From 02a4d11e752456409935252f192e9318df4da597 Mon Sep 17 00:00:00 2001
From: Taylor R Campbell <campbell@mumble.net>
Date: Mon, 2 Nov 2009 11:16:02 -0500
Subject: [PATCH] Check for an existing MIT Scheme in top-level Setup.sh and
 configure.

---
 src/Setup.sh     | 17 +++++++++++++++++
 src/configure.ac | 19 +++++++++++++++++++
 2 files changed, 36 insertions(+)

diff --git a/src/Setup.sh b/src/Setup.sh
index 459c63dc9..3d59e71a5 100755
--- a/src/Setup.sh
+++ b/src/Setup.sh
@@ -27,6 +27,23 @@
 
 set -e
 
+: ${MIT_SCHEME_EXE:=mit-scheme}
+
+if ! ${MIT_SCHEME_EXE} --batch-mode --eval '(%exit)' > /dev/null 2> /dev/null
+then
+    cat <<EOF >&2
+This script needs an existing MIT/GNU Scheme installation to function.
+
+If you have installed MIT/GNU Scheme in an unusual location, or with
+an unusual name, set the environment variable MIT_SCHEME_EXE to the
+name or pathname of the MIT/GNU Scheme executable, which is usually
+\`mit-scheme' or \`/usr/local/bin/mit-scheme', and set the environment
+variable MITSCHEME_LIBRARY_PATH to the pathname of the MIT/GNU Scheme
+library directory, which is usually \`/usr/local/lib/mit-scheme'.
+EOF
+    exit 1
+fi
+
 if [ ! -x configure ]; then
     echo "autoconf"
     autoconf
diff --git a/src/configure.ac b/src/configure.ac
index f6f196034..d437bf664 100644
--- a/src/configure.ac
+++ b/src/configure.ac
@@ -44,6 +44,25 @@ c)
     INSTALL_COM='$(INSTALL_DATA)'
     INSTALL_LIARC_BUNDLES=
     AUXDIR_NAME=mit-scheme
+
+    AC_MSG_CHECKING([for an existing MIT/GNU Scheme installation])
+    : ${MIT_SCHEME_EXE:=mit-scheme}
+    if ! ${MIT_SCHEME_EXE} --batch-mode --eval '(%exit)'	\
+	> /dev/null 2> /dev/null
+    then
+	AC_MSG_ERROR([
+This script needs an existing MIT/GNU Scheme installation to function.
+
+If you have installed MIT/GNU Scheme in an unusual location, or with
+an unusual name, set the environment variable MIT_SCHEME_EXE to the
+name or pathname of the MIT/GNU Scheme executable, which is usually
+\`mit-scheme' or \`/usr/local/bin/mit-scheme', and set the environment
+variable MITSCHEME_LIBRARY_PATH to the pathname of the MIT/GNU Scheme
+library directory, which is usually \`/usr/local/lib/mit-scheme'.
+])
+    else
+	AC_MSG_RESULT([yes])
+    fi
     ;;
 esac
 AUXDIR='$(libdir)'/${AUXDIR_NAME}
-- 
2.25.1