Workaround MSan false positive.

On Linux Kernels >= 5.4 MSan reports a false positive when accessing thread local storage data from loaded libraries.

This was reported on Chromium (which on some build configurations uses absl as a dynamic library). More info here: crbug.com/1414573.

PiperOrigin-RevId: 508645053
Change-Id: I5d5a97e1ee7230cc23f3934a4ec5594b883918b4

absl/container/BUILD.bazel

@@ -622,6 +622,7 @@ cc_library(
         ":hashtablez_sampler",
         ":hashtablez_sampler",
         "//absl/base:config",
         "//absl/base:config",
         "//absl/base:core_headers",
         "//absl/base:core_headers",
+        "//absl/base:dynamic_annotations",
         "//absl/base:endian",
         "//absl/base:endian",
         "//absl/base:prefetch",
         "//absl/base:prefetch",
         "//absl/base:raw_logging_internal",
         "//absl/base:raw_logging_internal",

absl/container/CMakeLists.txt

@@ -706,6 +706,7 @@ absl_cc_library(
     absl::container_common
     absl::container_common
     absl::container_memory
     absl::container_memory
     absl::core_headers
     absl::core_headers
+    absl::dynamic_annotations
     absl::endian
     absl::endian
     absl::hash
     absl::hash
     absl::hash_policy_traits
     absl::hash_policy_traits

absl/container/internal/raw_hash_set.cc

@@ -19,6 +19,7 @@
 #include <cstring>
 #include <cstring>
 
 
 #include "absl/base/config.h"
 #include "absl/base/config.h"
+#include "absl/base/dynamic_annotations.h"
 #include "absl/hash/hash.h"
 #include "absl/hash/hash.h"
 
 
 namespace absl {
 namespace absl {
@@ -44,6 +45,11 @@ constexpr size_t Group::kWidth;
 inline size_t RandomSeed() {
 inline size_t RandomSeed() {
 #ifdef ABSL_HAVE_THREAD_LOCAL
 #ifdef ABSL_HAVE_THREAD_LOCAL
   static thread_local size_t counter = 0;
   static thread_local size_t counter = 0;
+  // On Linux kernels >= 5.4 the MSAN runtime has a false-positive when
+  // accessing thread local storage data from loaded libraries
+  // (https://github.com/google/sanitizers/issues/1265), for this reason counter
+  // needs to be annotated as initialized.
+  ABSL_ANNOTATE_MEMORY_IS_INITIALIZED(&counter, sizeof(size_t));
   size_t value = ++counter;
   size_t value = ++counter;
 #else   // ABSL_HAVE_THREAD_LOCAL
 #else   // ABSL_HAVE_THREAD_LOCAL
   static std::atomic<size_t> counter(0);
   static std::atomic<size_t> counter(0);