Remove the implementation of absl::string_view, which was only needed

prior to C++17. `absl::string_view` is now an alias for `std::string_view`.
It is recommended that clients simply use `std::string_view`.

PiperOrigin-RevId: 845822478
Change-Id: I220530c84118e5b9ef110baa002c232ac8f2c5f2

Author: derekmauro

CMake/AbseilDll.cmake

@@ -345,8 +345,6 @@ set(ABSL_INTERNAL_DLL_FILES
   "strings/str_replace.h"
   "strings/str_split.cc"
   "strings/str_split.h"
-  "strings/string_view.cc"
-  "strings/string_view.h"
   "strings/strip.h"
   "strings/substitute.cc"
   "strings/substitute.h"
@@ -446,6 +444,7 @@ set(ABSL_INTERNAL_DLL_FILES
   "types/variant.h"
   "utility/utility.h"
   "debugging/leak_check.cc"
+  "strings/string_view.h"
 )
 
 if(MSVC)

absl/base/config.h

@@ -526,20 +526,11 @@ static_assert(ABSL_INTERNAL_INLINE_NAMESPACE_STR[0] != 'h' ||
 #define ABSL_USES_STD_ANY 1
 #define ABSL_HAVE_STD_OPTIONAL 1
 #define ABSL_USES_STD_OPTIONAL 1
+#define ABSL_HAVE_STD_STRING_VIEW 1
+#define ABSL_USES_STD_STRING_VIEW 1
 #define ABSL_HAVE_STD_VARIANT 1
 #define ABSL_USES_STD_VARIANT 1
 
-// ABSL_HAVE_STD_STRING_VIEW
-//
-// Deprecated: always defined to 1.
-// std::string_view was added in C++17, which means all versions of C++
-// supported by Abseil have it.
-#ifdef ABSL_HAVE_STD_STRING_VIEW
-#error "ABSL_HAVE_STD_STRING_VIEW cannot be directly set."
-#else
-#define ABSL_HAVE_STD_STRING_VIEW 1
-#endif
-
 // ABSL_HAVE_STD_ORDERING
 //
 // Checks whether C++20 std::{partial,weak,strong}_ordering are available.
@@ -556,20 +547,6 @@ static_assert(ABSL_INTERNAL_INLINE_NAMESPACE_STR[0] != 'h' ||
 #define ABSL_HAVE_STD_ORDERING 1
 #endif
 
-// ABSL_USES_STD_STRING_VIEW
-//
-// Indicates whether absl::string_view is an alias for std::string_view.
-#if !defined(ABSL_OPTION_USE_STD_STRING_VIEW)
-#error options.h is misconfigured.
-#elif ABSL_OPTION_USE_STD_STRING_VIEW == 0
-#undef ABSL_USES_STD_STRING_VIEW
-#elif ABSL_OPTION_USE_STD_STRING_VIEW == 1 || \
-    ABSL_OPTION_USE_STD_STRING_VIEW == 2
-#define ABSL_USES_STD_STRING_VIEW 1
-#else
-#error options.h is misconfigured.
-#endif
-
 // ABSL_USES_STD_ORDERING
 //
 // Indicates whether absl::{partial,weak,strong}_ordering are aliases for the

absl/base/options.h

@@ -73,32 +73,6 @@
 // Type Compatibility Options
 // -----------------------------------------------------------------------------
 
-// ABSL_OPTION_USE_STD_STRING_VIEW
-//
-// This option controls whether absl::string_view is implemented as an alias to
-// std::string_view, or as an independent implementation.
-//
-// A value of 0 means to use Abseil's implementation.  This requires only C++11
-// support, and is expected to work on every toolchain we support.
-//
-// A value of 1 means to use an alias to std::string_view.  This requires that
-// all code using Abseil is built in C++17 mode or later.
-//
-// A value of 2 means to detect the C++ version being used to compile Abseil,
-// and use an alias only if a working std::string_view is available.  This
-// option is useful when you are building your program from source.  It should
-// not be used otherwise -- for example, if you are distributing Abseil in a
-// binary package manager -- since in mode 2, absl::string_view will name a
-// different type, with a different mangled name and binary layout, depending on
-// the compiler flags passed by the end user.  For more info, see
-// https://abseil.io/about/design/dropin-types.
-//
-// User code should not inspect this macro.  To check in the preprocessor if
-// absl::string_view is a typedef of std::string_view, use the feature macro
-// ABSL_USES_STD_STRING_VIEW.
-
-#define ABSL_OPTION_USE_STD_STRING_VIEW 2
-
 // ABSL_OPTION_USE_STD_ORDERING
 //
 // This option controls whether absl::{partial,weak,strong}_ordering are

absl/strings/BUILD.bazel

@@ -36,16 +36,13 @@ licenses(["notice"])
 
 cc_library(
     name = "string_view",
-    srcs = ["string_view.cc"],
     hdrs = ["string_view.h"],
     copts = ABSL_DEFAULT_COPTS,
     linkopts = ABSL_DEFAULT_LINKOPTS,
     deps = [
-        "//absl/base",
         "//absl/base:config",
         "//absl/base:core_headers",
         "//absl/base:nullability",
-        "//absl/base:throw_delegate",
     ],
 )
 
@@ -410,23 +407,6 @@ cc_test(
     ],
 )
 
-cc_binary(
-    name = "string_view_benchmark",
-    testonly = True,
-    srcs = ["string_view_benchmark.cc"],
-    copts = ABSL_TEST_COPTS,
-    tags = ["benchmark"],
-    visibility = ["//visibility:private"],
-    deps = [
-        ":string_view",
-        ":strings",
-        "//absl/base:core_headers",
-        "//absl/base:raw_logging_internal",
-        "//absl/random",
-        "@google_benchmark//:benchmark_main",
-    ],
-)
-
 cc_test(
     name = "string_view_test",
     size = "small",

absl/strings/CMakeLists.txt

@@ -19,16 +19,12 @@ absl_cc_library(
     string_view
   HDRS
     "string_view.h"
-  SRCS
-    "string_view.cc"
   COPTS
     ${ABSL_DEFAULT_COPTS}
   DEPS
-    absl::base
     absl::config
     absl::core_headers
     absl::nullability
-    absl::throw_delegate
   PUBLIC
 )