https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112422
--- Comment #37 from David Binderman <dcb314 at hotmail dot com> ---
Nearly three years after I reported this problem, I have
the following output for a recent build:
$ grep "^checking for" mk.out | sort | uniq -c | sort -rn | head
22 checking for egrep... /usr/bin/grep -E
20 checking for strings.h... yes
20 checking for C compiler default output file name... a.out
19 checking for a BSD-compatible install... /usr/bin/install -c
18 checking for stdlib.h... yes
18 checking for inttypes.h... yes
17 checking for x86_64-pc-linux-gnu-llvm-config... no
16 checking for x86_64-pc-linux-gnu-ar... (cached) ar --plugin
/home/dcb42/gcc/results.20261028.ubsan/libexec/gcc/x86_64-pc-linux-gnu/17.0.0/liblto_plugin.so
16 checking for unistd.h... (cached) yes
16 checking for string.h... yes
$
Files strings.h, stdlib.h, inttypes.h, unistd.h and string.h
might be candidates for further work.
Most of the rest of them might well be covered by POSIX.
I can't think of any non-POSIX systems, but they are probably out there.
Would a simple check for POSIX remove a lot of this checking, I wonder ?
Non-POSIX systems would probably still require some detailed checking.