Export of internal Abseil changes.

--
78293ba4eb4981991ae7e6edd25eb9245fcd7515 by Andy Soffer <asoffer@google.com>:

internal changes

PiperOrigin-RevId: 247073879

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7bd97e3aad0c3012b89a39392a6ad3f254e9f3c3 by Derek Mauro <dmauro@google.com>:

Release commandline flags

PiperOrigin-RevId: 247065920

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2a991849fd7b140a43b073076d194b61533fd199 by Tom Manshreck <shreck@google.com>:

Add documentation for built-in usage flags

PiperOrigin-RevId: 247058863

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14157b0de45841706bbd631284191fd94c313db9 by Derek Mauro <dmauro@google.com>:

Internal change

PiperOrigin-RevId: 247058292

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ed67e0a80468596e30540b367727a250fa415b68 by Abseil Team <absl-team@google.com>:

Internal Change.

PiperOrigin-RevId: 246828655

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e1bc8c2aa3f90b3d56c55c5b7244e718c919265d by Abseil Team <absl-team@google.com>:

Internal change

PiperOrigin-RevId: 246822325

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907a68f287199f749cb9bdb48571b50bc34731e1 by Eric Fiselier <ericwf@google.com>:

Accept vector<bool>::reference in StrCat and friends.

Converting vector<bool>::reference to alphanum requires
two user defined conversions, which isn't allowed.
In order to accept this, we need a special constructor that
is only enabled for the bool proxy types.

PiperOrigin-RevId: 246626732

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fe4295fa95cc65dee8c881ba12dd8f516e68c40d by Abseil Team <absl-team@google.com>:

Clarify the proper way to define AbslHashValue, and fix confusing indentation.

PiperOrigin-RevId: 246406528

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d7174681a72d4a25c8fd2b4d9f515a0763eff87c by Gennadiy Rozental <rogeeff@google.com>:

Internal change

PiperOrigin-RevId: 246358214

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a7fdc19683cf1a5885e9e1af52fcdb2db1eda53b by Abseil Team <absl-team@google.com>:

Fix sample template instantiation.

PiperOrigin-RevId: 246354617

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29a23c6835f872948d09b24d890385bf195bc995 by Abseil Team <absl-team@google.com>:

Fix incorrectly copy-pasted static_assert in absl::optional::value_or

The static_assert for a move-constructible type previously said the type must be copy-constructible.

PiperOrigin-RevId: 246313827

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41884d5872d4ea2c67875b00144b8c8a5859a295 by Greg Falcon <gfalcon@google.com>:

Import of CCTZ from GitHub.

PiperOrigin-RevId: 245418790

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7f90a7f94cdd5e21232c749efe952a750b5c43a2 by Abseil Team <absl-team@google.com>:

Internal change

PiperOrigin-RevId: 245412658

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730a329cf047d54b46971fce1781edd857208c2a by Greg Falcon <gfalcon@google.com>:

internal change

PiperOrigin-RevId: 245293234

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cf0216be6338200cbb18167d3f3b2e98e372be77 by Greg Falcon <gfalcon@google.com>:

Internal change

PiperOrigin-RevId: 245288164
GitOrigin-RevId: 78293ba4eb4981991ae7e6edd25eb9245fcd7515
Change-Id: I5ea9a852c36c722bae2d6be65fb7f72473d94ab6

1 files changed, 152 insertions, 0 deletions

diff --git a/absl/flags/usage_config.cc b/absl/flags/usage_config.cc
new file mode 100644
index 000000000000..d34ecfc82c7b
--- /dev/null
+++ b/absl/flags/usage_config.cc
@@ -0,0 +1,152 @@
+//
+//  Copyright 2019 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/flags/usage_config.h"
+
+#include <iostream>
+#include <memory>
+
+#include "absl/base/attributes.h"
+#include "absl/flags/internal/path_util.h"
+#include "absl/flags/internal/program_name.h"
+#include "absl/strings/str_cat.h"
+#include "absl/strings/strip.h"
+#include "absl/synchronization/mutex.h"
+
+extern "C" {
+
+// Additional report of fatal usage error message before we std::exit. Error is
+// fatal if is_fatal argument to ReportUsageError is true.
+ABSL_ATTRIBUTE_WEAK void AbslInternalReportFatalUsageError(absl::string_view) {}
+
+}  // extern "C"
+
+namespace absl {
+namespace flags_internal {
+
+namespace {
+
+// --------------------------------------------------------------------
+// Returns true if flags defined in the filename should be reported with
+// -helpshort flag.
+
+bool ContainsHelpshortFlags(absl::string_view filename) {
+  // By default we only want flags in binary's main. We expect the main
+  // routine to reside in <program>.cc or <program>-main.cc or
+  // <program>_main.cc, where the <program> is the name of the binary.
+  auto suffix = flags_internal::Basename(filename);
+  if (!absl::ConsumePrefix(&suffix,
+                           flags_internal::ShortProgramInvocationName()))
+    return false;
+  return absl::StartsWith(suffix, ".") || absl::StartsWith(suffix, "-main.") ||
+         absl::StartsWith(suffix, "_main.");
+}
+
+// --------------------------------------------------------------------
+// Returns true if flags defined in the filename should be reported with
+// -helppackage flag.
+
+bool ContainsHelppackageFlags(absl::string_view filename) {
+  // TODO(rogeeff): implement properly when registry is available.
+  return ContainsHelpshortFlags(filename);
+}
+
+// --------------------------------------------------------------------
+// Generates program version information into supplied output.
+
+std::string VersionString() {
+  std::string version_str(flags_internal::ShortProgramInvocationName());
+
+  version_str += "\n";
+
+#if !defined(NDEBUG)
+  version_str += "Debug build (NDEBUG not #defined)\n";
+#endif
+
+  return version_str;
+}
+
+// --------------------------------------------------------------------
+// Normalizes the filename specific to the build system/filesystem used.
+
+std::string NormalizeFilename(absl::string_view filename) {
+  // Skip any leading slashes
+  auto pos = filename.find_first_not_of("\\/");
+  if (pos == absl::string_view::npos) return "";
+
+  filename.remove_prefix(pos);
+  return std::string(filename);
+}
+
+// --------------------------------------------------------------------
+
+ABSL_CONST_INIT absl::Mutex custom_usage_config_guard(absl::kConstInit);
+ABSL_CONST_INIT FlagsUsageConfig* custom_usage_config
+    GUARDED_BY(custom_usage_config_guard) = nullptr;
+
+}  // namespace
+
+FlagsUsageConfig GetUsageConfig() {
+  absl::MutexLock l(&custom_usage_config_guard);
+
+  if (custom_usage_config) return *custom_usage_config;
+
+  FlagsUsageConfig default_config;
+  default_config.contains_helpshort_flags = &ContainsHelpshortFlags;
+  default_config.contains_help_flags = &ContainsHelppackageFlags;
+  default_config.contains_helppackage_flags = &ContainsHelppackageFlags;
+  default_config.version_string = &VersionString;
+  default_config.normalize_filename = &NormalizeFilename;
+
+  return default_config;
+}
+
+void ReportUsageError(absl::string_view msg, bool is_fatal) {
+  std::cerr << "ERROR: " << msg << std::endl;
+
+  if (is_fatal) {
+    AbslInternalReportFatalUsageError(msg);
+  }
+}
+
+}  // namespace flags_internal
+
+void SetFlagsUsageConfig(FlagsUsageConfig usage_config) {
+  absl::MutexLock l(&flags_internal::custom_usage_config_guard);
+
+  if (!usage_config.contains_helpshort_flags)
+    usage_config.contains_helpshort_flags =
+        flags_internal::ContainsHelpshortFlags;
+
+  if (!usage_config.contains_help_flags)
+    usage_config.contains_help_flags = flags_internal::ContainsHelppackageFlags;
+
+  if (!usage_config.contains_helppackage_flags)
+    usage_config.contains_helppackage_flags =
+        flags_internal::ContainsHelppackageFlags;
+
+  if (!usage_config.version_string)
+    usage_config.version_string = flags_internal::VersionString;
+
+  if (!usage_config.normalize_filename)
+    usage_config.normalize_filename = flags_internal::NormalizeFilename;
+
+  if (flags_internal::custom_usage_config)
+    *flags_internal::custom_usage_config = usage_config;
+  else
+    flags_internal::custom_usage_config = new FlagsUsageConfig(usage_config);
+}
+
+}  // namespace absl