From 8322d3abcc155dcb8b18e4a702ecf1f1e19dafe0 Mon Sep 17 00:00:00 2001
From: Chris Mihelich <cmihelic@google.com>
Date: Wed, 5 Jun 2024 09:17:05 -0700
Subject: [PATCH] Demangle C++17 structured bindings, DC...E.

PiperOrigin-RevId: 640547784
Change-Id: Ib230993a358f89258367a1c10271c47be3b724e5
---
 absl/debugging/internal/demangle.cc      |  9 +++++++++
 absl/debugging/internal/demangle_test.cc | 15 +++++++++++++++
 2 files changed, 24 insertions(+)

diff --git a/absl/debugging/internal/demangle.cc b/absl/debugging/internal/demangle.cc
index ab611f71..99cc324b 100644
--- a/absl/debugging/internal/demangle.cc
+++ b/absl/debugging/internal/demangle.cc
@@ -821,6 +821,7 @@ static bool ParsePrefix(State *state) {
 //                    ::= <source-name> [<abi-tags>]
 //                    ::= <local-source-name> [<abi-tags>]
 //                    ::= <unnamed-type-name> [<abi-tags>]
+//                    ::= DC <source-name>+ E  # C++17 structured binding
 //
 // <local-source-name> is a GCC extension; see below.
 static bool ParseUnqualifiedName(State *state) {
@@ -831,6 +832,14 @@ static bool ParseUnqualifiedName(State *state) {
       ParseUnnamedTypeName(state)) {
     return ParseAbiTags(state);
   }
+
+  // DC <source-name>+ E
+  ParseState copy = state->parse_state;
+  if (ParseTwoCharToken(state, "DC") && OneOrMore(ParseSourceName, state) &&
+      ParseOneCharToken(state, 'E')) {
+    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 c70cf660..2f2a48a6 100644
--- a/absl/debugging/internal/demangle_test.cc
+++ b/absl/debugging/internal/demangle_test.cc
@@ -632,6 +632,21 @@ TEST(Demangle, GlobalInitializers) {
   EXPECT_STREQ("reference temporary for v", tmp);
 }
 
+TEST(Demangle, StructuredBindings) {
+  char tmp[80];
+
+  // Source:
+  //
+  // struct S { int a, b; };
+  // const auto& [x, y] = S{1, 2};
+
+  // [x, y]
+  EXPECT_TRUE(Demangle("_ZDC1x1yE", tmp, sizeof(tmp)));
+
+  // reference temporary for [x, y]
+  EXPECT_TRUE(Demangle("_ZGRDC1x1yE_", tmp, sizeof(tmp)));
+}
+
 // Test the GNU abi_tag extension.
 TEST(Demangle, AbiTags) {
   char tmp[80];