enhance reduce_vars (#5636)

test/compress/collapse_vars.js

@@ -9321,12 +9321,11 @@ issue_4874: {
         })(a = 42);
     }
     expect: {
-        var a;
         null;
         (function(b) {
-            for (var c in a && a[console.log("PASS")])
+            for (var c in 42, 42[console.log("PASS")])
                 console;
-        })(a = 42);
+        })();
     }
     expect_stdout: "PASS"
 }

test/compress/default-values.js

@@ -2505,7 +2505,7 @@ issue_5463: {
         var a, b, b;
         console.log("PASS") && (
             b = a = void 0,
-            b = [a = FAIL] = a && a
+            b = [a = FAIL] = a
         );
     }
     expect_stdout: "PASS"

test/compress/drop-unused.js

@@ -1878,7 +1878,7 @@ issue_2846: {
         var c = function(a, b) {
             a = 0;
             b && b(a);
-            return a++;
+            return +a;
         }();
         console.log(c);
     }
@@ -2976,14 +2976,12 @@ issue_4025: {
         console.log(a, b, d);
     }
     expect: {
-        var c = 0;
         try {
-            console.log(c);
+            console.log(0);
         } finally {
-            var d = c + 1;
-            c = 0;
+            0;
         }
-        console.log(1, 1, d);
+        console.log(1, 1, 1);
     }
     expect_stdout: [
         "0",
@@ -3696,7 +3694,7 @@ issue_5224: {
                 (function() {
                     var a = "FAIL 1";
                     null;
-                    a = console.log(a);
+                    console.log(a);
                 })(function() {
                     console.log(1 / 0);
                     a;

test/compress/hoist_vars.js

@@ -624,7 +624,7 @@ issue_5411_2: {
         var b, c;
         b++;
         b = "PASS",
-        c = c && c[b];
+        c;
         console.log(b);
     }
     expect_stdout: "PASS"

test/compress/if_return.js

@@ -1834,6 +1834,33 @@ switch_return_5: {
     ]
 }
 
+merged_references: {
+    options = {
+        if_return: true,
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        var a, b = "PASS";
+        console.log(function(c) {
+            if (c = b)
+                return a || c;
+            c = FAIL;
+            return a || c;
+        }());
+    }
+    expect: {
+        var a, b = "PASS";
+        console.log(function(c) {
+            if (c = b);
+            else
+                c = FAIL;
+            return a || c;
+        }());
+    }
+    expect_stdout: "PASS"
+}
+
 issue_5583: {
     options = {
         conditionals: true,

test/compress/reduce_vars.js

@@ -2488,7 +2488,7 @@ side_effects_assign: {
         console.log(a);
     }
     expect: {
-        var a = typeof void (a && a.in);
+        var a = "undefined";
         console.log(a);
     }
     expect_stdout: "undefined"
@@ -2530,7 +2530,8 @@ pure_getters_2: {
         var a = a && a.b;
     }
     expect: {
-        var a = a && a.b;
+        var a;
+        a && a.b;
     }
 }
 
@@ -5424,7 +5425,7 @@ issue_2774: {
             get a() {
                 var b;
                 (b = true) && b.c;
-                b = void 0;
+                void 0;
             }
         }.a);
     }