enhance `keep_fargs` (#3409)

6 files changed, 1145 insertions, 26 deletions

diff --git a/LICENSE b/LICENSE
index 4fdaa855..122e8fb9 100644
--- a/LICENSE
+++ b/LICENSE
@@ -1,6 +1,6 @@
 UglifyJS is released under the BSD license:
 
-Copyright 2012-2018 (c) Mihai Bazon <mihai.bazon@gmail.com>
+Copyright 2012-2019 (c) Mihai Bazon <mihai.bazon@gmail.com>
 
 Redistribution and use in source and binary forms, with or without
 modification, are permitted provided that the following conditions
diff --git a/README.md b/README.md
index a4f76229..270f20cb 100644
--- a/README.md
+++ b/README.md
@@ -664,8 +664,9 @@ If you're using the `X-SourceMap` header instead, you can just omit `sourceMap.u
 
 - `join_vars` (default: `true`) -- join consecutive `var` statements
 
-- `keep_fargs` (default: `true`) -- Prevents the compressor from discarding unused
-  function arguments.  You need this for code which relies on `Function.length`.
+- `keep_fargs` (default: `strict`) -- Discard unused function arguments. Code
+  which relies on `Function.length` will break if this is done indiscriminately,
+  i.e. when passing `true`. Pass `false` to always retain function arguments.
 
 - `keep_fnames` (default: `false`) -- Pass `true` to prevent the
   compressor from discarding function names.  Useful for code relying on
diff --git a/lib/ast.js b/lib/ast.js
index 1ced7631..03850d4f 100644
--- a/lib/ast.js
+++ b/lib/ast.js
@@ -376,7 +376,7 @@ var AST_Toplevel = DEFNODE("Toplevel", "globals", {
     }
 }, AST_Scope);
 
-var AST_Lambda = DEFNODE("Lambda", "name argnames uses_arguments", {
+var AST_Lambda = DEFNODE("Lambda", "name argnames uses_arguments length_read", {
     $documentation: "Base class for functions",
     $propdoc: {
         name: "[AST_SymbolDeclaration?] the name of this function",
@@ -614,6 +614,18 @@ var AST_PropAccess = DEFNODE("PropAccess", "expression property", {
     $propdoc: {
         expression: "[AST_Node] the “container” expression",
         property: "[AST_Node|string] the property to access.  For AST_Dot this is always a plain string, while for AST_Sub it's an arbitrary AST_Node"
+    },
+    getProperty: function() {
+        var p = this.property;
+        if (p instanceof AST_Constant) {
+            return p.getValue();
+        }
+        if (p instanceof AST_UnaryPrefix
+            && p.operator == "void"
+            && p.expression instanceof AST_Constant) {
+            return;
+        }
+        return p;
     }
 });
 
diff --git a/lib/compress.js b/lib/compress.js
index 638fb7c0..57df130a 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -69,7 +69,7 @@ function Compressor(options, false_by_default) {
         if_return       : !false_by_default,
         inline          : !false_by_default,
         join_vars       : !false_by_default,
-        keep_fargs      : true,
+        keep_fargs      : false_by_default || "strict",
         keep_fnames     : false,
         keep_infinity   : false,
         loops           : !false_by_default,
@@ -104,6 +104,17 @@ function Compressor(options, false_by_default) {
         }
     }
     if (this.options["inline"] === true) this.options["inline"] = 3;
+    var keep_fargs = this.options["keep_fargs"];
+    this.drop_fargs = keep_fargs == "strict" ? function(lambda) {
+        if (lambda.length_read) return false;
+        var name = lambda.name;
+        if (!name) return true;
+        if (name.fixed_value() !== lambda) return false;
+        var def = name.definition();
+        if (def.direct_access) return false;
+        var escaped = def.escaped;
+        return escaped && escaped.depth != 1;
+    } : keep_fargs ? return_false : return_true;
     var pure_funcs = this.options["pure_funcs"];
     if (typeof pure_funcs == "function") {
         this.pure_funcs = pure_funcs;
@@ -118,6 +129,8 @@ function Compressor(options, false_by_default) {
     } else {
         this.pure_funcs = return_true;
     }
+    var sequences = this.options["sequences"];
+    this.sequences_limit = sequences == 1 ? 800 : sequences | 0;
     var top_retain = this.options["top_retain"];
     if (top_retain instanceof RegExp) {
         this.top_retain = function(def) {
@@ -141,8 +154,6 @@ function Compressor(options, false_by_default) {
         funcs: toplevel,
         vars: toplevel
     };
-    var sequences = this.options["sequences"];
-    this.sequences_limit = sequences == 1 ? 800 : sequences | 0;
 }
 
 Compressor.prototype = new TreeTransformer;
@@ -272,14 +283,19 @@ merge(Compressor.prototype, {
         self.transform(tt);
     });
 
-    function read_property(obj, key) {
-        key = get_value(key);
+    function read_property(obj, node) {
+        var key = node.getProperty();
         if (key instanceof AST_Node) return;
         var value;
         if (obj instanceof AST_Array) {
             var elements = obj.elements;
             if (key == "length") return make_node_from_constant(elements.length, obj);
             if (typeof key == "number" && key in elements) value = elements[key];
+        } else if (obj instanceof AST_Lambda) {
+            if (key == "length") {
+                obj.length_read = true;
+                return make_node_from_constant(obj.argnames.length, obj);
+            }
         } else if (obj instanceof AST_Object) {
             key = "" + key;
             var props = obj.properties;
@@ -326,7 +342,7 @@ merge(Compressor.prototype, {
             return is_modified(compressor, tw, obj, obj, level + 2);
         }
         if (parent instanceof AST_PropAccess && parent.expression === node) {
-            var prop = read_property(value, parent.property);
+            var prop = read_property(value, parent);
             return !immutable && is_modified(compressor, tw, parent, prop, level + 1);
         }
     }
@@ -490,13 +506,15 @@ merge(Compressor.prototype, {
                 var obj = tw.parent(level + 1);
                 mark_escaped(tw, d, scope, obj, obj, level + 2, depth);
             } else if (parent instanceof AST_PropAccess && node === parent.expression) {
-                value = read_property(value, parent.property);
+                value = read_property(value, parent);
                 mark_escaped(tw, d, scope, parent, value, level + 1, depth + 1);
                 if (value) return;
             }
             if (level > 0) return;
+            if (parent instanceof AST_Call && node === parent.expression) return;
             if (parent instanceof AST_Sequence && node !== parent.tail_node()) return;
             if (parent instanceof AST_SimpleStatement) return;
+            if (parent instanceof AST_Unary) return;
             d.direct_access = true;
         }
 
@@ -2217,18 +2235,6 @@ merge(Compressor.prototype, {
         }));
     }
 
-    function get_value(key) {
-        if (key instanceof AST_Constant) {
-            return key.getValue();
-        }
-        if (key instanceof AST_UnaryPrefix
-            && key.operator == "void"
-            && key.expression instanceof AST_Constant) {
-            return;
-        }
-        return key;
-    }
-
     function is_undefined(node, compressor) {
         return node.is_undefined
             || node instanceof AST_Undefined
@@ -3621,7 +3627,7 @@ merge(Compressor.prototype, {
                 node.name = null;
             }
             if (node instanceof AST_Lambda && !(node instanceof AST_Accessor)) {
-                var trim = !compressor.option("keep_fargs");
+                var trim = compressor.drop_fargs(node);
                 for (var a = node.argnames, i = a.length; --i >= 0;) {
                     var sym = a[i];
                     if (!(sym.definition().id in in_use_ids)) {
@@ -4068,7 +4074,7 @@ merge(Compressor.prototype, {
             if (node instanceof AST_PropAccess && node.expression instanceof AST_SymbolRef) {
                 var defs = defs_by_id[node.expression.definition().id];
                 if (defs) {
-                    var def = defs.get(get_value(node.property));
+                    var def = defs.get(node.getProperty());
                     var sym = make_node(AST_SymbolRef, node, {
                         name: def.name,
                         scope: node.expression.scope,
@@ -6652,7 +6658,7 @@ merge(Compressor.prototype, {
                     || def.orig.length > 1) {
                     argname = null;
                 }
-            } else if (!argname && !compressor.option("keep_fargs") && index < fn.argnames.length + 5) {
+            } else if (!argname && compressor.drop_fargs(fn) && index < fn.argnames.length + 5) {
                 while (index >= fn.argnames.length) {
                     argname = make_node(AST_SymbolFunarg, fn, {
                         name: fn.make_var_name("argument_" + fn.argnames.length),
@@ -6665,6 +6671,7 @@ merge(Compressor.prototype, {
             if (argname && find_if(function(node) {
                 return node.name === argname.name;
             }, fn.argnames) === argname) {
+                expr.definition().reassigned = false;
                 var sym = make_node(AST_SymbolRef, self, argname);
                 sym.reference({});
                 delete argname.__unused;
diff --git a/test/compress/arguments.js b/test/compress/arguments.js
index fba271c7..eaff8119 100644
--- a/test/compress/arguments.js
+++ b/test/compress/arguments.js
@@ -405,6 +405,52 @@ issue_3273_global_strict_reduce_vars: {
     ]
 }
 
+issue_3273_keep_fargs_false: {
+    options = {
+        arguments: true,
+        keep_fargs: false,
+        reduce_vars: true,
+    }
+    input: {
+        (function() {
+            "use strict";
+            arguments[0]++;
+            console.log(arguments[0]);
+        })(0);
+    }
+    expect: {
+        (function(argument_0) {
+            "use strict";
+            argument_0++;
+            console.log(argument_0);
+        })(0);
+    }
+    expect_stdout: "1"
+}
+
+issue_3273_keep_fargs_strict: {
+    options = {
+        arguments: true,
+        keep_fargs: "strict",
+        reduce_vars: true,
+    }
+    input: {
+        (function() {
+            "use strict";
+            arguments[0]++;
+            console.log(arguments[0]);
+        })(0);
+    }
+    expect: {
+        (function(argument_0) {
+            "use strict";
+            argument_0++;
+            console.log(argument_0);
+        })(0);
+    }
+    expect_stdout: "1"
+}
+
 issue_3282_1: {
     options = {
         arguments: true,
diff --git a/test/compress/keep_fargs.js b/test/compress/keep_fargs.js
new file mode 100644
index 00000000..b23e96f0
--- /dev/null
+++ b/test/compress/keep_fargs.js
@@ -0,0 +1,1053 @@
+keep_fargs_false: {
+    options = {
+        keep_fargs: false,
+        unused: true,
+    }
+    input: {
+        console.log(function f(a) {
+            return f.length;
+        }(), function g(b) {
+            return g;
+        }().length);
+        function h(c) {
+            return h.length;
+        }
+        function i(d) {
+            return i;
+        }
+        function j(e) {}
+        console.log(h(), i().length, j.length);
+    }
+    expect: {
+        console.log(function f() {
+            return f.length;
+        }(), function g() {
+            return g;
+        }().length);
+        function h() {
+            return h.length;
+        }
+        function i() {
+            return i;
+        }
+        function j() {}
+        console.log(h(), i().length, j.length);
+    }
+}
+
+keep_fargs_strict: {
+    options = {
+        keep_fargs: "strict",
+        unused: true,
+    }
+    input: {
+        console.log(function f(a) {
+            return f.length;
+        }(), function g(b) {
+            return g;
+        }().length);
+        function h(c) {
+            return h.length;
+        }
+        function i(d) {
+            return i;
+        }
+        function j(e) {}
+        console.log(h(), i().length, j.length);
+    }
+    expect: {
+        console.log(function f(a) {
+            return f.length;
+        }(), function g(b) {
+            return g;
+        }().length);
+        function h(c) {
+            return h.length;
+        }
+        function i(d) {
+            return i;
+        }
+        function j(e) {}
+        console.log(h(), i().length, j.length);
+    }
+    expect_stdout: [
+        "1 1",
+        "1 1 1",
+    ]
+}
+
+keep_fargs_true: {
+    options = {
+        keep_fargs: true,
+        unused: true,
+    }
+    input: {
+        console.log(function f(a) {
+            return f.length;
+        }(), function g(b) {
+            return g;
+        }().length);
+        function h(c) {
+            return h.length;
+        }
+        function i(d) {
+            return i;
+        }
+        function j(e) {}
+        console.log(h(), i().length, j.length);
+    }
+    expect: {
+        console.log(function f(a) {
+            return f.length;
+        }(), function g(b) {
+            return g;
+        }().length);
+        function h(c) {
+            return h.length;
+        }
+        function i(d) {
+            return i;
+        }
+        function j(e) {}
+        console.log(h(), i().length, j.length);
+    }
+    expect_stdout: [
+        "1 1",
+        "1 1 1",
+    ]
+}
+
+replace_index: {
+    options = {
+        arguments: true,
+        evaluate: true,
+        keep_fargs: "strict",
+        properties: true,
+    }
+    input: {
+        var arguments = [];
+        console.log(arguments[0]);
+        (function() {
+            console.log(arguments[1], arguments["1"], arguments["foo"]);
+        })("bar", 42);
+        (function(a, b) {
+            console.log(arguments[1], arguments["1"], arguments["foo"]);
+        })("bar", 42);
+        (function(arguments) {
+            console.log(arguments[1], arguments["1"], arguments["foo"]);
+        })("bar", 42);
+        (function() {
+            var arguments;
+            console.log(arguments[1], arguments["1"], arguments["foo"]);
+        })("bar", 42);
+    }
+    expect: {
+        var arguments = [];
+        console.log(arguments[0]);
+        (function(argument_0, argument_1) {
+            console.log(argument_1, argument_1, arguments.foo);
+        })("bar", 42);
+        (function(a, b) {
+            console.log(b, b, arguments.foo);
+        })("bar", 42);
+        (function(arguments) {
+            console.log(arguments[1], arguments[1], arguments.foo);
+        })("bar", 42);
+        (function() {
+            var arguments;
+            console.log(arguments[1], arguments[1], arguments.foo);
+        })("bar", 42);
+    }
+    expect_stdout: [
+        "undefined",
+        "42 42 undefined",
+        "42 42 undefined",
+        "a a undefined",
+        "42 42 undefined",
+    ]
+}
+
+replace_index_strict: {
+    options = {
+        arguments: true,
+        evaluate: true,
+        keep_fargs: "strict",
+        properties: true,
+        reduce_vars: true,
+    }
+    input: {
+        "use strict";
+        (function() {
+            console.log(arguments[1], arguments["1"], arguments["foo"]);
+        })("bar", 42);
+        (function(a, b) {
+            console.log(arguments[1], arguments["1"], arguments["foo"]);
+        })("bar", 42);
+    }
+    expect: {
+        "use strict";
+        (function(argument_0, argument_1) {
+            console.log(argument_1, argument_1, arguments.foo);
+        })("bar", 42);
+        (function(a, b) {
+            console.log(b, b, arguments.foo);
+        })("bar", 42);
+    }
+    expect_stdout: [
+        "42 42 undefined",
+        "42 42 undefined",
+    ]
+}
+
+issue_1858: {
+    options = {
+        collapse_vars: true,
+        keep_fargs: "strict",
+        pure_getters: true,
+        unused: true,
+    }
+    input: {
+        console.log(function(x) {
+            var a = {}, b = a.b = x;
+            return a.b + b;
+        }(1));
+    }
+    expect: {
+        console.log(function() {
+            var a = {}, b = a.b = 1;
+            return a.b + b;
+        }());
+    }
+    expect_stdout: "2"
+}
+
+issue_2187_2: {
+    options = {
+        collapse_vars: true,
+        keep_fargs: "strict",
+        unused: true,
+    }
+    input: {
+        var b = 1;
+        console.log(function(a) {
+            return a && ++b;
+        }(b--));
+    }
+    expect: {
+        var b = 1;
+        console.log(function() {
+            return b-- && ++b;
+        }());
+    }
+    expect_stdout: "1"
+}
+
+issue_2203_2: {
+    options = {
+        collapse_vars: true,
+        keep_fargs: "strict",
+        unused: true,
+    }
+    input: {
+        a = "PASS";
+        console.log({
+            a: "FAIL",
+            b: function() {
+                return function(c) {
+                    return c.a;
+                }((String, (Object, function() {
+                    return this;
+                }())));
+            }
+        }.b());
+    }
+    expect: {
+        a = "PASS";
+        console.log({
+            a: "FAIL",
+            b: function() {
+                return function() {
+                    return (String, (Object, function() {
+                        return this;
+                    }())).a;
+                }();
+            }
+        }.b());
+    }
+    expect_stdout: "PASS"
+}
+
+issue_2298: {
+    options = {
+        collapse_vars: true,
+        keep_fargs: "strict",
+        passes: 2,
+        reduce_funcs: true,
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        !function() {
+            function f() {
+                var a = undefined;
+                var undefined = a++;
+                try {
+                    !function g(b) {
+                        b[1] = "foo";
+                    }();
+                    console.log("FAIL");
+                } catch (e) {
+                    console.log("PASS");
+                }
+            }
+            f();
+        }();
+    }
+    expect: {
+        !function() {
+            (function() {
+                var a = undefined;
+                var undefined = a++;
+                try {
+                    !function() {
+                        (void 0)[1] = "foo";
+                    }();
+                    console.log("FAIL");
+                } catch (e) {
+                    console.log("PASS");
+                }
+            })();
+        }();
+    }
+    expect_stdout: "PASS"
+}
+
+issue_2319_1: {
+    options = {
+        collapse_vars: true,
+        keep_fargs: "strict",
+        unused: true,
+    }
+    input: {
+        console.log(function(a) {
+            return a;
+        }(!function() {
+            return this;
+        }()));
+    }
+    expect: {
+        console.log(function() {
+            return !function() {
+                return this;
+            }();
+        }());
+    }
+    expect_stdout: "false"
+}
+
+issue_2319_2: {
+    options = {
+        collapse_vars: true,
+        keep_fargs: "strict",
+        unused: true,
+    }
+    input: {
+        console.log(function(a) {
+            "use strict";
+            return a;
+        }(!function() {
+            return this;
+        }()));
+    }
+    expect: {
+        console.log(function(a) {
+            "use strict";
+            return a;
+        }(!function() {
+            return this;
+        }()));
+    }
+    expect_stdout: "false"
+}
+
+issue_2319_3: {
+    options = {
+        collapse_vars: true,
+        keep_fargs: "strict",
+        unused: true,
+    }
+    input: {
+        "use strict";
+        console.log(function(a) {
+            return a;
+        }(!function() {
+            return this;
+        }()));
+    }
+    expect: {
+        "use strict";
+        console.log(function() {
+            return !function() {
+                return this;
+            }();
+        }());
+    }
+    expect_stdout: "true"
+}
+
+issue_2425_1: {
+    options = {
+        collapse_vars: true,
+        keep_fargs: "strict",
+        unused: true,
+    }
+    input: {
+        var a = 8;
+        (function(b) {
+            b.toString();
+        })(--a, a |= 10);
+        console.log(a);
+    }
+    expect: {
+        var a = 8;
+        (function(b) {
+            b.toString();
+        })(--a, a |= 10);
+        console.log(a);
+    }
+    expect_stdout: "15"
+}
+
+issue_2425_2: {
+    options = {
+        collapse_vars: true,
+        keep_fargs: "strict",
+        unused: true,
+    }
+    input: {
+        var a = 8;
+        (function(b, c) {
+            b.toString();
+        })(--a, a |= 10);
+        console.log(a);
+    }
+    expect: {
+        var a = 8;
+        (function(b) {
+            b.toString();
+        })(--a, a |= 10);
+        console.log(a);
+    }
+    expect_stdout: "15"
+}
+
+issue_2425_3: {
+    options = {
+        collapse_vars: true,
+        keep_fargs: "strict",
+        unused: true,
+    }
+    input: {
+        var a = 8;
+        (function(b, b) {
+            b.toString();
+        })(--a, a |= 10);
+        console.log(a);
+    }
+    expect: {
+        var a = 8;
+        (function() {
+            (a |= 10).toString();
+        })(--a);
+        console.log(a);
+    }
+    expect_stdout: "15"
+}
+
+issue_2436_13: {
+    options = {
+        collapse_vars: true,
+        keep_fargs: "strict",
+        passes: 2,
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        var a = "PASS";
+        (function() {
+            function f(b) {
+                (function g(b) {
+                    var b = b && (b.null = "FAIL");
+                })(a);
+            }
+            f();
+        })();
+        console.log(a);
+    }
+    expect: {
+        var a = "PASS";
+        (function() {
+            (function() {
+                (function() {
+                    a && (a.null = "FAIL");
+                })();
+            })();
+        })();
+        console.log(a);
+    }
+    expect_stdout: "PASS"
+}
+
+issue_2506: {
+    options = {
+        collapse_vars: true,
+        keep_fargs: "strict",
+        passes: 2,
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        var c = 0;
+        function f0(bar) {
+            function f1(Infinity_2) {
+                function f13(NaN) {
+                    if (false <= NaN & this >> 1 >= 0) {
+                        c++;
+                    }
+                }
+                var b_2 = f13(NaN, c++);
+            }
+            var bar = f1(-3, -1);
+        }
+        f0(false);
+        console.log(c);
+    }
+    expect: {
+        var c = 0;
+        function f0(bar) {
+            (function() {
+                (function() {
+                    if (false <= 0/0 & this >> 1 >= 0)
+                        c++;
+                })(c++);
+            })();
+        }
+        f0(false);
+        console.log(c);
+    }
+    expect_stdout: "1"
+}
+
+issue_2226_1: {
+    options = {
+        keep_fargs: "strict",
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        function f1() {
+            var a = b;
+            a += c;
+        }
+        function f2(a) {
+            a <<= b;
+        }
+        function f3(a) {
+            --a;
+        }
+        function f4() {
+            var a = b;
+            return a *= c;
+        }
+        function f5(a) {
+            x(a /= b);
+        }
+    }
+    expect: {
+        function f1() {
+            b;
+            c;
+        }
+        function f2(a) {
+            b;
+        }
+        function f3(a) {
+            0;
+        }
+        function f4() {
+            var a = b;
+            return a *= c;
+        }
+        function f5(a) {
+            x(a /= b);
+        }
+    }
+}
+
+issue_2226_2: {
+    options = {
+        collapse_vars: true,
+        keep_fargs: "strict",
+        sequences: true,
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        console.log(function(a, b) {
+            a += b;
+            return a;
+        }(1, 2));
+    }
+    expect: {
+        console.log(function(a) {
+            return a += 2;
+        }(1));
+    }
+    expect_stdout: "3"
+}
+
+issue_2226_3: {
+    options = {
+        collapse_vars: true,
+        keep_fargs: "strict",
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        console.log(function(a, b) {
+            a += b;
+            return a;
+        }(1, 2));
+    }
+    expect: {
+        console.log(function(a) {
+            return a += 2;
+        }(1));
+    }
+    expect_stdout: "3"
+}
+
+issue_3192: {
+    options = {
+        keep_fargs: "strict",
+        unused: true,
+    }
+    input: {
+        (function(a) {
+            console.log(a = "foo", arguments[0]);
+        })("bar");
+        (function(a) {
+            "use strict";
+            console.log(a = "foo", arguments[0]);
+        })("bar");
+    }
+    expect: {
+        (function(a) {
+            console.log(a = "foo", arguments[0]);
+        })("bar");
+        (function() {
+            "use strict";
+            console.log("foo", arguments[0]);
+        })("bar");
+    }
+    expect_stdout: [
+        "foo foo",
+        "foo bar",
+    ]
+}
+
+if_increment: {
+    options = {
+        evaluate: true,
+        keep_fargs: "strict",
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        console.log(function(a) {
+            if (console)
+                return ++a;
+        }(0));
+    }
+    expect: {
+        console.log(function() {
+            if (console)
+                return 1;
+        }());
+    }
+    expect_stdout: "1"
+}
+
+try_increment: {
+    options = {
+        evaluate: true,
+        keep_fargs: "strict",
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        console.log(function(a) {
+            try {
+                return ++a;
+            } catch (e) {}
+        }(0));
+    }
+    expect: {
+        console.log(function() {
+            try {
+                return 1;
+            } catch (e) {}
+        }());
+    }
+    expect_stdout: "1"
+}
+
+issue_2630_3: {
+    options = {
+        inline: true,
+        keep_fargs: "strict",
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        var x = 2, a = 1;
+        (function() {
+            function f1(a) {
+                f2();
+                --x >= 0 && f1({});
+            }
+            f1(a++);
+            function f2() {
+                a++;
+            }
+        })();
+        console.log(a);
+    }
+    expect: {
+        var x = 2, a = 1;
+        (function() {
+            (function f1() {
+                f2();
+                --x >= 0 && f1({});
+            })(a++);
+            function f2() {
+                a++;
+            }
+        })();
+        console.log(a);
+    }
+    expect_stdout: "5"
+}
+
+issue_3364: {
+    options = {
+        functions: true,
+        keep_fargs: "strict",
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    mangle = {}
+    input: {
+        var s = 2, a = 100, b = 10, c = 0;
+        function f(p, e, r) {
+            try {
+                for (var i = 1; i-- > 0;)
+                    var a = function(x) {
+                        function g(y) {
+                            y && y[a++];
+                        }
+                        var x = g(--s >= 0 && f(c++));
+                        for (var j = 1; --j > 0;);
+                    }();
+            } catch (e) {
+                try {
+                    return;
+                } catch (z) {
+                    for (var k = 1; --k > 0;) {
+                        for (var l = 1; l > 0; --l) {
+                            var n = function() {};
+                            for (var k in n)
+                                var o = (n, k);
+                        }
+                    }
+                }
+            }
+        }
+        var r = f();
+        console.log(c);
+    }
+    expect: {
+        var s = 2, c = 0;
+        (function o() {
+            try {
+                for (var r = 1; r-- > 0;)
+                    var n = function() {
+                        (function(r) {
+                            r && r[n++];
+                        })(--s >= 0 && o(c++));
+                        for (var r = 1; --r > 0;);
+                    }();
+            } catch (r) {
+                try {
+                    return;
+                } catch (r) {
+                    for (var a = 1; --a > 0;)
+                        for (var f = 1; f > 0; --f) {
+                            function t() {}
+                            for (var a in t);
+                        }
+                }
+            }
+        })();
+        console.log(c);
+    }
+    expect_stdout: "2"
+}
+
+defun_label: {
+    options = {
+        keep_fargs: "strict",
+        passes: 2,
+        reduce_funcs: true,
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        !function() {
+            function f(a) {
+                L: {
+                    if (a) break L;
+                    return 1;
+                }
+            }
+            console.log(f(2));
+        }();
+    }
+    expect: {
+        !function() {
+            console.log(function() {
+                L: {
+                    if (2) break L;
+                    return 1;
+                }
+            }());
+        }();
+    }
+    expect_stdout: true
+}
+
+iife_func_side_effects: {
+    options = {
+        keep_fargs: "strict",
+        reduce_funcs: true,
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        function x() {
+            console.log("x");
+        }
+        function y() {
+            console.log("y");
+        }
+        function z() {
+            console.log("z");
+        }
+        (function(a, b, c) {
+            function y() {
+                console.log("FAIL");
+            }
+            return y + b();
+        })(x(), function() {
+            return y();
+        }, z());
+    }
+    expect: {
+        function x() {
+            console.log("x");
+        }
+        function y() {
+            console.log("y");
+        }
+        function z() {
+            console.log("z");
+        }
+        (function(a, b) {
+            return function() {
+                console.log("FAIL");
+            } + b();
+        })(x(), function() {
+            return y();
+        }, z());
+    }
+    expect_stdout: [
+        "x",
+        "z",
+        "y",
+    ]
+}
+
+issue_1595_1: {
+    options = {
+        evaluate: true,
+        keep_fargs: "strict",
+        reduce_funcs: true,
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        (function f(a) {
+            return f(a + 1);
+        })(2);
+    }
+    expect: {
+        (function f(a) {
+            return f(a + 1);
+        })(2);
+    }
+}
+
+issue_1595_2: {
+    options = {
+        evaluate: true,
+        keep_fargs: "strict",
+        reduce_funcs: true,
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        (function f(a) {
+            return g(a + 1);
+        })(2);
+    }
+    expect: {
+        (function(a) {
+            return g(a + 1);
+        })(2);
+    }
+}
+
+issue_1595_3: {
+    options = {
+        evaluate: true,
+        keep_fargs: "strict",
+        passes: 2,
+        reduce_funcs: true,
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        (function f(a) {
+            return g(a + 1);
+        })(2);
+    }
+    expect: {
+        (function() {
+            return g(3);
+        })();
+    }
+}
+
+issue_1595_4: {
+    options = {
+        evaluate: true,
+        keep_fargs: "strict",
+        reduce_funcs: true,
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        (function iife(a, b, c) {
+            console.log(a, b, c);
+            if (a) iife(a - 1, b, c);
+        })(3, 4, 5);
+    }
+    expect: {
+        (function iife(a, b, c) {
+            console.log(a, b, c);
+            if (a) iife(a - 1, b, c);
+        })(3, 4, 5);
+    }
+    expect_stdout: true
+}
+
+duplicate_lambda_defun_name_1: {
+    options = {
+        keep_fargs: "strict",
+        reduce_vars: true,
+    }
+    input: {
+        console.log(function f(a) {
+            function f() {}
+            return f.length;
+        }());
+    }
+    expect: {
+        console.log(function f(a) {
+            function f() {}
+            return f.length;
+        }());
+    }
+    expect_stdout: "0"
+}
+
+duplicate_lambda_defun_name_2: {
+    options = {
+        keep_fargs: "strict",
+        passes: 2,
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        console.log(function f(a) {
+            function f() {}
+            return f.length;
+        }());
+    }
+    expect: {
+        console.log(function() {
+            return function() {}.length;
+        }());
+    }
+    expect_stdout: "0"
+}
+
+function_name_mangle: {
+    options = {
+        keep_fargs: "strict",
+        keep_fnames: true,
+        reduce_vars: true,
+        unused: true,
+    }
+    mangle = {}
+    input: {
+        (function() {
+            function foo(bar) {}
+            console.log(typeof foo);
+        })();
+    }
+    expect_exact: "(function(){console.log(typeof function o(){})})();"
+    expect_stdout: "function"
+}
+
+function_name_mangle_ie8: {
+    options = {
+        keep_fargs: "strict",
+        keep_fnames: true,
+        reduce_vars: true,
+        unused: true,
+    }
+    mangle = {
+        ie8: true,
+        toplevel: true,
+    }
+    input: {
+        (function() {
+            function foo(bar) {}
+            console.log(typeof foo);
+        })();
+    }
+    expect_exact: "(function(){console.log(typeof function o(){})})();"
+    expect_stdout: "function"
+}