Export of internal Abseil changes

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8bdb2020150ed0fd4a4e520e454dc5f54e33f776 by Eric Fiselier <ericwf@google.com>:

Workaround bug in GCC 9.2 and after.

PiperOrigin-RevId: 291982551

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47ff4820e595f96c082a90d733725f6882d83e3b by Abseil Team <absl-team@google.com>:

Improve ABSL_ATTRIBUTE_PACKED documentation

Recommend to apply ABSL_ATTRIBUTE_PACKED to structure members instead of to an entire structure because applying this attribute to an entire structure may cause the compiler to generate suboptimal code. It reduces the alignment of the data structure from a value larger than one to one. When applied to a structure, ABSL_ATTRIBUTE_PACKED reduces the alignment of a structure (alignof()) to 1. As a result, the compiler can no longer assume that e.g. uint32 members are aligned on a four byte boundary and hence is forced to use single-byte load and store instructions on CPU architectures that do not support non-aligned loads or stores.

PiperOrigin-RevId: 291977920

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902b7a86f860da699d3a2e5c738be5ef73ede3b4 by Mark Barolak <mbar@google.com>:

Internal change

PiperOrigin-RevId: 291963048

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bb3bd3247e376d53a3080b105f13ec7566d3ae50 by Abseil Team <absl-team@google.com>:

Support the C++17 insert_or_assign() API in btree_map.

PiperOrigin-RevId: 291945474

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ff3b3cfcbbc64f086f95501f48d49426bcde356f by Gennadiy Rozental <rogeeff@google.com>:

Import of CCTZ from GitHub.

PiperOrigin-RevId: 291861110

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fd465cd9cbbacd3962f67a7346d6462edaddd809 by Derek Mauro <dmauro@google.com>:

Add flaky=1 to beta_distribution_test.

PiperOrigin-RevId: 291757364

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3603adfb59c4128c542b670952cce250d59e1f67 by Derek Mauro <dmauro@google.com>:

Separate the initialization of NumCPUs() and NominalCPUFrequency()

The OSS version of Abseil never needs to call NominalCPUFrequency().
In some configurations, initializing NominalCPUFrequency() requires
spending at least 3ms measuring the CPU frequency. By separating the
initialization from NumCPUs(), which is called in most configurations,
we can save at least 3ms of program startup time.

PiperOrigin-RevId: 291737273

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bea9e4a6bff5a0351d340deab966641867e08c4d by Abseil Team <absl-team@google.com>:

Change the cmake library names not to have a redundant `absl_` prefix.

PiperOrigin-RevId: 291640501

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501b602ef260cd7c8c527342581ceffb3c5b6d4c by Gennadiy Rozental <rogeeff@google.com>:

Introducing benchmark for absl::GetFlag.

PiperOrigin-RevId: 291433394

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4eeaddc788da4b91c272a8adca77ca6dbbbc1d44 by Xiaoyi Zhang <zhangxy@google.com>:

fix: Add support for more ARM processors detection

Import of https://github.com/abseil/abseil-cpp/pull/608

PiperOrigin-RevId: 291420397

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a3087a8e883c5d71de7d9bd4ec8f4db5142dfcf5 by Derek Mauro <dmauro@google.com>:

Removes the flaky raw_hash_set prefetch test

PiperOrigin-RevId: 291197079

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aad6c2121c102ac36216e771c83227cf3e3bfd66 by Andy Soffer <asoffer@google.com>:

Enable building Abseil as a DLL.
This is currently experimental and unsupported.

This CL does a few things:
1. Adds the ABSL_DLL macro to any class holding a static data member, or to global constants in headers.
2. Adds a whitelist of all files in the DLL and all the build targets that are conglomerated into the DLL.
3. When BUILD_SHARED_LIBS is specified, any build target that would be in the DLL still exists, but we swap out all of it's dependencies so it just depends on abseil_dll

PiperOrigin-RevId: 291192055

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5e888cd6f2a7722805d41f872108a03a84e421c7 by Mark Barolak <mbar@google.com>:

Move absl/strings/internal/escaping.{cc,h} into internal build targets.

This puts absl/strings/internal/escaping.h behind a whitelist and it also resolves https://github.com/abseil/abseil-cpp/issues/604.

PiperOrigin-RevId: 291173320

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166836d24970da87587c1728036f53f05a28f0af by Eric Fiselier <ericwf@google.com>:

Internal Change.

PiperOrigin-RevId: 291012718

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996ddb3dffda02440fa93f30ca5d71b14b688875 by Abseil Team <absl-team@google.com>:

Fix shared libraries log spam for built-in types in absl::GetFlag

PiperOrigin-RevId: 290772743
GitOrigin-RevId: 8bdb2020150ed0fd4a4e520e454dc5f54e33f776
Change-Id: I8bf2265dd14ebbace220a1b6b982bb5040ad2a26

1 files changed, 25 insertions, 62 deletions

diff --git a/absl/time/time.h b/absl/time/time.h
index 1be5727c0dbc..33a4a630c296 100644
--- a/absl/time/time.h
+++ b/absl/time/time.h
@@ -527,59 +527,30 @@ std::chrono::seconds ToChronoSeconds(Duration d);
 std::chrono::minutes ToChronoMinutes(Duration d);
 std::chrono::hours ToChronoHours(Duration d);
 
-
 // FormatDuration()
 //
-// Returns a string represention of the duration in a format consisting of a
-// possibly-signed prefix and a sequence of decimal numbers, each with an
-// optional fractional part and a unit suffix.
-//
-// Valid unit suffixes are "ns", "us" "ms", "s", "m", and "h".
-//
-// Simple examples include "300ms", "-1.5h", and "2h45m". Returns "inf" or
-// "-inf" for +/- `InfiniteDuration()` values and "0" for `ZeroDuration()`
-// values.
-//
-// This string format is used both as an input for parsing (when handling
-// command-line flags of type `absl::Duration`) and as an output in
-// `FormatDuration()`
+// Returns a string representing the duration in the form "72h3m0.5s".
+// Returns "inf" or "-inf" for +/- `InfiniteDuration()`.
 std::string FormatDuration(Duration d);
 
+// Output stream operator.
+inline std::ostream& operator<<(std::ostream& os, Duration d) {
+  return os << FormatDuration(d);
+}
+
 // ParseDuration()
 //
-// Parses a `dur_string` of the format noted above into an `absl::Duration`
-// value.
-//
-// Parses "0" as a zero-length duration value. Parses "-inf" or "+inf" as
-// infinite durations values.
+// Parses a duration string consisting of a possibly signed sequence of
+// decimal numbers, each with an optional fractional part and a unit
+// 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);
 
-// AbslParseFlag()
-//
-// Parses the command-line flag string representation `text` (using the format
-// noted above) into an `absl::Duration` destination, setting `error` on
-// failure.
-//
-// Example:
-//
-//   --timeout=6h30m
-//   --timeout=inf       // Equivalent to `InfiniteDuration()`
-//   --timeout=0         // Equivalent to `ZeroDuration()`
+// Support for flag values of type Duration. Duration flags must be specified
+// in a format that is valid input for absl::ParseDuration().
 bool AbslParseFlag(absl::string_view text, Duration* dst, std::string* error);
-
-// AbslUnparseFlag()
-//
-// Unparses an `absl::Duration` into a command-line string representation using
-// the format noted above.
 std::string AbslUnparseFlag(Duration d);
-
-// operator<<()
-//
-// Output stream operator, returning a stream in the format noted above.
-inline std::ostream& operator<<(std::ostream& os, Duration d) {
-  return os << FormatDuration(d);
-}
-
 ABSL_DEPRECATED("Use AbslParseFlag() instead.")
 bool ParseFlag(const std::string& text, Duration* dst, std::string* error);
 ABSL_DEPRECATED("Use AbslUnparseFlag() instead.")
@@ -842,29 +813,18 @@ Time FromChrono(const std::chrono::system_clock::time_point& tp);
 //   // tp == std::chrono::system_clock::from_time_t(123);
 std::chrono::system_clock::time_point ToChronoTime(Time);
 
-// AbslParseFlag()
-//
-// Parses the command-line flag string representation `text` into an
-// `absl::Time` destination, setting `error` on failure. Time flag string
-// representations must be specified in a format that matches
-// `absl::RFC3339_full`.
-//
-// Example:
+// Support for flag values of type Time. Time flags must be specified in a
+// format that matches absl::RFC3339_full. For example:
 //
 //   --start_time=2016-01-02T03:04:05.678+08:00
 //
 // Note: A UTC offset (or 'Z' indicating a zero-offset from UTC) is required.
 //
 // Additionally, if you'd like to specify a time as a count of
-// seconds/milliseconds/etc from the Unix epoch, use an `absl::Duration` flag
-// and add that duration to `absl::UnixEpoch()` to get an `absl::Time`.
+// seconds/milliseconds/etc from the Unix epoch, use an absl::Duration flag
+// and add that duration to absl::UnixEpoch() to get an absl::Time.
 bool AbslParseFlag(absl::string_view text, Time* t, std::string* error);
-
-// AbslUnparseFlag()
-//
-// Unparses an `absl::Time` into a command-line string format as noted above.
 std::string AbslUnparseFlag(Time t);
-
 ABSL_DEPRECATED("Use AbslParseFlag() instead.")
 bool ParseFlag(const std::string& text, Time* t, std::string* error);
 ABSL_DEPRECATED("Use AbslUnparseFlag() instead.")
@@ -1243,15 +1203,18 @@ struct tm ToTM(Time t, TimeZone tz);
 // time with UTC offset.  Also note the use of "%Y": RFC3339 mandates that
 // years have exactly four digits, but we allow them to take their natural
 // width.
-extern const char RFC3339_full[];  // %Y-%m-%dT%H:%M:%E*S%Ez
-extern const char RFC3339_sec[];   // %Y-%m-%dT%H:%M:%S%Ez
+ABSL_DLL extern const char
+    RFC3339_full[];  // %Y-%m-%dT%H:%M:%E*S%Ez
+ABSL_DLL extern const char RFC3339_sec[];  // %Y-%m-%dT%H:%M:%S%Ez
 
 // RFC1123_full
 // RFC1123_no_wday
 //
 // FormatTime()/ParseTime() format specifiers for RFC1123 date/time strings.
-extern const char RFC1123_full[];     // %a, %d %b %E4Y %H:%M:%S %z
-extern const char RFC1123_no_wday[];  // %d %b %E4Y %H:%M:%S %z
+ABSL_DLL extern const char
+    RFC1123_full[];  // %a, %d %b %E4Y %H:%M:%S %z
+ABSL_DLL extern const char
+    RFC1123_no_wday[];  // %d %b %E4Y %H:%M:%S %z
 
 // FormatTime()
 //