fix corner cases in `assignments`, `reduce_vars` & `unused` (#3950)

fixes #3949
fixes #3951

8 files changed, 263 insertions, 23 deletions

diff --git a/test/compress/assignment.js b/test/compress/assignments.js
index 2230272a..0f87f9a0 100644
--- a/test/compress/assignment.js
+++ b/test/compress/assignments.js
@@ -407,3 +407,57 @@ issue_3429_2: {
     }
     expect_stdout: "undefined"
 }
+
+issue_3949_1: {
+    options = {
+        assignments: true,
+        evaluate: true,
+        reduce_vars: true,
+    }
+    input: {
+        var a = 42;
+        function f() {
+            var b = a;
+            b = b >> 2;
+            return 100 + b;
+        }
+        console.log(f());
+    }
+    expect: {
+        var a = 42;
+        function f() {
+            var b = a;
+            b >>= 2;
+            return 100 + b;
+        }
+        console.log(f());
+    }
+    expect_stdout: "110"
+}
+
+issue_3949_2: {
+    options = {
+        assignments: true,
+        evaluate: true,
+        reduce_vars: true,
+    }
+    input: {
+        var a = 42;
+        function f() {
+            var b = a;
+            b = 5 & b;
+            return 100 + b;
+        }
+        console.log(f());
+    }
+    expect: {
+        var a = 42;
+        function f() {
+            var b = a;
+            b &= 5;
+            return 100 + b;
+        }
+        console.log(f());
+    }
+    expect_stdout: "100"
+}
diff --git a/test/compress/collapse_vars.js b/test/compress/collapse_vars.js
index 546e0d3b..cea5ca84 100644
--- a/test/compress/collapse_vars.js
+++ b/test/compress/collapse_vars.js
@@ -3001,6 +3001,7 @@ issue_2298: {
     expect: {
         !function() {
             (function() {
+                0;
                 try {
                     !function(b) {
                         (void 0)[1] = "foo";
diff --git a/test/compress/drop-unused.js b/test/compress/drop-unused.js
index b21ca399..f3aeab21 100644
--- a/test/compress/drop-unused.js
+++ b/test/compress/drop-unused.js
@@ -2285,7 +2285,7 @@ issue_3598: {
         try {
             (function() {
                 a = "PASS";
-                var c = (void (c.p = 0))[!1];
+                (void ((void 0).p = 0))[!1];
             })();
         } catch (e) {}
         console.log(a);
@@ -2557,10 +2557,9 @@ issue_3899: {
         console.log(typeof a);
     }
     expect: {
-        0;
-        var a = function() {
+        function a() {
             return 2;
-        };
+        }
         console.log(typeof a);
     }
     expect_stdout: "function"
@@ -2625,3 +2624,31 @@ assign_if_assign_read: {
     }
     expect_stdout: "PASS"
 }
+
+issue_3951: {
+    options = {
+        pure_getters: "strict",
+        reduce_vars: true,
+        side_effects: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var a = console.log("PASS");
+        console.log(a);
+        a = "0";
+        console.log(a.p = 0);
+        a && a;
+    }
+    expect: {
+        var a = console.log("PASS");
+        console.log(a);
+        a = "0";
+        console.log(a.p = 0);
+    }
+    expect_stdout: [
+        "PASS",
+        "undefined",
+        "0",
+    ]
+}
diff --git a/test/compress/evaluate.js b/test/compress/evaluate.js
index 4e3bc725..fd8deab5 100644
--- a/test/compress/evaluate.js
+++ b/test/compress/evaluate.js
@@ -1579,9 +1579,9 @@ issue_2968_1: {
     expect: {
         var c = "FAIL";
         (function() {
-            b = -(a = 42),
-            void ((a <<= 0) && (a[(c = "PASS", 0 >>> (b += 1))] = 0));
-            var a, b;
+            a = 42,
+            void ((a <<= 0) && (a[(c = "PASS", 0)] = 0));
+            var a;
         })();
         console.log(c);
     }
@@ -2341,10 +2341,7 @@ issue_3878_1: {
         console.log(b ? "PASS" : "FAIL");
     }
     expect: {
-        var b = function(a) {
-            return (a = 0) == (a && this > (a += 0));
-        }();
-        console.log(b ? "PASS" : "FAIL");
+        console.log(true ? "PASS" : "FAIL");
     }
     expect_stdout: "PASS"
 }
@@ -2435,12 +2432,11 @@ issue_3903: {
         console.log(d);
     }
     expect: {
-        var a = "PASS";
         function f(b, c) {
             return console, c;
         }
-        var d = f(f(), a = a);
-        console.log(d);
+        f(f(), "PASS");
+        console.log("PASS");
     }
     expect_stdout: "PASS"
 }
@@ -2649,7 +2645,7 @@ issue_3933: {
     }
     expect: {
         (function(a, b) {
-            1, (b ^= 1), console.log("PASS");
+            1, 1, console.log("PASS");
         })();
     }
     expect_stdout: "PASS"
diff --git a/test/compress/join_vars.js b/test/compress/join_vars.js
index 590f9970..9f0b35b7 100644
--- a/test/compress/join_vars.js
+++ b/test/compress/join_vars.js
@@ -808,9 +808,9 @@ issue_3795: {
     }
     expect: {
         var a = "FAIL", d = function() {
-            if (a = 42, d) return -1;
+            if (void 0) return -1;
             a = "PASS";
-        }();
+        }(a = 42);
         console.log(a, d);
     }
     expect_stdout: "PASS undefined"
diff --git a/test/compress/keep_fargs.js b/test/compress/keep_fargs.js
index e1737081..e42b3978 100644
--- a/test/compress/keep_fargs.js
+++ b/test/compress/keep_fargs.js
@@ -306,6 +306,7 @@ issue_2298: {
     expect: {
         !function() {
             (function() {
+                0;
                 try {
                     !function() {
                         (void 0)[1] = "foo";
diff --git a/test/compress/reduce_vars.js b/test/compress/reduce_vars.js
index cb7599a9..3368cc6f 100644
--- a/test/compress/reduce_vars.js
+++ b/test/compress/reduce_vars.js
@@ -1520,8 +1520,7 @@ func_inline: {
     }
     expect: {
         function f() {
-            console.log(1 + h());
-            var h;
+            console.log(1 + (void 0)());
         }
     }
 }
@@ -2671,8 +2670,8 @@ var_assign_6: {
     }
     expect: {
         !function() {
-            var a = function(){}(a = 1);
-            console.log(a);
+            (function(){}());
+            console.log(void 0);
         }();
     }
     expect_stdout: "undefined"
@@ -7111,3 +7110,166 @@ issue_3922: {
     }
     expect_stdout: "PASS"
 }
+
+issue_3949_1: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+    }
+    input: {
+        (function f(a) {
+            var a = void (a = 0, g);
+            function g() {
+                console.log(typeof a);
+            }
+            g();
+        })();
+    }
+    expect: {
+        (function f(a) {
+            var a = void (a = 0, g);
+            function g() {
+                console.log(typeof a);
+            }
+            g();
+        })();
+    }
+    expect_stdout: "undefined"
+}
+
+issue_3949_2: {
+    options = {
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        (function f(a) {
+            var a = void (a = 0, g);
+            function g() {
+                console.log(typeof a);
+            }
+            g();
+        })();
+    }
+    expect: {
+        (function(a) {
+            a = void (a = 0, g);
+            function g() {
+                console.log(typeof a);
+            }
+            g();
+        })();
+    }
+    expect_stdout: "undefined"
+}
+
+issue_3949_3: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+        toplevel: true,
+    }
+    input: {
+        function f() {}
+        for (var a, i = 3; 0 <= --i; ) {
+            a = f;
+            console.log(a === b);
+            var b = a;
+        }
+    }
+    expect: {
+        function f() {}
+        for (var a, i = 3; 0 <= --i; ) {
+            a = f;
+            console.log(a === b);
+            var b = a;
+        }
+    }
+    expect_stdout: [
+        "false",
+        "true",
+        "true",
+    ]
+}
+
+issue_3949_4: {
+    options = {
+        reduce_vars: true,
+        unused: true,
+        toplevel: true,
+    }
+    input: {
+        function f() {}
+        for (var a, i = 3; 0 <= --i; ) {
+            a = f;
+            console.log(a === b);
+            var b = a;
+        }
+    }
+    expect: {
+        function f() {}
+        for (var a, i = 3; 0 <= --i; ) {
+            a = f;
+            console.log(a === b);
+            var b = a;
+        }
+    }
+    expect_stdout: [
+        "false",
+        "true",
+        "true",
+    ]
+}
+
+local_assignment_lambda: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+        sequences: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var a = "FAIL";
+        function f() {
+            a = "PASS";
+            console.log(a);
+        }
+        f();
+        f();
+    }
+    expect: {
+        function f() {
+            console.log("PASS");
+        }
+        f(),
+        f();
+    }
+    expect_stdout: [
+        "PASS",
+        "PASS",
+    ]
+}
+
+local_assignment_loop: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+        sequences: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var a = "FAIL";
+        do {
+            a = "PASS";
+            console.log(a);
+        } while (!console);
+    }
+    expect: {
+        do {
+            console.log("PASS");
+        } while (!console);
+    }
+    expect_stdout: "PASS"
+}
diff --git a/test/compress/side_effects.js b/test/compress/side_effects.js
index 8c263d47..63282660 100644
--- a/test/compress/side_effects.js
+++ b/test/compress/side_effects.js
@@ -97,9 +97,8 @@ issue_2233_2: {
         var RegExp;
         UndeclaredGlobal;
         function foo() {
-            var Number;
             AnotherUndeclaredGlobal;
-            Number.isNaN;
+            (void 0).isNaN;
         }
     }
 }