Re: Autoconf does not like "-D_FORTIFY_SOURCE=2 -O2"

[Paul Eggert]

On 05/08/13 11:26, Anatol Pomozov wrote:
> Why autoconf uses CPPFLAGS
> (and not CPPFLAGS+CXXFLAGS) for headers discovery?

It's a long story, but basically autoconf used to invoke
just the preprocessor to test for header existence, partly
on the grounds of making 'configure' go faster.  That turns
out to have problems, so it now tries to compile as well,
optionally, using a heuristic that I don't recall right now.
I expect that the goal is that it'll use the compiler exclusivly,
but doing that will require some developer effort, and nobody
has had the time and inclination to carry that through.