Export of internal Abseil changes

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8ae3cb636b81b6498ef30fbe59cc102a4098cad2 by Tom Manshreck <shreck@google.com>:

Upgrade absl::StatusOr<T> docs to Abseil standards

PiperOrigin-RevId: 329975341

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7c7baf586c7380497a751f1a186a4ef0e650161a by Tom Manshreck <shreck@google.com>:

Update absl::Status to Abseil documentation standards

PiperOrigin-RevId: 329942967

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6710d022ba987dbae7a5d83045a6697afeb972c4 by Derek Mauro <dmauro@google.com>:

Internal change

PiperOrigin-RevId: 329775111

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fd182dc699e18522ef16d269731c57669c5487d2 by Abseil Team <absl-team@google.com>:

Google-internal change.

PiperOrigin-RevId: 329737362

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c0df5e27ffb48d9c784e7019267580fcb4a3f92e by Xiaoyi Zhang <zhangxy@google.com>:

Remove obsolete `static_assert`.

PiperOrigin-RevId: 329727604
GitOrigin-RevId: 8ae3cb636b81b6498ef30fbe59cc102a4098cad2
Change-Id: Ic9dede0ab97f799e7f4093fae75ae0ec6cc21437

2 files changed, 25 insertions, 21 deletions

diff --git a/absl/base/internal/strerror.cc b/absl/base/internal/strerror.cc
index af181513..d66ba120 100644
--- a/absl/base/internal/strerror.cc
+++ b/absl/base/internal/strerror.cc
@@ -14,6 +14,7 @@
 
 #include "absl/base/internal/strerror.h"
 
+#include <array>
 #include <cerrno>
 #include <cstddef>
 #include <cstdio>
@@ -21,13 +22,13 @@
 #include <string>
 #include <type_traits>
 
-#include "absl/base/attributes.h"
 #include "absl/base/internal/errno_saver.h"
 
 namespace absl {
 ABSL_NAMESPACE_BEGIN
 namespace base_internal {
 namespace {
+
 const char* StrErrorAdaptor(int errnum, char* buf, size_t buflen) {
 #if defined(_WIN32)
   int rc = strerror_s(buf, buflen, errnum);
@@ -35,15 +36,6 @@ const char* StrErrorAdaptor(int errnum, char* buf, size_t buflen) {
   if (rc == 0 && strncmp(buf, "Unknown error", buflen) == 0) *buf = '\0';
   return buf;
 #else
-#if defined(__GLIBC__) || defined(__APPLE__)
-  // Use the BSD sys_errlist API provided by GNU glibc and others to
-  // avoid any need to copy the message into the local buffer first.
-  if (0 <= errnum && errnum < sys_nerr) {
-    if (const char* p = sys_errlist[errnum]) {
-      return p;
-    }
-  }
-#endif
   // The type of `ret` is platform-specific; both of these branches must compile
   // either way but only one will execute on any given platform:
   auto ret = strerror_r(errnum, buf, buflen);
@@ -57,9 +49,8 @@ const char* StrErrorAdaptor(int errnum, char* buf, size_t buflen) {
   }
 #endif
 }
-}  // namespace
 
-std::string StrError(int errnum) {
+std::string StrErrorInternal(int errnum) {
   absl::base_internal::ErrnoSaver errno_saver;
   char buf[100];
   const char* str = StrErrorAdaptor(errnum, buf, sizeof buf);
@@ -70,6 +61,28 @@ std::string StrError(int errnum) {
   return str;
 }
 
+// kSysNerr is the number of errors from a recent glibc. `StrError()` falls back
+// to `StrErrorAdaptor()` if the value is larger than this.
+constexpr int kSysNerr = 135;
+
+std::array<std::string, kSysNerr>* NewStrErrorTable() {
+  auto* table = new std::array<std::string, kSysNerr>;
+  for (int i = 0; i < static_cast<int>(table->size()); ++i) {
+    (*table)[i] = StrErrorInternal(i);
+  }
+  return table;
+}
+
+}  // namespace
+
+std::string StrError(int errnum) {
+  static const auto* table = NewStrErrorTable();
+  if (errnum >= 0 && errnum < static_cast<int>(table->size())) {
+    return (*table)[errnum];
+  }
+  return StrErrorInternal(errnum);
+}
+
 }  // namespace base_internal
 ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/base/internal/strerror_benchmark.cc b/absl/base/internal/strerror_benchmark.cc
index d8ca86b9..c9ab14a8 100644
--- a/absl/base/internal/strerror_benchmark.cc
+++ b/absl/base/internal/strerror_benchmark.cc
@@ -20,15 +20,6 @@
 #include "benchmark/benchmark.h"
 
 namespace {
-#if defined(__GLIBC__) || defined(__APPLE__)
-void BM_SysErrList(benchmark::State& state) {
-  for (auto _ : state) {
-    benchmark::DoNotOptimize(std::string(sys_errlist[ERANGE]));
-  }
-}
-BENCHMARK(BM_SysErrList);
-#endif
-
 void BM_AbslStrError(benchmark::State& state) {
   for (auto _ : state) {
     benchmark::DoNotOptimize(absl::base_internal::StrError(ERANGE));