fix inline & unused on AST_Expansion (#2138)

- handle rest parameters
- suppress cases with spread arguments

fixes #2136

lib/compress.js

@@ -3111,7 +3111,11 @@ merge(Compressor.prototype, {
     OPT(AST_Call, function(self, compressor){
         var exp = self.expression;
         var fn = exp;
+        var simple_args = all(self.args, function(arg) {
+            return !(arg instanceof AST_Expansion);
+        });
         if (compressor.option("unused")
+            && simple_args
             && (fn instanceof AST_Function
                 || compressor.option("reduce_vars")
                     && fn instanceof AST_SymbolRef
@@ -3120,6 +3124,18 @@ merge(Compressor.prototype, {
             && !fn.uses_eval) {
             var pos = 0, last = 0;
             for (var i = 0, len = self.args.length; i < len; i++) {
+                if (fn.argnames[i] instanceof AST_Expansion) {
+                    if (fn.argnames[i].__unused) while (i < len) {
+                        var node = self.args[i++].drop_side_effect_free(compressor);
+                        if (node) {
+                            self.args[pos++] = node;
+                        }
+                    } else while (i < len) {
+                        self.args[pos++] = self.args[i++];
+                    }
+                    last = pos;
+                    break;
+                }
                 var trim = i >= fn.argnames.length;
                 if (trim || fn.argnames[i].__unused) {
                     var node = self.args[i].drop_side_effect_free(compressor);
@@ -3340,6 +3356,7 @@ merge(Compressor.prototype, {
                 && exp.body.length == 1
                 && !exp.uses_arguments
                 && !exp.uses_eval
+                && simple_args
                 && !self.has_pure_annotation(compressor)) {
                 var value;
                 if (stat instanceof AST_Return) {
@@ -3357,6 +3374,16 @@ merge(Compressor.prototype, {
                     if (exp.argnames.length > 0) {
                         fn.body.push(make_node(AST_Var, self, {
                             definitions: exp.argnames.map(function(sym, i) {
+                                if (sym instanceof AST_Expansion) {
+                                    return make_node(AST_VarDef, sym, {
+                                        name: sym.expression,
+                                        value: make_node(AST_Array, self, {
+                                            elements: self.args.slice(i).map(function(arg) {
+                                                return arg.clone(true);
+                                            })
+                                        })
+                                    });
+                                }
                                 var arg = self.args[i];
                                 return make_node(AST_VarDef, sym, {
                                     name: sym,
@@ -3365,7 +3392,7 @@ merge(Compressor.prototype, {
                             })
                         }));
                     }
-                    if (self.args.length > exp.argnames.length) {
+                    if (self.args.length > exp.argnames.length && !(exp.argnames[exp.argnames.length - 1] instanceof AST_Expansion)) {
                         fn.body.push(make_node(AST_SimpleStatement, self, {
                             body: make_sequence(self, self.args.slice(exp.argnames.length).map(function(node) {
                                 return node.clone(true);

test/compress/drop-unused.js

@@ -1338,3 +1338,74 @@ issue_2105: {
     }
     expect_stdout: "PASS"
 }
+
+issue_2136_1: {
+    options = {
+        inline: true,
+        unused: true,
+    }
+    input: {
+        !function(a, ...b) {
+            console.log(b);
+        }();
+    }
+    expect: {
+        !function(a, ...b) {
+            console.log(b);
+        }();
+    }
+    expect_stdout: "[]"
+    node_version: ">=6"
+}
+
+issue_2136_2: {
+    options = {
+        collapse_vars: true,
+        inline: true,
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        function f(x) {
+            console.log(x);
+        }
+        !function(a, ...b) {
+            f(b[0]);
+        }(1, 2, 3);
+    }
+    expect: {
+        function f(x) {
+            console.log(x);
+        }
+        f([2,3][0]);
+    }
+    expect_stdout: "2"
+    node_version: ">=6"
+}
+
+issue_2136_3: {
+    options = {
+        collapse_vars: true,
+        evaluate: true,
+        inline: true,
+        passes: 3,
+        reduce_vars: true,
+        side_effects: true,
+        toplevel: true,
+        unsafe: true,
+        unused: true,
+    }
+    input: {
+        function f(x) {
+            console.log(x);
+        }
+        !function(a, ...b) {
+            f(b[0]);
+        }(1, 2, 3);
+    }
+    expect: {
+        console.log(2);
+    }
+    expect_stdout: "2"
+    node_version: ">=6"
+}