More correct handling of error cases C++ name parser

[eugene]

Summary

Now incorrect type argument that looks like T<A><B> doesn't cause an assert, but just a parsing error.

Bug: 36224

[eugene]

fix formating

[labath]

Being more resilient when handling demangler outputs seems like a good thing, but I think it is important to understand what made the demangler produce that output in the first place, to make sure we aren't missing anything.

Also, I think I found one more possible issue with this code.

source/Plugins/Language/CPlusPlus/CPlusPlusNameParser.cpp

199

While looking at the bug, this part here struck me as dubious.

Can you check that this properly handles a name like F<(3)>>(1)> f<3, 1>() (which is the demangled form of _Z1fILi3ELi1EE1FIXrsT_T0_EEv).

[eugene]

source/Plugins/Language/CPlusPlus/CPlusPlusNameParser.cpp

199

oh my, you're right. this code doesn't account for shifts in the name. I'm going to submit this code anyway and then think about it.

source/Plugins/Language/CPlusPlus/CPlusPlusNameParser.cpp

bool CPlusPlusNameParser::ConsumeTemplateArgs() {
   // Good thing that compiler makes sure that really ambiguous cases of
   // '>' usage should be enclosed within '()' brackets.
   int template_counter = 1;
   bool can_open_template = false;
   while (HasMoreTokens() && template_counter > 0) {
     tok::TokenKind kind = Peek().getKind();
     switch (kind) {
     case tok::greatergreater:
       template_counter -= 2;
       can_open_template = false;
       Advance();
       break;
     case tok::greater:
       --template_counter;
       can_open_template = false;
       Advance();
       break;
case tok::l_paren:
       break;
     default:
       can_open_template = false;
       Advance();
       break;
     }
   }
 
-  assert(template_counter >= 0);
-  if (template_counter > 0) {
+  if (template_counter != 0) {
     return false;
   }
   start_position.Remove();
   return true;
 }
 
 bool CPlusPlusNameParser::ConsumeAnonymousNamespace() {
   Bookmark start_position = SetBookmark();

unittests/Language/CPlusPlus/CPlusPlusLanguageTest.cpp

TEST(CPlusPlusLanguage, ExtractContextAndIdentifier) {
   EXPECT_FALSE(
       CPlusPlusLanguage::ExtractContextAndIdentifier("", context, basename));
   EXPECT_FALSE(CPlusPlusLanguage::ExtractContextAndIdentifier(
       "selector:", context, basename));
   EXPECT_FALSE(CPlusPlusLanguage::ExtractContextAndIdentifier(
       "selector:otherField:", context, basename));
   EXPECT_FALSE(CPlusPlusLanguage::ExtractContextAndIdentifier(
       "abc::", context, basename));
+  EXPECT_FALSE(CPlusPlusLanguage::ExtractContextAndIdentifier(
+      "f<A<B><C>>", context, basename));
 }