Export of internal Abseil changes

--
03700706d80f0939e2b5b8c02a326f045b643730 by Abseil Team <absl-team@google.com>:

Reduced latency and code-size of some InlinedVector methods:

1. Simpler fast path for push_back/emplace_back.
2. Do not inline slow path of push-back/emplace_back.
3. Simplify resize implementation.

Performance:
A simple benchmark that does the following per iteration:

```
push_back on an InlinedVector<int64>
push_back on an InlinedVector<bool>
```

Sees iteration time go from 4.3ns to 2.8ns and code size shrink from 1129 bytes to 175 bytes.

PiperOrigin-RevId: 343335635

--
16f74277a9e8bf228c164b053da8b8098f76de62 by Derek Mauro <dmauro@google.com>:

Internal change

PiperOrigin-RevId: 343332753

--
886b6d5d0244783d309e34f03c21710f411e3cb3 by Abseil Team <absl-team@google.com>:

Optimize `Status::Status`: When creating a status, we currently create an empty struct first, then assign fields. This is suboptimal: https://screenshot.googleplex.com/5HqDuFBKUEqrVgy.

Relevant Benchmarks:
```
BM_StatusCopyError_Deep/threads:1              26.9ns ±13%   21.2ns ±16%  -21.46%  (p=0.000 n=15+15)
BM_StatusCopyError_Deep/threads:2              32.0ns ±30%   25.6ns ±37%  -20.17%  (p=0.004 n=15+14)
BM_StatusCopyError_Deep/threads:4              37.4ns ±84%   30.6ns ±58%  -18.26%  (p=0.029 n=15+15)
BM_StatusCopyError_Deep/threads:8              47.2ns ±33%   33.5ns ±56%  -28.91%  (p=0.000 n=15+14)
```

PiperOrigin-RevId: 343303312

--
2f9d945654292e8e52cad410fa41dae794cff42c by Abseil Team <absl-team@google.com>:

Set SOVERSION for the installed libraries

PiperOrigin-RevId: 343287682

--
600bbfffe91cfbdc60b43cdad5619258298d0b0d by Abseil Team <absl-team@google.com>:

Fix a typo in a comment (than -> that)

PiperOrigin-RevId: 343187724

--
310c82cd97b3f1f0d1ee93a0ee2b0aee828b2a93 by Abseil Team <absl-team@google.com>:

Simplify unaligned memory access functions.

The #ifdef to produce calls to __sanitizer_unaligned_load16 etc were needed in past versions of this code, when we were lying to the compiler about the alignment of the loads/stores, by using a reinterpret_cast.

However, a year ago, absl switched to simply use memcpy. Sanitizers support this correctly by default, nothing extra is required.

PiperOrigin-RevId: 343159883

--
bdf6fcf99180c371fda6ba8af82fd44656e372fa by Gennadiy Rozental <rogeeff@google.com>:

Migrate usage flags to global variables instead of modeling them as Abseil Flags.

Also introduce new semantic for --help=substring command line argument.

PiperOrigin-RevId: 343019883
GitOrigin-RevId: 03700706d80f0939e2b5b8c02a326f045b643730
Change-Id: I4ad40dfa9606f8b8bfb2d91fd09e327105311bfb

1 files changed, 203 insertions, 71 deletions

diff --git a/absl/flags/internal/usage.cc b/absl/flags/internal/usage.cc
index 75573227..f29d7c9b 100644
--- a/absl/flags/internal/usage.cc
+++ b/absl/flags/internal/usage.cc
@@ -37,26 +37,26 @@
 #include "absl/strings/str_split.h"
 #include "absl/strings/string_view.h"
 
-ABSL_FLAG(bool, help, false,
-          "show help on important flags for this binary [tip: all flags can "
-          "have two dashes]");
-ABSL_FLAG(bool, helpfull, false, "show help on all flags");
-ABSL_FLAG(bool, helpshort, false,
-          "show help on only the main module for this program");
-ABSL_FLAG(bool, helppackage, false,
-          "show help on all modules in the main package");
-ABSL_FLAG(bool, version, false, "show version and build info and exit");
-ABSL_FLAG(bool, only_check_args, false, "exit after checking all flags");
-ABSL_FLAG(std::string, helpon, "",
-          "show help on the modules named by this flag value");
-ABSL_FLAG(std::string, helpmatch, "",
-          "show help on modules whose name contains the specified substr");
+// Dummy global variables to prevent anyone else defining these.
+bool FLAGS_help = false;
+bool FLAGS_helpfull = false;
+bool FLAGS_helpshort = false;
+bool FLAGS_helppackage = false;
+bool FLAGS_version = false;
+bool FLAGS_only_check_args = false;
+bool FLAGS_helpon = false;
+bool FLAGS_helpmatch = false;
 
 namespace absl {
 ABSL_NAMESPACE_BEGIN
 namespace flags_internal {
 namespace {
 
+using PerFlagFilter = std::function<bool(const absl::CommandLineFlag&)>;
+
+// Maximum length size in a human readable format.
+constexpr size_t kHrfMaxLineLength = 80;
+
 // This class is used to emit an XML element with `tag` and `text`.
 // It adds opening and closing tags and escapes special characters in the text.
 // For example:
@@ -109,9 +109,12 @@ class FlagHelpPrettyPrinter {
  public:
   // Pretty printer holds on to the std::ostream& reference to direct an output
   // to that stream.
-  FlagHelpPrettyPrinter(int max_line_len, std::ostream& out)
+  FlagHelpPrettyPrinter(size_t max_line_len, size_t min_line_len,
+                        size_t wrapped_line_indent, std::ostream& out)
       : out_(out),
         max_line_len_(max_line_len),
+        min_line_len_(min_line_len),
+        wrapped_line_indent_(wrapped_line_indent),
         line_len_(0),
         first_line_(true) {}
 
@@ -165,13 +168,12 @@ class FlagHelpPrettyPrinter {
 
   void StartLine() {
     if (first_line_) {
-      out_ << "    ";
-      line_len_ = 4;
+      line_len_ = min_line_len_;
       first_line_ = false;
     } else {
-      out_ << "      ";
-      line_len_ = 6;
+      line_len_ = min_line_len_ + wrapped_line_indent_;
     }
+    out_ << std::string(line_len_, ' ');
   }
   void EndLine() {
     out_ << '\n';
@@ -180,13 +182,15 @@ class FlagHelpPrettyPrinter {
 
  private:
   std::ostream& out_;
-  const int max_line_len_;
-  int line_len_;
+  const size_t max_line_len_;
+  const size_t min_line_len_;
+  const size_t wrapped_line_indent_;
+  size_t line_len_;
   bool first_line_;
 };
 
 void FlagHelpHumanReadable(const CommandLineFlag& flag, std::ostream& out) {
-  FlagHelpPrettyPrinter printer(80, out);  // Max line length is 80.
+  FlagHelpPrettyPrinter printer(kHrfMaxLineLength, 4, 2, out);
 
   // Flag name.
   printer.Write(absl::StrCat("--", flag.Name()));
@@ -222,7 +226,7 @@ void FlagHelpHumanReadable(const CommandLineFlag& flag, std::ostream& out) {
 // If a flag's help message has been stripped (e.g. by adding '#define
 // STRIP_FLAG_HELP 1' then this flag will not be displayed by '--help'
 // and its variants.
-void FlagsHelpImpl(std::ostream& out, flags_internal::FlagKindFilter filter_cb,
+void FlagsHelpImpl(std::ostream& out, PerFlagFilter filter_cb,
                    HelpFormat format, absl::string_view program_usage_message) {
   if (format == HelpFormat::kHumanReadable) {
     out << flags_internal::ShortProgramInvocationName() << ": "
@@ -257,10 +261,10 @@ void FlagsHelpImpl(std::ostream& out, flags_internal::FlagKindFilter filter_cb,
     // If the flag has been stripped, pretend that it doesn't exist.
     if (flag.Help() == flags_internal::kStrippedFlagHelp) return;
 
-    std::string flag_filename = flag.Filename();
-
     // Make sure flag satisfies the filter
-    if (!filter_cb || !filter_cb(flag_filename)) return;
+    if (!filter_cb(flag)) return;
+
+    std::string flag_filename = flag.Filename();
 
     matching_flags[std::string(flags_internal::Package(flag_filename))]
                   [flag_filename]
@@ -290,15 +294,34 @@ void FlagsHelpImpl(std::ostream& out, flags_internal::FlagKindFilter filter_cb,
   }
 
   if (format == HelpFormat::kHumanReadable) {
+    FlagHelpPrettyPrinter printer(kHrfMaxLineLength, 0, 0, out);
+
     if (filter_cb && matching_flags.empty()) {
-      out << "  No modules matched: use -helpfull\n";
+      printer.Write("No flags matched.\n", true);
     }
+    printer.EndLine();
+    printer.Write(
+        "Try --helpfull to get a list of all flags or --help=substring "
+        "shows help for flags which include specified substring in either "
+        "in the name, or description or path.\n",
+        true);
   } else {
     // The end of the document.
     out << "</AllFlags>\n";
   }
 }
 
+void FlagsHelpImpl(std::ostream& out,
+                   flags_internal::FlagKindFilter filename_filter_cb,
+                   HelpFormat format, absl::string_view program_usage_message) {
+  FlagsHelpImpl(
+      out,
+      [&](const absl::CommandLineFlag& flag) {
+        return filename_filter_cb && filename_filter_cb(flag.Filename());
+      },
+      format, program_usage_message);
+}
+
 }  // namespace
 
 // --------------------------------------------------------------------
@@ -310,7 +333,7 @@ void FlagHelp(std::ostream& out, const CommandLineFlag& flag,
 }
 
 // --------------------------------------------------------------------
-// Produces the help messages for all flags matching the filter.
+// Produces the help messages for all flags matching the filename filter.
 // If filter is empty produces help messages for all flags.
 void FlagsHelp(std::ostream& out, absl::string_view filter, HelpFormat format,
                absl::string_view program_usage_message) {
@@ -325,66 +348,175 @@ void FlagsHelp(std::ostream& out, absl::string_view filter, HelpFormat format,
 // If so, handles them appropriately.
 int HandleUsageFlags(std::ostream& out,
                      absl::string_view program_usage_message) {
-  if (absl::GetFlag(FLAGS_helpshort)) {
-    flags_internal::FlagsHelpImpl(
-        out, flags_internal::GetUsageConfig().contains_helpshort_flags,
-        HelpFormat::kHumanReadable, program_usage_message);
-    return 1;
-  }
+  switch (GetFlagsHelpMode()) {
+    case HelpMode::kNone:
+      break;
+    case HelpMode::kImportant:
+      flags_internal::FlagsHelpImpl(
+          out, flags_internal::GetUsageConfig().contains_help_flags,
+          GetFlagsHelpFormat(), program_usage_message);
+      return 1;
+
+    case HelpMode::kShort:
+      flags_internal::FlagsHelpImpl(
+          out, flags_internal::GetUsageConfig().contains_helpshort_flags,
+          GetFlagsHelpFormat(), program_usage_message);
+      return 1;
+
+    case HelpMode::kFull:
+      flags_internal::FlagsHelp(out, "", GetFlagsHelpFormat(),
+                                program_usage_message);
+      return 1;
+
+    case HelpMode::kPackage:
+      flags_internal::FlagsHelpImpl(
+          out, flags_internal::GetUsageConfig().contains_helppackage_flags,
+          GetFlagsHelpFormat(), program_usage_message);
+
+      return 1;
+
+    case HelpMode::kMatch: {
+      std::string substr = GetFlagsHelpMatchSubstr();
+      if (substr.empty()) {
+        // show all options
+        flags_internal::FlagsHelp(out, substr, GetFlagsHelpFormat(),
+                                  program_usage_message);
+      } else {
+        auto filter_cb = [&substr](const absl::CommandLineFlag& flag) {
+          if (absl::StrContains(flag.Name(), substr)) return true;
+          if (absl::StrContains(flag.Filename(), substr)) return true;
+          if (absl::StrContains(flag.Help(), substr)) return true;
+
+          return false;
+        };
+        flags_internal::FlagsHelpImpl(
+            out, filter_cb, HelpFormat::kHumanReadable, program_usage_message);
+      }
 
-  if (absl::GetFlag(FLAGS_helpfull)) {
-    // show all options
-    flags_internal::FlagsHelp(out, "", HelpFormat::kHumanReadable,
-                              program_usage_message);
-    return 1;
+      return 1;
+    }
+    case HelpMode::kVersion:
+      if (flags_internal::GetUsageConfig().version_string)
+        out << flags_internal::GetUsageConfig().version_string();
+      // Unlike help, we may be asking for version in a script, so return 0
+      return 0;
+
+    case HelpMode::kOnlyCheckArgs:
+      return 0;
   }
 
-  if (!absl::GetFlag(FLAGS_helpon).empty()) {
-    flags_internal::FlagsHelp(
-        out, absl::StrCat("/", absl::GetFlag(FLAGS_helpon), "."),
-        HelpFormat::kHumanReadable, program_usage_message);
-    return 1;
-  }
+  return -1;
+}
 
-  if (!absl::GetFlag(FLAGS_helpmatch).empty()) {
-    flags_internal::FlagsHelp(out, absl::GetFlag(FLAGS_helpmatch),
-                              HelpFormat::kHumanReadable,
-                              program_usage_message);
-    return 1;
-  }
+// --------------------------------------------------------------------
+// Globals representing usage reporting flags
+
+namespace {
+
+ABSL_CONST_INIT absl::Mutex help_attributes_guard(absl::kConstInit);
+ABSL_CONST_INIT std::string* match_substr
+    ABSL_GUARDED_BY(help_attributes_guard) = nullptr;
+ABSL_CONST_INIT HelpMode help_mode ABSL_GUARDED_BY(help_attributes_guard) =
+    HelpMode::kNone;
+ABSL_CONST_INIT HelpFormat help_format ABSL_GUARDED_BY(help_attributes_guard) =
+    HelpFormat::kHumanReadable;
+
+}  // namespace
 
-  if (absl::GetFlag(FLAGS_help)) {
-    flags_internal::FlagsHelpImpl(
-        out, flags_internal::GetUsageConfig().contains_help_flags,
-        HelpFormat::kHumanReadable, program_usage_message);
+std::string GetFlagsHelpMatchSubstr() {
+  absl::MutexLock l(&help_attributes_guard);
+  if (match_substr == nullptr) return "";
+  return *match_substr;
+}
 
-    out << "\nTry --helpfull to get a list of all flags.\n";
+void SetFlagsHelpMatchSubstr(absl::string_view substr) {
+  absl::MutexLock l(&help_attributes_guard);
+  if (match_substr == nullptr) match_substr = new std::string;
+  match_substr->assign(substr.data(), substr.size());
+}
 
-    return 1;
+HelpMode GetFlagsHelpMode() {
+  absl::MutexLock l(&help_attributes_guard);
+  // Refer to dummy variales to prevent linker dropping them
+  if (FLAGS_help || FLAGS_helpfull || FLAGS_helpshort || FLAGS_helppackage ||
+      FLAGS_version || FLAGS_only_check_args || FLAGS_helpon ||
+      FLAGS_helpmatch) {
+    help_mode = HelpMode::kNone;
   }
+  return help_mode;
+}
+
+void SetFlagsHelpMode(HelpMode mode) {
+  absl::MutexLock l(&help_attributes_guard);
+  help_mode = mode;
+}
 
-  if (absl::GetFlag(FLAGS_helppackage)) {
-    flags_internal::FlagsHelpImpl(
-        out, flags_internal::GetUsageConfig().contains_helppackage_flags,
-        HelpFormat::kHumanReadable, program_usage_message);
+HelpFormat GetFlagsHelpFormat() {
+  absl::MutexLock l(&help_attributes_guard);
+  return help_format;
+}
+
+void SetFlagsHelpFormat(HelpFormat format) {
+  absl::MutexLock l(&help_attributes_guard);
+  help_format = format;
+}
 
-    out << "\nTry --helpfull to get a list of all flags.\n";
+// Deduces usage flags from the input argument in a form --name=value or
+// --name. argument is already split into name and value before we call this
+// function.
+bool DeduceUsageFlags(absl::string_view name, absl::string_view value) {
+  if (absl::ConsumePrefix(&name, "help")) {
+    if (name == "") {
+      if (value.empty()) {
+        SetFlagsHelpMode(HelpMode::kImportant);
+      } else {
+        SetFlagsHelpMode(HelpMode::kMatch);
+        SetFlagsHelpMatchSubstr(value);
+      }
+      return true;
+    }
 
-    return 1;
+    if (name == "match") {
+      SetFlagsHelpMode(HelpMode::kMatch);
+      SetFlagsHelpMatchSubstr(value);
+      return true;
+    }
+
+    if (name == "on") {
+      SetFlagsHelpMode(HelpMode::kMatch);
+      SetFlagsHelpMatchSubstr(absl::StrCat("/", value, "."));
+      return true;
+    }
+
+    if (name == "full") {
+      SetFlagsHelpMode(HelpMode::kFull);
+      return true;
+    }
+
+    if (name == "short") {
+      SetFlagsHelpMode(HelpMode::kShort);
+      return true;
+    }
+
+    if (name == "package") {
+      SetFlagsHelpMode(HelpMode::kPackage);
+      return true;
+    }
+
+    return false;
   }
 
-  if (absl::GetFlag(FLAGS_version)) {
-    if (flags_internal::GetUsageConfig().version_string)
-      out << flags_internal::GetUsageConfig().version_string();
-    // Unlike help, we may be asking for version in a script, so return 0
-    return 0;
+  if (name == "version") {
+    SetFlagsHelpMode(HelpMode::kVersion);
+    return true;
   }
 
-  if (absl::GetFlag(FLAGS_only_check_args)) {
-    return 0;
+  if (name == "only_check_args") {
+    SetFlagsHelpMode(HelpMode::kOnlyCheckArgs);
+    return true;
   }
 
-  return -1;
+  return false;
 }
 
 }  // namespace flags_internal