Export of internal Abseil changes

--
aabb5093ff380fc60d9a75ace279b620fdc4bff9 by Abseil Team <absl-team@google.com>:

Demangle Clang-specific "<expression> ::= cp <simple-id> <expression>* E"
Cf. https://clang.llvm.org/doxygen/ItaniumMangle_8cpp_source.html#l04338

PiperOrigin-RevId: 391358031

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34dc7baa38f74a8c78b91ac94486707347a85e35 by Derek Mauro <dmauro@google.com>:

Internal change

PiperOrigin-RevId: 391282565
GitOrigin-RevId: aabb5093ff380fc60d9a75ace279b620fdc4bff9
Change-Id: I6d3e235a9c0a1b67a43071de205fed0fefe12912

absl/debugging/internal/demangle.cc

@@ -1617,6 +1617,7 @@ static bool ParseUnresolvedName(State *state) {
 //              ::= <2-ary operator-name> <expression> <expression>
 //              ::= <3-ary operator-name> <expression> <expression> <expression>
 //              ::= cl <expression>+ E
+//              ::= cp <simple-id> <expression>* E # Clang-specific.
 //              ::= cv <type> <expression>      # type (expression)
 //              ::= cv <type> _ <expression>* E # type (expr-list)
 //              ::= st <type>
@@ -1639,14 +1640,23 @@ static bool ParseExpression(State *state) {
     return true;
   }
 
-  // Object/function call expression.
   ParseState copy = state->parse_state;
+
+  // Object/function call expression.
   if (ParseTwoCharToken(state, "cl") && OneOrMore(ParseExpression, state) &&
       ParseOneCharToken(state, 'E')) {
     return true;
   }
   state->parse_state = copy;
 
+  // Clang-specific "cp <simple-id> <expression>* E"
+  //   https://clang.llvm.org/doxygen/ItaniumMangle_8cpp_source.html#l04338
+  if (ParseTwoCharToken(state, "cp") && ParseSimpleId(state) &&
+      ZeroOrMore(ParseExpression, state) && ParseOneCharToken(state, 'E')) {
+    return true;
+  }
+  state->parse_state = copy;
+
   // Function-param expression (level 0).
   if (ParseTwoCharToken(state, "fp") && Optional(ParseCVQualifiers(state)) &&
       Optional(ParseNumber(state, nullptr)) && ParseOneCharToken(state, '_')) {