1 files changed, 21 insertions, 0 deletions
diff --git a/absl/debugging/internal/demangle.cc b/absl/debugging/internal/demangle.cc
index 71d4eb0a..d53a04e0 100644
--- a/absl/debugging/internal/demangle.cc
+++ b/absl/debugging/internal/demangle.cc
@@ -578,6 +578,7 @@ static bool ParseTemplateArgs(State *state);
 static bool ParseTemplateArg(State *state);
 static bool ParseBaseUnresolvedName(State *state);
 static bool ParseUnresolvedName(State *state);
+static bool ParseUnionSelector(State* state);
 static bool ParseExpression(State *state);
 static bool ParseExprPrimary(State *state);
 static bool ParseExprCastValue(State *state);
@@ -1743,11 +1744,19 @@ static bool ParseUnresolvedName(State *state) {
   return false;
 }
 
+// <union-selector> ::= _ [<number>]
+//
+// https://github.com/itanium-cxx-abi/cxx-abi/issues/47
+static bool ParseUnionSelector(State *state) {
+  return ParseOneCharToken(state, '_') && Optional(ParseNumber(state, nullptr));
+}
+
 // <expression> ::= <1-ary operator-name> <expression>
 //              ::= <2-ary operator-name> <expression> <expression>
 //              ::= <3-ary operator-name> <expression> <expression> <expression>
 //              ::= cl <expression>+ E
 //              ::= cp <simple-id> <expression>* E # Clang-specific.
+//              ::= so <type> <expression> [<number>] <union-selector>* [p] E
 //              ::= cv <type> <expression>      # type (expression)
 //              ::= cv <type> _ <expression>* E # type (expr-list)
 //              ::= st <type>
@@ -1787,6 +1796,18 @@ static bool ParseExpression(State *state) {
   }
   state->parse_state = copy;
 
+  // <expression> ::= so <type> <expression> [<number>] <union-selector>* [p] E
+  //
+  // https://github.com/itanium-cxx-abi/cxx-abi/issues/47
+  if (ParseTwoCharToken(state, "so") && ParseType(state) &&
+      ParseExpression(state) && Optional(ParseNumber(state, nullptr)) &&
+      ZeroOrMore(ParseUnionSelector, state) &&
+      Optional(ParseOneCharToken(state, 'p')) &&
+      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, '_')) {