Export of internal Abseil changes

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1609589925459c2c0b2a17912c0d65227f709db9 by Abseil Team <absl-team@google.com>:

Clarify the "Potential Mutex deadlock" reason message.

PiperOrigin-RevId: 351367862

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88bf28863db2c2d2d48767c3e4dfab6a48bdff79 by Abseil Team <absl-team@google.com>:

Print CPU number is fault handler.

This CL adds code to print CPU number inside the fault handler.  This is only supported on Linux.  The CPU number is also a hint only.  There is no guarantee that it is indeed the CPU on which a fault happened.

PiperOrigin-RevId: 351238373

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66a9c8e44b5744fec1ca0d7b8db7e1d50772d9a2 by Samuel Benzaquen <sbenza@google.com>:

Add better error message for ODR violations of flags.

PiperOrigin-RevId: 351197423

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6efd1efb341563148dd43255aaa4bf959dfd9554 by Chris Kennelly <ckennelly@google.com>:

Assume bitwise builtins are available on GCC.

These are long-standing builtins but are not consistently detected by
ABSL_HAVE_BUILTIN.

PiperOrigin-RevId: 350814036
GitOrigin-RevId: 1609589925459c2c0b2a17912c0d65227f709db9
Change-Id: Ied3fd2f135187f2c316b403fba45f3bbaea54138

5 files changed, 29 insertions, 13 deletions

diff --git a/absl/flags/flag.h b/absl/flags/flag.h
index a9cb2b79..f09580b0 100644
--- a/absl/flags/flag.h
+++ b/absl/flags/flag.h
@@ -301,13 +301,15 @@ ABSL_NAMESPACE_END
 #if ABSL_FLAGS_STRIP_NAMES
 #define ABSL_FLAG_IMPL_FLAGNAME(txt) ""
 #define ABSL_FLAG_IMPL_FILENAME() ""
-#define ABSL_FLAG_IMPL_REGISTRAR(T, flag) \
-  absl::flags_internal::FlagRegistrar<T, false>(ABSL_FLAG_IMPL_FLAG_PTR(flag))
+#define ABSL_FLAG_IMPL_REGISTRAR(T, flag)                                      \
+  absl::flags_internal::FlagRegistrar<T, false>(ABSL_FLAG_IMPL_FLAG_PTR(flag), \
+                                                nullptr)
 #else
 #define ABSL_FLAG_IMPL_FLAGNAME(txt) txt
 #define ABSL_FLAG_IMPL_FILENAME() __FILE__
-#define ABSL_FLAG_IMPL_REGISTRAR(T, flag) \
-  absl::flags_internal::FlagRegistrar<T, true>(ABSL_FLAG_IMPL_FLAG_PTR(flag))
+#define ABSL_FLAG_IMPL_REGISTRAR(T, flag)                                     \
+  absl::flags_internal::FlagRegistrar<T, true>(ABSL_FLAG_IMPL_FLAG_PTR(flag), \
+                                               __FILE__)
 #endif
 
 // ABSL_FLAG_IMPL macro definition conditional on ABSL_FLAGS_STRIP_HELP
diff --git a/absl/flags/flag_test.cc b/absl/flags/flag_test.cc
index 72507b99..6912b546 100644
--- a/absl/flags/flag_test.cc
+++ b/absl/flags/flag_test.cc
@@ -177,7 +177,7 @@ bool TestConstructionFor(const absl::Flag<T>& f1, absl::Flag<T>& f2) {
   EXPECT_EQ(absl::GetFlagReflectionHandle(f1).Help(), "literal help");
   EXPECT_EQ(absl::GetFlagReflectionHandle(f1).Filename(), "file");
 
-  flags::FlagRegistrar<T, false>(ABSL_FLAG_IMPL_FLAG_PTR(f2))
+  flags::FlagRegistrar<T, false>(ABSL_FLAG_IMPL_FLAG_PTR(f2), nullptr)
       .OnUpdate(TestCallback);
 
   EXPECT_EQ(absl::GetFlagReflectionHandle(f2).Name(), "f2");
diff --git a/absl/flags/internal/flag.h b/absl/flags/internal/flag.h
index 83548143..e6bade0a 100644
--- a/absl/flags/internal/flag.h
+++ b/absl/flags/internal/flag.h
@@ -721,8 +721,9 @@ struct FlagRegistrarEmpty {};
 template <typename T, bool do_register>
 class FlagRegistrar {
  public:
-  explicit FlagRegistrar(Flag<T>& flag) : flag_(flag) {
-    if (do_register) flags_internal::RegisterCommandLineFlag(flag_.impl_);
+  explicit FlagRegistrar(Flag<T>& flag, const char* filename) : flag_(flag) {
+    if (do_register)
+      flags_internal::RegisterCommandLineFlag(flag_.impl_, filename);
   }
 
   FlagRegistrar OnUpdate(FlagCallbackFunc cb) && {
diff --git a/absl/flags/internal/registry.h b/absl/flags/internal/registry.h
index a8d9eb9c..4b68c85f 100644
--- a/absl/flags/internal/registry.h
+++ b/absl/flags/internal/registry.h
@@ -36,7 +36,7 @@ void ForEachFlag(std::function<void(CommandLineFlag&)> visitor);
 
 //-----------------------------------------------------------------------------
 
-bool RegisterCommandLineFlag(CommandLineFlag&);
+bool RegisterCommandLineFlag(CommandLineFlag&, const char* filename);
 
 void FinalizeRegistry();
 
diff --git a/absl/flags/reflection.cc b/absl/flags/reflection.cc
index c976d467..0c761101 100644
--- a/absl/flags/reflection.cc
+++ b/absl/flags/reflection.cc
@@ -50,7 +50,7 @@ class FlagRegistry {
   ~FlagRegistry() = default;
 
   // Store a flag in this registry. Takes ownership of *flag.
-  void RegisterFlag(CommandLineFlag& flag);
+  void RegisterFlag(CommandLineFlag& flag, const char* filename);
 
   void Lock() ABSL_EXCLUSIVE_LOCK_FUNCTION(lock_) { lock_.Lock(); }
   void Unlock() ABSL_UNLOCK_FUNCTION(lock_) { lock_.Unlock(); }
@@ -110,7 +110,20 @@ CommandLineFlag* FlagRegistry::FindFlag(absl::string_view name) {
   return it != flags_.end() ? it->second : nullptr;
 }
 
-void FlagRegistry::RegisterFlag(CommandLineFlag& flag) {
+void FlagRegistry::RegisterFlag(CommandLineFlag& flag, const char* filename) {
+  if (filename != nullptr &&
+      flag.Filename() != GetUsageConfig().normalize_filename(filename)) {
+    flags_internal::ReportUsageError(
+        absl::StrCat(
+            "Inconsistency between flag object and registration for flag '",
+            flag.Name(),
+            "', likely due to duplicate flags or an ODR violation. Relevant "
+            "files: ",
+            flag.Filename(), " and ", filename),
+        true);
+    std::exit(1);
+  }
+
   FlagRegistryLock registry_lock(*this);
 
   std::pair<FlagIterator, bool> ins =
@@ -175,8 +188,8 @@ void ForEachFlag(std::function<void(CommandLineFlag&)> visitor) {
 
 // --------------------------------------------------------------------
 
-bool RegisterCommandLineFlag(CommandLineFlag& flag) {
-  FlagRegistry::GlobalRegistry().RegisterFlag(flag);
+bool RegisterCommandLineFlag(CommandLineFlag& flag, const char* filename) {
+  FlagRegistry::GlobalRegistry().RegisterFlag(flag, filename);
   return true;
 }
 
@@ -266,7 +279,7 @@ void Retire(const char* name, FlagFastTypeId type_id, char* buf) {
   static_assert(alignof(RetiredFlagObj) == kRetiredFlagObjAlignment, "");
   auto* flag = ::new (static_cast<void*>(buf))
       flags_internal::RetiredFlagObj(name, type_id);
-  FlagRegistry::GlobalRegistry().RegisterFlag(*flag);
+  FlagRegistry::GlobalRegistry().RegisterFlag(*flag, nullptr);
 }
 
 // --------------------------------------------------------------------