Revert of Remove Scope::scope_uses_this_ flag

test/cctest/test-parsing.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 944 matching lines @@
     { "class C { constructor() {", "} }" },
   };
 
   enum Expected {
     NONE = 0,
     ARGUMENTS = 1,
     SUPER_PROPERTY = 1 << 1,
     THIS = 1 << 2,
     INNER_ARGUMENTS = 1 << 3,
     INNER_SUPER_PROPERTY = 1 << 4,
+    INNER_THIS = 1 << 5
   };
 
   static const struct {
     const char* body;
     int expected;
   } source_data[] = {
     {"", NONE},
     {"return this", THIS},
     {"return arguments", ARGUMENTS},
     {"return super.x", SUPER_PROPERTY},
     {"return arguments[0]", ARGUMENTS},
     {"return this + arguments[0]", ARGUMENTS | THIS},
     {"return this + arguments[0] + super.x",
      ARGUMENTS | SUPER_PROPERTY | THIS},
-    {"return x => this + x", THIS},
+    {"return x => this + x", INNER_THIS},
     {"return x => super.f() + x", INNER_SUPER_PROPERTY},
     {"this.foo = 42;", THIS},
     {"this.foo();", THIS},
     {"if (foo()) { this.f() }", THIS},
     {"if (foo()) { super.f() }", SUPER_PROPERTY},
     {"if (arguments.length) { this.f() }", ARGUMENTS | THIS},
     {"while (true) { this.f() }", THIS},
     {"while (true) { super.f() }", SUPER_PROPERTY},
     {"if (true) { while (true) this.foo(arguments) }", ARGUMENTS | THIS},
     // Multiple nesting levels must work as well.
     {"while (true) { while (true) { while (true) return this } }", THIS},
     {"while (true) { while (true) { while (true) return super.f() } }",
      SUPER_PROPERTY},
-    {"if (1) { return () => { while (true) new this() } }", THIS},
+    {"if (1) { return () => { while (true) new this() } }", INNER_THIS},
+    // Note that propagation of the inner_uses_this() value does not
+    // cross boundaries of normal functions onto parent scopes.
     {"return function (x) { return this + x }", NONE},
     {"return { m(x) { return super.m() + x } }", NONE},
     {"var x = function () { this.foo = 42 };", NONE},
     {"var x = { m() { super.foo = 42 } };", NONE},
     {"if (1) { return function () { while (true) new this() } }", NONE},
     {"if (1) { return { m() { while (true) super.m() } } }", NONE},
     {"return function (x) { return () => this }", NONE},
     {"return { m(x) { return () => super.m() } }", NONE},
     // Flags must be correctly set when using block scoping.
     {"\"use strict\"; while (true) { let x; this, arguments; }",
-     INNER_ARGUMENTS | THIS},
+     INNER_ARGUMENTS | INNER_THIS},
     {"\"use strict\"; while (true) { let x; this, super.f(), arguments; }",
-     INNER_ARGUMENTS | INNER_SUPER_PROPERTY | THIS},
-    {"\"use strict\"; if (foo()) { let x; this.f() }", THIS},
+     INNER_ARGUMENTS | INNER_SUPER_PROPERTY | INNER_THIS},
+    {"\"use strict\"; if (foo()) { let x; this.f() }", INNER_THIS},
     {"\"use strict\"; if (foo()) { let x; super.f() }",
      INNER_SUPER_PROPERTY},
     {"\"use strict\"; if (1) {"
      "  let x; return { m() { return this + super.m() + arguments } }"
      "}",
      NONE},
   };
 
   i::Isolate* isolate = CcTest::i_isolate();
   i::Factory* factory = isolate->factory();
@@ skipping 43 matching lines @@
       i::Scope* scope = script_scope->inner_scopes()->at(0);
       // Adjust for constructor scope.
       if (j == 2) {
         CHECK_EQ(1, scope->inner_scopes()->length());
         scope = scope->inner_scopes()->at(0);
       }
       CHECK_EQ((source_data[i].expected & ARGUMENTS) != 0,
                scope->uses_arguments());
       CHECK_EQ((source_data[i].expected & SUPER_PROPERTY) != 0,
                scope->uses_super_property());
-      if ((source_data[i].expected & THIS) != 0) {
-        // Currently the is_used() flag is conservative; all variables in a
-        // script scope are marked as used.
-        CHECK(scope->LookupThis()->is_used());
-      }
+      CHECK_EQ((source_data[i].expected & THIS) != 0, scope->uses_this());
       CHECK_EQ((source_data[i].expected & INNER_ARGUMENTS) != 0,
                scope->inner_uses_arguments());
       CHECK_EQ((source_data[i].expected & INNER_SUPER_PROPERTY) != 0,
                scope->inner_uses_super_property());
+      CHECK_EQ((source_data[i].expected & INNER_THIS) != 0,
+               scope->inner_uses_this());
     }
   }
 }
 
 
 TEST(ScopePositions) {
   // Test the parser for correctly setting the start and end positions
   // of a scope. We check the scope positions of exactly one scope
   // nested in the global scope of a program. 'inner source' is the
   // source code that determines the part of the source belonging
@@ skipping 5377 matching lines @@
     const char* data[] = {
       "yield",
       "[yield]",
       "{ x : yield }",
       NULL};
     // clang-format on
     RunParserSyncTest(context_data, data, kError, NULL, 0, always_flags,
                       arraysize(always_flags));
   }
 }