Export of internal Abseil changes

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620668e56950d7cfc39db2cd321adf265199ad77 by Abseil Team <absl-team@google.com>:

absl::random compiles (at least for some cases) with -Wconversion -Wsign-compare

PiperOrigin-RevId: 419595521

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746651e5fbcab6080d25c4eef8617fc289a448f6 by Abseil Team <absl-team@google.com>:

Annotate FlagImpl storage buffer

Flag type can contain legit uninitialized bits, e.g. padding.
When the code calls bit_cast as int64_t, it will contain those bits as well.
Then when we pass the int into the store it's UB for C++ and will be
reported by the new msan.

PiperOrigin-RevId: 418666492
GitOrigin-RevId: 620668e56950d7cfc39db2cd321adf265199ad77
Change-Id: Idd1190f5c98a0a13c4019f3d92cec0313822084c

1 files changed, 3 insertions, 0 deletions

diff --git a/absl/flags/internal/flag.cc b/absl/flags/internal/flag.cc
index 7102559e..55892d77 100644
--- a/absl/flags/internal/flag.cc
+++ b/absl/flags/internal/flag.cc
@@ -30,6 +30,7 @@
 #include "absl/base/call_once.h"
 #include "absl/base/casts.h"
 #include "absl/base/config.h"
+#include "absl/base/dynamic_annotations.h"
 #include "absl/base/optimization.h"
 #include "absl/flags/config.h"
 #include "absl/flags/internal/commandlineflag.h"
@@ -160,6 +161,8 @@ void FlagImpl::Init() {
         std::memcpy(buf.data() + Sizeof(op_), &initialized,
                     sizeof(initialized));
       }
+      // Type can contain valid uninitialized bits, e.g. padding.
+      ABSL_ANNOTATE_MEMORY_IS_INITIALIZED(buf.data(), buf.size());
       OneWordValue().store(absl::bit_cast<int64_t>(buf),
                            std::memory_order_release);
       break;