compiler to be in C99 mode if it handles @code{_Bool},
 @code{//} comments, flexible array members, @code{inline}, signed and
 unsigned @code{long long int}, mixed code and declarations, named




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