chore: allow build using MinGW on windows

CMakeLists.txt

@@ -2,7 +2,7 @@ cmake_minimum_required(VERSION 3.25)
 
 option(OCCUTILS_BUILD_TESTS "Build tests" OFF)
 if (OCCUTILS_BUILD_TESTS)
-  list(APPEND VCPKG_MANIFEST_FEATURES "tests")
+    list(APPEND VCPKG_MANIFEST_FEATURES "tests")
 endif ()
 
 set(VCPKG_OVERLAY_TRIPLETS "${CMAKE_CURRENT_LIST_DIR}/vcpkg/triplets" CACHE STRING "")
@@ -16,7 +16,7 @@ set(cmake_package_name occutils CACHE INTERNAL "")
 
 # Set default build to release
 if (NOT CMAKE_BUILD_TYPE)
-  set(CMAKE_BUILD_TYPE "Release" CACHE STRING "Choose Release or Debug" FORCE)
+    set(CMAKE_BUILD_TYPE "Release" CACHE STRING "Choose Release or Debug" FORCE)
 endif ()
 
 # Compiler config
@@ -25,20 +25,20 @@ set(CMAKE_CXX_STANDARD_REQUIRED ON)
 
 # make sure __cplusplus is defined when using msvc and enable parallel build
 if (MSVC)
-  string(APPEND CMAKE_CXX_FLAGS " /Zc:__cplusplus /MP")
+    string(APPEND CMAKE_CXX_FLAGS " /Zc:__cplusplus /MP")
 endif ()
 
 set(CMAKE_CXX_EXTENSIONS OFF)
 
-if (CMAKE_SYSTEM_NAME MATCHES "CYGWIN" OR CMAKE_SYSTEM_NAME MATCHES "MSYS")
-  set(CMAKE_CXX_EXTENSIONS ON)
+if (CMAKE_SYSTEM_NAME MATCHES "CYGWIN" OR CMAKE_SYSTEM_NAME MATCHES "MSYS" OR (CMAKE_SYSTEM_NAME STREQUAL "Windows" AND CMAKE_CXX_COMPILER_ID STREQUAL "GNU"))
+    set(CMAKE_CXX_EXTENSIONS ON)
 endif ()
 
 # These commands only run if this is the main project
 if (CMAKE_PROJECT_NAME STREQUAL "occutils")
-  # BUILD_SHARED_LIBS is a standard CMake variable, but we declare it here to
-  # make it prominent in the GUI.
-  option(BUILD_SHARED_LIBS "Build shared libraries (DLLs)." OFF)
+    # BUILD_SHARED_LIBS is a standard CMake variable, but we declare it here to
+    # make it prominent in the GUI.
+    option(BUILD_SHARED_LIBS "Build shared libraries (DLLs)." OFF)
 endif ()
 
 # warning options
@@ -62,22 +62,22 @@ find_package(GTest CONFIG REQUIRED)
 cxx_library(${PROJECT_NAME} src/occutils-all.cc)
 
 target_include_directories(${PROJECT_NAME} SYSTEM PRIVATE
-                           ${OpenCASCADE_INCLUDE_DIR}
-                           ${Boost_INCLUDE_DIRS}
-                           )
+        ${OpenCASCADE_INCLUDE_DIR}
+        ${Boost_INCLUDE_DIRS}
+        )
 
 if (OCCUTILS_BUILD_WARNINGS)
-  target_enable_warnings(${PROJECT_NAME})
+    target_enable_warnings(${PROJECT_NAME})
 endif ()
 
 # If the CMake version supports it, attach header directory information
 # to the targets for when we are part of a parent build (ie being pulled
 # in via add_subdirectory() rather than being a standalone build).
 if (DEFINED CMAKE_VERSION AND NOT "${CMAKE_VERSION}" VERSION_LESS "2.8.11")
-  target_include_directories(${PROJECT_NAME} PUBLIC
-                             "$<BUILD_INTERFACE:${CMAKE_CURRENT_LIST_DIR}/include>"
-                             "$<INSTALL_INTERFACE:$<INSTALL_PREFIX>/${CMAKE_INSTALL_INCLUDEDIR}>"
-                             )
+    target_include_directories(${PROJECT_NAME} PUBLIC
+            "$<BUILD_INTERFACE:${CMAKE_CURRENT_LIST_DIR}/include>"
+            "$<INSTALL_INTERFACE:$<INSTALL_PREFIX>/${CMAKE_INSTALL_INCLUDEDIR}>"
+            )
 endif ()
 
 # Configure install
@@ -110,7 +110,7 @@ install(EXPORT ${PROJECT_NAME} DESTINATION ${export_dest_dir} NAMESPACE ${PROJEC
 
 # Configure package config file
 configure_package_config_file("${project_config_in}" "${project_config_out}"
-                              INSTALL_DESTINATION ${export_dest_dir})
+        INSTALL_DESTINATION ${export_dest_dir})
 
 # Write version config file
 write_basic_package_version_file("${version_config_file}" COMPATIBILITY SameMajorVersion)
@@ -120,9 +120,9 @@ install(FILES "${project_config_out}" "${version_config_file}" DESTINATION "${ex
 
 # Testing
 if (OCCUTILS_BUILD_TESTS)
-  message(STATUS "Generating tests")
-  enable_testing()
-  add_subdirectory(test)
+    message(STATUS "Generating tests")
+    enable_testing()
+    add_subdirectory(test)
 endif ()
 
 # Packaging

vcpkg/ports/opencascade/portfile.cmake

@@ -11,6 +11,14 @@ vcpkg_from_github(
   fix-depend-freetype.patch
 )
 
+# message("VCPKG_CMAKE_SYSTEM_NAME: ${VCPKG_CMAKE_SYSTEM_NAME}")
+
+# MinGW compiler does generate import libraries (.dll.a files) for DLLs on Windows.
+# Suppresses Warning: Import libraries were not present (only looking for ".lib" files)
+if (WIN32 AND VCPKG_CMAKE_SYSTEM_NAME STREQUAL "MinGW")
+  set(VCPKG_POLICY_DLLS_WITHOUT_LIBS enabled)
+endif ()
+
 if (VCPKG_LIBRARY_LINKAGE STREQUAL dynamic)
   set(BUILD_TYPE "Shared")
 else ()
@@ -26,7 +34,7 @@ vcpkg_check_features(OUT_FEATURE_OPTIONS FEATURE_OPTIONS
 
 # VTK option in opencascade not currently supported because only 6.1.0 is supported but vcpkg has >= 9.0
 
-# We turn off BUILD_MODULE_Draw as it requires TCL 8.6 and TK 8.6 specifically which conflicts with vcpkg only having TCL 9.0 
+# We turn off BUILD_MODULE_Draw as it requires TCL 8.6 and TK 8.6 specifically which conflicts with vcpkg only having TCL 9.0
 # And pre-built ActiveTCL binaries are behind a marketing wall :(
 # We use the Unix install layout for Windows as it matches vcpkg
 vcpkg_cmake_configure(
@@ -69,7 +77,7 @@ foreach (file_name IN LISTS files)
 endforeach ()
 
 # Remove libd to lib, libd just has cmake files we dont want too
-if (WIN32)
+if (WIN32 AND NOT VCPKG_CMAKE_SYSTEM_NAME STREQUAL "MinGW")
   file(REMOVE_RECURSE "${CURRENT_PACKAGES_DIR}/debug/lib")
   file(RENAME "${CURRENT_PACKAGES_DIR}/debug/libd" "${CURRENT_PACKAGES_DIR}/debug/lib")
 endif ()
@@ -79,7 +87,7 @@ file(REMOVE_RECURSE "${CURRENT_PACKAGES_DIR}/debug/share")
 
 if (VCPKG_LIBRARY_LINKAGE STREQUAL dynamic)
   # debug creates libd and bind directories that need moving
-  if (WIN32)
+  if (WIN32 AND NOT VCPKG_CMAKE_SYSTEM_NAME STREQUAL "MinGW")
     file(REMOVE_RECURSE "${CURRENT_PACKAGES_DIR}/debug/bin")
     file(RENAME "${CURRENT_PACKAGES_DIR}/debug/bind" "${CURRENT_PACKAGES_DIR}/debug/bin")
   endif ()

vcpkg/triplets/x64-mingw-static.cmake

@@ -0,0 +1,10 @@
+set(VCPKG_TARGET_ARCHITECTURE x64)
+set(VCPKG_CRT_LINKAGE dynamic)
+set(VCPKG_LIBRARY_LINKAGE static)
+set(VCPKG_ENV_PASSTHROUGH PATH)
+
+set(VCPKG_CMAKE_SYSTEM_NAME MinGW)
+
+if (PORT MATCHES "opencascade")
+    set(VCPKG_LIBRARY_LINKAGE dynamic)
+endif ()