Export of internal Abseil changes.

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70f43a482d7d4ae4a255f17ca02b0106653dd600 by Shaindel Schwartz <shaindel@google.com>:

Internal change

PiperOrigin-RevId: 201571193

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93e6e9c2e683158be49d9dd1f5cb1a91d0c0f556 by Abseil Team <absl-team@google.com>:

Internal change.

PiperOrigin-RevId: 201567108

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fbd8ee94fbe9f2448e5adf5e88706f9c8216048f by Juemin Yang <jueminyang@google.com>:

str_format release

PiperOrigin-RevId: 201565129

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387faa301555a8a888c4429df52734aa806dca46 by Abseil Team <absl-team@google.com>:

Adds a defaulted allocator parameter to the size_type constructor of InlinedVector

PiperOrigin-RevId: 201558711

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39b15ea2c68d7129d70cbde7e71af900032595ec by Matt Calabrese <calabrese@google.com>:

Update the variant implementation to eliminate unnecessary checking on alternative access when the index is known or required to be correct.

PiperOrigin-RevId: 201529535

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adab77f1f7bb363aa534297f22aae2b0f08889ea by Abseil Team <absl-team@google.com>:

Import of CCTZ from GitHub.

PiperOrigin-RevId: 201458388

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a701dc0ba62e3cadf0de14203415b91df4ee8151 by Greg Falcon <gfalcon@google.com>:

Internal cleanup

PiperOrigin-RevId: 201394836

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8a7191410b8f440fdfa27f722ff05e451502ab61 by Abseil Team <absl-team@google.com>:

Import of CCTZ from GitHub.

PiperOrigin-RevId: 201369269
GitOrigin-RevId: 70f43a482d7d4ae4a255f17ca02b0106653dd600
Change-Id: I8ab073b30b4e27405a3b6da2c826bb4f3f0b9af6

1 files changed, 11 insertions, 4 deletions

diff --git a/absl/types/internal/variant.h b/absl/types/internal/variant.h
index 3414c9142daf..7db5e0535f68 100644
--- a/absl/types/internal/variant.h
+++ b/absl/types/internal/variant.h
@@ -579,12 +579,9 @@ struct VariantCoreAccess {
     self.index_ = other.index();
   }
 
+  // Access a variant alternative, assuming the index is correct.
   template <std::size_t I, class Variant>
   static VariantAccessResult<I, Variant> Access(Variant&& self) {
-    if (ABSL_PREDICT_FALSE(self.index_ != I)) {
-      TypedThrowBadVariantAccess<VariantAccessResult<I, Variant>>();
-    }
-
     // This cast instead of invocation of AccessUnion with an rvalue is a
     // workaround for msvc. Without this there is a runtime failure when dealing
     // with rvalues.
@@ -593,6 +590,16 @@ struct VariantCoreAccess {
         variant_internal::AccessUnion(self.state_, SizeT<I>()));
   }
 
+  // Access a variant alternative, throwing if the index is incorrect.
+  template <std::size_t I, class Variant>
+  static VariantAccessResult<I, Variant> CheckedAccess(Variant&& self) {
+    if (ABSL_PREDICT_FALSE(self.index_ != I)) {
+      TypedThrowBadVariantAccess<VariantAccessResult<I, Variant>>();
+    }
+
+    return Access<I>(absl::forward<Variant>(self));
+  }
+
   // The implementation of the move-assignment operation for a variant.
   template <class VType>
   struct MoveAssignVisitor {