On 7/14/21 8:51 AM, 林宏雄 wrote:
> We expect that configure should not use the included regex.c
> on the system with up-to-date glibc.

Recently that has not been the case, as glibc has been trailing behind 
Gnulib a bit. At some point I hope they will become more in sync.

> Returning 0 by re_compile_pattern() is correct behavior. It should not fail.
Thank you for reporting the problem. There is no formal spec for 
re_compile_pattern and the regular expression is in some sense invalid 
and in another sense valid, so it's not clear which is the correct 
behavior here. However, Gnulib should allow the latest glibc behavior, 
as that behavior is arguably correct.

I installed the attached patches. The first patch merely fixes some 
longstanding quoting problems. The second patch updates the Gnulib tests 
to match the latest Gnulib, and to allow glibc implementations that 
behave as you describe. However, glibc 2.33 (the current version) still 
fails to pass the configure-time test, due to glibc bug 11053 which is 
fixed in Gnulib; see:

https://sourceware.org/bugzilla/show_bug.cgi?id=11053