From 3693bde2dde9cbe0aaa7d7e914ee506ded977705 Mon Sep 17 00:00:00 2001
From: "Alex Lam S.L" <alexlamsl@gmail.com>
Date: Thu, 27 Jan 2022 23:17:17 +0000
Subject: [PATCH] fix corner case in `inline` (#5317)

fixes #5316
---
 lib/compress.js            | 40 +++++++++++++++---------------
 test/compress/functions.js | 50 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 69 insertions(+), 21 deletions(-)

diff --git a/lib/compress.js b/lib/compress.js
index 016216ba..2a8977a1 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -10515,16 +10515,8 @@ Compressor.prototype.compress = function(node) {
                     append_var(decl_var, expr_var, name, value);
                     if (!in_loop) continue;
                     if (arg_used.has(name.name)) continue;
-                    var def = name.definition();
-                    if (def.orig.length == 1 && fn.functions.has(name.name)) continue;
-                    var sym = make_node(AST_SymbolRef, name, name);
-                    def.assignments++;
-                    def.references.push(sym);
-                    expr_loop.push(make_node(AST_Assign, var_def, {
-                        operator: "=",
-                        left: sym,
-                        right: make_node(AST_Undefined, name),
-                    }));
+                    if (name.definition().orig.length == 1 && fn.functions.has(name.name)) continue;
+                    expr_loop.push(init_ref(compressor, name));
                 }
             });
             [].push.apply(decls, decl_var);
@@ -13001,6 +12993,22 @@ Compressor.prototype.compress = function(node) {
         return found;
     }
 
+    function init_ref(compressor, name) {
+        var sym = make_node(AST_SymbolRef, name, name);
+        var def = name.definition();
+        def.assignments++;
+        def.references.push(sym);
+        var assign = make_node(AST_Assign, name, {
+            operator: "=",
+            left: sym,
+            right: make_node(AST_Undefined, name).transform(compressor),
+        });
+        sym.fixed = function() {
+            return assign.right;
+        };
+        return assign;
+    }
+
     (function(def) {
         def(AST_Node, noop);
         def(AST_Assign, noop);
@@ -13183,17 +13191,7 @@ Compressor.prototype.compress = function(node) {
                 })) return;
                 var sym = def.orig[0];
                 if (sym instanceof AST_SymbolCatch) return;
-                var ref = make_node(AST_SymbolRef, sym, flatten_var(sym));
-                def = ref.definition();
-                def.assignments++;
-                def.references.push(ref);
-                body.push(make_node(AST_SimpleStatement, sym, {
-                    body: make_node(AST_Assign, sym, {
-                        operator: "=",
-                        left: ref,
-                        right: make_node(AST_Undefined, sym).transform(compressor),
-                    }),
-                }));
+                body.push(make_node(AST_SimpleStatement, sym, { body: init_ref(compressor, flatten_var(sym)) }));
             });
             if (fn.variables.has("NaN")) scope.transform(new TreeTransformer(function(node) {
                 if (node instanceof AST_NaN) return make_node(AST_Binary, node, {
diff --git a/test/compress/functions.js b/test/compress/functions.js
index 863f990d..0e55e753 100644
--- a/test/compress/functions.js
+++ b/test/compress/functions.js
@@ -8084,3 +8084,53 @@ issue_5296: {
     }
     expect_stdout: "PASS"
 }
+
+issue_5316_1: {
+    options = {
+        collapse_vars: true,
+        evaluate: true,
+        inline: true,
+        reduce_vars: true,
+        toplevel: true,
+    }
+    input: {
+        do {
+            console.log("PASS");
+        } while (function() {
+            var a, b = 42 && (console[a = b] = a++);
+        }());
+    }
+    expect: {
+        do {
+            console.log("PASS");
+        } while (b = a = void 0, b = (42, console[a = a] = a++), void 0);
+        var a, b;
+    }
+    expect_stdout: "PASS"
+}
+
+issue_5316_2: {
+    options = {
+        collapse_vars: true,
+        evaluate: true,
+        inline: true,
+        reduce_vars: true,
+        toplevel: true,
+    }
+    input: {
+        do {
+            (function() {
+                var a, b = 42 && (console[a = b] = a++);
+                while (console.log("PASS"));
+            })();
+        } while (!console);
+    }
+    expect: {
+        do {
+            a = void 0;
+            var a, b = (42, console[a = b = void 0] = a++);
+            while (console.log("PASS"));
+        } while (!console);
+    }
+    expect_stdout: "PASS"
+}