support `const` (#4190)

1 files changed, 40 insertions, 21 deletions

diff --git a/lib/scope.js b/lib/scope.js
index ec2c1f6d..fa558640 100644
--- a/lib/scope.js
+++ b/lib/scope.js
@@ -80,7 +80,12 @@ SymbolDef.prototype = {
         }
     },
     redefined: function() {
-        return this.defun && this.defun.variables.get(this.name);
+        var scope = this.defun;
+        if (!scope) return;
+        var def = scope.variables.get(this.name);
+        if (!def && scope instanceof AST_Toplevel) def = scope.globals.get(this.name);
+        if (def === this) return;
+        return def;
     },
     unmangleable: function(options) {
         return this.global && !options.toplevel
@@ -114,6 +119,11 @@ AST_Toplevel.DEFMETHOD("figure_out_scope", function(options) {
             });
             return true;
         }
+        if (node instanceof AST_SwitchBranch) {
+            node.init_vars(scope);
+            descend();
+            return true;
+        }
         if (node instanceof AST_Try) {
             walk_scope(function() {
                 walk_body(node, tw);
@@ -122,10 +132,6 @@ AST_Toplevel.DEFMETHOD("figure_out_scope", function(options) {
             if (node.bfinally) node.bfinally.walk(tw);
             return true;
         }
-        if (node instanceof AST_BlockScope) {
-            walk_scope(descend);
-            return true;
-        }
         if (node instanceof AST_With) {
             var s = scope;
             do {
@@ -133,7 +139,12 @@ AST_Toplevel.DEFMETHOD("figure_out_scope", function(options) {
                 if (s.uses_with) break;
                 s.uses_with = true;
             } while (s = s.parent_scope);
-            return;
+            walk_scope(descend);
+            return true;
+        }
+        if (node instanceof AST_BlockScope) {
+            walk_scope(descend);
+            return true;
         }
         if (node instanceof AST_Symbol) {
             node.scope = scope;
@@ -144,6 +155,8 @@ AST_Toplevel.DEFMETHOD("figure_out_scope", function(options) {
         }
         if (node instanceof AST_SymbolCatch) {
             scope.def_variable(node).defun = defun;
+        } else if (node instanceof AST_SymbolConst) {
+            scope.def_variable(node).defun = defun;
         } else if (node instanceof AST_SymbolDefun) {
             defun.def_function(node, tw.parent());
             entangle(defun, scope);
@@ -216,7 +229,7 @@ AST_Toplevel.DEFMETHOD("figure_out_scope", function(options) {
             node.reference(options);
             return true;
         }
-        // ensure mangling works if catch reuses a scope variable
+        // ensure mangling works if `catch` reuses a scope variable
         if (node instanceof AST_SymbolCatch) {
             var def = node.definition().redefined();
             if (def) for (var s = node.scope; s; s = s.parent_scope) {
@@ -225,6 +238,16 @@ AST_Toplevel.DEFMETHOD("figure_out_scope", function(options) {
             }
             return true;
         }
+        // ensure compression works if `const` reuses a scope variable
+        if (node instanceof AST_SymbolConst) {
+            var def = node.definition();
+            var redef = def.redefined();
+            if (redef) {
+                if (!redef.const_redefs) redef.const_redefs = [];
+                redef.const_redefs.push(def);
+            }
+            return true;
+        }
     });
     self.walk(tw);
 
@@ -290,7 +313,6 @@ AST_Toplevel.DEFMETHOD("def_global", function(node) {
 });
 
 function init_block_vars(scope, parent) {
-    scope.cname = -1;                               // the current index for mangling functions/variables
     scope.enclosed = [];                            // variables from this or outer scope(s) that are referenced from this or inner scopes
     scope.parent_scope = parent;                    // the parent scope (null if this is the top level)
     scope.functions = new Dictionary();             // map name to AST_SymbolDefun (functions defined in this scope)
@@ -368,8 +390,9 @@ AST_BlockScope.DEFMETHOD("def_variable", function(symbol, init) {
 function names_in_use(scope, options) {
     var names = scope.names_in_use;
     if (!names) {
-        scope.names_in_use = names = Object.create(null);
+        scope.cname = -1;
         scope.cname_holes = [];
+        scope.names_in_use = names = Object.create(null);
         var cache = options.cache && options.cache.props;
         scope.enclosed.forEach(function(def) {
             if (def.unmangleable(options)) names[def.name] = true;
@@ -467,7 +490,11 @@ AST_Toplevel.DEFMETHOD("mangle_names", function(options) {
             lname = save_nesting;
             return true;
         }
-        if (node instanceof AST_Scope) {
+        if (node instanceof AST_BlockScope) {
+            var to_mangle = [];
+            node.variables.each(function(def) {
+                if (!defer_redef(def)) to_mangle.push(def);
+            });
             descend();
             if (options.cache && node instanceof AST_Toplevel) {
                 node.globals.each(mangle);
@@ -477,9 +504,7 @@ AST_Toplevel.DEFMETHOD("mangle_names", function(options) {
                 sym.scope = node;
                 sym.reference(options);
             }
-            node.variables.each(function(def) {
-                if (!defer_redef(def)) mangle(def);
-            });
+            to_mangle.forEach(mangle);
             return true;
         }
         if (node instanceof AST_Label) {
@@ -490,13 +515,6 @@ AST_Toplevel.DEFMETHOD("mangle_names", function(options) {
             node.mangled_name = name;
             return true;
         }
-        if (!options.ie8 && node instanceof AST_Catch && node.argname) {
-            var def = node.argname.definition();
-            var redef = defer_redef(def, node.argname);
-            descend();
-            if (!redef) mangle(def);
-            return true;
-        }
     });
     this.walk(tw);
     redefined.forEach(mangle);
@@ -511,7 +529,8 @@ AST_Toplevel.DEFMETHOD("mangle_names", function(options) {
         if (!redef) return false;
         redefined.push(def);
         def.references.forEach(reference);
-        if (node) reference(node);
+        var node = def.orig[0];
+        if (node instanceof AST_SymbolCatch || node instanceof AST_SymbolConst) reference(node);
         return true;
 
         function reference(sym) {