[es8] More spec compliant syntactic tail calls implementation.

test/mjsunit/es8/syntactic-tail-call-parsing.js

+// Copyright 2016 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Flags: --allow-natives-syntax --harmony-explicit-tailcalls
+// Flags: --harmony-do-expressions
+
+var SyntaxErrorTests = [
+  { msg: "Unexpected expression inside tail call",
+    tests: [
+      { src: `()=>{ return continue  foo ; }`,
+        err: `                       ^^^`,
+      },
+      { src: `()=>{ return  continue 42 ; }`,
+        err: `                       ^^`,
+      },
+      { src: `()=>{ return  continue   new foo ()  ; }`,
+        err: `                         ^^^^^^^^^^`,
+      },
+      { src: `()=>{ loop: return  continue  loop ; }`,
+        err: `                              ^^^^`,
+      },
+      { src: `class A { foo() { return  continue   super.x ; } }`,
+        err: `                                     ^^^^^^^`,
+      },
+      { src: `()=>{ return  continue  this  ; }`,
+        err: `                        ^^^^`,
+      },
+      { src: `()=>{ return  continue class A {} ; }`,
+        err: `                       ^^^^^^^^^^`,
+      },
+      { src: `()=>{ return  continue class A extends B {} ; }`,
+        err: `                       ^^^^^^^^^^^^^^^^^^^^`,
+      },
+      { src: `()=>{ return  continue function A() { } ; }`,
+        err: `                       ^^^^^^^^^^^^^^^^`,
+      },
+      { src: `()=>{ return  continue { a: b, c: d} ; }`,
+        err: `                       ^^^^^^^^^^^^^`,
+      },
+      { src: `()=>{ return  continue function* Gen() { yield 1; } ; }`,
+        err: `                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^`,
+      },
+      { src: `function A() { return  continue new.target ; }`,
+        err: `                                ^^^^^^^^^^`,
+      },
+      { src: `()=>{ return  continue () ; }`,
+        err: `                       ^^`,
+      },
+      { src: `()=>{ return  continue ( 42 ) ; }`,
+        err: `                       ^^^^^^`,
+      },
+      { src: "()=>{ return continue `123 ${foo} 34lk` ;  }",
+        err: `                      ^^^^^^^^^^^^^^^^^`,
+      },
+      { src: `()=>{ return continue do { x ? foo() : bar() ; } }`,
+        err: `                      ^^^^^^^^^^^^^^^^^^^^^^^^^^`,
+      },
+    ],
+  },
+  { msg: "Tail call expression is not allowed here",
+    tests: [
+      { src: `()=>{ return  continue continue continue b()  ; }`,
+        err: `                                ^^^^^^^^^^^^`,
+      },
+      { src: `()=>{ return  continue ( continue b() ) ; }`,
+        err: `                         ^^^^^^^^^^^^`,
+      },
+      { src: `()=>{ return   continue  f()   - a ; }`,
+        err: `               ^^^^^^^^^^^^^`,
+      },
+      { src: `()=>{ return b + continue   f()  ; }`,
+        err: `                 ^^^^^^^^^^^^^^`,
+      },
+      { src: `()=>{ return 1, 2, 3,   continue  f() , 4  ; }`,
+        err: `                        ^^^^^^^^^^^^^`,
+      },
+      { src: `()=>{ var x =  continue  f ( ) ; }`,
+        err: `               ^^^^^^^^^^^^^^^`,
+      },
+      { src: `()=>{ return   continue f () ? 1 : 2 ; }`,
+        err: `               ^^^^^^^^^^^^^`,
+      },
+      { src: `()=>{ return (1, 2, 3, continue f()), 4; }`,
+        err: `                       ^^^^^^^^^^^^`,
+      },
+      { src: `()=>{ return [1, 2, continue f() ] ;  }`,
+        err: `                    ^^^^^^^^^^^^`,
+      },
+      { src: `()=>{ return [1, 2, ... continue f() ] ;  }`,
+        err: `                        ^^^^^^^^^^^^`,
+      },
+      { src: `()=>{ return [1, 2, continue f(), 3 ] ;  }`,
+        err: `                    ^^^^^^^^^^^^`,
+      },
+      { src: "()=>{ return `123 ${a} ${ continue foo ( ) } 34lk` ;  }",
+        err: `                          ^^^^^^^^^^^^^^^^`,
+      },
+      { src: `()=>{ return g( 1, 2, continue f() ); }`,
+        err: `                      ^^^^^^^^^^^^`,
+      },
+      { src: `()=>{ return continue f() || a; }`,
+        err: `             ^^^^^^^^^^^^`,
+      },
+      { src: `()=>{ return continue foo() instanceof bar ; }`,
+        err: `             ^^^^^^^^^^^^^^`,
+      },
+      { src: `()=>{ return bar instanceof continue foo() ; }`,
+        err: `                            ^^^^^^^^^^^^^^`,
+      },
+      { src: `()=>{ return continue foo() in bar ; }`,
+        err: `             ^^^^^^^^^^^^^^`,
+      },
+      { src: `()=>{ return bar in continue foo() ; }`,
+        err: `                    ^^^^^^^^^^^^^^`,
+      },
+      { src: `()=>{ function* G() { yield continue foo(); } }`,
+        err: `                            ^^^^^^^^^^^^^^`,
+      },
+      { src: `()=>{ (1, 2, 3, continue f() ) => {} }`,
+        err: `                ^^^^^^^^^^^^`,
+      },
+      { src: `()=>{ (... continue f()) => {}  }`,
+        err: `           ^^^^^^^^^^^^`,
+      },
+      { src: `()=>{ (a, b, c, ... continue f() ) => {}  }`,
+        err: `                    ^^^^^^^^^^^^`,
+      },
+      { src: `()=>{ return a <= continue f(); }`,
+        err: `                  ^^^^^^^^^^^^`,
+      },
+      { src: `()=>{ return b > continue f(); }`,
+        err: `                 ^^^^^^^^^^^^`,
+      },
+      { src: `()=>{ return a << continue f(); }`,
+        err: `                  ^^^^^^^^^^^^`,
+      },
+      { src: `()=>{ return b >> continue f(); }`,
+        err: `                  ^^^^^^^^^^^^`,
+      },
+      { src: `()=>{ return c >>> continue f(); }`,
+        err: `                   ^^^^^^^^^^^^`,
+      },
+      { src: `()=>{ return continue f() = a ; }`,
+        err: `             ^^^^^^^^^^^^`,
+      },
+      { src: `()=>{ return a = continue f() ; }`,
+        err: `                 ^^^^^^^^^^^^`,
+      },
+      { src: `()=>{ return a += continue f(); }`,
+        err: `                  ^^^^^^^^^^^^`,
+      },
+      { src: `()=>{ return a ** continue f() ; }`,
+        err: `                  ^^^^^^^^^^^^`,
+      },
+      { src: `()=>{ return delete continue foo() ; }`,
+        err: `                    ^^^^^^^^^^^^^^`,
+      },
+      { src: `()=>{ typeof continue foo()  ; }`,
+        err: `             ^^^^^^^^^^^^^^`,
+      },
+      { src: `()=>{ return ~ continue foo() ; }`,
+        err: `               ^^^^^^^^^^^^^^`,
+      },
+      { src: `()=>{ return void  continue foo() ; }`,
+        err: `                   ^^^^^^^^^^^^^^`,
+      },
+      { src: `()=>{ return !continue foo() ; }`,
+        err: `              ^^^^^^^^^^^^^^`,
+      },
+      { src: `()=>{ return -continue foo() ; }`,
+        err: `              ^^^^^^^^^^^^^^`,
+      },
+      { src: `()=>{ return +continue foo() ; }`,
+        err: `              ^^^^^^^^^^^^^^`,
+      },
+      { src: `()=>{ return ++ continue f( ) ; }`,
+        err: `                ^^^^^^^^^^^^^`,
+      },
+      { src: `()=>{ return continue f()  ++; }`,
+        err: `             ^^^^^^^^^^^^`,
+      },
+      { src: `()=>{ return continue f() --; }`,
+        err: `             ^^^^^^^^^^^^`,
+      },
+      { src: `()=>{ return (continue foo()) () ;  }`,
+        err: `              ^^^^^^^^^^^^^^`,
+      },
+      { src: `()=>{ for (var i = continue foo(); i < 10; i++) bar(); }`,
+        err: `                   ^^^^^^^^^^^^^^`,
+      },
+      { src: `()=>{ for (var i = 0; i < continue foo(); i++) bar(); }`,
+        err: `                          ^^^^^^^^^^^^^^`,
+      },
+      { src: `()=>{ for (var i = 0; i < 10; continue foo()) bar(); }`,
+        err: `                              ^^^^^^^^^^^^^^`,
+      },
+      { src: `()=>{ if (continue foo()) bar(); }`,
+        err: `          ^^^^^^^^^^^^^^`,
+      },
+      { src: `()=>{ while (continue foo()) bar(); }`,
+        err: `             ^^^^^^^^^^^^^^`,
+      },
+      { src: `()=>{ do { smth; } while (continue foo()) ; }`,
+        err: `                          ^^^^^^^^^^^^^^`,
+      },
+      { src: `()=>{ throw continue foo() ; }`,
+        err: `            ^^^^^^^^^^^^^^`,
+      },
+      { src: `()=>{ switch (continue foo()) { case 1: break; } ; }`,
+        err: `              ^^^^^^^^^^^^^^`,
+      },
+      { src: `()=>{ with (continue foo()) { smth; } }`,
+        err: `            ^^^^^^^^^^^^^^`,
+      },
+      { src: `()=>{ let x = continue foo() }`,
+        err: `              ^^^^^^^^^^^^^^`,
+      },
+      { src: `()=>{ const c = continue  foo() }`,
+        err: `                ^^^^^^^^^^^^^^^`,
+      },
+      { src: `class A {}; class B extends A { constructor() { return continue super () ; } }`,
+        err: `                                                       ^^^^^^^^^^^^^^^^^`,
+      },
+      { src: `class A extends continue f () {}; }`,
+        err: `                ^^^^^^^^^^^^^`,
+      },
+    ],
+  },
+  { msg: "Tail call expression in try block",
+    tests: [
+      { src: `()=>{ try { return  continue   f ( ) ; } catch(e) {} }`,
+        err: `                    ^^^^^^^^^^^^^^^^`,
+      },
+      { src: `()=>{ try { try { smth; } catch(e) { return  continue  f( ) ; } }`,
+        err: `                                             ^^^^^^^^^^^^^^`,
+      },
+      { src: `()=>{ try { try { smth; } catch(e) { return  continue  f( ) ; } } finally { bla; } }`,
+        err: `                                             ^^^^^^^^^^^^^^`,
+      },
+    ],
+  },
+  { msg: "Tail call expression in catch block when finally block is also present",
+    tests: [
+      { src: `()=>{ try { smth; } catch(e) { return  continue   f ( ) ; } finally { blah; } }`,
+        err: `                                       ^^^^^^^^^^^^^^^^`,
+      },
+      { src: `()=>{ try { smth; } catch(e) { try { smth; } catch (e) { return  continue   f ( ) ; } } finally { blah; } }`,
+        err: `                                                                 ^^^^^^^^^^^^^^^^`,
+      },
+    ],
+  },
+  { msg: "Tail call expression in for-in/of body",
+    tests: [
+      { src: `()=>{ for (var v in {a:0}) { return continue  foo () ; } }`,
+        err: `                                    ^^^^^^^^^^^^^^^^`,
+      },
+      { src: `()=>{ for (var v of [1, 2, 3]) { return continue  foo () ; } }`,
+        err: `                                        ^^^^^^^^^^^^^^^^`,
+      },
+    ],
+  },
+  { msg: "Undefined label 'foo'",
+    tests: [
+      { src: `()=>{ continue  foo () ; }`,
+        err: `                ^^^`,
+      },
+    ],
+  },
+];
+
+
+// Should parse successfully.
+var NoErrorTests = [
+  `()=>{ return continue  a.b.c.foo () ; }`,
+  `()=>{ return continue  a().b.c().d.foo () ; }`,
+  `()=>{ return continue  foo (1)(2)(3, 4) ; }`,
+  `()=>{ return ( continue b() ) ; }`,
+  "()=>{ return continue bar`ab cd ef` ; }",
+  "()=>{ return continue bar`ab ${cd} ef` ; }",
+  `()=>{ return a || continue f() ; }`,
+  `()=>{ return a && continue f() ; }`,
+  `()=>{ return a , continue f() ; }`,
+  `()=>{ function* G() { return continue foo(); } }`,
+  `()=>{ class A { foo() { return continue super.f() ; } } }`,
+  `()=>{ function B() { return continue new.target() ; } }`,
+  `()=>{ return continue do { x ? foo() : bar() ; }() }`,

[rossberg, 2016/05/04 10:45:30]

Wait, why is this legal? A do expression shouldn't be allowed as an argument to
continue.

[Igor Sheludko, 2016/05/04 11:50:14]

Because it's actually a
  return continue (do {...}) ();

+  `()=>{ return do { 1, continue foo() } }`,
+  `()=>{ return do { x ? continue foo() : y } }`,
+  `()=> continue  (foo ()) ;`,
+  `()=> a || continue  foo () ;`,
+  `()=> a && continue  foo () ;`,
+  `()=> a ? continue  foo () : b;`,
+];
+
+
+(function() {
+  for (test_set of SyntaxErrorTests) {
+    var expected_message = "SyntaxError: " + test_set.msg;
+    for (test of test_set.tests) {
+      var passed = true;
+      var e = null;
+      try {
+        Realm.eval(0, test.src);
+      } catch (ee) {
+        e = ee;
+      }
+      print("=======================================");
+      print("Expected | " + expected_message);
+      print("Source   | " + test.src);
+      print("         | " + test.err);
+
+      if (e === null) {
+        print("FAILED");
+        throw new Error("SyntaxError was not thrown");
+      }
+
+      var details = %GetMessageFromException(e);
+      if (details.start_pos == undefined ||
+          details.end_pos == undefined) {
+        throw new Error("Bad message object returned");
+      }
+      var underline = " ".repeat(details.start_pos) +
+                      "^".repeat(details.end_pos - details.start_pos);
+      var passed = expected_message === e.toString() &&
+                   test.err === underline;
+
+      if (passed) {
+        print("PASSED");
+        print();
+      } else {
+        print("---------------------------------------");
+        print("Actual   | " + e);
+        print("Source   | " + test.src);
+        print("         | " + underline);
+        print("FAILED");
+        throw new Error("Test failed");
+      }
+    }
+  }
+})();
+
+
+(function() {
+  for (src of NoErrorTests) {
+    print("=======================================");
+    print("Source   | " + src);
+    Realm.eval(0, src);
+    print("PASSED");
+    print();
+  }
+})();