Support AbslStringify in absl::Time and absl::Duration.

PiperOrigin-RevId: 516363556
Change-Id: Iae5e781d46dc8a8c4242ab460b57b65271b93159

absl/time/BUILD.bazel

@@ -91,6 +91,7 @@ cc_test(
         "//absl/base:config",
         "//absl/base:core_headers",
         "//absl/numeric:int128",
+        "//absl/strings:str_format",
         "//absl/time/internal/cctz:time_zone",
         "@com_google_googletest//:gtest_main",
     ],

absl/time/CMakeLists.txt

@@ -122,6 +122,8 @@ absl_cc_test(
     absl::time
     absl::config
     absl::core_headers
+    absl::strings
+    absl::str_format
     absl::time_zone
     GTest::gmock_main
 )

absl/time/duration_test.cc

@@ -16,8 +16,8 @@
 #include <winsock2.h>  // for timeval
 #endif
 
-#include <chrono>  // NOLINT(build/c++11)
 #include <cfloat>
+#include <chrono>  // NOLINT(build/c++11)
 #include <cmath>
 #include <cstdint>
 #include <ctime>
@@ -28,6 +28,7 @@
 
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
+#include "absl/strings/str_format.h"
 #include "absl/time/time.h"
 
 namespace {
@@ -1853,4 +1854,11 @@ TEST(Duration, FormatParseRoundTrip) {
 #undef TEST_PARSE_ROUNDTRIP
 }
 
+TEST(Duration, AbslStringify) {
+  // FormatDuration is already well tested, so just use one test case here to
+  // verify that StrFormat("%v", d) works as expected.
+  absl::Duration d = absl::Seconds(1);
+  EXPECT_EQ(absl::StrFormat("%v", d), absl::FormatDuration(d));
+}
+
 }  // namespace

absl/time/time.h

@@ -609,6 +609,12 @@ inline std::ostream& operator<<(std::ostream& os, Duration d) {
   return os << FormatDuration(d);
 }
 
+// Support for StrFormat(), StrCat() etc.
+template <typename Sink>
+void AbslStringify(Sink& sink, Duration d) {
+  sink.Append(FormatDuration(d));
+}
+
 // ParseDuration()
 //
 // Parses a duration string consisting of a possibly signed sequence of
@@ -1386,6 +1392,12 @@ inline std::ostream& operator<<(std::ostream& os, Time t) {
   return os << FormatTime(t);
 }
 
+// Support for StrFormat(), StrCat() etc.
+template <typename Sink>
+void AbslStringify(Sink& sink, Time t) {
+  sink.Append(FormatTime(t));
+}
+
 // ParseTime()
 //
 // Parses an input string according to the provided format string and

absl/time/time_test.cc

@@ -28,6 +28,7 @@
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
 #include "absl/numeric/int128.h"
+#include "absl/strings/str_format.h"
 #include "absl/time/clock.h"
 #include "absl/time/internal/test_util.h"
 
@@ -1287,4 +1288,11 @@ TEST(Time, PrevTransitionNYC) {
   // We have a transition but we don't know which one.
 }
 
+TEST(Time, AbslStringify) {
+  // FormatTime is already well tested, so just use one test case here to
+  // verify that StrFormat("%v", t) works as expected.
+  absl::Time t = absl::Now();
+  EXPECT_EQ(absl::StrFormat("%v", t), absl::FormatTime(t));
+}
+
 }  // namespace