Description: Revert^3 "Add rust demangling."
 To avoid introduce new dependecy:
 - https://android.googlesource.com/platform/external/rust/crates/rustc-demangle-capi
 .
 This reverts commit a8345a5764ceb0750729396ccfbaa763ae248f21.
Forwarded: not-needed
--- a/system/unwinding/libunwindstack/Android.bp
+++ b/system/unwinding/libunwindstack/Android.bp
@@ -54,7 +54,6 @@ cc_defaults {
 libunwindstack_common_src_files = [
     "AndroidUnwinder.cpp",
     "ArmExidx.cpp",
-    "Demangle.cpp",
     "DexFiles.cpp",
     "DwarfCfa.cpp",
     "DwarfEhFrameWithHdr.cpp",
@@ -314,7 +313,6 @@ cc_defaults {
         "tests/AndroidUnwinderTest.cpp",
         "tests/ArmExidxDecodeTest.cpp",
         "tests/ArmExidxExtractTest.cpp",
-        "tests/DemangleTest.cpp",
         "tests/DexFileTest.cpp",
         "tests/DexFilesTest.cpp",
         "tests/DwarfCfaLogTest.cpp",
--- a/system/unwinding/libunwindstack/AndroidUnwinder.cpp
+++ b/system/unwinding/libunwindstack/AndroidUnwinder.cpp
@@ -28,7 +28,6 @@
 
 #include <unwindstack/AndroidUnwinder.h>
 #include <unwindstack/Arch.h>
-#include <unwindstack/Demangle.h>
 #include <unwindstack/DexFiles.h>
 #include <unwindstack/Error.h>
 #include <unwindstack/JitDebug.h>
@@ -46,11 +45,18 @@ static constexpr int kThreadUnwindSignal = BIONIC_SIGNAL_BACKTRACE;
 static int kThreadUnwindSignal = SIGRTMIN;
 #endif
 
+// Use the demangler from libc++.
+extern "C" char* __cxa_demangle(const char*, char*, size_t*, int* status);
+
 namespace unwindstack {
 
 void AndroidUnwinderData::DemangleFunctionNames() {
   for (auto& frame : frames) {
-    frame.function_name = DemangleNameIfNeeded(frame.function_name);
+    char* demangled_name = __cxa_demangle(frame.function_name.c_str(), nullptr, nullptr, nullptr);
+    if (demangled_name != nullptr) {
+      frame.function_name = demangled_name;
+      free(demangled_name);
+    }
   }
 }
 
--- a/system/unwinding/libunwindstack/Demangle.cpp
+++ /dev/null
@@ -1,51 +0,0 @@
-/*
- * Copyright (C) 2023 The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include <cxxabi.h>
-#include <stdlib.h>
-
-#include <string>
-
-#include <rustc_demangle.h>
-
-#include <unwindstack/Demangle.h>
-
-namespace unwindstack {
-
-std::string DemangleNameIfNeeded(const std::string& name) {
-  if (name.length() < 2 || name[0] != '_') {
-    return name;
-  }
-
-  char* demangled_str = nullptr;
-  if (name[1] == 'Z') {
-    // Try to demangle C++ name.
-    demangled_str = abi::__cxa_demangle(name.c_str(), nullptr, nullptr, nullptr);
-  } else if (name[1] == 'R') {
-    // Try to demangle rust name.
-    demangled_str = rustc_demangle(name.c_str(), nullptr, nullptr, nullptr);
-  }
-
-  if (demangled_str == nullptr) {
-    return name;
-  }
-
-  std::string demangled_name(demangled_str);
-  free(demangled_str);
-  return demangled_name;
-}
-
-}  // namespace unwindstack
--- a/system/unwinding/libunwindstack/Unwinder.cpp
+++ b/system/unwinding/libunwindstack/Unwinder.cpp
@@ -25,12 +25,10 @@
 
 #include <algorithm>
 #include <memory>
-#include <string>
 
 #include <android-base/file.h>
 #include <android-base/stringprintf.h>
 
-#include <unwindstack/Demangle.h>
 #include <unwindstack/DexFiles.h>
 #include <unwindstack/Elf.h>
 #include <unwindstack/JitDebug.h>
@@ -41,6 +39,9 @@
 
 #include "Check.h"
 
+// Use the demangler from libc++.
+extern "C" char* __cxa_demangle(const char*, char*, size_t*, int* status);
+
 namespace unwindstack {
 
 // Inject extra 'virtual' frame that represents the dex pc data.
@@ -325,7 +326,15 @@ std::string Unwinder::FormatFrame(ArchEnum arch, const FrameData& frame, bool di
   }
 
   if (!frame.function_name.empty()) {
-    data += " (" + DemangleNameIfNeeded(frame.function_name);
+    char* demangled_name = __cxa_demangle(frame.function_name.c_str(), nullptr, nullptr, nullptr);
+    if (demangled_name == nullptr) {
+      data += " (";
+      data += frame.function_name;
+    } else {
+      data += " (";
+      data += demangled_name;
+      free(demangled_name);
+    }
     if (frame.function_offset != 0) {
       data += android::base::StringPrintf("+%" PRId64, frame.function_offset);
     }
--- a/system/unwinding/libunwindstack/include/unwindstack/Demangle.h
+++ /dev/null
@@ -1,25 +0,0 @@
-/*
- * Copyright (C) 2023 The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#pragma once
-
-#include <string>
-
-namespace unwindstack {
-
-std::string DemangleNameIfNeeded(const std::string& name);
-
-}  // namespace unwindstack