RCORE-2166 Fix building with Xcode 16

CHANGELOG.md

@@ -9,6 +9,7 @@
 * <How do the end-user experience this issue? what was the impact?> ([#????](https://github.com/realm/realm-core/issues/????), since v?.?.?)
 * Valgrind could report a branch on an uninitialized read when opening something that is not an encrypted Realm file as an encrypted Realm file ([PR #7789](https://github.com/realm/realm-core/pull/7789), since v14.10.0).
 * Opening an FLX realm asynchronously may not wait to download all data ([#7720](https://github.com/realm/realm-core/issues/7720), since FLX sync was introduced).
+* Fix compilation with Xcode 16 ([PR #7802](https://github.com/realm/realm-core/pull/7802))
 
 ### Breaking changes
 * None.
@@ -19,7 +20,7 @@
 -----------
 
 ### Internals
-* None.
+* Switch to building the Swift package and Cocoa binaries as C++20 ([PR #7802](https://github.com/realm/realm-core/pull/7802)).
 
 ----------------------------------------------
 

CMakeLists.txt

@@ -34,7 +34,9 @@ endif()
 set(PROJECT_VERSION ${DEP_VERSION})
 
 # Project-wide build flags
-set(CMAKE_CXX_STANDARD 17)
+if (NOT DEFINED CMAKE_CXX_STANDARD)
+    set(CMAKE_CXX_STANDARD 17)
+endif()
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
 set(CMAKE_CXX_EXTENSIONS OFF)
 

Package.swift

@@ -565,5 +565,5 @@ let package = Package(
                 .headerSearchPath("../"),
             ] + cxxSettings) as [CXXSetting]),
     ],
-    cxxLanguageStandard: .cxx17
+    cxxLanguageStandard: .cxx20
 )

evergreen/config.yml

@@ -1674,7 +1674,6 @@ buildvariants:
   expansions:
     cmake_bindir: "/opt/homebrew/bin"
     cmake_toolchain_file: "./tools/cmake/xcode.toolchain.cmake"
-    extra_flags: "-DCMAKE_XCODE_ATTRIBUTE_SDKROOT=iphoneos"
     cmake_build_tool_options: "-sdk iphonesimulator -arch arm64"
     cmake_generator: Xcode
     max_jobs: $(sysctl -n hw.logicalcpu)
@@ -1707,12 +1706,11 @@ buildvariants:
   expansions:
     cmake_url: "https://s3.amazonaws.com/static.realm.io/evergreen-assets/cmake-3.26.3-macos-universal.tar.gz"
     cmake_bindir: "./cmake_binaries/CMake.app/Contents/bin"
-    cmake_toolchain_file: "./tools/cmake/xcode.toolchain.cmake"
     cmake_generator: Xcode
     max_jobs: $(sysctl -n hw.logicalcpu)
     cmake_build_type: Release
     xcode_developer_dir: /Applications/Xcode13.1.app/Contents/Developer
-    extra_flags: -DCMAKE_SYSTEM_NAME=Darwin -DCMAKE_OSX_ARCHITECTURES=x86_64
+    extra_flags: -DREALM_ENABLE_ASSERTIONS=ON
   tasks:
   - name: benchmarks
   - name: compile_test
@@ -1724,12 +1722,11 @@ buildvariants:
   expansions:
     cmake_url: "https://s3.amazonaws.com/static.realm.io/evergreen-assets/cmake-3.26.3-macos-universal.tar.gz"
     cmake_bindir: "./cmake_binaries/CMake.app/Contents/bin"
-    cmake_toolchain_file: "./tools/cmake/xcode.toolchain.cmake"
     cmake_generator: Xcode
     max_jobs: $(sysctl -n hw.logicalcpu)
     cmake_build_type: Release
     xcode_developer_dir: /Applications/Xcode13.1.app/Contents/Developer
-    extra_flags: -DCMAKE_SYSTEM_NAME=Darwin -DCMAKE_OSX_ARCHITECTURES=arm64
+    extra_flags: -DREALM_ENABLE_ASSERTIONS=ON
   tasks:
   - name: benchmarks
 

src/CMakeLists.txt

@@ -1,6 +1,8 @@
 add_subdirectory(realm)
 add_subdirectory(external/IntelRDFPMathLib20U2)
-add_subdirectory(external/bson EXCLUDE_FROM_ALL)
+if (NOT REALM_BUILD_LIB_ONLY)
+    add_subdirectory(external/bson EXCLUDE_FROM_ALL)
+endif()
 
 if (REALM_ENABLE_GEOSPATIAL)
     add_subdirectory(external/s2)

src/realm/util/time.hpp

@@ -69,7 +69,7 @@ inline std::string format_utc_time(std::time_t time, const char* format)
 
 } // namespace realm::util
 
-#if __cplusplus < 202002L
+#if __cplusplus < 202002L || (defined(__apple_build_version__) && __apple_build_version__ < 15000309)
 // This is a C++17 version of https://en.cppreference.com/w/cpp/chrono/duration/operator_ltlt to make
 // logging and comparing durations easier - especially in tests.
 //

test/benchmark-larger/main.cpp

@@ -163,7 +163,7 @@ int main()
                               << std::endl;
                     start = end;
                     for (size_t i = 0; i < probe_size; ++i) {
-                        sum += objects[i].get<Int>(col2);
+                        sum = sum + objects[i].get<Int>(col2);
                     }
                     end = std::chrono::steady_clock::now();
                     diff = end - start;

test/test_util_file.cpp

@@ -117,9 +117,15 @@ TEST(Utils_File_dir)
 
 TEST(Utils_File_dir_unicode)
 {
+#if __cplusplus < 202002L
     using std::filesystem::u8path;
+#else
+    auto u8path = [](const std::string& str) {
+        return std::filesystem::path(reinterpret_cast<const char8_t*>(str.c_str()));
+    };
+#endif
 
-    constexpr char all_the_unicode[] = u8"фоо-бар Λορεμ ლორემ 植物 החלל جمعت søren";
+    const char* all_the_unicode = (const char*)u8"фоо-бар Λορεμ ლორემ 植物 החלל جمعت søren";
     std::string dir_name = File::resolve(all_the_unicode, test_util::get_test_path_prefix());
 
     // Create directory

tools/cmake/xcode.toolchain.cmake

@@ -15,19 +15,11 @@ set(CMAKE_XCODE_EFFECTIVE_PLATFORMS "-iphoneos;-iphonesimulator;-appletvos;-appl
 set(CMAKE_XCODE_ATTRIBUTE_SUPPORTS_MACCATALYST "YES")
 set(CMAKE_XCODE_ATTRIBUTE_TARGETED_DEVICE_FAMILY "1,2,3,4,7")
 
-# With Xcode 14+ the base SDK *mostly* doesn't matter any more, as it
-# officially supports multi-platform builds from a single target.
-# However, as of Xcode 15 beta 8 xcodebuild (but not Xcode itself) requires the
-# visionOS SDK to build for visionOS. 15.0 final doesn't include the visionOS
-# SDK, so the SDKROOT is explicitly set by the invoker when building with the
-# beta Xcode rather than here.
-# Xcode 13 requires using the correct SDK. We no longer support Xcode 13, but
-# still use it on evergreen to build the macOS tests (and nothing else).
+# As of Xcode 14 the iphoneos SDK supports building for all platforms to
+# support multi-platform builds. However, we still have some Xcode 13 builds (for
+# benchmarks) that need to set the SDKROOT to macosx.
 if(NOT DEFINED CMAKE_XCODE_ATTRIBUTE_SDKROOT)
-    set(CMAKE_XCODE_ATTRIBUTE_SDKROOT_1500 "iphoneos")
-    set(CMAKE_XCODE_ATTRIBUTE_SDKROOT_1400 "iphoneos")
-    set(CMAKE_XCODE_ATTRIBUTE_SDKROOT_1300 "macosx")
-    set(CMAKE_XCODE_ATTRIBUTE_SDKROOT "$(SDKROOT_$(XCODE_VERSION_MAJOR))")
+    set(CMAKE_XCODE_ATTRIBUTE_SDKROOT "iphoneos")
 endif()
 
 set(CMAKE_XCODE_ATTRIBUTE_IPHONEOS_DEPLOYMENT_TARGET "12.0")
@@ -39,3 +31,4 @@ set(CMAKE_XCODE_ATTRIBUTE_TVOS_DEPLOYMENT_TARGET "12.0")
 
 set(REALM_ENABLE_ASSERTIONS ON CACHE BOOL "Enable release assertions")
 set(REALM_XCODE_TOOLCHAIN TRUE)
+set(CMAKE_CXX_STANDARD 20)