Export of internal Abseil changes.

--
e7f892a0b9b313b434c5f9e9a2365b377204b60e by Abseil Team <absl-team@google.com>:

Remove internal CaseEqual helper now that we have the equivalent absl::EqualsIgnoreCase.

PiperOrigin-RevId: 225189084

--
722af2c74766d2fe3cee13c8dc886d39aedda597 by Abseil Team <absl-team@google.com>:

Add -Wno-extra-semi-stmt to silence that warning.

The [-Wno-extra-semi] is already disabled in the build.  This
change will allow the build to remain consistent across newer
versions of clang which are now issuing a new similiar warning
[-Wextra-semi-stmt]:

  https://clang.llvm.org/docs/ReleaseNotes.html#major-new-features
  https://clang.llvm.org/docs/DiagnosticsReference.html#wextra-semi-stmt

PiperOrigin-RevId: 225185101

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f7fd6244b4efcf0331631a54b7b0cf5f1f691a89 by CJ Johnson <johnsoncj@google.com>:

Move using directive in swap implementation

PiperOrigin-RevId: 225017825

--
3005841725df5b9cdb35c8a5319bb4c78b5dc2b7 by Abseil Team <absl-team@google.com>:

Update absl/strings/CMakeLists.txt to use new functions
i.e. absl_cc_(library|test)

PiperOrigin-RevId: 224860689

--
eeaf7099924b182472bfea3636ef6d9a39adfc50 by CJ Johnson <johnsoncj@google.com>:

Prefer public method over private for InlinedVector allocator access

PiperOrigin-RevId: 224825775

--
db9d218e3ca7ab400eef97778b720cb082a03281 by Eric Fiselier <ericwf@google.com>:

Take advantage of secret libc++ resize uninitialized function in string.

PiperOrigin-RevId: 224817877
GitOrigin-RevId: e7f892a0b9b313b434c5f9e9a2365b377204b60e
Change-Id: I051beee37ee03f0570bd2e068355ad75c8bdfcf8

1 files changed, 19 insertions, 16 deletions

diff --git a/absl/strings/internal/resize_uninitialized.h b/absl/strings/internal/resize_uninitialized.h
index a94e0547b50f..c2da0da9e4a2 100644
--- a/absl/strings/internal/resize_uninitialized.h
+++ b/absl/strings/internal/resize_uninitialized.h
@@ -18,6 +18,7 @@
 #define ABSL_STRINGS_INTERNAL_RESIZE_UNINITIALIZED_H_
 
 #include <string>
+#include <type_traits>
 #include <utility>
 
 #include "absl/base/port.h"
@@ -27,22 +28,24 @@ namespace absl {
 namespace strings_internal {
 
 // Is a subclass of true_type or false_type, depending on whether or not
-// T has a resize_uninitialized member.
-template <typename T, typename = void>
-struct HasResizeUninitialized : std::false_type {};
-template <typename T>
-struct HasResizeUninitialized<
-    T, absl::void_t<decltype(std::declval<T>().resize_uninitialized(237))>>
-    : std::true_type {};
+// T has a __resize_default_init member.
+template <typename string_type, typename = void>
+struct ResizeUninitializedTraits {
+  using HasMember = std::false_type;
+  static void Resize(string_type* s, size_t new_size) { s->resize(new_size); }
+};
 
+// __resize_default_init is provided by libc++ >= 8.0 and by Google's internal
+// ::string implementation.
 template <typename string_type>
-void ResizeUninit(string_type* s, size_t new_size, std::true_type) {
-  s->resize_uninitialized(new_size);
-}
-template <typename string_type>
-void ResizeUninit(string_type* s, size_t new_size, std::false_type) {
-  s->resize(new_size);
-}
+struct ResizeUninitializedTraits<
+    string_type, absl::void_t<decltype(std::declval<string_type&>()
+                                           .__resize_default_init(237))> > {
+  using HasMember = std::true_type;
+  static void Resize(string_type* s, size_t new_size) {
+    s->__resize_default_init(new_size);
+  }
+};
 
 // Returns true if the string implementation supports a resize where
 // the new characters added to the string are left untouched.
@@ -51,7 +54,7 @@ void ResizeUninit(string_type* s, size_t new_size, std::false_type) {
 // the previous function.)
 template <typename string_type>
 inline constexpr bool STLStringSupportsNontrashingResize(string_type*) {
-  return HasResizeUninitialized<string_type>();
+  return ResizeUninitializedTraits<string_type>::HasMember::value;
 }
 
 // Like str->resize(new_size), except any new characters added to "*str" as a
@@ -60,7 +63,7 @@ inline constexpr bool STLStringSupportsNontrashingResize(string_type*) {
 // store of the string with known data. Uses a Google extension to ::string.
 template <typename string_type, typename = void>
 inline void STLStringResizeUninitialized(string_type* s, size_t new_size) {
-  ResizeUninit(s, new_size, HasResizeUninitialized<string_type>());
+  ResizeUninitializedTraits<string_type>::Resize(s, new_size);
 }
 
 }  // namespace strings_internal