Prevent linking against too new of a SpiderMonkey

Versions of SpiderMonkey newer than js185-1.0.0 have removed the
JSOPTION_ANONFUNFIX which basically invalidates all CouchDB JavaScript
functions ever written.

This configure patch prevents the accidental linking to a library that
has this new behavior while allowing people to forcefully override the
check.

1 files changed, 21 insertions, 0 deletions

diff --git a/configure.ac b/configure.ac
index 5124b8b1..6f9327d0 100644
--- a/configure.ac
+++ b/configure.ac
@@ -81,6 +81,12 @@ AC_ARG_WITH([js-lib], [AC_HELP_STRING([--with-js-lib=PATH],
 ])
 AC_SUBST(JS_LIB_DIR)
 
+use_js_trunk=no
+AC_ARG_ENABLE([js-trunk], [AC_HELP_STRING([--enable-js-trunk],
+    [allow use of SpiderMonkey versions newer than js185-1.0.0])], [
+    use_js_trunk=$enableval
+], [])
+
 AC_ARG_VAR([ERLC_FLAGS], [general flags to prepend to ERLC_FLAGS])
 AC_ARG_VAR([FLAGS], [general flags to prepend to LDFLAGS and CPPFLAGS])
 
@@ -177,6 +183,21 @@ AC_CHECK_HEADER([jsapi.h], [], [
 Are the Mozilla SpiderMonkey headers installed?])
         ])])
 
+# Prevent people from accidentally using SpiderMonkey's that are too new
+
+if test "$use_js_trunk" = "no"; then
+AC_CHECK_DECL([JSOPTION_ANONFUNFIX], [], [
+    AC_MSG_ERROR([Your SpiderMonkey library is too new.
+
+Versions of SpiderMonkey after the js185-1.0.0 release remove the optional
+enforcement of preventing anonymous functions in a statement context. This
+will most likely break your existing JavaScript code as well as render all
+example code invalid.
+
+If you wish to ignore this error pass --enable-js-trunk to ./configure.])],
+    [[#include <jsapi.h>]])
+fi
+
 AC_SUBST(JSLIB)
 
 AC_LANG_PUSH(C)