findvars on recursive custom functions doesn't include that function's name

When finding unbound variables inside the definition of a custom JME
function, the scope didn't yet know about the function being defined, so
a recursive call of that function would produce the function's own name
as a free variable.

This changes makeJMEFunction to add the function to the scope that is
used when finding unbound variables inside its definition.

Author: christianp

runtime/scripts/jme-variables.js

@@ -49,7 +49,9 @@ jme.variables = /** @lends Numbas.jme.variables */ {
      */
     makeJMEFunction: function(fn,scope) {
         fn.tree = jme.compile(fn.definition,scope,true);
-        var external_vars = jme.findvars(fn.tree,fn.paramNames.map(function(v) { return jme.normaliseName(v,scope) }),scope);
+        const nscope = new jme.Scope([scope]);
+        nscope.addFunction(fn);
+        var external_vars = jme.findvars(fn.tree,fn.paramNames.map(function(v) { return jme.normaliseName(v,scope) }),nscope);
         jme.findvarsOps[fn.name] = function(tree,boundvars,scope) {
             var vars = external_vars.slice();
             for(var i=0;i<tree.args.length;i++) {

tests/jme-runtime.js

@@ -19971,7 +19971,9 @@ jme.variables = /** @lends Numbas.jme.variables */ {
      */
     makeJMEFunction: function(fn,scope) {
         fn.tree = jme.compile(fn.definition,scope,true);
-        var external_vars = jme.findvars(fn.tree,fn.paramNames.map(function(v) { return jme.normaliseName(v,scope) }),scope);
+        const nscope = new jme.Scope([scope]);
+        nscope.addFunction(fn);
+        var external_vars = jme.findvars(fn.tree,fn.paramNames.map(function(v) { return jme.normaliseName(v,scope) }),nscope);
         jme.findvarsOps[fn.name] = function(tree,boundvars,scope) {
             var vars = external_vars.slice();
             for(var i=0;i<tree.args.length;i++) {

tests/jme/jme-tests.mjs

@@ -95,6 +95,18 @@ Numbas.queueScript('jme_tests',['qunit','jme','jme-rules','jme-display','jme-cal
         deepCloseEqual(assert, Numbas.jme.findvars(Numbas.jme.compile('a -> a(x)')),['x'],'findvars on lambda where an argument is another lambda');
         deepCloseEqual(assert, Numbas.jme.findvars(Numbas.jme.compile('[x,[y,z]] -> x+y+z+w')),['w'],'findvars on lambda with destructuring');
         deepCloseEqual(assert, Numbas.jme.findvars(Numbas.jme.compile('undefined_function(x)')),['x', 'undefined_function'],'Undefined function names are presumed to be missing variables.');
+
+        const fn = Numbas.jme.variables.makeFunction({
+            parameters: [{type:'number', name:'x'}],
+            definition: 'if(x>0,0,f(x-1))',
+            name: 'f',
+            language: 'jme'
+        }, Numbas.jme.builtinScope);
+
+        const scope = new Numbas.jme.Scope([Numbas.jme.builtinScope]);
+        scope.addFunction(fn);
+        const vars = Numbas.jme.findvars(Numbas.jme.compile('f(2)'), scope);
+        assert.deepEqual(vars, [], "Recursive custom functions don't produce their own names in findvars");
     });
 
     QUnit.test('findvars in HTML',function(assert) {

tests/numbas-runtime.js

@@ -19307,7 +19307,9 @@ jme.variables = /** @lends Numbas.jme.variables */ {
      */
     makeJMEFunction: function(fn,scope) {
         fn.tree = jme.compile(fn.definition,scope,true);
-        var external_vars = jme.findvars(fn.tree,fn.paramNames.map(function(v) { return jme.normaliseName(v,scope) }),scope);
+        const nscope = new jme.Scope([scope]);
+        nscope.addFunction(fn);
+        var external_vars = jme.findvars(fn.tree,fn.paramNames.map(function(v) { return jme.normaliseName(v,scope) }),nscope);
         jme.findvarsOps[fn.name] = function(tree,boundvars,scope) {
             var vars = external_vars.slice();
             for(var i=0;i<tree.args.length;i++) {