From 36c2a14c5966d06f4f8c3bd02e3ef9d517ead081 Mon Sep 17 00:00:00 2001
From: Chris Mihelich <cmihelic@google.com>
Date: Wed, 29 May 2024 15:23:58 -0700
Subject: Demangle unofficial <unresolved-qualifier-level> encodings like
 S0_IT_E.

PiperOrigin-RevId: 638430573
Change-Id: Ifc4d93bc4ea30951404546436f5397c8fb1bda57
---
 absl/debugging/internal/demangle.cc | 28 ++++++++++++++++++++++++++--
 1 file changed, 26 insertions(+), 2 deletions(-)

(limited to 'absl/debugging/internal/demangle.cc')

diff --git a/absl/debugging/internal/demangle.cc b/absl/debugging/internal/demangle.cc
index c9dbb3c6..2d9cd018 100644
--- a/absl/debugging/internal/demangle.cc
+++ b/absl/debugging/internal/demangle.cc
@@ -612,6 +612,7 @@ static bool ParseTemplateArgs(State *state);
 static bool ParseTemplateArg(State *state);
 static bool ParseBaseUnresolvedName(State *state);
 static bool ParseUnresolvedName(State *state);
+static bool ParseUnresolvedQualifierLevel(State *state);
 static bool ParseUnionSelector(State* state);
 static bool ParseFunctionParam(State* state);
 static bool ParseBracedExpression(State *state);
@@ -1826,7 +1827,7 @@ static bool ParseUnresolvedName(State *state) {
 
   if (ParseTwoCharToken(state, "sr") && ParseOneCharToken(state, 'N') &&
       ParseUnresolvedType(state) &&
-      OneOrMore(/* <unresolved-qualifier-level> ::= */ ParseSimpleId, state) &&
+      OneOrMore(ParseUnresolvedQualifierLevel, state) &&
       ParseOneCharToken(state, 'E') && ParseBaseUnresolvedName(state)) {
     return true;
   }
@@ -1834,7 +1835,7 @@ static bool ParseUnresolvedName(State *state) {
 
   if (Optional(ParseTwoCharToken(state, "gs")) &&
       ParseTwoCharToken(state, "sr") &&
-      OneOrMore(/* <unresolved-qualifier-level> ::= */ ParseSimpleId, state) &&
+      OneOrMore(ParseUnresolvedQualifierLevel, state) &&
       ParseOneCharToken(state, 'E') && ParseBaseUnresolvedName(state)) {
     return true;
   }
@@ -1843,6 +1844,29 @@ static bool ParseUnresolvedName(State *state) {
   return false;
 }
 
+// <unresolved-qualifier-level> ::= <simple-id>
+//                              ::= <substitution> <template-args>
+//
+// The production <substitution> <template-args> is nonstandard but is observed
+// in practice.  An upstream discussion on the best shape of <unresolved-name>
+// has not converged:
+//
+// https://github.com/itanium-cxx-abi/cxx-abi/issues/38
+static bool ParseUnresolvedQualifierLevel(State *state) {
+  ComplexityGuard guard(state);
+  if (guard.IsTooComplex()) return false;
+
+  if (ParseSimpleId(state)) return true;
+
+  ParseState copy = state->parse_state;
+  if (ParseSubstitution(state, /*accept_std=*/false) &&
+      ParseTemplateArgs(state)) {
+    return true;
+  }
+  state->parse_state = copy;
+  return false;
+}
+
 // <union-selector> ::= _ [<number>]
 //
 // https://github.com/itanium-cxx-abi/cxx-abi/issues/47
-- 
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