Bug 1083476 - Add console warnings for JS1.7 legacy generators. r=arai

MozReview-Commit-ID: LnctQK4EEOM

--HG--
extra : rebase_source : a3598ce5a91ffb87e698c88604c32937306baf53

js/src/frontend/Parser.cpp

@@ -6800,6 +6800,8 @@ Parser<ParseHandler, CharT>::yieldExpression(InHandling inHandling)
 
         pc->functionBox()->setGeneratorKind(LegacyGenerator);
         addTelemetry(DeprecatedLanguageExtension::LegacyGenerator);
+        if (!warnOnceAboutLegacyGenerator())
+            return null();
 
         MOZ_FALLTHROUGH;
 
@@ -10441,6 +10443,20 @@ ParserBase::warnOnceAboutForEach()
     return true;
 }
 
+bool
+ParserBase::warnOnceAboutLegacyGenerator()
+{
+    if (context->helperThread())
+        return true;
+
+    if (!context->compartment()->warnedAboutLegacyGenerator) {
+        if (!warning(JSMSG_DEPRECATED_LEGACY_GENERATOR))
+            return false;
+        context->compartment()->warnedAboutLegacyGenerator = true;
+    }
+    return true;
+}
+
 template class Parser<FullParseHandler, char16_t>;
 template class Parser<SyntaxParseHandler, char16_t>;
 

js/src/frontend/Parser.h

@@ -251,6 +251,7 @@ class ParserBase : public StrictModeGetter
 
     bool warnOnceAboutExprClosure();
     bool warnOnceAboutForEach();
+    bool warnOnceAboutLegacyGenerator();
 
     bool allowsForEachIn() {
 #if !JS_HAS_FOR_EACH_IN

js/src/jit-test/tests/parser/legacy-generator-warn.js

@@ -0,0 +1,55 @@
+// Legacy generators should be warned once and only once.
+
+version(170);
+
+function testWarn(code) {
+  enableLastWarning();
+  var g = newGlobal();
+  g.code = code;
+  g.eval('eval(code)');
+  var warning = getLastWarning();
+  assertEq(warning !== null, true, "warning should be caught for " + code);
+  assertEq(warning.name, "Warning");
+
+  clearLastWarning();
+  g.eval('eval(code)');
+  warning = getLastWarning();
+  assertEq(warning, null, "warning should not be caught for 2nd ocurrence");
+
+  clearLastWarning();
+  g = newGlobal();
+  g.code = code;
+  g.eval('Reflect.parse(code);');
+  warning = getLastWarning();
+  assertEq(warning !== null, true, "warning should be caught for " + code);
+  assertEq(warning.name, "Warning");
+
+  clearLastWarning();
+  g.eval('Reflect.parse(code);');
+  warning = getLastWarning();
+  assertEq(warning, null, "warning should not be caught for 2nd ocurrence");
+  disableLastWarning();
+}
+
+function testPass(code) {
+  enableLastWarning();
+  var g = newGlobal();
+  g.code = code;
+  g.eval('eval(code)');
+  var warning = getLastWarning();
+  assertEq(warning, null, "warning should not be caught for " + code);
+
+  clearLastWarning();
+  g = newGlobal();
+  g.code = code;
+  g.eval('Reflect.parse(code);');
+  warning = getLastWarning();
+  assertEq(warning, null, "warning should not be caught for " + code);
+  disableLastWarning();
+}
+
+testWarn("(function() { yield; })");
+testWarn("function a() { yield; }");
+
+testPass("(function*() { yield; })");
+testPass("function* a() { yield; }");

js/src/jit-test/tests/parser/yield-without-operand.js

@@ -1,26 +0,0 @@
-// yield without an operand is fine and dandy.
-
-load(libdir + "asserts.js");
-
-assertNoWarning(() => Function("yield"), SyntaxError,
-                "yield followed by EOF is fine");
-assertNoWarning(() => Function("yield;"), SyntaxError,
-                "yield followed by semicolon is fine");
-assertNoWarning(() => Function("yield\n"), SyntaxError,
-                "yield followed by newline is fine");
-assertNoWarning(() => Function("yield\n  print('ok');"), SyntaxError,
-                "yield followed by newline and statement is fine");
-assertNoWarning(() => Function("yield\n  /x/;"), SyntaxError,
-                "yield followed by newline and regexp is fine");
-assertThrowsInstanceOf(() => Function("yield\n  /"), SyntaxError,
-                       "yield followed by newline and slash is fine");
-
-assertNoWarning(() => eval("(function () { yield; })"), SyntaxError,
-                "yield followed by semicolon in eval code is fine");
-assertNoWarning(() => eval("(function () { yield })"), SyntaxError,
-                "yield followed by } in eval code is fine");
-
-assertNoWarning(() => Function("yield 0;"),
-                "yield with an operand should be fine");
-assertNoWarning(() => Function("yield 0"),
-                "yield with an operand should be fine, even without a semicolon");

js/src/js.msg

@@ -251,6 +251,7 @@ MSG_DEF(JSMSG_DECLARATION_AFTER_IMPORT,0, JSEXN_SYNTAXERR, "missing declaration
 MSG_DEF(JSMSG_DEPRECATED_DELETE_OPERAND, 0, JSEXN_SYNTAXERR, "applying the 'delete' operator to an unqualified name is deprecated")
 MSG_DEF(JSMSG_DEPRECATED_EXPR_CLOSURE, 0, JSEXN_WARN, "expression closures are deprecated")
 MSG_DEF(JSMSG_DEPRECATED_FOR_EACH,     0, JSEXN_WARN, "JavaScript 1.6's for-each-in loops are deprecated; consider using ES6 for-of instead")
+MSG_DEF(JSMSG_DEPRECATED_LEGACY_GENERATOR, 0, JSEXN_WARN, "JavaScript 1.7's legacy generators are deprecated; consider using ES6 generators instead. See https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/function* for details.")
 MSG_DEF(JSMSG_DEPRECATED_OCTAL,        0, JSEXN_SYNTAXERR, "\"0\"-prefixed octal literals and octal escape sequences are deprecated; for octal literals use the \"0o\" prefix instead")
 MSG_DEF(JSMSG_DEPRECATED_PRAGMA,       1, JSEXN_WARN, "Using //@ to indicate {0} pragmas is deprecated. Use //# instead")
 MSG_DEF(JSMSG_DEPRECATED_BLOCK_SCOPE_FUN_REDECL, 1, JSEXN_WARN, "redeclaration of block-scoped function `{0}' is deprecated")

js/src/jscompartment.cpp

@@ -59,6 +59,7 @@ JSCompartment::JSCompartment(Zone* zone, const JS::CompartmentOptions& options =
     warnedAboutDateToLocaleFormat(false),
     warnedAboutExprClosure(false),
     warnedAboutForEach(false),
+    warnedAboutLegacyGenerator(false),
     warnedAboutStringGenericsMethods(0),
 #ifdef DEBUG
     firedOnNewGlobalObject(false),

js/src/jscompartment.h

@@ -621,9 +621,10 @@ struct JSCompartment
   public:
     bool                         isSelfHosting;
     bool                         marked;
-    bool                         warnedAboutDateToLocaleFormat;
-    bool                         warnedAboutExprClosure;
-    bool                         warnedAboutForEach;
+    bool                         warnedAboutDateToLocaleFormat : 1;
+    bool                         warnedAboutExprClosure : 1;
+    bool                         warnedAboutForEach : 1;
+    bool                         warnedAboutLegacyGenerator : 1;
     uint32_t                     warnedAboutStringGenericsMethods;
 
 #ifdef DEBUG