bug#64879: Error: obstack.c: In function '_obstack_allocated_p':

[Sajjad Ali]

I am trying to build grep for windows on MSYS2.

here are the packages which i had installed (development and end user packages) 
:
```
$ pacman -Q 'libiconv' 'libintl' 'libpcre' 'sh' 'texinfo' 'gettext-devel' 
'libiconv-devel' 'pcre-devel' 'autotools' 'gcc' 'automake' 'gettext' 'git' 
'gperf' 'gzip' 'help2man' 'm4' 'make' 'pkg-config' 'tar' 'wget' 'xz'
libiconv 1.17-1
libintl 0.22-1
libpcre 8.45-3
bash 5.2.015-1
texinfo 7.0.3-3
gettext-devel 0.22-1
libiconv-devel 1.17-1
pcre-devel 8.45-3
autotools 2022.01.16-2
gcc 11.3.0-4
automake-wrapper 20221207-1
gettext 0.22-1
git 2.41.0-1
gperf 3.1-5
gzip 1.12-2
help2man 1.49.3-1
m4 1.4.19-2
make 4.4.1-1
pkgconf 1.9.4-1
tar 1.34-3
wget 1.21.4-1
xz 5.4.3-1
```

no error while ./bootstrap​ and ./configure​. when running make​ after a while 
it throws error:

​```
obstack.c: In function '_obstack_allocated_p':
obstack.c:240:1: error: function might be candidate for attribute 'pure' if it 
is known to return normally [-Werror=suggest-attribute=pure]
  240 | _obstack_allocated_p (struct obstack *h, void *obj)
      | ^~~~~~~~~~~~~~~~~~~~
obstack.c: In function '_obstack_memory_used':
obstack.c:291:1: error: function might be candidate for attribute 'pure' if it 
is known to return normally [-Werror=suggest-attribute=pure]
  291 | _obstack_memory_used (struct obstack *h)
      | ^~~~~~~~~~~~~~~~~~~~
cc1: all warnings being treated as errors
```

here are the complete logs from ./bootstrap​ to make​.
[https://res-h3.public.cdn.office.net/assets/mail/file-icon/png/txt_16x16.png]logs.txt<https://1drv.ms/t/s!Ak1RUL7i7AyEhChY_Y3q2L1tqKkK>