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From: Ryan VanderMeulen <rvandermeulen@mozilla.com>
Date: Sat, 3 May 2026 18:00:00 +0000
Subject: Bug 2038068 - Make abseil-cpp use the Win32 path on mingw. r?#firefox-build-system-reviewers
The __MINGW32__ branches in absl's thread_identity and waiter code
assume winpthreads is available, but Mozilla's clangmingw toolchain
doesn't ship pthread headers. Drop the carve-outs so mingw uses absl's
native Windows path (CPP11 thread_local + win32_waiter), which clang
already supports for the mingw target.
---
abseil-cpp/absl/base/internal/thread_identity.cc | 8 ++++----
abseil-cpp/absl/base/internal/thread_identity.h | 2 +-
abseil-cpp/absl/synchronization/internal/pthread_waiter.h | 4 ++--
abseil-cpp/absl/synchronization/internal/win32_waiter.h | 4 ++--
4 files changed, 9 insertions(+), 9 deletions(-)
diff --git a/abseil-cpp/absl/base/internal/thread_identity.cc b/abseil-cpp/absl/base/internal/thread_identity.cc
index 0471a25dceab..8b918843541c 100644
--- a/abseil-cpp/absl/base/internal/thread_identity.cc
+++ b/abseil-cpp/absl/base/internal/thread_identity.cc
@@ -14,7 +14,7 @@
#include "absl/base/internal/thread_identity.h"
-#if !defined(_WIN32) || defined(__MINGW32__)
+#if !defined(_WIN32)
#include <pthread.h>
#ifndef __wasi__
// WASI does not provide this header, either way we disable use
@@ -84,9 +84,9 @@ void SetCurrentThreadIdentity(ThreadIdentity* identity,
absl::call_once(init_thread_identity_key_once, AllocateThreadIdentityKey,
reclaimer);
-#if defined(__wasi__) || defined(__EMSCRIPTEN__) || defined(__MINGW32__) || \
+#if defined(__wasi__) || defined(__EMSCRIPTEN__) || \
defined(__hexagon__)
- // Emscripten, WASI and MinGW pthread implementations does not support
+ // Emscripten and WASI pthread implementations does not support
// signals. See
// more information.
@@ -106,7 +106,7 @@ void SetCurrentThreadIdentity(ThreadIdentity* identity,
pthread_setspecific(thread_identity_pthread_key,
reinterpret_cast<void*>(identity));
pthread_sigmask(SIG_SETMASK, &curr_signals, nullptr);
-#endif // !__EMSCRIPTEN__ && !__MINGW32__
+#endif // !__EMSCRIPTEN__
#elif ABSL_THREAD_IDENTITY_MODE == ABSL_THREAD_IDENTITY_MODE_USE_TLS
// NOTE: Not async-safe. But can be open-coded.
diff --git a/abseil-cpp/absl/base/internal/thread_identity.h b/abseil-cpp/absl/base/internal/thread_identity.h
index acfc15a8f697..6a538897660c 100644
--- a/abseil-cpp/absl/base/internal/thread_identity.h
+++ b/abseil-cpp/absl/base/internal/thread_identity.h
@@ -217,7 +217,7 @@ void ClearCurrentThreadIdentity();
#error ABSL_THREAD_IDENTITY_MODE cannot be directly set
#elif defined(ABSL_FORCE_THREAD_IDENTITY_MODE)
#define ABSL_THREAD_IDENTITY_MODE ABSL_FORCE_THREAD_IDENTITY_MODE
-#elif defined(_WIN32) && !defined(__MINGW32__)
+#elif defined(_WIN32)
#define ABSL_THREAD_IDENTITY_MODE ABSL_THREAD_IDENTITY_MODE_USE_CPP11
#elif defined(__APPLE__) && defined(ABSL_HAVE_THREAD_LOCAL)
#define ABSL_THREAD_IDENTITY_MODE ABSL_THREAD_IDENTITY_MODE_USE_CPP11
diff --git a/abseil-cpp/absl/synchronization/internal/pthread_waiter.h b/abseil-cpp/absl/synchronization/internal/pthread_waiter.h
index 23db76ad442e..eb30b24d0e3b 100644
--- a/abseil-cpp/absl/synchronization/internal/pthread_waiter.h
+++ b/abseil-cpp/absl/synchronization/internal/pthread_waiter.h
@@ -16,7 +16,7 @@
#ifndef ABSL_SYNCHRONIZATION_INTERNAL_PTHREAD_WAITER_H_
#define ABSL_SYNCHRONIZATION_INTERNAL_PTHREAD_WAITER_H_
-#if !defined(_WIN32) && !defined(__MINGW32__)
+#if !defined(_WIN32)
#include <pthread.h>
#include "absl/base/config.h"
@@ -55,6 +55,6 @@ class PthreadWaiter : public WaiterCrtp<PthreadWaiter> {
ABSL_NAMESPACE_END
} // namespace absl
-#endif // !defined(_WIN32) && !defined(__MINGW32__)
+#endif // !defined(_WIN32)
#endif // ABSL_SYNCHRONIZATION_INTERNAL_PTHREAD_WAITER_H_
diff --git a/abseil-cpp/absl/synchronization/internal/win32_waiter.h b/abseil-cpp/absl/synchronization/internal/win32_waiter.h
index fdab264e8cb7..cba1c9d8834f 100644
--- a/abseil-cpp/absl/synchronization/internal/win32_waiter.h
+++ b/abseil-cpp/absl/synchronization/internal/win32_waiter.h
@@ -20,7 +20,7 @@
#include <sdkddkver.h>
#endif
-#if defined(_WIN32) && !defined(__MINGW32__) && \
+#if defined(_WIN32) && \
_WIN32_WINNT >= _WIN32_WINNT_VISTA
#include "absl/base/config.h"
@@ -66,7 +66,7 @@ class Win32Waiter : public WaiterCrtp<Win32Waiter> {
ABSL_NAMESPACE_END
} // namespace absl
-#endif // defined(_WIN32) && !defined(__MINGW32__) &&
+#endif // defined(_WIN32) &&
// _WIN32_WINNT >= _WIN32_WINNT_VISTA
#endif // ABSL_SYNCHRONIZATION_INTERNAL_WIN32_WAITER_H_