fix corner case in inline & reduce_vars (#5579)

test/compress/functions.js

@@ -8646,3 +8646,42 @@ module_inline: {
     }
     expect_stdout: "true"
 }
+
+single_use_inline_collision: {
+    options = {
+        inline: true,
+        reduce_funcs: true,
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        var a = "PASS";
+        (function() {
+            var f = function() {
+                while (console.log(a));
+            };
+            (function() {
+                (function() {
+                    f();
+                })();
+                (function(a) {
+                    a || a("FAIL");
+                })(console.log);
+            })();
+        })();
+    }
+    expect: {
+        var a = "PASS";
+        (function() {
+            (function() {
+                while (console.log(a));
+                return;
+            })();
+            (function(a) {
+                a || a("FAIL");
+            })(console.log);
+            return;
+        })();
+    }
+    expect_stdout: "PASS"
+}

test/reduce.js

@@ -160,6 +160,11 @@ module.exports = function reduce_test(testcase, minify_options, reduce_options)
                 return expr instanceof U.AST_Spread ? expr.expression : expr;
             }
         }
+        else if (node instanceof U.AST_Await) {
+            node.start._permute++;
+            CHANGED = true;
+            return node.expression;
+        }
         else if (node instanceof U.AST_Binary) {
             var permute = ((node.start._permute += step) * steps | 0) % 4;
             var expr = [