On 11/06/2017 11:23 AM, Bruno Haible wrote:
When the error rate is so high, we should
1) improve the documentation (this is mainly install.texi from Autoconf),
2) add a consistency check in AC_PROG_CC or AC_PROG_CPP.
(2) would be better than what we have now, yes. But how could such a
check be implemented robustly? Wouldn't it require a comprehensive
knowledge of which compiler options affect which predefined macros on
which platforms?
The problem is not limited to flags like -m32 and -m64. Flags like
-fsanitize=address can also affect preprocessor behavior. A complete
list of such flags would be daunting to maintain.
In contrast, it's relatively simple to say "Don't use AC_EGREP_CPP
unless you know the result isn't likely to depend on compiler options."
