Recognize HTMLCloseComment after multiline comment

test/cctest/test-parsing.cc

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 // modification, are permitted provided that the following conditions are
 // met:
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@@ skipping 102 matching lines @@
   v8::Isolate* isolate = CcTest::isolate();
   v8::HandleScope handles(isolate);
 
   // Regression test. See:
   //    http://code.google.com/p/chromium/issues/detail?id=53548
   // Tests that --> is correctly interpreted as comment-to-end-of-line if there
   // is only whitespace before it on the line (with comments considered as
   // whitespace, even a multiline-comment containing a newline).
   // This was not the case if it occurred before the first real token
   // in the input.
+  // clang-format off
   const char* tests[] = {
       // Before first real token.
       "--> is eol-comment\nvar y = 37;\n",
       "\n --> is eol-comment\nvar y = 37;\n",
       "/* precomment */ --> is eol-comment\nvar y = 37;\n",
       "\n/* precomment */ --> is eol-comment\nvar y = 37;\n",
       // After first real token.
       "var x = 42;\n--> is eol-comment\nvar y = 37;\n",
       "var x = 42;\n/* precomment */ --> is eol-comment\nvar y = 37;\n",
+      "x/* precomment\n */ --> is eol-comment\nvar y = 37;\n",
+      "var x = 42; /* precomment\n */ --> is eol-comment\nvar y = 37;\n",

[nickie, 2016/07/04 08:27:10]

According to the spec [1], the end of a real multi-line comment
(MultiLineComment) can be followed by an optional HTMLCloseComment.  This can
start with a sequence of not only white space, but also 
single line delimited comments (SingleLineDelimitedComment), i.e., comments of
the form /* no line terminator here */.

I am not sure if we handle this case correctly.  In any case, we should have
tests for this.  E.g.

"/* MLC \n */ /* SLDC */ --> is eol-comment\nvar y = 37;\n",
"/* MLC \n */ /* SLDC1 */ /* SLDC2 */ --> is eol-comment\nvar y = 37;\n",
"/* MLC1 \n */ /* MLC2 \n */ --> is eol-comment\nvar y = 37;\n",
"/* SLDC */ /* MLC \n */ --> is eol-comment\nvar y = 37;\n",
"/* MLC1 \n */ /* SLDC1 */ /* MLC2 \n */ /* SLDC2 */ --> is eol-comment\nvar y =
37;\n",

Also, we should possibly have tests without spaces in between the comments or
around "-->".

[1] https://tc39.github.io/ecma262/#sec-html-like-comments

       NULL
   };
 
   const char* fail_tests[] = {
       "x --> is eol-comment\nvar y = 37;\n",
       "\"\\n\" --> is eol-comment\nvar y = 37;\n",
       "x/* precomment */ --> is eol-comment\nvar y = 37;\n",
-      "x/* precomment\n */ --> is eol-comment\nvar y = 37;\n",
       "var x = 42; --> is eol-comment\nvar y = 37;\n",
-      "var x = 42; /* precomment\n */ --> is eol-comment\nvar y = 37;\n",
       NULL
   };
+  // clang-format on
 
   // Parser/Scanner needs a stack limit.
   CcTest::i_isolate()->stack_guard()->SetStackLimit(
       i::GetCurrentStackPosition() - 128 * 1024);
   uintptr_t stack_limit = CcTest::i_isolate()->stack_guard()->real_climit();
   for (int i = 0; tests[i]; i++) {
     const i::byte* source =
         reinterpret_cast<const i::byte*>(tests[i]);
     i::Utf8ToUtf16CharacterStream stream(source, i::StrLength(tests[i]));
     i::CompleteParserRecorder log;
@@ skipping 7786 matching lines @@
     "(a,);",
     "(a,b,c,);",
     NULL
   };
   // clang-format on
 
   static const ParserFlag always_flags[] = {kAllowHarmonyTrailingCommas};
   RunParserSyncTest(context_data, data, kError, NULL, 0, always_flags,
                     arraysize(always_flags));
 }