fix corner cases in collapse_vars (#5553)

fixes #5552

lib/compress.js

@@ -2477,24 +2477,24 @@ Compressor.prototype.compress = function(node) {
                     can_replace = false;
                     var after = stop_after;
                     var if_hit = stop_if_hit;
-                    if (!all(fn.argnames, function(argname) {
+                    for (var i = 0; !abort && i < fn.argnames.length; i++) {
-                        if (argname instanceof AST_DefaultValue) {
+                        if (may_throw_arg(reject, fn.argnames[i], node.args[i])) abort = true;
-                            argname.value.transform(scanner);
+                    }
-                            if (abort) return false;
+                    if (!abort) {
-                            argname = argname.name;
+                        if (fn.rest && may_throw_arg(reject, fn.rest, make_node(AST_Array, node, {
+                            elements: node.args.slice(i),
+                        }))) {
+                            abort = true;
+                        } else if (is_arrow(fn) && fn.value) {
+                            fn.value.transform(scanner);
+                        } else for (var i = 0; !abort && i < fn.body.length; i++) {
+                            var stat = fn.body[i];
+                            if (stat instanceof AST_Return) {
+                                if (stat.value) stat.value.transform(scanner);
+                                break;
+                            }
+                            stat.transform(scanner);
                         }
-                        return !(argname instanceof AST_Destructured);
-                    })) {
-                        abort = true;
-                    } else if (is_arrow(fn) && fn.value) {
-                        fn.value.transform(scanner);
-                    } else for (var i = 0; !abort && i < fn.body.length; i++) {
-                        var stat = fn.body[i];
-                        if (stat instanceof AST_Return) {
-                            if (stat.value) stat.value.transform(scanner);
-                            break;
-                        }
-                        stat.transform(scanner);
                     }
                     stop_if_hit = if_hit;
                     stop_after = after;
@@ -2560,28 +2560,35 @@ Compressor.prototype.compress = function(node) {
                     return node instanceof AST_SymbolRef
                         && (lvalues.has(node.name) || read_toplevel && compressor.exposed(node.definition()));
                 }, true);
+
+                function reject(node) {
+                    node.transform(scanner);
+                    return abort;
+                }
             }
 
-            function may_throw_destructured(node, value) {
+            function may_throw_arg(reject, node, value) {
-                if (!value) return !(node instanceof AST_Symbol);
                 if (node instanceof AST_DefaultValue) {
-                    return value.has_side_effects(compressor)
+                    return reject(node.value)
-                        || node.value.has_side_effects(compressor)
+                        || may_throw_arg(reject, node.name, node.value)
-                        || may_throw_destructured(node.name, is_undefined(value) && node.value);
+                        || !is_undefined(value) && may_throw_arg(reject, node.name, value);
                 }
+                if (!value) return !(node instanceof AST_Symbol);
                 if (node instanceof AST_Destructured) {
-                    if (node.rest && may_throw_destructured(node.rest)) return true;
+                    if (node.rest && may_throw_arg(reject, node.rest)) return true;
                     if (node instanceof AST_DestructuredArray) {
-                        if (!(value instanceof AST_Array || value.is_string(compressor))) return true;
+                        if (value instanceof AST_Array) return !all(node.elements, function(element, index) {
-                        return !all(node.elements, function(element) {
+                            return !may_throw_arg(reject, element, value[index]);
-                            return !may_throw_destructured(element);
+                        });
+                        return value.is_string(compressor) && !all(node.elements, function(element) {
+                            return !may_throw_arg(reject, element);
                         });
                     }
                     if (node instanceof AST_DestructuredObject) {
                         if (!value.is_defined(compressor)) return true;
                         return !all(node.properties, function(prop) {
-                            if (prop instanceof AST_Node && prop.has_side_effects(compressor)) return false;
+                            if (prop.key instanceof AST_Node && reject(prop.key)) return false;
-                            return !may_throw_destructured(prop.value);
+                            return !may_throw_arg(reject, prop.value);
                         });
                     }
                 }
@@ -2645,7 +2652,9 @@ Compressor.prototype.compress = function(node) {
                             args[len + i] = value;
                         }
                         if (sym instanceof AST_Destructured) {
-                            if (!may_throw_destructured(sym, arg)) continue;
+                            if (!may_throw_arg(function(node) {
+                                return node.has_side_effects(compressor);
+                            }, sym, arg)) continue;
                             candidates.length = 0;
                             break;
                         }
@@ -2668,6 +2677,7 @@ Compressor.prototype.compress = function(node) {
                         candidate.arg_index = value ? len + i : i;
                         candidates.unshift([ candidate ]);
                     }
+                    if (fn.rest) args.push(fn.rest);
                 }
             }
 

test/compress/rests.js

@@ -1531,3 +1531,96 @@ issue_5533_2_drop_fargs: {
     expect_stdout: "PASS"
     node_version: ">=6"
 }
+
+issue_5552_1: {
+    options = {
+        collapse_vars: true,
+        reduce_vars: true,
+        toplevel: true,
+    }
+    input: {
+        var log = console.log;
+        var a = f, b = log();
+        function f(...[ c = a = "PASS" ]) {}
+        f((a = "FAIL", b));
+        log(a);
+    }
+    expect: {
+        var log = console.log;
+        var a = f, b = log();
+        function f(...[ c = a = "PASS" ]) {}
+        f((a = "FAIL", b));
+        log(a);
+    }
+    expect_stdout: [
+        "",
+        "PASS",
+    ]
+    node_version: ">=6"
+}
+
+issue_5552_2: {
+    options = {
+        collapse_vars: true,
+        reduce_vars: true,
+        toplevel: true,
+    }
+    input: {
+        var log = console.log;
+        var a = f;
+        function f(...{ [a = "PASS"]: b }) {}
+        f((a = "FAIL", 42));
+        log(a);
+    }
+    expect: {
+        var log = console.log;
+        var a = f;
+        function f(...{ [a = "PASS"]: b }) {}
+        f((a = "FAIL", 42));
+        log(a);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5552_3: {
+    options = {
+        collapse_vars: true,
+        unused: true,
+    }
+    input: {
+        var a = [ "FAIL", "PASS" ];
+        console.log(function(b, ...[ c = a.pop() ]) {
+            return b;
+        }(a.pop()));
+    }
+    expect: {
+        var a = [ "FAIL", "PASS" ];
+        console.log(function(b, ...[ c = a.pop() ]) {
+            return b;
+        }(a.pop()));
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5552_4: {
+    options = {
+        collapse_vars: true,
+        unused: true,
+    }
+    input: {
+        var a = [ "FAIL", "PASS" ];
+        console.log(function(b, ...{ [a.pop()]: c }) {
+            return b;
+        }(a.pop()));
+    }
+    expect: {
+        var a = [ "FAIL", "PASS" ];
+        console.log(function(b, ...{ [a.pop()]: c }) {
+            return b;
+        }(a.pop()));
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}