consolidate & enhance unused

- defer declaration removal in `collapse_vars`
- account for `AST_SymbolFunarg` in deduplication

lib/compress.js

@@ -1009,6 +1009,10 @@ merge(Compressor.prototype, {
                 }
             }
 
+            function get_rvalue(expr) {
+                return expr[expr instanceof AST_Assign ? "right" : "value"];
+            }
+
             function get_lvalues(expr) {
                 var lvalues = Object.create(null);
                 if (expr instanceof AST_Unary) return lvalues;
@@ -1019,7 +1023,7 @@ merge(Compressor.prototype, {
                         lvalues[sym.name] = lvalues[sym.name] || is_lhs(node, tw.parent());
                     }
                 });
-                expr[expr instanceof AST_Assign ? "right" : "value"].walk(tw);
+                get_rvalue(expr).walk(tw);
                 return lvalues;
             }
 
@@ -1044,6 +1048,8 @@ merge(Compressor.prototype, {
                         found = true;
                         if (node instanceof AST_VarDef) {
                             remove(node.name.definition().orig, node.name);
+                            node.value = null;
+                            return node;
                         }
                         return in_list ? MAP.skip : null;
                     }
@@ -1052,16 +1058,13 @@ merge(Compressor.prototype, {
                       case 0: return null;
                       case 1: return node.expressions[0];
                     }
-                    if (node instanceof AST_Definitions && node.definitions.length == 0
+                    if (node instanceof AST_SimpleStatement && !node.body) return null;
-                        || node instanceof AST_SimpleStatement && !node.body) {
-                        return null;
-                    }
                 }));
             }
 
             function value_has_side_effects(expr) {
                 if (expr instanceof AST_Unary) return false;
-                return expr[expr instanceof AST_Assign ? "right" : "value"].has_side_effects(compressor);
+                return get_rvalue(expr).has_side_effects(compressor);
             }
 
             function references_in_scope(def) {
@@ -2303,7 +2306,7 @@ merge(Compressor.prototype, {
         // this scope (not in nested scopes).
         var scope = this;
         var tw = new TreeWalker(function(node, descend){
-            if (node !== self) {
+            if (node === self) return;
             if (node instanceof AST_Defun) {
                 if (!drop_funcs && scope === self) {
                     var node_def = node.name.definition();
@@ -2315,6 +2318,9 @@ merge(Compressor.prototype, {
                 initializations.add(node.name.name, node);
                 return true; // don't go in nested scopes
             }
+            if (node instanceof AST_SymbolFunarg && scope === self) {
+                var_defs_by_id.add(node.definition().id, node);
+            }
             if (node instanceof AST_Definitions && scope === self) {
                 node.definitions.forEach(function(def){
                     var node_def = def.name.definition();
@@ -2358,7 +2364,6 @@ merge(Compressor.prototype, {
                 scope = save_scope;
                 return true;
             }
-            }
         });
         self.walk(tw);
         // pass 2: for every used symbol we need to walk its

test/compress/collapse_vars.js

@@ -1388,6 +1388,7 @@ issue_1605_1: {
     options = {
         collapse_vars: true,
         toplevel: false,
+        unused: true,
     }
     input: {
         function foo(x) {
@@ -1410,6 +1411,7 @@ issue_1605_2: {
     options = {
         collapse_vars: true,
         toplevel: "vars",
+        unused: true,
     }
     input: {
         function foo(x) {
@@ -1537,6 +1539,7 @@ issue_1631_3: {
 var_side_effects_1: {
     options = {
         collapse_vars: true,
+        unused: true,
     }
     input: {
         var print = console.log.bind(console);
@@ -1559,6 +1562,7 @@ var_side_effects_1: {
 var_side_effects_2: {
     options = {
         collapse_vars: true,
+        unused: true,
     }
     input: {
         var print = console.log.bind(console);
@@ -1584,6 +1588,7 @@ var_side_effects_3: {
         collapse_vars: true,
         pure_getters: true,
         unsafe: true,
+        unused: true,
     }
     input: {
         var print = console.log.bind(console);
@@ -1659,6 +1664,7 @@ iife_2: {
         }(foo);
     }
     expect: {
+        var foo;
         !function(x) {
             console.log(x);
         }(bar());
@@ -1945,6 +1951,7 @@ ref_scope: {
 chained_1: {
     options = {
         collapse_vars: true,
+        unused: true,
     }
     input: {
         var a = 2;
@@ -1961,6 +1968,7 @@ chained_1: {
 chained_2: {
     options = {
         collapse_vars: true,
+        unused: true,
     }
     input: {
         var a;
@@ -2061,6 +2069,7 @@ inner_lvalues: {
 double_def: {
     options = {
         collapse_vars: true,
+        unused: true,
     }
     input: {
         var a = x, a = a && y;
@@ -2075,6 +2084,7 @@ double_def: {
 toplevel_single_reference: {
     options = {
         collapse_vars: true,
+        unused: true,
     }
     input: {
         var a;
@@ -2084,10 +2094,11 @@ toplevel_single_reference: {
         }
     }
     expect: {
+        for (var b in x) {
             var a;
-        for (var b in x)
             b(a = b);
         }
+    }
 }
 
 unused_orig: {
@@ -2889,6 +2900,7 @@ pure_getters_chain: {
     options = {
         collapse_vars: true,
         pure_getters: true,
+        unused: true,
     }
     input: {
         function o(t, r) {
@@ -2909,6 +2921,7 @@ pure_getters_chain: {
 conditional_1: {
     options = {
         collapse_vars: true,
+        unused: true,
     }
     input: {
         function f(a, b) {
@@ -2933,6 +2946,7 @@ conditional_1: {
 conditional_2: {
     options = {
         collapse_vars: true,
+        unused: true,
     }
     input: {
         function f(a, b) {

test/compress/issue-973.js

@@ -51,6 +51,7 @@ this_binding_collapse_vars: {
     options = {
         collapse_vars: true,
         toplevel: true,
+        unused: true,
     };
     input: {
         var c = a; c();

test/compress/reduce_vars.js

@@ -2131,14 +2131,13 @@ redefine_farg_1: {
     }
     expect: {
         function f(a) {
-            var a;
             return typeof a;
         }
         function g() {
-            return"number";
+            return "number";
         }
         function h(a, b) {
-            var a = b;
+            a = b;
             return typeof a;
         }
         console.log(f([]), g([]), h([]));
@@ -2173,10 +2172,9 @@ redefine_farg_2: {
     }
     expect: {
         console.log(function(a) {
-            var a;
             return typeof a;
         }([]), "number",function(a, b) {
-            var a = b;
+            a = b;
             return typeof a;
         }([]));
     }
@@ -2185,11 +2183,13 @@ redefine_farg_2: {
 
 redefine_farg_3: {
     options = {
+        cascade: true,
         evaluate: true,
         inline: true,
         keep_fargs: false,
-        passes: 3,
+        passes: 2,
         reduce_vars: true,
+        sequences: true,
         side_effects: true,
         toplevel: true,
         unused: true,