%% Dan Espen <dane_at_mk.telcordia.com> writes:
de> I'm still looking at gcc 2.8.1, the results could be different
de> for other versions of gcc.
Indeed.
The scoop is this:
Older versions of GCC were ANSI-compliant and wanted to work on systems
which very often (in those days) didn't have compliant system headers.
This meant that developers were seriously stuck: they either had to
turn off most of the warnings and other good stuff in ANSI C, or they
had to modify their system headers themselves, or they had to live with
tons of bogus warnings.
So, GCC's install step would examine the system headers, correct these
bogosities, and install the corrected copies in a location private to
GCC. GCC would look there _first_ for any system header and only
include the "real" system header, from /usr/include, if there wasn't a
private one.
The bad thing about this is that when you built GCC for one version of
the OS, then upgraded to a new version of the OS without reinstalling
GCC, now your compiler was using system headers from the old OS. Very
bad, esp. for vendors like Sun who feel no compunction about completely
rewriting/rearranging their system headers wth just about every release.
Of course, as new versions came out, the system header copy became less
important as the vendors fixed their own headers.
But, GCC was left for a long time around 2.7.* without any upgrade at
all, so long after it was necessary GCC was copying the system headers
for Solaris.
When 2.8.* and EGCS came out, they fixed this and stopped copying the
system headers: now it has only the fundamental ones like stdarg.h,
etc.
The short story is as I said before: it's very dangerous to use GCC's
before 2.8 with a version of Solaris that it wasn't compiled for.
Even with newer GCC's it _can_ cause problems, but very very rarely.
--
-------------------------------------------------------------------------------
Paul D. Smith <psmith_at_baynetworks.com> HASMAT--HA Software Methods & Tools
"Please remain calm...I may be mad, but I am a professional." --Mad Scientist
-------------------------------------------------------------------------------
These are my opinions---Nortel Networks takes no responsibility for them.
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Received on Mon Jun 04 2001 - 17:29:45 BST