Export of internal Abseil changes

--
a85860e450815776c8753f34348f41ab0e918d36 by Gennadiy Rozental <rogeeff@google.com>:

Rename ComamndLineFlag's interface SetFromString as ParseFrom.

This is the name approved by C++ API review.

PiperOrigin-RevId: 301543521

--
28f31bae2a136854fd89f0a32f281d12a40f702c by Abseil Team <absl-team@google.com>:

Internal change

PiperOrigin-RevId: 301524919

--
a68da3d6fbbca4c5f41a20e99ed72bb1c5dd1165 by Abseil Team <absl-team@google.com>:

Introduce absl::base_internal::StrError, a portability wrapper around the various thread-safe alternatives to C89's strerror.

PiperOrigin-RevId: 301513962

--
92ccac3b6eb18cb41cddedbfdab53b9ad481505d by Andy Getzendanner <durandal@google.com>:

Introduce absl::base_internal::StrError, a portability wrapper around the various thread-safe alternatives to C89's strerror.

PiperOrigin-RevId: 301493389

--
8e196def47c250941202840d6a1de686d681cd3e by Abseil Team <absl-team@google.com>:

Internal change

PiperOrigin-RevId: 301363394

--
dd1dcffa6c47675ba4d198730a301bd408142298 by Gennadiy Rozental <rogeeff@google.com>:

Add validation for size of void* to match the size of free function pointer.

PiperOrigin-RevId: 301341331
GitOrigin-RevId: a85860e450815776c8753f34348f41ab0e918d36
Change-Id: I27c9d1365d3c9b4328d1587ab3ac38e2d09a6ec2

14 files changed, 377 insertions, 52 deletions

diff --git a/absl/base/BUILD.bazel b/absl/base/BUILD.bazel
index bae79427..24dab791 100644
--- a/absl/base/BUILD.bazel
+++ b/absl/base/BUILD.bazel
@@ -307,6 +307,7 @@ cc_test(
     linkopts = ABSL_DEFAULT_LINKOPTS,
     deps = [
         ":errno_saver",
+        ":strerror",
         "@com_google_googletest//:gtest_main",
     ],
 )
@@ -451,6 +452,7 @@ cc_binary(
     testonly = 1,
     copts = ABSL_DEFAULT_COPTS,
     linkopts = ABSL_DEFAULT_LINKOPTS,
+    tags = ["benchmark"],
     visibility = ["//visibility:private"],
     deps = [
         ":spinlock_benchmark_common",
@@ -705,3 +707,46 @@ cc_test(
         "@com_google_googletest//:gtest_main",
     ],
 )
+
+cc_library(
+    name = "strerror",
+    srcs = ["internal/strerror.cc"],
+    hdrs = ["internal/strerror.h"],
+    copts = ABSL_DEFAULT_COPTS,
+    linkopts = ABSL_DEFAULT_LINKOPTS,
+    visibility = [
+        "//absl:__subpackages__",
+    ],
+    deps = [
+        ":config",
+        ":core_headers",
+        ":errno_saver",
+    ],
+)
+
+cc_test(
+    name = "strerror_test",
+    size = "small",
+    srcs = ["internal/strerror_test.cc"],
+    copts = ABSL_TEST_COPTS,
+    linkopts = ABSL_DEFAULT_LINKOPTS,
+    deps = [
+        ":strerror",
+        "//absl/strings",
+        "@com_google_googletest//:gtest_main",
+    ],
+)
+
+cc_binary(
+    name = "strerror_benchmark",
+    testonly = 1,
+    srcs = ["internal/strerror_benchmark.cc"],
+    copts = ABSL_TEST_COPTS,
+    linkopts = ABSL_DEFAULT_LINKOPTS,
+    tags = ["benchmark"],
+    visibility = ["//visibility:private"],
+    deps = [
+        ":strerror",
+        "@com_github_google_benchmark//:benchmark_main",
+    ],
+)
diff --git a/absl/base/CMakeLists.txt b/absl/base/CMakeLists.txt
index 14c52eab..4230d2e7 100644
--- a/absl/base/CMakeLists.txt
+++ b/absl/base/CMakeLists.txt
@@ -326,6 +326,7 @@ absl_cc_test(
     ${ABSL_TEST_COPTS}
   DEPS
     absl::errno_saver
+    absl::strerror
     gmock
     gtest_main
 )
@@ -642,3 +643,34 @@ absl_cc_test(
     gmock
     gtest_main
 )
+
+absl_cc_library(
+  NAME
+    strerror
+  SRCS
+    "internal/strerror.cc"
+  HDRS
+    "internal/strerror.h"
+  COPTS
+    ${ABSL_DEFAULT_COPTS}
+  LINKOPTS
+    ${ABSL_DEFAULT_LINKOPTS}
+  DEPS
+    absl::config
+    absl::core_headers
+    absl::errno_saver
+)
+
+absl_cc_test(
+  NAME
+    strerror_test
+  SRCS
+    "internal/strerror_test.cc"
+  COPTS
+    ${ABSL_TEST_COPTS}
+  DEPS
+    absl::strerror
+    absl::strings
+    gmock
+    gtest_main
+)
diff --git a/absl/base/internal/errno_saver_test.cc b/absl/base/internal/errno_saver_test.cc
index b845e2dd..e9b742c5 100644
--- a/absl/base/internal/errno_saver_test.cc
+++ b/absl/base/internal/errno_saver_test.cc
@@ -18,6 +18,7 @@
 
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
+#include "absl/base/internal/strerror.h"
 
 namespace {
 using ::testing::Eq;
@@ -26,7 +27,7 @@ struct ErrnoPrinter {
   int no;
 };
 std::ostream &operator<<(std::ostream &os, ErrnoPrinter ep) {
-  return os << strerror(ep.no) << " [" << ep.no << "]";
+  return os << absl::base_internal::StrError(ep.no) << " [" << ep.no << "]";
 }
 bool operator==(ErrnoPrinter one, ErrnoPrinter two) { return one.no == two.no; }
 
diff --git a/absl/base/internal/strerror.cc b/absl/base/internal/strerror.cc
new file mode 100644
index 00000000..af181513
--- /dev/null
+++ b/absl/base/internal/strerror.cc
@@ -0,0 +1,75 @@
+// Copyright 2020 The Abseil Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "absl/base/internal/strerror.h"
+
+#include <cerrno>
+#include <cstddef>
+#include <cstdio>
+#include <cstring>
+#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);
+  buf[buflen - 1] = '\0';  // guarantee NUL termination
+  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);
+  if (std::is_same<decltype(ret), int>::value) {
+    // XSI `strerror_r`; `ret` is `int`:
+    if (ret) *buf = '\0';
+    return buf;
+  } else {
+    // GNU `strerror_r`; `ret` is `char *`:
+    return reinterpret_cast<const char*>(ret);
+  }
+#endif
+}
+}  // namespace
+
+std::string StrError(int errnum) {
+  absl::base_internal::ErrnoSaver errno_saver;
+  char buf[100];
+  const char* str = StrErrorAdaptor(errnum, buf, sizeof buf);
+  if (*str == '\0') {
+    snprintf(buf, sizeof buf, "Unknown error %d", errnum);
+    str = buf;
+  }
+  return str;
+}
+
+}  // namespace base_internal
+ABSL_NAMESPACE_END
+}  // namespace absl
diff --git a/absl/base/internal/strerror.h b/absl/base/internal/strerror.h
new file mode 100644
index 00000000..35009736
--- /dev/null
+++ b/absl/base/internal/strerror.h
@@ -0,0 +1,39 @@
+// Copyright 2020 The Abseil Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef ABSL_BASE_INTERNAL_STRERROR_H_
+#define ABSL_BASE_INTERNAL_STRERROR_H_
+
+#include <string>
+
+#include "absl/base/config.h"
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+namespace base_internal {
+
+// A portable and thread-safe alternative to C89's `strerror`.
+//
+// The C89 specification of `strerror` is not suitable for use in a
+// multi-threaded application as the returned string may be changed by calls to
+// `strerror` from another thread.  The many non-stdlib alternatives differ
+// enough in their names, availability, and semantics to justify this wrapper
+// around them.  `errno` will not be modified by a call to `absl::StrError`.
+std::string StrError(int errnum);
+
+}  // namespace base_internal
+ABSL_NAMESPACE_END
+}  // namespace absl
+
+#endif  // ABSL_BASE_INTERNAL_STRERROR_H_
diff --git a/absl/base/internal/strerror_benchmark.cc b/absl/base/internal/strerror_benchmark.cc
new file mode 100644
index 00000000..d8ca86b9
--- /dev/null
+++ b/absl/base/internal/strerror_benchmark.cc
@@ -0,0 +1,38 @@
+// Copyright 2020 The Abseil Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include <cerrno>
+#include <cstdio>
+#include <string>
+
+#include "absl/base/internal/strerror.h"
+#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));
+  }
+}
+BENCHMARK(BM_AbslStrError);
+}  // namespace
diff --git a/absl/base/internal/strerror_test.cc b/absl/base/internal/strerror_test.cc
new file mode 100644
index 00000000..a53da97f
--- /dev/null
+++ b/absl/base/internal/strerror_test.cc
@@ -0,0 +1,86 @@
+// Copyright 2020 The Abseil Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "absl/base/internal/strerror.h"
+
+#include <atomic>
+#include <cerrno>
+#include <cstdio>
+#include <cstring>
+#include <string>
+#include <thread>  // NOLINT(build/c++11)
+#include <vector>
+
+#include "gmock/gmock.h"
+#include "gtest/gtest.h"
+#include "absl/strings/match.h"
+
+namespace {
+using ::testing::AnyOf;
+using ::testing::Eq;
+
+TEST(StrErrorTest, ValidErrorCode) {
+  errno = ERANGE;
+  EXPECT_THAT(absl::base_internal::StrError(EDOM), Eq(strerror(EDOM)));
+  EXPECT_THAT(errno, Eq(ERANGE));
+}
+
+TEST(StrErrorTest, InvalidErrorCode) {
+  errno = ERANGE;
+  EXPECT_THAT(absl::base_internal::StrError(-1),
+              AnyOf(Eq("No error information"), Eq("Unknown error -1")));
+  EXPECT_THAT(errno, Eq(ERANGE));
+}
+
+TEST(StrErrorTest, MultipleThreads) {
+  // In this test, we will start up 2 threads and have each one call
+  // StrError 1000 times, each time with a different errnum.  We
+  // expect that StrError(errnum) will return a string equal to the
+  // one returned by strerror(errnum), if the code is known.  Since
+  // strerror is known to be thread-hostile, collect all the expected
+  // strings up front.
+  const int kNumCodes = 1000;
+  std::vector<std::string> expected_strings(kNumCodes);
+  for (int i = 0; i < kNumCodes; ++i) {
+    expected_strings[i] = strerror(i);
+  }
+
+  std::atomic_int counter(0);
+  auto thread_fun = [&]() {
+    for (int i = 0; i < kNumCodes; ++i) {
+      ++counter;
+      errno = ERANGE;
+      const std::string value = absl::base_internal::StrError(i);
+      // Only the GNU implementation is guaranteed to provide the
+      // string "Unknown error nnn". POSIX doesn't say anything.
+      if (!absl::StartsWith(value, "Unknown error ")) {
+        EXPECT_THAT(absl::base_internal::StrError(i), Eq(expected_strings[i]));
+      }
+      EXPECT_THAT(errno, Eq(ERANGE));
+    }
+  };
+
+  const int kNumThreads = 100;
+  std::vector<std::thread> threads;
+  for (int i = 0; i < kNumThreads; ++i) {
+    threads.push_back(std::thread(thread_fun));
+  }
+  for (auto& thread : threads) {
+    thread.join();
+  }
+
+  EXPECT_THAT(counter, Eq(kNumThreads * kNumCodes));
+}
+
+}  // namespace
diff --git a/absl/flags/internal/commandlineflag.h b/absl/flags/internal/commandlineflag.h
index 9a740d57..338a1228 100644
--- a/absl/flags/internal/commandlineflag.h
+++ b/absl/flags/internal/commandlineflag.h
@@ -65,7 +65,7 @@ enum FlagSettingMode {
   SET_FLAGS_DEFAULT
 };
 
-// Options that control SetFromString: Source of a value.
+// Options that control ParseFrom: Source of a value.
 enum ValueSource {
   // Flag is being set by value specified on a command line.
   kCommandLine,
@@ -171,10 +171,10 @@ class CommandLineFlag {
   //  * Update the flag's default value
   //  * Update the current flag value if it was never set before
   // The mode is selected based on `set_mode` parameter.
-  virtual bool SetFromString(absl::string_view value,
-                             flags_internal::FlagSettingMode set_mode,
-                             flags_internal::ValueSource source,
-                             std::string* error) = 0;
+  virtual bool ParseFrom(absl::string_view value,
+                         flags_internal::FlagSettingMode set_mode,
+                         flags_internal::ValueSource source,
+                         std::string* error) = 0;
 
   // Checks that flags default value can be converted to string and back to the
   // flag's value type.
diff --git a/absl/flags/internal/commandlineflag_test.cc b/absl/flags/internal/commandlineflag_test.cc
index 0e8bc313..c1142b7c 100644
--- a/absl/flags/internal/commandlineflag_test.cc
+++ b/absl/flags/internal/commandlineflag_test.cc
@@ -119,99 +119,99 @@ TEST_F(CommandLineFlagTest, TestValueAccessMethods) {
 
 // --------------------------------------------------------------------
 
-TEST_F(CommandLineFlagTest, TestSetFromStringCurrentValue) {
+TEST_F(CommandLineFlagTest, TestParseFromCurrentValue) {
   std::string err;
 
   auto* flag_01 = flags::FindCommandLineFlag("int_flag");
   EXPECT_FALSE(flag_01->IsSpecifiedOnCommandLine());
 
-  EXPECT_TRUE(flag_01->SetFromString("11", flags::SET_FLAGS_VALUE,
-                                     flags::kProgrammaticChange, &err));
+  EXPECT_TRUE(flag_01->ParseFrom("11", flags::SET_FLAGS_VALUE,
+                                 flags::kProgrammaticChange, &err));
   EXPECT_EQ(absl::GetFlag(FLAGS_int_flag), 11);
   EXPECT_FALSE(flag_01->IsSpecifiedOnCommandLine());
 
-  EXPECT_TRUE(flag_01->SetFromString("-123", flags::SET_FLAGS_VALUE,
-                                     flags::kProgrammaticChange, &err));
+  EXPECT_TRUE(flag_01->ParseFrom("-123", flags::SET_FLAGS_VALUE,
+                                 flags::kProgrammaticChange, &err));
   EXPECT_EQ(absl::GetFlag(FLAGS_int_flag), -123);
   EXPECT_FALSE(flag_01->IsSpecifiedOnCommandLine());
 
-  EXPECT_TRUE(!flag_01->SetFromString("xyz", flags::SET_FLAGS_VALUE,
-                                      flags::kProgrammaticChange, &err));
+  EXPECT_TRUE(!flag_01->ParseFrom("xyz", flags::SET_FLAGS_VALUE,
+                                  flags::kProgrammaticChange, &err));
   EXPECT_EQ(absl::GetFlag(FLAGS_int_flag), -123);
   EXPECT_EQ(err, "Illegal value 'xyz' specified for flag 'int_flag'");
   EXPECT_FALSE(flag_01->IsSpecifiedOnCommandLine());
 
-  EXPECT_TRUE(!flag_01->SetFromString("A1", flags::SET_FLAGS_VALUE,
-                                      flags::kProgrammaticChange, &err));
+  EXPECT_TRUE(!flag_01->ParseFrom("A1", flags::SET_FLAGS_VALUE,
+                                  flags::kProgrammaticChange, &err));
   EXPECT_EQ(absl::GetFlag(FLAGS_int_flag), -123);
   EXPECT_EQ(err, "Illegal value 'A1' specified for flag 'int_flag'");
   EXPECT_FALSE(flag_01->IsSpecifiedOnCommandLine());
 
-  EXPECT_TRUE(flag_01->SetFromString("0x10", flags::SET_FLAGS_VALUE,
-                                     flags::kProgrammaticChange, &err));
+  EXPECT_TRUE(flag_01->ParseFrom("0x10", flags::SET_FLAGS_VALUE,
+                                 flags::kProgrammaticChange, &err));
   EXPECT_EQ(absl::GetFlag(FLAGS_int_flag), 16);
   EXPECT_FALSE(flag_01->IsSpecifiedOnCommandLine());
 
-  EXPECT_TRUE(flag_01->SetFromString("011", flags::SET_FLAGS_VALUE,
-                                     flags::kCommandLine, &err));
+  EXPECT_TRUE(flag_01->ParseFrom("011", flags::SET_FLAGS_VALUE,
+                                 flags::kCommandLine, &err));
   EXPECT_EQ(absl::GetFlag(FLAGS_int_flag), 11);
   EXPECT_TRUE(flag_01->IsSpecifiedOnCommandLine());
 
-  EXPECT_TRUE(!flag_01->SetFromString("", flags::SET_FLAGS_VALUE,
-                                      flags::kProgrammaticChange, &err));
+  EXPECT_TRUE(!flag_01->ParseFrom("", flags::SET_FLAGS_VALUE,
+                                  flags::kProgrammaticChange, &err));
   EXPECT_EQ(err, "Illegal value '' specified for flag 'int_flag'");
 
   auto* flag_02 = flags::FindCommandLineFlag("string_flag");
-  EXPECT_TRUE(flag_02->SetFromString("xyz", flags::SET_FLAGS_VALUE,
-                                     flags::kProgrammaticChange, &err));
+  EXPECT_TRUE(flag_02->ParseFrom("xyz", flags::SET_FLAGS_VALUE,
+                                 flags::kProgrammaticChange, &err));
   EXPECT_EQ(absl::GetFlag(FLAGS_string_flag), "xyz");
 
-  EXPECT_TRUE(flag_02->SetFromString("", flags::SET_FLAGS_VALUE,
-                                     flags::kProgrammaticChange, &err));
+  EXPECT_TRUE(flag_02->ParseFrom("", flags::SET_FLAGS_VALUE,
+                                 flags::kProgrammaticChange, &err));
   EXPECT_EQ(absl::GetFlag(FLAGS_string_flag), "");
 }
 
 // --------------------------------------------------------------------
 
-TEST_F(CommandLineFlagTest, TestSetFromStringDefaultValue) {
+TEST_F(CommandLineFlagTest, TestParseFromDefaultValue) {
   std::string err;
 
   auto* flag_01 = flags::FindCommandLineFlag("int_flag");
 
-  EXPECT_TRUE(flag_01->SetFromString("111", flags::SET_FLAGS_DEFAULT,
-                                     flags::kProgrammaticChange, &err));
+  EXPECT_TRUE(flag_01->ParseFrom("111", flags::SET_FLAGS_DEFAULT,
+                                 flags::kProgrammaticChange, &err));
   EXPECT_EQ(flag_01->DefaultValue(), "111");
 
   auto* flag_02 = flags::FindCommandLineFlag("string_flag");
 
-  EXPECT_TRUE(flag_02->SetFromString("abc", flags::SET_FLAGS_DEFAULT,
-                                     flags::kProgrammaticChange, &err));
+  EXPECT_TRUE(flag_02->ParseFrom("abc", flags::SET_FLAGS_DEFAULT,
+                                 flags::kProgrammaticChange, &err));
   EXPECT_EQ(flag_02->DefaultValue(), "abc");
 }
 
 // --------------------------------------------------------------------
 
-TEST_F(CommandLineFlagTest, TestSetFromStringIfDefault) {
+TEST_F(CommandLineFlagTest, TestParseFromIfDefault) {
   std::string err;
 
   auto* flag_01 = flags::FindCommandLineFlag("int_flag");
 
-  EXPECT_TRUE(flag_01->SetFromString("22", flags::SET_FLAG_IF_DEFAULT,
-                                     flags::kProgrammaticChange, &err))
+  EXPECT_TRUE(flag_01->ParseFrom("22", flags::SET_FLAG_IF_DEFAULT,
+                                 flags::kProgrammaticChange, &err))
       << err;
   EXPECT_EQ(absl::GetFlag(FLAGS_int_flag), 22);
 
-  EXPECT_TRUE(flag_01->SetFromString("33", flags::SET_FLAG_IF_DEFAULT,
-                                     flags::kProgrammaticChange, &err));
+  EXPECT_TRUE(flag_01->ParseFrom("33", flags::SET_FLAG_IF_DEFAULT,
+                                 flags::kProgrammaticChange, &err));
   EXPECT_EQ(absl::GetFlag(FLAGS_int_flag), 22);
   // EXPECT_EQ(err, "ERROR: int_flag is already set to 22");
 
   // Reset back to default value
-  EXPECT_TRUE(flag_01->SetFromString("201", flags::SET_FLAGS_VALUE,
-                                     flags::kProgrammaticChange, &err));
+  EXPECT_TRUE(flag_01->ParseFrom("201", flags::SET_FLAGS_VALUE,
+                                 flags::kProgrammaticChange, &err));
 
-  EXPECT_TRUE(flag_01->SetFromString("33", flags::SET_FLAG_IF_DEFAULT,
-                                     flags::kProgrammaticChange, &err));
+  EXPECT_TRUE(flag_01->ParseFrom("33", flags::SET_FLAG_IF_DEFAULT,
+                                 flags::kProgrammaticChange, &err));
   EXPECT_EQ(absl::GetFlag(FLAGS_int_flag), 201);
   // EXPECT_EQ(err, "ERROR: int_flag is already set to 201");
 }
diff --git a/absl/flags/internal/flag.cc b/absl/flags/internal/flag.cc
index a12fe7c5..a45e883e 100644
--- a/absl/flags/internal/flag.cc
+++ b/absl/flags/internal/flag.cc
@@ -338,8 +338,8 @@ void FlagImpl::Write(const void* src) {
 //  * Update the flag's default value
 //  * Update the current flag value if it was never set before
 // The mode is selected based on 'set_mode' parameter.
-bool FlagImpl::SetFromString(absl::string_view value, FlagSettingMode set_mode,
-                             ValueSource source, std::string* err) {
+bool FlagImpl::ParseFrom(absl::string_view value, FlagSettingMode set_mode,
+                         ValueSource source, std::string* err) {
   absl::MutexLock l(DataGuard());
 
   switch (set_mode) {
diff --git a/absl/flags/internal/flag.h b/absl/flags/internal/flag.h
index 0ef0ee74..2c4aba68 100644
--- a/absl/flags/internal/flag.h
+++ b/absl/flags/internal/flag.h
@@ -76,8 +76,17 @@ void* FlagOps(FlagOp op, const void* v1, void* v2, void* v3) {
       return nullptr;
     case FlagOp::kSizeof:
       return reinterpret_cast<void*>(sizeof(T));
-    case FlagOp::kStaticTypeId:
-      return reinterpret_cast<void*>(&FlagStaticTypeIdGen<T>);
+    case FlagOp::kStaticTypeId: {
+      auto* static_id = &FlagStaticTypeIdGen<T>;
+
+      // Cast from function pointer to void* is not portable.
+      // We don't have an easy way to work around this, but it works fine
+      // on all the platforms we test and as long as size of pointers match
+      // we should be fine to do reinterpret cast.
+      static_assert(sizeof(void*) == sizeof(static_id),
+                    "Flag's static type id does not work on this platform");
+      return reinterpret_cast<void*>(static_id);
+    }
     case FlagOp::kParse: {
       // Initialize the temporary instance of type T based on current value in
       // destination (which is going to be flag's default value).
@@ -395,8 +404,8 @@ class FlagImpl {
 
   // Mutating access methods
   void Write(const void* src) ABSL_LOCKS_EXCLUDED(*DataGuard());
-  bool SetFromString(absl::string_view value, FlagSettingMode set_mode,
-                     ValueSource source, std::string* err)
+  bool ParseFrom(absl::string_view value, FlagSettingMode set_mode,
+                 ValueSource source, std::string* err)
       ABSL_LOCKS_EXCLUDED(*DataGuard());
 
   // Interfaces to operate on callbacks.
@@ -586,9 +595,9 @@ class Flag final : public flags_internal::CommandLineFlag {
     return impl_.RestoreState(&flag_state.cur_value_, flag_state.modified_,
                               flag_state.on_command_line_, flag_state.counter_);
   }
-  bool SetFromString(absl::string_view value, FlagSettingMode set_mode,
-                     ValueSource source, std::string* error) override {
-    return impl_.SetFromString(value, set_mode, source, error);
+  bool ParseFrom(absl::string_view value, FlagSettingMode set_mode,
+                 ValueSource source, std::string* error) override {
+    return impl_.ParseFrom(value, set_mode, source, error);
   }
   void CheckDefaultValueParsingRoundtrip() const override {
     impl_.CheckDefaultValueParsingRoundtrip();
diff --git a/absl/flags/internal/registry.cc b/absl/flags/internal/registry.cc
index e434a859..9ed91214 100644
--- a/absl/flags/internal/registry.cc
+++ b/absl/flags/internal/registry.cc
@@ -306,8 +306,8 @@ class RetiredFlagObj final : public flags_internal::CommandLineFlag {
     return nullptr;
   }
 
-  bool SetFromString(absl::string_view, flags_internal::FlagSettingMode,
-                     flags_internal::ValueSource, std::string*) override {
+  bool ParseFrom(absl::string_view, flags_internal::FlagSettingMode,
+                 flags_internal::ValueSource, std::string*) override {
     return false;
   }
 
diff --git a/absl/flags/internal/type_erased.cc b/absl/flags/internal/type_erased.cc
index 490bc4eb..75b4cdf8 100644
--- a/absl/flags/internal/type_erased.cc
+++ b/absl/flags/internal/type_erased.cc
@@ -56,7 +56,7 @@ bool SetCommandLineOptionWithMode(absl::string_view name,
   if (!flag || flag->IsRetired()) return false;
 
   std::string error;
-  if (!flag->SetFromString(value, set_mode, kProgrammaticChange, &error)) {
+  if (!flag->ParseFrom(value, set_mode, kProgrammaticChange, &error)) {
     // Errors here are all of the form: the provided name was a recognized
     // flag, but the value was invalid (bad type, or validation failed).
     flags_internal::ReportUsageError(error, false);
diff --git a/absl/flags/parse.cc b/absl/flags/parse.cc
index af5fb12d..b60b36f6 100644
--- a/absl/flags/parse.cc
+++ b/absl/flags/parse.cc
@@ -696,7 +696,7 @@ std::vector<char*> ParseCommandLineImpl(int argc, char* argv[],
     if (flag->IsRetired()) continue;
 
     std::string error;
-    if (!flag->SetFromString(value, SET_FLAGS_VALUE, kCommandLine, &error)) {
+    if (!flag->ParseFrom(value, SET_FLAGS_VALUE, kCommandLine, &error)) {
       flags_internal::ReportUsageError(error, true);
       success = false;
     }