fix corner case in inline & reduce_vars (#5579)

Author: alexlamsl

Diff for: lib/compress.js

@@ -8387,9 +8387,8 @@ Compressor.prototype.compress = function(node) {
         var scopes = [ this ];
         if (orig instanceof AST_SymbolDeclaration) orig.definition().references.forEach(function(ref) {
             var s = ref.scope;
-            if (member(s, scopes)) return;
             do {
-                push_uniq(scopes, s);
+                if (!push_uniq(scopes, s)) return;
                 s = s.parent_scope;
             } while (s && s !== this);
         });
@@ -12251,12 +12250,19 @@ Compressor.prototype.compress = function(node) {
                 if (fixed instanceof AST_DefClass) fixed = to_class_expr(fixed);
                 if (fixed instanceof AST_LambdaDefinition) fixed = to_func_expr(fixed);
                 if (is_lambda(fixed)) {
-                    var scope = self.scope.resolve();
+                    var scopes = [];
+                    var scope = self.scope;
+                    do {
+                        scopes.push(scope);
+                        if (scope === def.scope) break;
+                    } while (scope = scope.parent_scope);
                     fixed.enclosed.forEach(function(def) {
                         if (fixed.variables.has(def.name)) return;
-                        if (scope.var_names().has(def.name)) return;
-                        scope.enclosed.push(def);
-                        scope.var_names().set(def.name, true);
+                        for (var i = 0; i < scopes.length; i++) {
+                            var scope = scopes[i];
+                            if (!push_uniq(scope.enclosed, def)) return;
+                            scope.var_names().set(def.name, true);
+                        }
                     });
                 }
                 var value;

Diff for: lib/scope.js

@@ -286,7 +286,7 @@ AST_Toplevel.DEFMETHOD("figure_out_scope", function(options) {
                 // ensure mangling works if `catch` reuses a scope variable
                 var redef = def.redefined();
                 if (redef) for (var s = node.scope; s; s = s.parent_scope) {
-                    push_uniq(s.enclosed, redef);
+                    if (!push_uniq(s.enclosed, redef)) break;
                     if (s === redef.scope) break;
                 }
             } else if (node instanceof AST_SymbolConst) {
@@ -480,7 +480,7 @@ AST_Lambda.DEFMETHOD("init_vars", function(parent_scope) {
 AST_Symbol.DEFMETHOD("mark_enclosed", function(options) {
     var def = this.definition();
     for (var s = this.scope; s; s = s.parent_scope) {
-        push_uniq(s.enclosed, def);
+        if (!push_uniq(s.enclosed, def)) break;
         if (!options) {
             s._var_names = undefined;
         } else {

Diff for: 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"
+}

Diff for: 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 = [