init.sh: fix EXEEXT shims to work also for names like test-prog

[Jim Meyering]

Per discussion last week, here's a patch for init.sh.
The main goal is to allow the EXEEXT shim business to work
also for program names like test-program, (containing a hyphen).

I would have liked to skip the invocation of $re_shell_ -c ...
if the current shell is deemed adequate, but determining that is
a rats nest, since it would require use of eval, and Solaris'
/bin/sh handles failing "eval" very poorly.  If someone knows how to
make that more efficient (yet still clean and reliable) for common,
working shells like dash-or-bash-as-/bin/sh, I'd welcome the tip.

I suppose it could test e.g., $BASH_VERSION, if bash has supported
the desired features for long enough, or even do version number comparisons,
but the latter seems not worthwhile.

>From 63509688315d9a8c8e60d8e776736b454f3019f5 Mon Sep 17 00:00:00 2001
From: Jim Meyering <address@hidden>
Date: Sun, 21 Feb 2010 17:47:43 +0100
Subject: [PATCH] init.sh: fix EXEEXT shims to work also for names like test-prog

* tests/init.sh: Re-exec a better shell, when needed.
If the current shell lacks support for posix $(...), an init.sh-using
test will now try to find a shell that supports that.  If EXEEXT is
nonempty, we also require support for hyphen-in-alias-name and shell
substitutions like ${var#glob}.  Failure to find such a shell results
in a skipped test.
---
 ChangeLog     |   10 ++++++++++
 tests/init.sh |   48 +++++++++++++++++++++++++++++++++++++++++-------
 2 files changed, 51 insertions(+), 7 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 3fe0b44..6d35c21 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,13 @@
+2010-02-21  Jim Meyering  <address@hidden>
+
+       init.sh: fix EXEEXT shims to work also for names like test-prog
+       * tests/init.sh: Re-exec a better shell, when needed.
+       If the current shell lacks support for posix $(...), an init.sh-using
+       test will now try to find a shell that supports that.  If EXEEXT is
+       nonempty, we also require support for hyphen-in-alias-name and shell
+       substitutions like ${var#glob}.  Failure to find such a shell results
+       in a skipped test.
+
 2010-02-21  Bruno Haible  <address@hidden>

        Really work around around "broken pipe" error message from bash 3.2.
diff --git a/tests/init.sh b/tests/init.sh
index e7664b8..4debc65 100644
--- a/tests/init.sh
+++ b/tests/init.sh
@@ -52,6 +52,41 @@
 #   4. Finally
 #   $ exit

+# We require $(...) support unconditionally.
+# We require a few additional shell features only when $EXEEXT is nonempty,
+# in order to support automatic $EXEEXT emulation:
+# - hyphen-containing alias names
+# - we prefer to use ${var#...} substitution, rather than having
+#   to work around lack of support for that feature.
+# The following code attempts to find a shell with support for these features
+# and re-exec's it.  If not, it skips the current test.
+
+gl_shell_test_script_='
+test $(echo y) = y || exit 1
+test -z "$EXEEXT" && exit 0
+shopt -s expand_aliases
+alias a-b="echo zoo"
+v=abx
+     test ${v%x} = ab \
+  && test ${v#a} = bx \
+  && test $(a-b) = zoo
+'
+
+if test "x$1" = "x--no-reexec"; then
+  shift
+else
+  for re_shell_ in "${CONFIG_SHELL:-no_shell}" /bin/sh bash dash zsh pdksh fail
+  do
+    test "$re_shell_" = no_shell && continue
+    test "$re_shell_" = fail && skip_ failed to find an adequate shell
+    if "$re_shell_" -c "$gl_shell_test_script_" 2>/dev/null; then
+      exec "$re_shell_" "$0" --no-reexec "$@"
+      echo "$ME_: exec failed" 1>&2
+      exit 127
+    fi
+  done
+fi
+
 # We use a trap below for cleanup.  This requires us to go through
 # hoops to get the right exit status transported through the handler.
 # So use `Exit STATUS' instead of `exit STATUS' inside of the tests.
@@ -117,11 +152,11 @@ find_exe_basenames_()
 }

 # Consider the files in directory, $1.
-# For each file name of the form PROG.exe, create a shim function named
+# For each file name of the form PROG.exe, create an alias named
 # PROG that simply invokes PROG.exe, then return 0.  If any selected
 # file name or the directory name, $1, contains an unexpected character,
 # define no function and return 1.
-create_exe_shim_functions_()
+create_exe_shims_()
 {
   case $EXEEXT in
     '') return 0 ;;
@@ -134,9 +169,7 @@ create_exe_shim_functions_()

   if test -n "$base_names_"; then
     for base_ in $base_names_; do
-      # Create a function named $base whose sole job is to invoke
-      # $base_$EXEEXT, assuming its containing dir is already in PATH.
-      eval "$base_() { $base_$EXEEXT"' "$@"; }'
+      alias "$base_"="$base_$EXEEXT"
     done
   fi

@@ -160,8 +193,9 @@ path_prepend_()
     esac
     PATH="$abs_path_dir_:$PATH"

-    # Create a function FOO for each FOO.exe in this directory.
-    create_exe_shim_functions_ "$abs_path_dir_"
+    # Create an alias, FOO, for each FOO.exe in this directory.
+    create_exe_shims_ "$abs_path_dir_" \
+      || fail_ "something failed (above): $abs_path_dir_"
     shift
   done
   export PATH
--
1.7.0.256.g2d4f4