extend `inline` (#2714)

- compress `function` with variables within loops
- restrict to `AST_Var` for better compatibility with ES6+

2 files changed, 40 insertions, 25 deletions

diff --git a/lib/compress.js b/lib/compress.js
index 300bc61d..85bb0910 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -4109,7 +4109,7 @@ merge(Compressor.prototype, {
             stat = null;
             for (var i = 0; i < len; i++) {
                 var line = fn.body[i];
-                if (line instanceof AST_Definitions) {
+                if (line instanceof AST_Var) {
                     if (stat && !all(line.definitions, function(var_def) {
                         return !var_def.value;
                     })) {
@@ -4124,7 +4124,7 @@ merge(Compressor.prototype, {
             return return_value(stat);
         }
 
-        function can_inject_args(catches, defs, safe_to_inject) {
+        function can_inject_args(catches, safe_to_inject) {
             for (var i = 0, len = fn.argnames.length; i < len; i++) {
                 var arg = fn.argnames[i];
                 if (arg.__unused) continue;
@@ -4143,7 +4143,7 @@ merge(Compressor.prototype, {
             var len = fn.body.length;
             for (var i = 0; i < len; i++) {
                 var stat = fn.body[i];
-                if (!(stat instanceof AST_Definitions)) continue;
+                if (!(stat instanceof AST_Var)) continue;
                 if (!safe_to_inject) return false;
                 for (var j = stat.definitions.length; --j >= 0;) {
                     var name = stat.definitions[j].name;
@@ -4152,6 +4152,7 @@ merge(Compressor.prototype, {
                         || scope.var_names()[name.name]) {
                         return false;
                     }
+                    if (in_loop) in_loop.push(name.definition());
                 }
             }
             return true;
@@ -4171,8 +4172,8 @@ merge(Compressor.prototype, {
             } while (!(scope instanceof AST_Scope));
             var safe_to_inject = !(scope instanceof AST_Toplevel) || compressor.toplevel.vars;
             var inline = compressor.option("inline");
-            if (!can_inject_vars(catches, !in_loop && inline >= 3 && safe_to_inject)) return false;
-            if (!can_inject_args(catches, in_loop, inline >= 2 && safe_to_inject)) return false;
+            if (!can_inject_vars(catches, inline >= 3 && safe_to_inject)) return false;
+            if (!can_inject_args(catches, inline >= 2 && safe_to_inject)) return false;
             return !in_loop || in_loop.length == 0 || !is_reachable(fn, in_loop);
         }
 
@@ -4181,13 +4182,13 @@ merge(Compressor.prototype, {
             scope.var_names()[name.name] = true;
             scope.variables.set(name.name, def);
             scope.enclosed.push(def);
-            decls.push(make_node(AST_VarDef, name, {
+            decls.unshift(make_node(AST_VarDef, name, {
                 name: name,
                 value: null
             }));
             var sym = make_node(AST_SymbolRef, name, name);
             def.references.push(sym);
-            if (value) expressions.push(make_node(AST_Assign, self, {
+            if (value) expressions.unshift(make_node(AST_Assign, self, {
                 operator: "=",
                 left: sym,
                 right: value
@@ -4195,11 +4196,15 @@ merge(Compressor.prototype, {
         }
 
         function flatten_args(decls, expressions) {
-            for (var len = fn.argnames.length, i = len; --i >= 0;) {
+            var len = fn.argnames.length;
+            for (var i = self.args.length; --i >= len;) {
+                expressions.unshift(self.args[i]);
+            }
+            for (i = len; --i >= 0;) {
                 var name = fn.argnames[i];
                 var value = self.args[i];
                 if (name.__unused || scope.var_names()[name.name]) {
-                    if (value) expressions.push(value);
+                    if (value) expressions.unshift(value);
                 } else {
                     var symbol = make_node(AST_SymbolVar, name, name);
                     name.definition().orig.push(symbol);
@@ -4207,30 +4212,38 @@ merge(Compressor.prototype, {
                     append_var(decls, expressions, symbol, value);
                 }
             }
-            decls.reverse();
-            expressions.reverse();
-            for (i = len, len = self.args.length; i < len; i++) {
-                expressions.push(self.args[i]);
-            }
         }
 
-        function flatten_body(decls, expressions) {
-            for (i = 0, len = fn.body.length; i < len; i++) {
+        function flatten_vars(decls, expressions) {
+            if (in_loop) in_loop.length = 0;
+            for (var i = fn.body.length; --i >= 0;) {
                 var stat = fn.body[i];
-                if (stat instanceof AST_Definitions) {
-                    stat.definitions.forEach(function(var_def) {
-                        append_var(decls, expressions, var_def.name, var_def.value);
-                    });
+                if (!(stat instanceof AST_Var)) continue;
+                for (var j = stat.definitions.length; --j >= 0;) {
+                    var var_def = stat.definitions[j];
+                    var name = var_def.name;
+                    append_var(decls, expressions, name, var_def.value);
+                    if (in_loop) {
+                        var def = name.definition();
+                        var sym = make_node(AST_SymbolRef, name, name);
+                        def.references.push(sym);
+                        in_loop.unshift(make_node(AST_Assign, var_def, {
+                            operator: "=",
+                            left: sym,
+                            right: make_node(AST_Undefined, name)
+                        }));
+                    }
                 }
             }
-            expressions.push(value);
+            if (in_loop) [].unshift.apply(expressions, in_loop);
         }
 
         function flatten_fn() {
             var decls = [];
             var expressions = [];
+            flatten_vars(decls, expressions);
             flatten_args(decls, expressions);
-            flatten_body(decls, expressions);
+            expressions.push(value);
             if (decls.length) {
                 i = scope.body.indexOf(compressor.parent(level - 1)) + 1;
                 scope.body.splice(i, 0, make_node(AST_Var, fn, {
diff --git a/test/compress/functions.js b/test/compress/functions.js
index b6b68982..ff3baeb2 100644
--- a/test/compress/functions.js
+++ b/test/compress/functions.js
@@ -1299,6 +1299,7 @@ issue_2630_2: {
         passes: 2,
         reduce_vars: true,
         sequences: true,
+        side_effects: true,
         unused: true,
     }
     input: {
@@ -1905,6 +1906,7 @@ inline_true: {
 use_before_init_in_loop: {
     options = {
         inline: true,
+        side_effects: true,
         toplevel: true,
     }
     input: {
@@ -1918,9 +1920,9 @@ use_before_init_in_loop: {
     }
     expect: {
         var a = "PASS";
-        for (var b = 2; --b >= 0;) (function() {
-            var c = (c && (a = "FAIL"), 1);
-        })();
+        for (var b = 2; --b >= 0;)
+            c = void 0, c = (c && (a = "FAIL"), 1);
+        var c;
         console.log(a);
     }
     expect_stdout: "PASS"