fix corner case in merge_vars (#5472)

fixes #5471

lib/compress.js

@@ -6161,15 +6161,8 @@ Compressor.prototype.compress = function(node) {
                 return true;
             }
             if (node instanceof AST_Scope) {
-                var in_iife = false;
-                if (node instanceof AST_LambdaExpression && !node.name && !is_async(node) && !is_generator(node)) {
-                    var parent = tw.parent();
-                    in_iife = parent && parent.TYPE == "Call" && parent.expression === node;
-                }
-                if (!in_iife) {
                 push();
                 segment.block = node;
-                }
                 if (node === self) root = segment;
                 if (node instanceof AST_Lambda) {
                     if (node.name) references[node.name.definition().id] = false;
@@ -6186,7 +6179,7 @@ Compressor.prototype.compress = function(node) {
                     in_arg.pop();
                 }
                 walk_lambda(node, tw);
-                if (!in_iife) pop();
+                pop();
                 return true;
             }
             if (node instanceof AST_Sub) {

test/compress/arrows.js

@@ -726,8 +726,8 @@ issue_4401: {
     expect: {
         (function() {
             var a = (b => b(a))(console.log || a);
-            var a = console.log;
+            var c = console.log;
-            a && a(typeof b);
+            c && c(typeof b);
         })();
     }
     expect_stdout: [

test/compress/awaits.js

@@ -2986,15 +2986,15 @@ issue_5456: {
         var a = true;
         (function() {
             b = (i = a, console.log("foo") && i),
-            i = async function() {
+            d = async function() {
                 c = await null;
             }(),
             e = function() {
-                if (c) console.log(typeof i);
+                if (c) console.log(typeof d);
                 while (b);
             }(),
             void 0;
-            var b, c, i, e;
+            var b, c, d, e;
             var i;
         })();
     }

test/compress/merge_vars.js

@@ -3754,3 +3754,94 @@ issue_5451: {
     }
     expect_stdout: "0"
 }
+
+issue_5471_1: {
+    options = {
+        conditionals: true,
+        inline: true,
+        merge_vars: true,
+        reduce_vars: true,
+        sequences: true,
+        side_effects: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var a = "FAIL 1";
+        function f(b, c) {
+            function g() {
+                if (console)
+                    return 42;
+                else
+                    c = "FAIL 2";
+            }
+            var d = g();
+            console.log(c || "PASS");
+            var e = function h() {
+                while (b && e);
+            }();
+        }
+        f(a++) && a;
+    }
+    expect: {
+        var a = "FAIL 1";
+        var b, c, e;
+        b = +a,
+        function() {
+            if (console)
+                return;
+            c = "FAIL 2";
+        }(),
+        console.log(c || "PASS"),
+        e = function() {
+            while (b && e);
+        }();
+    }
+    expect_stdout: "PASS"
+}
+
+issue_5471_2: {
+    options = {
+        conditionals: true,
+        evaluate: true,
+        inline: true,
+        merge_vars: true,
+        reduce_vars: true,
+        sequences: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var a = "FAIL 1";
+        function f(b, c) {
+            function g() {
+                if (console)
+                    return 42;
+                else
+                    c = "FAIL 2";
+            }
+            var d = g();
+            console.log(c || "PASS");
+            var e = function h() {
+                while (b && e);
+            }();
+        }
+        f(a++) && a;
+    }
+    expect: {
+        var a = "FAIL 1";
+        var b, c, e;
+        b = +a,
+        function() {
+            if (console)
+                return;
+            c = "FAIL 2";
+        }(),
+        console.log(c || "PASS"),
+        e = function() {
+            while (b && e);
+        }(),
+        void 0;
+    }
+    expect_stdout: "PASS"
+}

test/compress/yields.js

@@ -1574,15 +1574,15 @@ issue_5456: {
         var a = true;
         (function() {
             b = (i = a, console.log("foo") && i),
-            i = function*() {
+            d = function*() {
                 c = null;
             }(),
             e = function() {
-                if (c) console.log(typeof i);
+                if (c) console.log(typeof d);
                 while (b);
             }(),
             void 0;
-            var b, c, i, e;
+            var b, c, d, e;
             var i;
         })();
     }