[sr #110377] AC_CACHE_CHECK is affected by 's' variable override.

[Sergei Trofimovich]

URL:
  <https://savannah.gnu.org/support/?110377>

                 Summary: AC_CACHE_CHECK is affected by 's' variable override.
                 Project: Autoconf
            Submitted by: slyfox
            Submitted on: Mon 16 Nov 2020 11:42:31 AM UTC
                Category: None
                Priority: 5 - Normal
                Severity: 3 - Normal
                  Status: None
                 Privacy: Public
             Assigned to: None
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
        Operating System: None

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Details:

Initial failure happens on ruby git version against autoconf-2.69d. It has a
few issues, but I'm focusing here on redefinition of `s` variable.

Here is a minimal example that demonstrates a problem of substituted variable.
If does not show behaviour difference in minimal snippet, but points at
mangled printf argument.


$ autoreconf-2.69 --install && ./configure --host=x86_64-pc-linux-gnu
checking size of int... 1
rbcv_sizeof_size is defined as 42
ac_cv_sizeof_int=1
configure: creating ./config.status



$ autoreconf-2.70_beta3 --install && ./configure --host=x86_64-pc-linux-gnu
./configure: line 1716: printf: `r': invalid format character
./configure: line 1717: printf: `r': invalid format character
./configure: line 1724: printf: `r': invalid format character
./configure: line 1725: printf: `r': invalid format character
rbcv_sizeof_size is defined as 42
ac_cv_sizeof_int=1
configure: creating ./config.status



$ cat configure.ac
AC_INIT

dnl trimmed douwn version of orifginal 'RUBY_CHECK_SIZEOF' macro
dnl from
https://github.com/ruby/ruby/blob/master/tool/m4/ruby_check_sizeof.m4
dnl
dnl The important bit is 's' m4 variable that breaks printf call.
AC_DEFUN([RUBY_CHECK_SIZEOF],[
AS_VAR_PUSHDEF([s], [rbcv_sizeof_size])dnl
AC_CACHE_CHECK([size of $1], [AS_TR_SH([ac_cv_sizeof_$1])],
[AS_TR_SH(ac_cv_sizeof_$1)=1])

# fake use of 's' for illustratve purposes:
s=42
echo "s is defined as ${s}"

AS_VAR_POPDEF([s])
])

RUBY_CHECK_SIZEOF(int)
echo "ac_cv_sizeof_int=${ac_cv_sizeof_int}"

AC_OUTPUT





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