From 5195c35dc4361618d89733e63fd53a717d54c7a2 Mon Sep 17 00:00:00 2001
From: Chris Mihelich <cmihelic@google.com>
Date: Mon, 10 Jun 2024 07:25:53 -0700
Subject: Demangle template parameter object names, TA <template-arg>.

PiperOrigin-RevId: 641893938
Change-Id: I8a21e322c9cf1d5dab7477af5367aad134fbf2ab
---
 absl/debugging/internal/demangle.cc      | 15 +++++++++++++++
 absl/debugging/internal/demangle_test.cc | 23 +++++++++++++++++++++++
 2 files changed, 38 insertions(+)

diff --git a/absl/debugging/internal/demangle.cc b/absl/debugging/internal/demangle.cc
index f9dff5d8..26163416 100644
--- a/absl/debugging/internal/demangle.cc
+++ b/absl/debugging/internal/demangle.cc
@@ -1176,6 +1176,7 @@ static bool ParseConversionOperatorType(State *state) {
 //                ::= GR <(object) name> [<seq-id>] _
 //                ::= T <call-offset> <(base) encoding>
 //                ::= GTt <encoding>  # transaction-safe entry point
+//                ::= TA <template-arg>  # nontype template parameter object
 // G++ extensions:
 //                ::= TC <type> <(offset) number> _ <(base) type>
 //                ::= TF <type>
@@ -1190,6 +1191,8 @@ static bool ParseConversionOperatorType(State *state) {
 // thread_local feature.  For these see:
 //
 // https://maskray.me/blog/2021-02-14-all-about-thread-local-storage
+//
+// For TA see https://github.com/itanium-cxx-abi/cxx-abi/issues/63.
 static bool ParseSpecialName(State *state) {
   ComplexityGuard guard(state);
   if (guard.IsTooComplex()) return false;
@@ -1280,6 +1283,18 @@ static bool ParseSpecialName(State *state) {
     return true;
   }
   state->parse_state = copy;
+
+  if (ParseTwoCharToken(state, "TA")) {
+    bool append = state->parse_state.append;
+    DisableAppend(state);
+    if (ParseTemplateArg(state)) {
+      RestoreAppend(state, append);
+      MaybeAppend(state, "template parameter object");
+      return true;
+    }
+  }
+  state->parse_state = copy;
+
   return false;
 }
 
diff --git a/absl/debugging/internal/demangle_test.cc b/absl/debugging/internal/demangle_test.cc
index 68a759c1..55686814 100644
--- a/absl/debugging/internal/demangle_test.cc
+++ b/absl/debugging/internal/demangle_test.cc
@@ -943,6 +943,29 @@ TEST(Demangle, TransactionSafeFunctionType) {
   EXPECT_STREQ("f()", tmp);
 }
 
+TEST(Demangle, TemplateParameterObject) {
+  char tmp[80];
+
+  // Source:
+  //
+  // struct S { int x, y; };
+  // template <S s, const S* p = &s> void f() {}
+  // template void f<S{1, 2}>();
+  //
+  // LLVM demangling:
+  //
+  // void f<S{1, 2}, &template parameter object for S{1, 2}>()
+  EXPECT_TRUE(Demangle("_Z1fIXtl1SLi1ELi2EEEXadL_ZTAXtlS0_Li1ELi2EEEEEEvv",
+                       tmp, sizeof(tmp)));
+  EXPECT_STREQ("f<>()", tmp);
+
+  // The name of the object standing alone.
+  //
+  // LLVM demangling: template parameter object for S{1, 2}
+  EXPECT_TRUE(Demangle("_ZTAXtl1SLi1ELi2EEE", tmp, sizeof(tmp)));
+  EXPECT_STREQ("template parameter object", tmp);
+}
+
 TEST(Demangle, EnableIfAttributeOnGlobalFunction) {
   char tmp[80];
 
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