fix corner cases with block-scoped functions (#4695)

2 files changed, 30 insertions, 13 deletions

diff --git a/lib/compress.js b/lib/compress.js
index 16d86d90..0e698804 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -1509,11 +1509,22 @@ merge(Compressor.prototype, {
         return stat instanceof AST_Const || stat instanceof AST_DefClass || stat instanceof AST_Let;
     }
 
+    function safe_to_trim(stat) {
+        if (stat instanceof AST_LambdaDefinition) {
+            var def = stat.name.definition();
+            return def.scope === stat.name.scope || all(def.references, function(ref) {
+                var scope = ref.scope;
+                do {
+                    if (scope === stat.name.scope) return true;
+                } while (scope = scope.parent_scope);
+            });
+        }
+        return !is_lexical_definition(stat);
+    }
+
     function as_statement_array(thing) {
         if (thing === null) return [];
-        if (thing instanceof AST_BlockStatement) return all(thing.body, function(stat) {
-            return !is_lexical_definition(stat);
-        }) ? thing.body : [ thing ];
+        if (thing instanceof AST_BlockStatement) return all(thing.body, safe_to_trim) ? thing.body : [ thing ];
         if (thing instanceof AST_EmptyStatement) return [];
         if (is_statement(thing)) return [ thing ];
         throw new Error("Can't convert thing to statement array");
@@ -2732,9 +2743,7 @@ merge(Compressor.prototype, {
             for (var i = 0; i < statements.length;) {
                 var stat = statements[i];
                 if (stat instanceof AST_BlockStatement) {
-                    if (all(stat.body, function(stat) {
-                        return !is_lexical_definition(stat);
-                    })) {
+                    if (all(stat.body, safe_to_trim)) {
                         CHANGED = true;
                         eliminate_spurious_blocks(stat.body);
                         [].splice.apply(statements, [i, 1].concat(stat.body));
@@ -2972,15 +2981,16 @@ merge(Compressor.prototype, {
             }
 
             function extract_functions() {
-                var tail = statements.slice(i + 1);
-                statements.length = i + 1;
-                return tail.filter(function(stat) {
-                    if (stat instanceof AST_Defun) {
-                        statements.push(stat);
+                var defuns = [];
+                var tail = statements.splice(i + 1).filter(function(stat) {
+                    if (stat instanceof AST_LambdaDefinition) {
+                        defuns.push(stat);
                         return false;
                     }
                     return true;
                 });
+                [].push.apply(all(tail, safe_to_trim) ? statements : tail, defuns);
+                return tail;
             }
 
             function as_statement_array_with_return(node, ab) {
@@ -3439,7 +3449,7 @@ merge(Compressor.prototype, {
         function push(node) {
             if (block) {
                 block.push(node);
-                if (is_lexical_definition(node)) block.required = true;
+                if (!safe_to_trim(node)) block.required = true;
             } else {
                 target.push(node);
             }
@@ -5118,7 +5128,7 @@ merge(Compressor.prototype, {
             return in_list ? List.skip : make_node(AST_EmptyStatement, node);
           case 1:
             var stat = node.body[0];
-            if (is_lexical_definition(stat)) return node;
+            if (!safe_to_trim(stat)) return node;
             if (parent instanceof AST_IterationStatement && stat instanceof AST_LambdaDefinition) return node;
             return stat;
         }
diff --git a/lib/scope.js b/lib/scope.js
index 799b0dc6..600a6869 100644
--- a/lib/scope.js
+++ b/lib/scope.js
@@ -327,6 +327,13 @@ AST_Toplevel.DEFMETHOD("figure_out_scope", function(options) {
                     self.uses_eval = true;
                 }
             }
+            if (sym.init instanceof AST_LambdaDefinition && sym.scope !== sym.init.name.scope) {
+                var scope = node.scope;
+                do {
+                    if (scope === sym.init.name.scope) break;
+                } while (scope = scope.parent_scope);
+                if (!scope) sym.init = undefined;
+            }
             node.thedef = sym;
             node.reference(options);
             return true;