From 28528f595ebe3553ddb465de24f21ae8bbfb5c37 Mon Sep 17 00:00:00 2001
From: Abseil Team <absl-team@google.com>
Date: Tue, 10 Dec 2024 12:14:58 -0800
Subject: [PATCH] Add support for std::string_view in StrCat even when
 absl::string_view != std::string_view.

PiperOrigin-RevId: 704802270
Change-Id: I8293f755a688707db575f0df22440f24ffad430e
---
 absl/strings/BUILD.bazel     |  1 +
 absl/strings/CMakeLists.txt  |  1 +
 absl/strings/str_cat.h       | 11 +++++++++++
 absl/strings/str_cat_test.cc | 13 +++++++++++++
 4 files changed, 26 insertions(+)

diff --git a/absl/strings/BUILD.bazel b/absl/strings/BUILD.bazel
index 00ed5270..1b5fbea6 100644
--- a/absl/strings/BUILD.bazel
+++ b/absl/strings/BUILD.bazel
@@ -1118,6 +1118,7 @@ cc_test(
     deps = [
         ":str_format",
         ":strings",
+        "//absl/base:config",
         "@com_google_googletest//:gtest",
         "@com_google_googletest//:gtest_main",
     ],
diff --git a/absl/strings/CMakeLists.txt b/absl/strings/CMakeLists.txt
index f6f4b10e..993d7517 100644
--- a/absl/strings/CMakeLists.txt
+++ b/absl/strings/CMakeLists.txt
@@ -371,6 +371,7 @@ absl_cc_test(
   DEPS
     absl::strings
     absl::str_format
+    absl::config
     absl::core_headers
     GTest::gmock_main
 )
diff --git a/absl/strings/str_cat.h b/absl/strings/str_cat.h
index b98adc02..1a806627 100644
--- a/absl/strings/str_cat.h
+++ b/absl/strings/str_cat.h
@@ -101,6 +101,7 @@
 #include <vector>
 
 #include "absl/base/attributes.h"
+#include "absl/base/config.h"
 #include "absl/base/nullability.h"
 #include "absl/base/port.h"
 #include "absl/meta/type_traits.h"
@@ -110,6 +111,10 @@
 #include "absl/strings/numbers.h"
 #include "absl/strings/string_view.h"
 
+#if defined(ABSL_HAVE_STD_STRING_VIEW) && !defined(ABSL_USES_STD_STRING_VIEW)
+#include <string_view>
+#endif
+
 namespace absl {
 ABSL_NAMESPACE_BEGIN
 
@@ -361,6 +366,12 @@ class AlphaNum {
                ABSL_ATTRIBUTE_LIFETIME_BOUND)
       : piece_(pc) {}
 
+#if defined(ABSL_HAVE_STD_STRING_VIEW) && !defined(ABSL_USES_STD_STRING_VIEW)
+  AlphaNum(std::string_view pc  // NOLINT(runtime/explicit)
+               ABSL_ATTRIBUTE_LIFETIME_BOUND)
+      : piece_(pc.data(), pc.size()) {}
+#endif  // !ABSL_USES_STD_STRING_VIEW
+
   template <typename T, typename = typename std::enable_if<
                             HasAbslStringify<T>::value>::type>
   AlphaNum(  // NOLINT(runtime/explicit)
diff --git a/absl/strings/str_cat_test.cc b/absl/strings/str_cat_test.cc
index 66eddf0d..fb11734d 100644
--- a/absl/strings/str_cat_test.cc
+++ b/absl/strings/str_cat_test.cc
@@ -24,9 +24,14 @@
 #include <vector>
 
 #include "gtest/gtest.h"
+#include "absl/base/config.h"
 #include "absl/strings/str_format.h"
 #include "absl/strings/string_view.h"
 
+#if defined(ABSL_HAVE_STD_STRING_VIEW)
+#include <string_view>
+#endif
+
 #ifdef __ANDROID__
 // Android assert messages only go to system log, so death tests cannot inspect
 // the message for matching.
@@ -214,6 +219,14 @@ TEST(StrCat, CornerCases) {
   EXPECT_EQ(result, "");
 }
 
+#if defined(ABSL_HAVE_STD_STRING_VIEW)
+TEST(StrCat, StdStringView) {
+  std::string_view pieces[] = {"Hello", ", ", "World", "!"};
+  EXPECT_EQ(absl::StrCat(pieces[0], pieces[1], pieces[2], pieces[3]),
+                         "Hello, World!");
+}
+#endif  // ABSL_HAVE_STD_STRING_VIEW
+
 TEST(StrCat, NullConstCharPtr) {
   const char* null = nullptr;
   EXPECT_EQ(absl::StrCat("mon", null, "key"), "monkey");