[Bug bootstrap/12173] IRIX 6 O32 (with as) bootstrap failure due to gcc -g -E warning

[ro at techfak dot uni-bielefeld dot de]

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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=12173



------- Additional Comments From ro at techfak dot uni-bielefeld dot de  2003-09-15 20:15 -------
Subject: Re:  IRIX 6 O32 (with as) bootstrap failure due to gcc -g -E warning

> This could be construed as a bug in autoconf.  It's already fixed in autoconf
> 2.5x, that knows to ignore warning messages from the preprocessor when testing

... which seems to cause other problems: this way, e.g. deprecation
warnings from headers are ignored as well.  And even if autoconf 2.5x get
this right (or at least can cope with this case), this neither helps for
the current bootstrap problem nor for building other packages which come
with configure from older autoconf versions.

> for header files.  Anyway, if -g is not supported, it shouldn't be passed down
> to target library configuration, right?

True in principle, though -g isn't passed explicitly, but automatically
added by configure if no {C,CXX,FC,JC}FLAGS (or however they are called for
the language in question) are given.  Thus it might become quite messy to
bootstrap for targets without -g support.

> As for why we have to pass -g to the preprocessor, I might instead pass
> -fworking-directory if there's any -g* in the command line and no
> -fno-working-directory.  This would solve the immediate problem.  The
> alternative would be to have -fworking-directory enabled by default, which would
> (slightly) impact those who don't need entirely-accurate debug information (or
> error mesasges, FWIW).
> 
> Which one would be preferrable?

Since getcwd may be expensive in some environments, I prefer the former.

	Rainer