URL:
<https://savannah.gnu.org/support/?110656>
Summary: On AT&T UnixPC (3b1), parameter $3 gets overwritten
(cleared) by call to subfunction.
Project: Autoconf
Submitted by: alainknaff
Submitted on: Sun 15 May 2022 07:55:22 PM CEST
Category: None
Priority: 5 - Normal
Severity: 3 - Normal
Status: None
Privacy: Public
Assigned to: None
Originator Email:
Open/Closed: Open
Discussion Lock: Any
Operating System: None
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Details:
In many tests in autoconf generated configure scripts we have the following
pattern:
ac_fn_c_check_header_compile ()
{
...
do preparatory work
...
if ac_fn_c_try_compile "$LINENO"; then :
eval "$3=yes"
else
eval "$3=no"
fi
...
}
On entry to ac_fn_c_check_header_compile, positional parameter 3 contains the
name of the variable where to put the test result.
However, on AT&T UnixPC, this is cleared by any call to another function (such
as ac_fn_c_try_compile in this case), leading to an eval that does just
"=yes", which obviously fails, as it will try to look for a command named
"=yes"
Solution: store $3 in a variable:
ac_fn_c_check_header_compile ()
{
result_var=$3
...
do preparatory work
...
if ac_fn_c_try_compile "$LINENO"; then :
eval "$result_var=yes"
else
eval "$result_var=no"
fi
...
}
Interestingly enough, configure prints out "positional parameters were not
saved." early on the the configure process, so it seems to notice the problem,
but then fails to act on it.
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