A user of the SANE project has an issue with a generated configure script.

A reference to the original conversation is here:

https://gitlab.com/sane-project/backends/-/issues/468

They are running autoconf 2.71. Attached at the above bug report can be found their generated configure script.

The issue seems to be related to the generation of this segment in a couple of places which has invalid syntax:

...
for as_dir in $PATH
do
  IFS=$as_save_IFS
  case $as_dir in #(((
    ''
 as_dir=./ ;;
    */) ;;
    *) as_dir=$as_dir/ ;;
  esac
    for ac_exec_ext in '' $ac_executable_extensions; do
  if as_fn_executable_p "$as_dir$ac_word$ac_exec_ext"; then
    ac_cv_prog_CC="${ac_tool_prefix}gcc"
    printf "%s\n" "$as_me:${as_lineno-$LINENO}: found $as_dir$ac_word$ac_exec_ext" >&5
    break 2
  fi
done
...
IFS=$as_save_IFS

In other areas this segment has valid syntax:

...
for as_dir in $PATH
do
  IFS=$as_save_IFS
  case $as_dir in #(((
    '') as_dir=./ ;;
    */) ;;
    *) as_dir=$as_dir/ ;;
  esac
    for ac_exec_ext in '' $ac_executable_extensions; do
  if as_fn_executable_p "$as_dir$ac_word$ac_exec_ext"; then
    ac_cv_prog_CC="${ac_tool_prefix}cc"
    printf "%s\n" "$as_me:${as_lineno-$LINENO}: found $as_dir$ac_word$ac_exec_ext" >&5
    break 2
  fi
done
...

Any hints as to how we can track this down would be appreciated.