macOS: build libzip from submodule against Homebrew zlib-ng-compat

requirements/macos.txt

@@ -11,7 +11,6 @@ jsoncpp
 libharu
 libpng
 libtiff
-libzip
 llvm@14
 ninja
 opencascade
@@ -23,4 +22,4 @@ spdlog
 tbb
 tinyxml2
 tl-expected
-zlib
+zlib-ng-compat

scripts/build_source.sh

@@ -92,6 +92,13 @@ if [[ $OSTYPE == 'darwin'* ]]; then
     -D PYTHON_INCLUDE_DIR=${PYTHON_INCLUDE_DIR} \
     -D PYTHON_EXECUTABLE:FILEPATH=${PYTHON_EXECUTABLE} \
   "
+
+  # Homebrew's zlib-ng-compat is keg-only; point CMake at it so MRMesh's
+  # find_package(ZLIB) resolves to zlib-ng rather than the macOS system zlib.
+  ZLIB_NG_COMPAT_PREFIX=$(brew --prefix zlib-ng-compat 2>/dev/null || true)
+  if [ -n "${ZLIB_NG_COMPAT_PREFIX}" ] && [ -d "${ZLIB_NG_COMPAT_PREFIX}" ]; then
+    MR_CMAKE_OPTIONS="${MR_CMAKE_OPTIONS} -D ZLIB_ROOT=${ZLIB_NG_COMPAT_PREFIX}"
+  fi
 fi
 
 if [[ $OSTYPE == 'darwin'* ]]; then

scripts/build_thirdparty.sh

@@ -100,6 +100,15 @@ fi
 
 if [[ $OSTYPE == 'darwin'* ]]; then
   NPROC=$(sysctl -n hw.logicalcpu)
+  # Homebrew's zlib-ng-compat is keg-only (shadowed by macOS system zlib),
+  # so CMake's find_package(ZLIB) won't pick it up unless we point at its
+  # keg prefix explicitly. We want our libzip submodule (built just below)
+  # and MeshLib's own ZLIB::ZLIB consumers to link against zlib-ng, not the
+  # macOS-provided zlib.
+  ZLIB_NG_COMPAT_PREFIX=$(brew --prefix zlib-ng-compat 2>/dev/null || true)
+  if [ -n "${ZLIB_NG_COMPAT_PREFIX}" ] && [ -d "${ZLIB_NG_COMPAT_PREFIX}" ]; then
+    MR_CMAKE_OPTIONS="${MR_CMAKE_OPTIONS} -D ZLIB_ROOT=${ZLIB_NG_COMPAT_PREFIX}"
+  fi
 else
   NPROC=$(nproc)
 fi

source/MRMesh/CMakeLists.txt

@@ -55,8 +55,15 @@ find_package(ZLIB REQUIRED)
 target_link_libraries(${PROJECT_NAME} PRIVATE ZLIB::ZLIB)
 # libzip prior to version 1.11.4 has incorrect CMake config that requires libzip tools to be installed
 IF(MESHLIB_USE_VCPKG OR APPLE OR EMSCRIPTEN)
-  # vcpkg, homebrew, and submodule versions are already updated
-  find_package(libzip REQUIRED)
+  # vcpkg, homebrew, and submodule versions are already updated.
+  # On APPLE (and EMSCRIPTEN) we build libzip from thirdparty/libzip and
+  # install it to MESHLIB_THIRDPARTY_ROOT_DIR, which is not on CMake's default
+  # find_package search path, so hint it explicitly. The hint is harmless on
+  # vcpkg-based configurations (they still find the vcpkg-supplied libzip
+  # via the toolchain-provided CMAKE_PREFIX_PATH).
+  find_package(libzip REQUIRED
+    HINTS ${MESHLIB_THIRDPARTY_ROOT_DIR}/lib/cmake/libzip
+  )
 ELSE()
   # on Ubuntu LTS (22.04, 24.04) we have to use pkg-config instead
   find_package(PkgConfig REQUIRED)

source/MRTest/MRZipCompressTests.cpp

@@ -27,7 +27,7 @@ TEST( MRMesh, CompressSphereToZip )
     UniqueTemporaryFolder srcFolder;
     ASSERT_TRUE( bool( srcFolder ) );
 
-    constexpr int targetVerts = 1000; // increase it to make the file being compressed larger, 100'000 vertices -> 12M bytes
+    constexpr int targetVerts = 100000; // increase it to make the file being compressed larger, 100'000 vertices -> 12M bytes
     SphereParams params;
     params.radius = 1.0f;
     params.numMeshVertices = targetVerts;
@@ -81,9 +81,9 @@ TEST( MRMesh, CompressManySmallFilesToZip )
     ASSERT_TRUE( bool( srcFolder ) );
 
     // increase both below numbers to make the files being compressed larger, 200 * 2 files * 60'000 bytes -> 24M bytes
-    constexpr int numBinaryFiles = 20;
+    constexpr int numBinaryFiles = 200;
     constexpr int numJsonFiles = numBinaryFiles;
-    constexpr size_t bytesPerFile = 6000;
+    constexpr size_t bytesPerFile = 60000;
 
     // Simple LCG used to produce deterministic pseudo-random bytes.
     // Keeps the test reproducible across runs and platforms while avoiding

source/MRTest/MRZlibTests.cpp

@@ -157,8 +157,14 @@ TEST( MRMesh, ZlibCompressStats )
 
         EXPECT_EQ( stats.crc32, expectedCrc );
         EXPECT_EQ( stats.uncompressedSize, sizeof( cInput ) );
-        EXPECT_EQ( stats.compressedSize, c.expectedCompSize );
-        EXPECT_EQ( out.str().size(), c.expectedCompSize );
+        // Compressed size is not pinned to an exact reference: different
+        // deflate implementations (stock zlib, zlib-ng, etc.) may encode the
+        // same input into equivalently valid but slightly differently sized
+        // output. The internal-consistency check + a small ± window around
+        // the stock-zlib reference is enough.
+        EXPECT_EQ( stats.compressedSize, out.str().size() );
+        EXPECT_GE( stats.compressedSize, c.expectedCompSize - 4 );
+        EXPECT_LE( stats.compressedSize, c.expectedCompSize + 4 );
     }
 }
 

thirdparty/CMakeLists.txt

@@ -96,14 +96,25 @@ IF(EMSCRIPTEN)
   set(GDCM_BUILD_TESTING OFF)
   set(GDCM_BUILD_DOCBOOK_MANPAGES OFF)
   add_subdirectory(./GDCM)
+ENDIF()
 
+# Build libzip from our submodule on Emscripten (no system libzip available)
+# and on macOS (so we can link it against Homebrew's zlib-ng-compat drop-in
+# replacement for zlib, reached via ZLIB_ROOT / CMAKE_PREFIX_PATH from the
+# build scripts). Other platforms still pick libzip up from apt/brew/vcpkg.
+IF(EMSCRIPTEN OR APPLE)
   set(BUILD_TOOLS OFF CACHE BOOL "")
   set(BUILD_REGRESS OFF CACHE BOOL "")
   set(BUILD_EXAMPLES OFF CACHE BOOL "")
-  set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -s USE_ZLIB=1")
+  IF(EMSCRIPTEN)
+    # Emscripten ships a bundled zlib port activated by this flag.
+    set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -s USE_ZLIB=1")
+  ENDIF()
   set(LIBZIP_DO_INSTALL ON)
   add_subdirectory(./libzip)
+ENDIF()
 
+IF(EMSCRIPTEN)
   set(CMAKE_CXX_FLAGS_BACKUP "${CMAKE_CXX_FLAGS}")
   set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -s NO_DISABLE_EXCEPTION_CATCHING=1")
   set(JSONCPP_WITH_TESTS OFF)