Export of internal Abseil changes

--
6a60bc6c79a3069f49986c2567dd51d2792f8ec1 by Abseil Team <absl-team@google.com>:

Internal cleanup

PiperOrigin-RevId: 311210039

--
a1049de1dd9071efa3a3dda1c3f25ab578b23e27 by Laramie Leavitt <lar@google.com>:

Internal change

PiperOrigin-RevId: 311188627

--
c2ccddd1cd89ef9d79c35bbe9e1813164db27031 by Matt Kulukundis <kfm@google.com>:

Migrate time parsing/formatting to string_view.

- make a copy before handing to cctz but handle local cases without

PiperOrigin-RevId: 311009254

--
d91d0cd68f3672a727ff76ee43f2da5226673d60 by Gennadiy Rozental <rogeeff@google.com>:

Eliminate public method absl::Flag<T>::IsSpecfiedOnCommandLine. This interface was never intended to be supported. Prefer to react to the current value of flag.

PiperOrigin-RevId: 310991916

--
8ad41e7ec24f43598ed232545314117802e7895c by Gennadiy Rozental <rogeeff@google.com>:

Internal change

PiperOrigin-RevId: 310757743

--
f091f77a13ce9481218cb356f8b4ceb49c1530f9 by Jorg Brown <jorg@google.com>:

Change #include of <iostream> to <iosfwd> from absl/strings/cord.h

PiperOrigin-RevId: 310657413

--
39419418af6be4ac9b9204ebe2c7a92a6c3a0bc9 by Derek Mauro <dmauro@google.com>:

Internal change

PiperOrigin-RevId: 310615554
GitOrigin-RevId: 6a60bc6c79a3069f49986c2567dd51d2792f8ec1
Change-Id: I57dd35424269d67740272c4f88b2de54d8022cb2

18 files changed, 280 insertions, 127 deletions

diff --git a/absl/base/BUILD.bazel b/absl/base/BUILD.bazel
index 816e592..76122da 100644
--- a/absl/base/BUILD.bazel
+++ b/absl/base/BUILD.bazel
@@ -777,3 +777,17 @@ cc_test(
         "@com_google_googletest//:gtest_main",
     ],
 )
+
+cc_test(
+    name = "unique_small_name_test",
+    size = "small",
+    srcs = ["internal/unique_small_name_test.cc"],
+    copts = ABSL_TEST_COPTS,
+    linkopts = ABSL_DEFAULT_LINKOPTS,
+    linkstatic = 1,
+    deps = [
+        ":core_headers",
+        "//absl/strings",
+        "@com_google_googletest//:gtest_main",
+    ],
+)
diff --git a/absl/base/internal/unique_small_name_test.cc b/absl/base/internal/unique_small_name_test.cc
new file mode 100644
index 0000000..ff8c2b3
--- /dev/null
+++ b/absl/base/internal/unique_small_name_test.cc
@@ -0,0 +1,77 @@
+// 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 "gtest/gtest.h"
+#include "absl/base/optimization.h"
+#include "absl/strings/string_view.h"
+
+// This test by itself does not do anything fancy, but it serves as binary I can
+// query in shell test.
+
+namespace {
+
+template <class T>
+void DoNotOptimize(const T& var) {
+#ifdef __GNUC__
+  asm volatile("" : "+m"(const_cast<T&>(var)));
+#else
+  std::cout << (void*)&var;
+#endif
+}
+
+int very_long_int_variable_name ABSL_INTERNAL_UNIQUE_SMALL_NAME() = 0;
+char very_long_str_variable_name[] ABSL_INTERNAL_UNIQUE_SMALL_NAME() = "abc";
+
+TEST(UniqueSmallName, NonAutomaticVar) {
+  EXPECT_EQ(very_long_int_variable_name, 0);
+  EXPECT_EQ(absl::string_view(very_long_str_variable_name), "abc");
+}
+
+int VeryLongFreeFunctionName() ABSL_INTERNAL_UNIQUE_SMALL_NAME();
+
+TEST(UniqueSmallName, FreeFunction) {
+  DoNotOptimize(&VeryLongFreeFunctionName);
+
+  EXPECT_EQ(VeryLongFreeFunctionName(), 456);
+}
+
+int VeryLongFreeFunctionName() { return 456; }
+
+struct VeryLongStructName {
+  explicit VeryLongStructName(int i);
+
+  int VeryLongMethodName() ABSL_INTERNAL_UNIQUE_SMALL_NAME();
+
+  static int VeryLongStaticMethodName() ABSL_INTERNAL_UNIQUE_SMALL_NAME();
+
+ private:
+  int fld;
+};
+
+TEST(UniqueSmallName, Struct) {
+  VeryLongStructName var(10);
+
+  DoNotOptimize(var);
+  DoNotOptimize(&VeryLongStructName::VeryLongMethodName);
+  DoNotOptimize(&VeryLongStructName::VeryLongStaticMethodName);
+
+  EXPECT_EQ(var.VeryLongMethodName(), 10);
+  EXPECT_EQ(VeryLongStructName::VeryLongStaticMethodName(), 123);
+}
+
+VeryLongStructName::VeryLongStructName(int i) : fld(i) {}
+int VeryLongStructName::VeryLongMethodName() { return fld; }
+int VeryLongStructName::VeryLongStaticMethodName() { return 123; }
+
+}  // namespace
diff --git a/absl/base/optimization.h b/absl/base/optimization.h
index 1541d7a..92bf9cd 100644
--- a/absl/base/optimization.h
+++ b/absl/base/optimization.h
@@ -212,4 +212,30 @@
   } while (0)
 #endif
 
+// ABSL_INTERNAL_UNIQUE_SMALL_NAME(cond)
+// This macro forces small unique name on a static file level symbols like
+// static local variables or static functions. This is intended to be used in
+// macro definitions to optimize the cost of generated code. Do NOT use it on
+// symbols exported from translation unit since it may casue a link time
+// conflict.
+//
+// Example:
+//
+// #define MY_MACRO(txt)
+// namespace {
+//  char VeryVeryLongVarName[] ABSL_INTERNAL_UNIQUE_SMALL_NAME() = txt;
+//  const char* VeryVeryLongFuncName() ABSL_INTERNAL_UNIQUE_SMALL_NAME();
+//  const char* VeryVeryLongFuncName() { return txt; }
+// }
+//
+
+#if defined(__GNUC__)
+#define ABSL_INTERNAL_UNIQUE_SMALL_NAME2(x) #x
+#define ABSL_INTERNAL_UNIQUE_SMALL_NAME1(x) ABSL_INTERNAL_UNIQUE_SMALL_NAME2(x)
+#define ABSL_INTERNAL_UNIQUE_SMALL_NAME() \
+  asm(ABSL_INTERNAL_UNIQUE_SMALL_NAME1(.absl.__COUNTER__))
+#else
+#define ABSL_INTERNAL_UNIQUE_SMALL_NAME()
+#endif
+
 #endif  // ABSL_BASE_OPTIMIZATION_H_
diff --git a/absl/flags/internal/commandlineflag.h b/absl/flags/internal/commandlineflag.h
index 2d3b794..0a7197b 100644
--- a/absl/flags/internal/commandlineflag.h
+++ b/absl/flags/internal/commandlineflag.h
@@ -128,7 +128,6 @@ class CommandLineFlag {
   virtual std::string Help() const = 0;
   // Returns true iff this object corresponds to retired flag.
   virtual bool IsRetired() const;
-  virtual bool IsSpecifiedOnCommandLine() const = 0;
   virtual std::string DefaultValue() const = 0;
   virtual std::string CurrentValue() const = 0;
 
@@ -167,6 +166,10 @@ class CommandLineFlag {
   // the dst based on the current flag's value.
   virtual void Read(void* dst) const = 0;
 
+  // To be deleted. Used to return true if flag's current value originated from
+  // command line.
+  virtual bool IsSpecifiedOnCommandLine() const = 0;
+
   // Validates supplied value usign validator or parseflag routine
   virtual bool ValidateInputValue(absl::string_view value) const = 0;
 
diff --git a/absl/flags/internal/commandlineflag_test.cc b/absl/flags/internal/commandlineflag_test.cc
index 54d50ff..0b5aea3 100644
--- a/absl/flags/internal/commandlineflag_test.cc
+++ b/absl/flags/internal/commandlineflag_test.cc
@@ -121,42 +121,48 @@ TEST_F(CommandLineFlagTest, TestParseFromCurrentValue) {
   std::string err;
 
   auto* flag_01 = flags::FindCommandLineFlag("int_flag");
-  EXPECT_FALSE(flag_01->IsSpecifiedOnCommandLine());
+  EXPECT_FALSE(
+      flags::PrivateHandleAccessor::IsSpecifiedOnCommandLine(*flag_01));
 
   EXPECT_TRUE(flags::PrivateHandleAccessor::ParseFrom(
       flag_01, "11", flags::SET_FLAGS_VALUE, flags::kProgrammaticChange, &err));
   EXPECT_EQ(absl::GetFlag(FLAGS_int_flag), 11);
-  EXPECT_FALSE(flag_01->IsSpecifiedOnCommandLine());
+  EXPECT_FALSE(
+      flags::PrivateHandleAccessor::IsSpecifiedOnCommandLine(*flag_01));
 
   EXPECT_TRUE(flags::PrivateHandleAccessor::ParseFrom(
       flag_01, "-123", flags::SET_FLAGS_VALUE, flags::kProgrammaticChange,
       &err));
   EXPECT_EQ(absl::GetFlag(FLAGS_int_flag), -123);
-  EXPECT_FALSE(flag_01->IsSpecifiedOnCommandLine());
+  EXPECT_FALSE(
+      flags::PrivateHandleAccessor::IsSpecifiedOnCommandLine(*flag_01));
 
   EXPECT_TRUE(!flags::PrivateHandleAccessor::ParseFrom(
       flag_01, "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_FALSE(
+      flags::PrivateHandleAccessor::IsSpecifiedOnCommandLine(*flag_01));
 
   EXPECT_TRUE(!flags::PrivateHandleAccessor::ParseFrom(
       flag_01, "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_FALSE(
+      flags::PrivateHandleAccessor::IsSpecifiedOnCommandLine(*flag_01));
 
   EXPECT_TRUE(flags::PrivateHandleAccessor::ParseFrom(
       flag_01, "0x10", flags::SET_FLAGS_VALUE, flags::kProgrammaticChange,
       &err));
   EXPECT_EQ(absl::GetFlag(FLAGS_int_flag), 16);
-  EXPECT_FALSE(flag_01->IsSpecifiedOnCommandLine());
+  EXPECT_FALSE(
+      flags::PrivateHandleAccessor::IsSpecifiedOnCommandLine(*flag_01));
 
   EXPECT_TRUE(flags::PrivateHandleAccessor::ParseFrom(
       flag_01, "011", flags::SET_FLAGS_VALUE, flags::kCommandLine, &err));
   EXPECT_EQ(absl::GetFlag(FLAGS_int_flag), 11);
-  EXPECT_TRUE(flag_01->IsSpecifiedOnCommandLine());
+  EXPECT_TRUE(flags::PrivateHandleAccessor::IsSpecifiedOnCommandLine(*flag_01));
 
   EXPECT_TRUE(!flags::PrivateHandleAccessor::ParseFrom(
       flag_01, "", flags::SET_FLAGS_VALUE, flags::kProgrammaticChange, &err));
diff --git a/absl/flags/internal/flag.h b/absl/flags/internal/flag.h
index b060199..146c3ef 100644
--- a/absl/flags/internal/flag.h
+++ b/absl/flags/internal/flag.h
@@ -624,6 +624,7 @@ class Flag {
   absl::string_view Name() const { return impl_.Name(); }
   std::string Filename() const { return impl_.Filename(); }
   std::string Help() const { return impl_.Help(); }
+  // Do not use. To be removed.
   bool IsSpecifiedOnCommandLine() const {
     return impl_.IsSpecifiedOnCommandLine();
   }
diff --git a/absl/flags/internal/private_handle_accessor.cc b/absl/flags/internal/private_handle_accessor.cc
index ec5776b..64fe316 100644
--- a/absl/flags/internal/private_handle_accessor.cc
+++ b/absl/flags/internal/private_handle_accessor.cc
@@ -28,6 +28,11 @@ std::unique_ptr<FlagStateInterface> PrivateHandleAccessor::SaveState(
   return flag->SaveState();
 }
 
+bool PrivateHandleAccessor::IsSpecifiedOnCommandLine(
+    const CommandLineFlag& flag) {
+  return flag.IsSpecifiedOnCommandLine();
+}
+
 bool PrivateHandleAccessor::ValidateInputValue(const CommandLineFlag& flag,
                                                absl::string_view value) {
   return flag.ValidateInputValue(value);
diff --git a/absl/flags/internal/private_handle_accessor.h b/absl/flags/internal/private_handle_accessor.h
index fbb4409..40591de 100644
--- a/absl/flags/internal/private_handle_accessor.h
+++ b/absl/flags/internal/private_handle_accessor.h
@@ -33,6 +33,9 @@ class PrivateHandleAccessor {
   // Access to CommandLineFlag::SaveState.
   static std::unique_ptr<FlagStateInterface> SaveState(CommandLineFlag* flag);
 
+  // Access to CommandLineFlag::IsSpecifiedOnCommandLine.
+  static bool IsSpecifiedOnCommandLine(const CommandLineFlag& flag);
+
   // Access to CommandLineFlag::ValidateInputValue.
   static bool ValidateInputValue(const CommandLineFlag& flag,
                                  absl::string_view value);
diff --git a/absl/flags/internal/type_erased.cc b/absl/flags/internal/type_erased.cc
index 3cfc9b2..c13fb9b 100644
--- a/absl/flags/internal/type_erased.cc
+++ b/absl/flags/internal/type_erased.cc
@@ -81,14 +81,6 @@ bool IsValidFlagValue(absl::string_view name, absl::string_view value) {
 
 // --------------------------------------------------------------------
 
-bool SpecifiedOnCommandLine(absl::string_view name) {
-  CommandLineFlag* flag = flags_internal::FindCommandLineFlag(name);
-  if (flag != nullptr && !flag->IsRetired()) {
-    return flag->IsSpecifiedOnCommandLine();
-  }
-  return false;
-}
-
 }  // namespace flags_internal
 ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/flags/internal/type_erased.h b/absl/flags/internal/type_erased.h
index ffe319b..b43a0ff 100644
--- a/absl/flags/internal/type_erased.h
+++ b/absl/flags/internal/type_erased.h
@@ -55,17 +55,6 @@ bool IsValidFlagValue(absl::string_view name, absl::string_view value);
 
 //-----------------------------------------------------------------------------
 
-// Returns true iff a flag named "name" was specified on the command line
-// (either directly, or via one of --flagfile or --fromenv or --tryfromenv).
-//
-// Any non-command-line modification of the flag does not affect the
-// result of this function.  So for example, if a flag was passed on
-// the command line but then reset via SET_FLAGS_DEFAULT, this
-// function will still return true.
-bool SpecifiedOnCommandLine(absl::string_view name);
-
-//-----------------------------------------------------------------------------
-
 // If a flag with specified "name" exists and has type T, store
 // its current value in *dst and return true.  Else return false
 // without touching *dst.  T must obey all of the requirements for
diff --git a/absl/random/internal/BUILD.bazel b/absl/random/internal/BUILD.bazel
index 1c9dabb..dc45281 100644
--- a/absl/random/internal/BUILD.bazel
+++ b/absl/random/internal/BUILD.bazel
@@ -37,9 +37,6 @@ cc_library(
     hdrs = ["traits.h"],
     copts = ABSL_DEFAULT_COPTS,
     linkopts = ABSL_DEFAULT_LINKOPTS,
-    visibility = [
-        "//absl/random:__pkg__",
-    ],
     deps = ["//absl/base:config"],
 )
 
@@ -48,9 +45,6 @@ cc_library(
     hdrs = ["distribution_caller.h"],
     copts = ABSL_DEFAULT_COPTS,
     linkopts = ABSL_DEFAULT_LINKOPTS,
-    visibility = [
-        "//absl/random:__pkg__",
-    ],
     deps = ["//absl/base:config"],
 )
 
@@ -76,9 +70,6 @@ cc_library(
     ],
     copts = ABSL_DEFAULT_COPTS,
     linkopts = ABSL_DEFAULT_LINKOPTS,
-    visibility = [
-        "//absl/random:__pkg__",
-    ],
     deps = ["//absl/base:config"],
 )
 
@@ -517,9 +508,6 @@ cc_library(
     name = "mock_overload_set",
     testonly = 1,
     hdrs = ["mock_overload_set.h"],
-    visibility = [
-        "//absl/random:__pkg__",
-    ],
     deps = [
         "//absl/random:mocking_bit_gen",
         "@com_google_googletest//:gtest",
@@ -669,6 +657,7 @@ cc_library(
     deps = [
         ":platform",
         ":randen_engine",
+        "//absl/base:config",
         "//absl/base:core_headers",
         "//absl/base:raw_logging_internal",
     ],
diff --git a/absl/strings/cord.cc b/absl/strings/cord.cc
index 0403cc6..1ddd6ae 100644
--- a/absl/strings/cord.cc
+++ b/absl/strings/cord.cc
@@ -20,6 +20,7 @@
 #include <cstdio>
 #include <cstdlib>
 #include <iomanip>
+#include <iostream>
 #include <limits>
 #include <ostream>
 #include <sstream>
diff --git a/absl/strings/cord.h b/absl/strings/cord.h
index 86ae76f..3be8d7d 100644
--- a/absl/strings/cord.h
+++ b/absl/strings/cord.h
@@ -65,7 +65,7 @@
 #include <cstddef>
 #include <cstdint>
 #include <cstring>
-#include <iostream>
+#include <iosfwd>
 #include <iterator>
 #include <string>
 #include <type_traits>
diff --git a/absl/strings/substitute.h b/absl/strings/substitute.h
index 92c4723..c6da4dc 100644
--- a/absl/strings/substitute.h
+++ b/absl/strings/substitute.h
@@ -120,7 +120,9 @@ class Arg {
   // representation. However, we can't really know, so we make the caller decide
   // what to do.
   Arg(char value)  // NOLINT(runtime/explicit)
-      : piece_(scratch_, 1) { scratch_[0] = value; }
+      : piece_(scratch_, 1) {
+    scratch_[0] = value;
+  }
   Arg(short value)  // NOLINT(*)
       : piece_(scratch_,
                numbers_internal::FastIntToBuffer(value, scratch_) - scratch_) {}
@@ -203,10 +205,11 @@ constexpr const char* SkipNumber(const char* format) {
 }
 
 constexpr int PlaceholderBitmask(const char* format) {
-  return !*format ? 0 : *format != '$'
-                             ? PlaceholderBitmask(format + 1)
-                             : (CalculateOneBit(format + 1) |
-                                   PlaceholderBitmask(SkipNumber(format + 1)));
+  return !*format
+             ? 0
+             : *format != '$' ? PlaceholderBitmask(format + 1)
+                              : (CalculateOneBit(format + 1) |
+                                 PlaceholderBitmask(SkipNumber(format + 1)));
 }
 #endif  // ABSL_BAD_CALL_IF
 
diff --git a/absl/synchronization/mutex.h b/absl/synchronization/mutex.h
index 961ff52..876698c 100644
--- a/absl/synchronization/mutex.h
+++ b/absl/synchronization/mutex.h
@@ -769,6 +769,8 @@ class Condition {
 //
 class CondVar {
  public:
+  // A `CondVar` allocated on the heap or on the stack can use the this
+  // constructor.
   CondVar();
   ~CondVar();
 
@@ -900,9 +902,11 @@ class ABSL_SCOPED_LOCKABLE ReleasableMutexLock {
 };
 
 #ifdef ABSL_INTERNAL_USE_NONPROD_MUTEX
+
 inline constexpr Mutex::Mutex(absl::ConstInitType) : impl_(absl::kConstInit) {}
 
 #else
+
 inline Mutex::Mutex() : mu_(0) {
   ABSL_TSAN_MUTEX_CREATE(this, __tsan_mutex_not_static);
 }
@@ -910,7 +914,8 @@ inline Mutex::Mutex() : mu_(0) {
 inline constexpr Mutex::Mutex(absl::ConstInitType) : mu_(0) {}
 
 inline CondVar::CondVar() : cv_(0) {}
-#endif
+
+#endif  // ABSL_INTERNAL_USE_NONPROD_MUTEX
 
 // static
 template <typename T>
diff --git a/absl/time/duration.cc b/absl/time/duration.cc
index f018255..d0f1aad 100644
--- a/absl/time/duration.cc
+++ b/absl/time/duration.cc
@@ -67,7 +67,9 @@
 #include <string>
 
 #include "absl/base/casts.h"
+#include "absl/base/macros.h"
 #include "absl/numeric/int128.h"
+#include "absl/strings/strip.h"
 #include "absl/time/time.h"
 
 namespace absl {
@@ -800,23 +802,27 @@ namespace {
 // A helper for ParseDuration() that parses a leading number from the given
 // string and stores the result in *int_part/*frac_part/*frac_scale.  The
 // given string pointer is modified to point to the first unconsumed char.
-bool ConsumeDurationNumber(const char** dpp, int64_t* int_part,
+bool ConsumeDurationNumber(const char** dpp, const char* ep, int64_t* int_part,
                            int64_t* frac_part, int64_t* frac_scale) {
   *int_part = 0;
   *frac_part = 0;
   *frac_scale = 1;  // invariant: *frac_part < *frac_scale
   const char* start = *dpp;
-  for (; std::isdigit(**dpp); *dpp += 1) {
+  for (; *dpp != ep; *dpp += 1) {
     const int d = **dpp - '0';  // contiguous digits
+    if (d < 0 || 10 <= d) break;
+
     if (*int_part > kint64max / 10) return false;
     *int_part *= 10;
     if (*int_part > kint64max - d) return false;
     *int_part += d;
   }
   const bool int_part_empty = (*dpp == start);
-  if (**dpp != '.') return !int_part_empty;
-  for (*dpp += 1; std::isdigit(**dpp); *dpp += 1) {
+  if (*dpp == ep || **dpp != '.') return !int_part_empty;
+
+  for (*dpp += 1; *dpp != ep; *dpp += 1) {
     const int d = **dpp - '0';  // contiguous digits
+    if (d < 0 || 10 <= d) break;
     if (*frac_scale <= kint64max / 10) {
       *frac_part *= 10;
       *frac_part += d;
@@ -830,32 +836,56 @@ bool ConsumeDurationNumber(const char** dpp, int64_t* int_part,
 // ns, us, ms, s, m, h) from the given string and stores the resulting unit
 // in "*unit".  The given string pointer is modified to point to the first
 // unconsumed char.
-bool ConsumeDurationUnit(const char** start, Duration* unit) {
-  const char *s = *start;
-  bool ok = true;
-  if (strncmp(s, "ns", 2) == 0) {
-    s += 2;
-    *unit = Nanoseconds(1);
-  } else if (strncmp(s, "us", 2) == 0) {
-    s += 2;
-    *unit = Microseconds(1);
-  } else if (strncmp(s, "ms", 2) == 0) {
-    s += 2;
-    *unit = Milliseconds(1);
-  } else if (strncmp(s, "s", 1) == 0) {
-    s += 1;
-    *unit = Seconds(1);
-  } else if (strncmp(s, "m", 1) == 0) {
-    s += 1;
-    *unit = Minutes(1);
-  } else if (strncmp(s, "h", 1) == 0) {
-    s += 1;
-    *unit = Hours(1);
-  } else {
-    ok = false;
+bool ConsumeDurationUnit(const char** start, const char* end, Duration* unit) {
+  size_t size = end - *start;
+  switch (size) {
+    case 0:
+      return false;
+    default:
+      switch (**start) {
+        case 'n':
+          if (*(*start + 1) == 's') {
+            *start += 2;
+            *unit = Nanoseconds(1);
+            return true;
+          }
+          break;
+        case 'u':
+          if (*(*start + 1) == 's') {
+            *start += 2;
+            *unit = Microseconds(1);
+            return true;
+          }
+          break;
+        case 'm':
+          if (*(*start + 1) == 's') {
+            *start += 2;
+            *unit = Milliseconds(1);
+            return true;
+          }
+          break;
+        default:
+          break;
+      }
+      ABSL_FALLTHROUGH_INTENDED;
+    case 1:
+      switch (**start) {
+        case 's':
+          *unit = Seconds(1);
+          *start += 1;
+          return true;
+        case 'm':
+          *unit = Minutes(1);
+          *start += 1;
+          return true;
+        case 'h':
+          *unit = Hours(1);
+          *start += 1;
+          return true;
+        default:
+          return false;
+      }
   }
-  *start = s;
-  return ok;
 }
 
 }  // namespace
@@ -865,39 +895,38 @@ bool ConsumeDurationUnit(const char** start, Duration* unit) {
 //   a possibly signed sequence of decimal numbers, each with optional
 //   fraction and a unit suffix, such as "300ms", "-1.5h" or "2h45m".
 //   Valid time units are "ns", "us" "ms", "s", "m", "h".
-bool ParseDuration(const std::string& dur_string, Duration* d) {
-  const char* start = dur_string.c_str();
+bool ParseDuration(absl::string_view dur_sv, Duration* d) {
   int sign = 1;
-
-  if (*start == '-' || *start == '+') {
-    sign = *start == '-' ? -1 : 1;
-    ++start;
-  }
-
-  // Can't parse a duration from an empty string.
-  if (*start == '\0') {
-    return false;
+  if (absl::ConsumePrefix(&dur_sv, "-")) {
+    sign = -1;
+  } else {
+    absl::ConsumePrefix(&dur_sv, "+");
   }
+  if (dur_sv.empty()) return false;
 
   // Special case for a string of "0".
-  if (*start == '0' && *(start + 1) == '\0') {
+  if (dur_sv == "0") {
     *d = ZeroDuration();
     return true;
   }
 
-  if (strcmp(start, "inf") == 0) {
+  if (dur_sv == "inf") {
     *d = sign * InfiniteDuration();
     return true;
   }
 
+  const char* start = dur_sv.data();
+  const char* end = start + dur_sv.size();
+
   Duration dur;
-  while (*start != '\0') {
+  while (start != end) {
     int64_t int_part;
     int64_t frac_part;
     int64_t frac_scale;
     Duration unit;
-    if (!ConsumeDurationNumber(&start, &int_part, &frac_part, &frac_scale) ||
-        !ConsumeDurationUnit(&start, &unit)) {
+    if (!ConsumeDurationNumber(&start, end, &int_part, &frac_part,
+                               &frac_scale) ||
+        !ConsumeDurationUnit(&start, end, &unit)) {
       return false;
     }
     if (int_part != 0) dur += sign * int_part * unit;
@@ -908,7 +937,7 @@ bool ParseDuration(const std::string& dur_string, Duration* d) {
 }
 
 bool AbslParseFlag(absl::string_view text, Duration* dst, std::string*) {
-  return ParseDuration(std::string(text), dst);
+  return ParseDuration(text, dst);
 }
 
 std::string AbslUnparseFlag(Duration d) { return FormatDuration(d); }
diff --git a/absl/time/format.cc b/absl/time/format.cc
index ee088f3..228940e 100644
--- a/absl/time/format.cc
+++ b/absl/time/format.cc
@@ -13,9 +13,12 @@
 // limitations under the License.
 
 #include <string.h>
+
 #include <cctype>
 #include <cstdint>
 
+#include "absl/strings/match.h"
+#include "absl/strings/string_view.h"
 #include "absl/time/internal/cctz/include/cctz/time_zone.h"
 #include "absl/time/time.h"
 
@@ -71,12 +74,12 @@ absl::Time Join(const cctz_parts& parts) {
 
 }  // namespace
 
-std::string FormatTime(const std::string& format, absl::Time t,
+std::string FormatTime(absl::string_view format, absl::Time t,
                        absl::TimeZone tz) {
-  if (t == absl::InfiniteFuture()) return kInfiniteFutureStr;
-  if (t == absl::InfinitePast()) return kInfinitePastStr;
+  if (t == absl::InfiniteFuture()) return std::string(kInfiniteFutureStr);
+  if (t == absl::InfinitePast()) return std::string(kInfinitePastStr);
   const auto parts = Split(t);
-  return cctz::detail::format(format, parts.sec, parts.fem,
+  return cctz::detail::format(std::string(format), parts.sec, parts.fem,
                               cctz::time_zone(tz));
 }
 
@@ -88,42 +91,50 @@ std::string FormatTime(absl::Time t) {
   return absl::FormatTime(RFC3339_full, t, absl::LocalTimeZone());
 }
 
-bool ParseTime(const std::string& format, const std::string& input,
+bool ParseTime(absl::string_view format, absl::string_view input,
                absl::Time* time, std::string* err) {
   return absl::ParseTime(format, input, absl::UTCTimeZone(), time, err);
 }
 
 // If the input string does not contain an explicit UTC offset, interpret
 // the fields with respect to the given TimeZone.
-bool ParseTime(const std::string& format, const std::string& input,
+bool ParseTime(absl::string_view format, absl::string_view input,
                absl::TimeZone tz, absl::Time* time, std::string* err) {
-  const char* data = input.c_str();
-  while (std::isspace(*data)) ++data;
-
-  size_t inf_size = strlen(kInfiniteFutureStr);
-  if (strncmp(data, kInfiniteFutureStr, inf_size) == 0) {
-    const char* new_data = data + inf_size;
-    while (std::isspace(*new_data)) ++new_data;
-    if (*new_data == '\0') {
-      *time = InfiniteFuture();
-      return true;
+  auto strip_leading_space = [](absl::string_view* sv) {
+    while (!sv->empty()) {
+      if (!std::isspace(sv->front())) return;
+      sv->remove_prefix(1);
     }
-  }
-
-  inf_size = strlen(kInfinitePastStr);
-  if (strncmp(data, kInfinitePastStr, inf_size) == 0) {
-    const char* new_data = data + inf_size;
-    while (std::isspace(*new_data)) ++new_data;
-    if (*new_data == '\0') {
-      *time = InfinitePast();
-      return true;
+  };
+
+  // Portable toolchains means we don't get nice constexpr here.
+  struct Literal {
+    const char* name;
+    size_t size;
+    absl::Time value;
+  };
+  static Literal literals[] = {
+      {kInfiniteFutureStr, strlen(kInfiniteFutureStr), InfiniteFuture()},
+      {kInfinitePastStr, strlen(kInfinitePastStr), InfinitePast()},
+  };
+  strip_leading_space(&input);
+  for (const auto& lit : literals) {
+    if (absl::StartsWith(input, absl::string_view(lit.name, lit.size))) {
+      absl::string_view tail = input;
+      tail.remove_prefix(lit.size);
+      strip_leading_space(&tail);
+      if (tail.empty()) {
+        *time = lit.value;
+        return true;
+      }
     }
   }
 
   std::string error;
   cctz_parts parts;
-  const bool b = cctz::detail::parse(format, input, cctz::time_zone(tz),
-                                     &parts.sec, &parts.fem, &error);
+  const bool b =
+      cctz::detail::parse(std::string(format), std::string(input),
+                          cctz::time_zone(tz), &parts.sec, &parts.fem, &error);
   if (b) {
     *time = Join(parts);
   } else if (err != nullptr) {
@@ -134,8 +145,7 @@ bool ParseTime(const std::string& format, const std::string& input,
 
 // Functions required to support absl::Time flags.
 bool AbslParseFlag(absl::string_view text, absl::Time* t, std::string* error) {
-  return absl::ParseTime(RFC3339_full, std::string(text), absl::UTCTimeZone(),
-                         t, error);
+  return absl::ParseTime(RFC3339_full, text, absl::UTCTimeZone(), t, error);
 }
 
 std::string AbslUnparseFlag(absl::Time t) {
diff --git a/absl/time/time.h b/absl/time/time.h
index 152f3ff..b456a13 100644
--- a/absl/time/time.h
+++ b/absl/time/time.h
@@ -545,7 +545,7 @@ inline std::ostream& operator<<(std::ostream& os, Duration d) {
 // suffix.  The valid suffixes are "ns", "us" "ms", "s", "m", and "h".
 // Simple examples include "300ms", "-1.5h", and "2h45m".  Parses "0" as
 // `ZeroDuration()`. Parses "inf" and "-inf" as +/- `InfiniteDuration()`.
-bool ParseDuration(const std::string& dur_string, Duration* d);
+bool ParseDuration(absl::string_view dur_string, Duration* d);
 
 // Support for flag values of type Duration. Duration flags must be specified
 // in a format that is valid input for absl::ParseDuration().
@@ -1021,13 +1021,13 @@ class TimeZone {
 // Loads the named zone. May perform I/O on the initial load of the named
 // zone. If the name is invalid, or some other kind of error occurs, returns
 // `false` and `*tz` is set to the UTC time zone.
-inline bool LoadTimeZone(const std::string& name, TimeZone* tz) {
+inline bool LoadTimeZone(absl::string_view name, TimeZone* tz) {
   if (name == "localtime") {
     *tz = TimeZone(time_internal::cctz::local_time_zone());
     return true;
   }
   time_internal::cctz::time_zone cz;
-  const bool b = time_internal::cctz::load_time_zone(name, &cz);
+  const bool b = time_internal::cctz::load_time_zone(std::string(name), &cz);
   *tz = TimeZone(cz);
   return b;
 }
@@ -1252,7 +1252,7 @@ ABSL_DLL extern const char
 // `absl::InfinitePast()`, the returned string will be exactly "infinite-past".
 // In both cases the given format string and `absl::TimeZone` are ignored.
 //
-std::string FormatTime(const std::string& format, Time t, TimeZone tz);
+std::string FormatTime(absl::string_view format, Time t, TimeZone tz);
 
 // Convenience functions that format the given time using the RFC3339_full
 // format.  The first overload uses the provided TimeZone, while the second
@@ -1313,7 +1313,7 @@ inline std::ostream& operator<<(std::ostream& os, Time t) {
 // If the input string is "infinite-past", the returned `absl::Time` will be
 // `absl::InfinitePast()` and `true` will be returned.
 //
-bool ParseTime(const std::string& format, const std::string& input, Time* time,
+bool ParseTime(absl::string_view format, absl::string_view input, Time* time,
                std::string* err);
 
 // Like ParseTime() above, but if the format string does not contain a UTC
@@ -1323,7 +1323,7 @@ bool ParseTime(const std::string& format, const std::string& input, Time* time,
 // of ambiguity or non-existence, in which case the "pre" time (as defined
 // by TimeZone::TimeInfo) is returned.  For these reasons we recommend that
 // all date/time strings include a UTC offset so they're context independent.
-bool ParseTime(const std::string& format, const std::string& input, TimeZone tz,
+bool ParseTime(absl::string_view format, absl::string_view input, TimeZone tz,
                Time* time, std::string* err);
 
 // ============================================================================