Remove dependency on ZLIB (#8023)

* Deleted mentions of ZLIB

* Delete util::compression

* Remove libcompression dependency from CMake build

* Removed compression dependencies from Swift build

---------

Co-authored-by: Kræn Hansen <[email protected]>
Co-authored-by: Yavor Georgiev <[email protected]>

CMakeLists.txt

@@ -305,32 +305,6 @@ if(REALM_NEEDS_OPENSSL OR REALM_FORCE_OPENSSL)
     string(REGEX MATCH "^([0-9]+)\\.([0-9]+)" OPENSSL_VERSION_MAJOR_MINOR "${OPENSSL_VERSION}")
 endif()
 
-# Use Zlib for Sync, but allow integrators to override it
-# Don't use find_library(ZLIB) on Apple platforms - it hardcodes the path per platform,
-# so for an iOS build it'll use the path from the Device plaform, which is an error on Simulator.
-# Just use -lz and let Xcode figure it out
-# Emscripten does provide Zlib, but it doesn't work with find_package and is handled specially
-if(NOT APPLE AND NOT EMSCRIPTEN AND NOT TARGET ZLIB::ZLIB)
-    if(WIN32 OR (CMAKE_SYSTEM_NAME STREQUAL "Linux" AND REALM_LINUX_TOOLCHAIN))
-        find_package(ZLIB)
-        if (NOT ZLIB_FOUND)
-            realm_acquire_dependency(zlib ${DEP_ZLIB_VERSION} ZLIB_CMAKE_INCLUDE_FILE)
-            include(${ZLIB_CMAKE_INCLUDE_FILE})
-        endif()
-    elseif(ANDROID)
-        # On Android FindZLIB chooses the static libz over the dynamic one, but this leads to issues
-        # (see https://github.com/android/ndk/issues/1179)
-        # We want to link against the stub library instead of statically linking anyway,
-        # so we hack find_library to only consider shared object libraries when looking for libz
-        set(_CMAKE_FIND_LIBRARY_SUFFIXES_orig ${CMAKE_FIND_LIBRARY_SUFFIXES})
-        set(CMAKE_FIND_LIBRARY_SUFFIXES .so)
-    endif()
-    find_package(ZLIB REQUIRED)
-    if(ANDROID)
-        set(CMAKE_FIND_LIBRARY_SUFFIXES ${_CMAKE_FIND_LIBRARY_SUFFIXES_orig})
-    endif()
-endif()
-
 # Store configuration in header file
 configure_file(src/realm/util/config.h.in src/realm/util/config.h)
 

Package.swift

@@ -380,8 +380,6 @@ let package = Package(
                 .headerSearchPath("external"),
             ] + cxxSettings) as [CXXSetting],
             linkerSettings: [
-                .linkedLibrary("compression"),
-                .linkedLibrary("z"),
                 .linkedFramework("Foundation", .when(platforms: [.macOS, .iOS, .tvOS, .watchOS, .macCatalyst])),
                 .linkedFramework("Security", .when(platforms: [.macOS, .iOS, .tvOS, .watchOS, .macCatalyst])),
             ]),

dependencies.yml

@@ -1,7 +1,6 @@
 PACKAGE_NAME: realm-core
 VERSION: 20.0.0
 OPENSSL_VERSION: 3.3.1
-ZLIB_VERSION: 1.2.13
 # https://github.com/10gen/baas/commits
 # 2f308db is 2024 July 10
 BAAS_VERSION: 2f308db6f65333728a101d1fecbb792f9659a5ce

src/realm/CMakeLists.txt

@@ -76,7 +76,6 @@ set(UTIL_SOURCES
     util/base64.cpp
     util/basic_system_errors.cpp
     util/cli_args.cpp
-    util/compression.cpp
     util/encrypted_file_mapping.cpp
     util/fifo_helper.cpp
     util/file.cpp
@@ -224,7 +223,6 @@ set(REALM_INSTALL_HEADERS
     util/buffer_stream.hpp
     util/cf_ptr.hpp
     util/checked_mutex.hpp
-    util/compression.hpp
     util/encrypted_file_mapping.hpp
     util/errno.hpp
     util/features.h
@@ -397,22 +395,6 @@ if(REALM_HAVE_OPENSSL AND (UNIX OR WIN32))
     target_link_libraries(Storage PUBLIC OpenSSL::Crypto)
 endif()
 
-# Use Zlib if the imported target is defined, otherise use -lz on Apple platforms
-if(TARGET ZLIB::ZLIB)
-    target_link_libraries(Storage PUBLIC ZLIB::ZLIB)
-elseif(APPLE)
-    target_link_options(Storage PUBLIC "-lz")
-elseif(EMSCRIPTEN)
-    target_compile_options(Storage PUBLIC "-sUSE_ZLIB=1")
-    target_link_options(Storage PUBLIC "-sUSE_ZLIB=1")
-else()
-    message(FATAL_ERROR "No zlib dependency defined")
-endif()
-
-if(APPLE)
-    target_link_libraries(Storage PUBLIC "-lcompression")
-endif()
-
 install(TARGETS Storage EXPORT realm
         ARCHIVE DESTINATION lib
         COMPONENT devel)