Bug 1556230 - Add comments and a test. r=arai

Differential Revision: https://phabricator.services.mozilla.com/D33675

--HG--
extra : moz-landing-system : lando

js/src/tests/non262/Unicode/non-bmp-non-spaces.js

@@ -0,0 +1,60 @@
+/* -*- indent-tabs-mode: nil; js-indent-level: 4 -*-
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// White space must not be determined by truncating char32_t to char16_t.
+
+assertThrowsInstanceOf(() => eval("\u{40008}"), SyntaxError);
+assertThrowsInstanceOf(() => eval("\u{40009}"), SyntaxError); // U+0009 CHARACTER TABULATION
+assertThrowsInstanceOf(() => eval("\u{4000A}"), SyntaxError); // U+000A LINE FEED
+assertThrowsInstanceOf(() => eval("\u{4000B}"), SyntaxError); // U+000B LINE TABULATION
+assertThrowsInstanceOf(() => eval("\u{4000C}"), SyntaxError); // U+000C FORM FEED
+assertThrowsInstanceOf(() => eval("\u{4000D}"), SyntaxError); // U+000D CARRIAGE RETURN
+assertThrowsInstanceOf(() => eval("\u{4000E}"), SyntaxError);
+
+assertThrowsInstanceOf(() => eval("\u{4001F}"), SyntaxError);
+assertThrowsInstanceOf(() => eval("\u{40020}"), SyntaxError); // U+0020 SPACE
+assertThrowsInstanceOf(() => eval("\u{40021}"), SyntaxError);
+
+assertThrowsInstanceOf(() => eval("\u{4009F}"), SyntaxError);
+assertThrowsInstanceOf(() => eval("\u{400A0}"), SyntaxError); // U+00A0 NO-BREAK SPACE
+assertThrowsInstanceOf(() => eval("\u{400A1}"), SyntaxError);
+
+assertThrowsInstanceOf(() => eval("\u{4167F}"), SyntaxError);
+assertThrowsInstanceOf(() => eval("\u{41680}"), SyntaxError); // U+1680 OGHAM SPACE MARK
+assertThrowsInstanceOf(() => eval("\u{41681}"), SyntaxError);
+
+assertThrowsInstanceOf(() => eval("\u{41FFF}"), SyntaxError);
+assertThrowsInstanceOf(() => eval("\u{42000}"), SyntaxError); // U+2000 EN QUAD
+assertThrowsInstanceOf(() => eval("\u{42001}"), SyntaxError); // U+2001 EM QUAD
+assertThrowsInstanceOf(() => eval("\u{42002}"), SyntaxError); // U+2002 EN SPACE
+assertThrowsInstanceOf(() => eval("\u{42003}"), SyntaxError); // U+2003 EM SPACE
+assertThrowsInstanceOf(() => eval("\u{42004}"), SyntaxError); // U+2004 THREE-PER-EM SPACE
+assertThrowsInstanceOf(() => eval("\u{42005}"), SyntaxError); // U+2005 FOUR-PER-EM SPACE
+assertThrowsInstanceOf(() => eval("\u{42006}"), SyntaxError); // U+2006 SIX-PER-EM SPACE
+assertThrowsInstanceOf(() => eval("\u{42007}"), SyntaxError); // U+2007 FIGURE SPACE
+assertThrowsInstanceOf(() => eval("\u{42008}"), SyntaxError); // U+2008 PUNCTUATION SPACE
+assertThrowsInstanceOf(() => eval("\u{42009}"), SyntaxError); // U+2009 THIN SPACE
+assertThrowsInstanceOf(() => eval("\u{4200A}"), SyntaxError); // U+200A HAIR SPACE
+assertThrowsInstanceOf(() => eval("\u{4200B}"), SyntaxError);
+
+assertThrowsInstanceOf(() => eval("\u{42027}"), SyntaxError);
+assertThrowsInstanceOf(() => eval("\u{42028}"), SyntaxError); // U+2028 LINE SEPARATOR
+assertThrowsInstanceOf(() => eval("\u{42029}"), SyntaxError); // U+2028 PARAGRAPH SEPARATOR
+assertThrowsInstanceOf(() => eval("\u{4202A}"), SyntaxError);
+
+assertThrowsInstanceOf(() => eval("\u{4202E}"), SyntaxError);
+assertThrowsInstanceOf(() => eval("\u{4202F}"), SyntaxError); // U+202F NARROW NO-BREAK SPACE
+assertThrowsInstanceOf(() => eval("\u{42030}"), SyntaxError);
+
+assertThrowsInstanceOf(() => eval("\u{4205E}"), SyntaxError);
+assertThrowsInstanceOf(() => eval("\u{4205F}"), SyntaxError); // U+205F MEDIUM MATHEMATICAL SPACE
+assertThrowsInstanceOf(() => eval("\u{42060}"), SyntaxError);
+
+assertThrowsInstanceOf(() => eval("\u{42FFF}"), SyntaxError);
+assertThrowsInstanceOf(() => eval("\u{43000}"), SyntaxError); // U+3000 IDEOGRAPHIC SPACE
+assertThrowsInstanceOf(() => eval("\u{43001}"), SyntaxError);
+
+if (typeof reportCompare === "function")
+  reportCompare(true, true);

js/src/util/Unicode.h

@@ -7,6 +7,8 @@
 #ifndef util_Unicode_h
 #define util_Unicode_h
 
+#include "mozilla/Casting.h"  // mozilla::AssertedCast
+
 #include "jspubtd.h"
 
 #include "util/UnicodeNonBMP.h"
@@ -241,6 +243,7 @@ inline bool IsSpace(char ch) {
   return IsSpace(static_cast<JS::Latin1Char>(ch));
 }
 
+// IsSpace(char32_t) must additionally exclude everything non-BMP.
 inline bool IsSpace(char32_t ch) {
   if (ch < 128) {
     return js_isspace[ch];
@@ -250,11 +253,13 @@ inline bool IsSpace(char32_t ch) {
     return true;
   }
 
+  // An assertion in make_unicode.py:make_unicode_file guarantees that there are
+  // no Space_Separator (Zs) code points outside the BMP.
   if (ch >= NonBMPMin) {
     return false;
   }
 
-  return CharInfo(ch).isSpace();
+  return CharInfo(mozilla::AssertedCast<char16_t>(ch)).isSpace();
 }
 
 /*

js/src/util/make_unicode.py

@@ -1255,7 +1255,8 @@ def make_unicode_file(version,
 
         # If the following assert fails, it means space character is added to
         # non-BMP area.  In that case the following code should be uncommented
-        # and the corresponding code should be added to frontend.
+        # and the corresponding code should be added to frontend.  (At least
+        # unicode::IsSpace will require updating to handle this.)
         assert len(non_bmp_space_set.keys()) == 0
 
         write_supplemental_identifier_method('IsIdentifierStartNonBMP', non_bmp_id_start_set,