Apply LTS transformations for 20260526 LTS branch (#2063) * Apply LTS transformations for 20260526 LTS branch * [Cherry-pick] Fix logging when absl::SourceLocation is an alias of std::source_location

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 3583e3d..2b6bbfe 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt

@@ -23,8 +23,8 @@
   cmake_policy(SET CMP0141 NEW)
 endif (POLICY CMP0141)
 
-project(absl LANGUAGES CXX)
-set(ABSL_SOVERSION 0)
+project(absl LANGUAGES CXX VERSION 20260526)
+set(ABSL_SOVERSION "2605.0.0")
 include(CTest)
 
 # Output directory is correct by default for most build setups. However, when
@@ -170,17 +170,7 @@
 add_subdirectory(absl)
 
 if(ABSL_ENABLE_INSTALL)
-  # absl:lts-remove-begin(system installation is supported for LTS releases)
-  # We don't support system-wide installation
-  list(APPEND SYSTEM_INSTALL_DIRS "/usr/local" "/usr" "/opt/" "/opt/local" "c:/Program Files/${PROJECT_NAME}")
-  if(NOT DEFINED CMAKE_INSTALL_PREFIX OR CMAKE_INSTALL_PREFIX IN_LIST SYSTEM_INSTALL_DIRS)
-    message(WARNING "\
-  The default and system-level install directories are unsupported except in LTS \
-  releases of Abseil.  Please set CMAKE_INSTALL_PREFIX to install Abseil in your \
-  source or build tree directly.\
-    ")
-  endif()
-  # absl:lts-remove-end
+  
 
   # install as a subdirectory only
   install(EXPORT ${PROJECT_NAME}Targets

diff --git a/MODULE.bazel b/MODULE.bazel
index cc60d22..7ed0b92 100644
--- a/MODULE.bazel
+++ b/MODULE.bazel

@@ -16,7 +16,7 @@
 
 module(
     name = "abseil-cpp",
-    version = "head",
+    version = "20260526.0",
 )
 
 cc_configure = use_extension("@rules_cc//cc:extensions.bzl",

diff --git a/absl/base/config.h b/absl/base/config.h
index d4a7bfb..6b2c81c 100644
--- a/absl/base/config.h
+++ b/absl/base/config.h

@@ -117,8 +117,8 @@
 //
 // LTS releases can be obtained from
 // https://github.com/abseil/abseil-cpp/releases.
-#undef ABSL_LTS_RELEASE_VERSION
-#undef ABSL_LTS_RELEASE_PATCH_LEVEL
+#define ABSL_LTS_RELEASE_VERSION 20260526
+#define ABSL_LTS_RELEASE_PATCH_LEVEL 0
 
 // Helper macro to convert a CPP variable to a string literal.
 #define ABSL_INTERNAL_DO_TOKEN_STR(x) #x

diff --git a/absl/base/options.h b/absl/base/options.h
index 033eac3..bc344e9 100644
--- a/absl/base/options.h
+++ b/absl/base/options.h

@@ -150,8 +150,8 @@
 // be changed to a new, unique identifier name.  In particular "head" is not
 // allowed.
 
-#define ABSL_OPTION_USE_INLINE_NAMESPACE 0
-#define ABSL_OPTION_INLINE_NAMESPACE_NAME head
+#define ABSL_OPTION_USE_INLINE_NAMESPACE 1
+#define ABSL_OPTION_INLINE_NAMESPACE_NAME lts_20260526
 
 // ABSL_OPTION_HARDENED
 //

diff --git a/absl/log/BUILD.bazel b/absl/log/BUILD.bazel
index e6793b1..b1cff4b 100644
--- a/absl/log/BUILD.bazel
+++ b/absl/log/BUILD.bazel

@@ -502,6 +502,7 @@
         "//absl/log/internal:test_matchers",
         "//absl/strings",
         "//absl/strings:str_format",
+        "//absl/types:source_location",
         "@googletest//:gtest",
         "@googletest//:gtest_main",
     ],

diff --git a/absl/log/CMakeLists.txt b/absl/log/CMakeLists.txt
index b271d09..e0a307b 100644
--- a/absl/log/CMakeLists.txt
+++ b/absl/log/CMakeLists.txt

@@ -1017,6 +1017,7 @@
     absl::log
     absl::log_internal_test_matchers
     absl::scoped_mock_log
+    absl::source_location
     absl::str_format
     absl::strings
     GTest::gmock_main

diff --git a/absl/log/internal/log_message.h b/absl/log/internal/log_message.h
index 7e2a86a..b9b533e 100644
--- a/absl/log/internal/log_message.h
+++ b/absl/log/internal/log_message.h

@@ -179,6 +179,13 @@
   LogMessage& operator<<(wchar_t* absl_nullable v);
   LogMessage& operator<<(wchar_t v);
 
+  // Overload for absl::SourceLocation or the std::source_location alias.
+  LogMessage& operator<<(const absl::SourceLocation& loc) {
+    OstreamView view(*data_);
+    view.stream() << loc.file_name() << ':' << loc.line();
+    return *this;
+  }
+
   // Handle stream manipulators e.g. std::endl.
   LogMessage& operator<<(std::ostream& (*absl_nonnull m)(std::ostream& os));
   LogMessage& operator<<(std::ios_base& (*absl_nonnull m)(std::ios_base& os));

diff --git a/absl/log/log_format_test.cc b/absl/log/log_format_test.cc
index b23d90f..06ce2f5 100644
--- a/absl/log/log_format_test.cc
+++ b/absl/log/log_format_test.cc

@@ -41,6 +41,7 @@
 #include "absl/strings/str_cat.h"
 #include "absl/strings/str_format.h"
 #include "absl/strings/string_view.h"
+#include "absl/types/source_location.h"
 
 namespace {
 using ::absl::log_internal::AsString;
@@ -291,6 +292,21 @@
   LOG(INFO) << value.bits;
 }
 
+TEST(SourceLocationTest, Format) {
+  absl::ScopedMockLog test_sink(absl::MockLogDefault::kDisallowUnexpected);
+  EXPECT_CALL(test_sink, Send).Times(0);
+
+  absl::SourceLocation loc = absl::SourceLocation::current();
+  std::string expected = absl::StrCat(__FILE__, ":", __LINE__ - 1);
+
+  EXPECT_CALL(test_sink, Send(AllOf(TextMessage(Eq(expected)),
+                                    ENCODED_MESSAGE(HasValues(ElementsAre(
+                                        ValueWithStr(Eq(expected))))))));
+
+  test_sink.StartCapturingLogs();
+  LOG(INFO) << loc;
+}
+
 // Ignore these test cases on GCC due to "is too small to hold all values ..."
 // warning.
 #if !defined(__GNUC__) || defined(__clang__)