Demangle modern _ZGR..._ symbols.

PiperOrigin-RevId: 640517212
Change-Id: Ideaaf45d2104a3c82cc9b6807894554335e5b904

absl/debugging/internal/demangle.cc

@@ -1080,12 +1080,13 @@ static bool ParseOperatorName(State *state, int *arity) {
 //                ::= TH <name>  # thread-local initialization
 //                ::= Tc <call-offset> <call-offset> <(base) encoding>
 //                ::= GV <(object) name>
+//                ::= GR <(object) name> [<seq-id>] _
 //                ::= T <call-offset> <(base) encoding>
 // G++ extensions:
 //                ::= TC <type> <(offset) number> _ <(base) type>
 //                ::= TF <type>
 //                ::= TJ <type>
-//                ::= GR <name>
+//                ::= GR <name>  # without final _, perhaps an earlier form?
 //                ::= GA <encoding>
 //                ::= Th <call-offset> <(base) encoding>
 //                ::= Tv <call-offset> <(base) encoding>
@@ -1152,10 +1153,22 @@ static bool ParseSpecialName(State *state) {
   }
   state->parse_state = copy;
 
-  if (ParseTwoCharToken(state, "GR") && ParseName(state)) {
-    return true;
+  // <special-name> ::= GR <(object) name> [<seq-id>] _  # modern standard
+  //                ::= GR <(object) name>  # also recognized
+  if (ParseTwoCharToken(state, "GR")) {
+    MaybeAppend(state, "reference temporary for ");
+    if (!ParseName(state)) {
+      state->parse_state = copy;
+      return false;
     }
+    const bool has_seq_id = ParseSeqId(state);
+    const bool has_underscore = ParseOneCharToken(state, '_');
+    if (has_seq_id && !has_underscore) {
       state->parse_state = copy;
+      return false;
+    }
+    return true;
+  }
 
   if (ParseTwoCharToken(state, "GA") && ParseEncoding(state)) {
     return true;

absl/debugging/internal/demangle_test.cc

@@ -612,6 +612,26 @@ TEST(Demangle, StringLiterals) {
   EXPECT_STREQ("f<>()", tmp);
 }
 
+TEST(Demangle, GlobalInitializers) {
+  char tmp[80];
+
+  // old form without suffix
+  EXPECT_TRUE(Demangle("_ZGR1v", tmp, sizeof(tmp)));
+  EXPECT_STREQ("reference temporary for v", tmp);
+
+  // modern form for the whole initializer
+  EXPECT_TRUE(Demangle("_ZGR1v_", tmp, sizeof(tmp)));
+  EXPECT_STREQ("reference temporary for v", tmp);
+
+  // next subobject in depth-first preorder traversal
+  EXPECT_TRUE(Demangle("_ZGR1v0_", tmp, sizeof(tmp)));
+  EXPECT_STREQ("reference temporary for v", tmp);
+
+  // subobject with a larger seq-id
+  EXPECT_TRUE(Demangle("_ZGR1v1Z_", tmp, sizeof(tmp)));
+  EXPECT_STREQ("reference temporary for v", tmp);
+}
+
 // Test the GNU abi_tag extension.
 TEST(Demangle, AbiTags) {
   char tmp[80];