Bug 1221737 - Drop some BytecodeEmitter checks for cases that the Parser rules out. r=jonco.

--HG--
extra : commitid : AdGjcp4XF2w
extra : rebase_source : 29da4df939bcdf4a078f55a87c8f8eb12bf9091f

js/src/frontend/BytecodeEmitter.cpp

@@ -8034,13 +8034,11 @@ BytecodeEmitter::emitTree(ParseNode* pn, EmitLineNumberNote emitLineNote)
         break;
 
       case PNK_IMPORT:
-        if (!checkIsModule())
-            return false;
+        MOZ_ASSERT(sc->isModuleBox());
         break;
 
       case PNK_EXPORT:
-        if (!checkIsModule())
-            return false;
+        MOZ_ASSERT(sc->isModuleBox());
         if (pn->pn_kid->getKind() != PNK_EXPORT_SPEC_LIST) {
             if (!emitTree(pn->pn_kid))
                 return false;
@@ -8048,8 +8046,7 @@ BytecodeEmitter::emitTree(ParseNode* pn, EmitLineNumberNote emitLineNote)
         break;
 
       case PNK_EXPORT_DEFAULT:
-        if (!checkIsModule())
-            return false;
+        MOZ_ASSERT(sc->isModuleBox());
         if (!emitTree(pn->pn_kid))
             return false;
         if (pn->pn_right) {
@@ -8061,8 +8058,7 @@ BytecodeEmitter::emitTree(ParseNode* pn, EmitLineNumberNote emitLineNote)
         break;
 
       case PNK_EXPORT_FROM:
-        if (!checkIsModule())
-            return false;
+        MOZ_ASSERT(sc->isModuleBox());
         break;
 
       case PNK_ARRAYPUSH:
@@ -8170,16 +8166,6 @@ BytecodeEmitter::emitTree(ParseNode* pn, EmitLineNumberNote emitLineNote)
     return true;
 }
 
-bool
-BytecodeEmitter::checkIsModule()
-{
-    if (!sc->isModuleBox()) {
-        reportError(nullptr, JSMSG_INVALID_OUTSIDE_MODULE);
-        return false;
-    }
-    return true;
-}
-
 static bool
 AllocSrcNote(ExclusiveContext* cx, SrcNotesVector& notes, unsigned* index)
 {

js/src/frontend/BytecodeEmitter.h

@@ -351,9 +351,6 @@ struct BytecodeEmitter
     // Emit module code for the tree rooted at body.
     bool emitModuleScript(ParseNode* body);
 
-    // Report an error if we are not processing a module.
-    bool checkIsModule();
-
     // If op is JOF_TYPESET (see the type barriers comment in TypeInference.h),
     // reserve a type set to store its result.
     void checkTypeSet(JSOp op);

js/src/js.msg

@@ -255,16 +255,15 @@ MSG_DEF(JSMSG_DUPLICATE_LABEL,         0, JSEXN_SYNTAXERR, "duplicate label")
 MSG_DEF(JSMSG_DUPLICATE_PROPERTY,      1, JSEXN_SYNTAXERR, "property name {0} appears more than once in object literal")
 MSG_DEF(JSMSG_EMPTY_CONSEQUENT,        0, JSEXN_SYNTAXERR, "mistyped ; after conditional?")
 MSG_DEF(JSMSG_EQUAL_AS_ASSIGN,         0, JSEXN_SYNTAXERR, "test for equality (==) mistyped as assignment (=)?")
-MSG_DEF(JSMSG_EXPORT_DECL_AT_TOP_LEVEL,0, JSEXN_SYNTAXERR, "export declarations may only appear at top level")
+MSG_DEF(JSMSG_EXPORT_DECL_AT_TOP_LEVEL,0, JSEXN_SYNTAXERR, "export declarations may only appear at top level of a module")
 MSG_DEF(JSMSG_FINALLY_WITHOUT_TRY,     0, JSEXN_SYNTAXERR, "finally without try")
 MSG_DEF(JSMSG_FROM_AFTER_IMPORT_CLAUSE, 0, JSEXN_SYNTAXERR, "missing keyword 'from' after import clause")
 MSG_DEF(JSMSG_FROM_AFTER_EXPORT_STAR,  0, JSEXN_SYNTAXERR, "missing keyword 'from' after export *")
 MSG_DEF(JSMSG_GARBAGE_AFTER_INPUT,     2, JSEXN_SYNTAXERR, "unexpected garbage after {0}, starting with {1}")
 MSG_DEF(JSMSG_IDSTART_AFTER_NUMBER,    0, JSEXN_SYNTAXERR, "identifier starts immediately after numeric literal")
 MSG_DEF(JSMSG_ILLEGAL_CHARACTER,       0, JSEXN_SYNTAXERR, "illegal character")
-MSG_DEF(JSMSG_IMPORT_DECL_AT_TOP_LEVEL, 0, JSEXN_SYNTAXERR, "import declarations may only appear at top level")
+MSG_DEF(JSMSG_IMPORT_DECL_AT_TOP_LEVEL, 0, JSEXN_SYNTAXERR, "import declarations may only appear at top level of a module")
 MSG_DEF(JSMSG_INVALID_FOR_INOF_DECL_WITH_INIT,1,JSEXN_SYNTAXERR,"for-{0} loop head declarations may not have initializers")
-MSG_DEF(JSMSG_INVALID_OUTSIDE_MODULE,  0, JSEXN_SYNTAXERR, "import and export declarations are only valid at the top level of a module")
 MSG_DEF(JSMSG_IN_AFTER_FOR_NAME,       0, JSEXN_SYNTAXERR, "missing 'in' or 'of' after for")
 MSG_DEF(JSMSG_LABEL_NOT_FOUND,         0, JSEXN_SYNTAXERR, "label not found")
 MSG_DEF(JSMSG_LET_CLASS_BINDING,       0, JSEXN_SYNTAXERR, "'let' is not a valid name for a class")