Add support for building with MinGW (#9137)

* Add support for building with MinGW

Tested with MSYS2 MinGW 8.3.0, gcc-mcf.lhmouse MinGW 9.2.1,
and StephanTLavavej/mingw-distro!

* Add MinGW toolchain

From your MinGW configured shell you could just use vcpkg to
configure packages.

An x64-mingw triplet would look like:
```
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)
```

* Add MinGW community tripplets

x64 tested with https://github.com/StephanTLavavej/mingw-distro
x86, arm64, arm tested with https://github.com/mstorsjo/llvm-mingw

2 files changed, 18 insertions, 9 deletions

diff --git a/scripts/cmake/vcpkg_common_definitions.cmake b/scripts/cmake/vcpkg_common_definitions.cmake
index 14cf460af..3a1818bf5 100644
--- a/scripts/cmake/vcpkg_common_definitions.cmake
+++ b/scripts/cmake/vcpkg_common_definitions.cmake
@@ -37,9 +37,12 @@ elseif(VCPKG_CMAKE_SYSTEM_NAME STREQUAL "Android")
     set(VCPKG_TARGET_IS_ANDROID 1)
 elseif(VCPKG_CMAKE_SYSTEM_NAME STREQUAL "FreeBSD")
     set(VCPKG_TARGET_IS_FREEBSD 1)
+elseif(VCPKG_CMAKE_SYSTEM_NAME STREQUAL "MinGW")
+    set(VCPKG_TARGET_IS_WINDOWS 1)
+    set(VCPKG_TARGET_IS_MINGW 1)
 endif()
 
-#Helper variable to identify the host path separator. 
+#Helper variable to identify the host path separator.
 if(CMAKE_HOST_WIN32)
     set(VCPKG_HOST_PATH_SEPARATOR ";")
 elseif(CMAKE_HOST_UNIX)
@@ -71,11 +74,15 @@ if(VCPKG_TARGET_IS_WINDOWS)
     set(VCPKG_TARGET_IMPORT_LIBRARY_PREFIX "")
     set(VCPKG_FIND_LIBRARY_SUFFIXES ".lib" ".dll") #This is a slight modification to CMakes value which does not include ".dll".
     set(VCPKG_FIND_LIBRARY_PREFIXES "" "lib") #This is a slight modification to CMakes value which does not include "lib".
-    ## For CYGWIN and Windows GNU, maybe VCPKG will support that in the future?
-    #set(VCPKG_TARGET_IMPORT_LIBRARY_SUFFIX ".dll.a")
-    #set(VCPKG_TARGET_IMPORT_LIBRARY_PREFIX "lib")
-    #set(VCPKG_FIND_LIBRARY_SUFFIXES ".dll" ".dll.a" ".a" ".lib")
-    #set(VCPKG_FIND_LIBRARY_PREFIXES "lib" "")
+elseif(VCPKG_TARGET_IS_MINGW)
+    set(VCPKG_TARGET_STATIC_LIBRARY_SUFFIX ".a")
+    set(VCPKG_TARGET_IMPORT_LIBRARY_SUFFIX ".dll.a")
+    set(VCPKG_TARGET_SHARED_LIBRARY_SUFFIX ".dll")
+    set(VCPKG_TARGET_STATIC_LIBRARY_PREFIX "lib")
+    set(VCPKG_TARGET_SHARED_LIBRARY_PREFIX "lib")
+    set(VCPKG_TARGET_IMPORT_LIBRARY_PREFIX "lib")
+    set(VCPKG_FIND_LIBRARY_SUFFIXES ".dll" ".dll.a" ".a" ".lib")
+    set(VCPKG_FIND_LIBRARY_PREFIXES "lib" "")
 elseif(VCPKG_TARGET_IS_OSX)
     set(VCPKG_TARGET_STATIC_LIBRARY_SUFFIX ".a")
     set(VCPKG_TARGET_IMPORT_LIBRARY_SUFFIX "")
diff --git a/scripts/cmake/vcpkg_configure_cmake.cmake b/scripts/cmake/vcpkg_configure_cmake.cmake
index c31955fb2..260f2471e 100644
--- a/scripts/cmake/vcpkg_configure_cmake.cmake
+++ b/scripts/cmake/vcpkg_configure_cmake.cmake
@@ -59,7 +59,7 @@
 ## * [poco](https://github.com/Microsoft/vcpkg/blob/master/ports/poco/portfile.cmake)
 ## * [opencv](https://github.com/Microsoft/vcpkg/blob/master/ports/opencv/portfile.cmake)
 function(vcpkg_configure_cmake)
-    cmake_parse_arguments(_csc 
+    cmake_parse_arguments(_csc
         "PREFER_NINJA;DISABLE_PARALLEL_CONFIGURE;NO_CHARSET_FLAG"
         "SOURCE_PATH;GENERATOR"
         "OPTIONS;OPTIONS_DEBUG;OPTIONS_RELEASE"
@@ -177,13 +177,13 @@ function(vcpkg_configure_cmake)
             "Invalid setting for VCPKG_LIBRARY_LINKAGE: \"${VCPKG_LIBRARY_LINKAGE}\". "
             "It must be \"static\" or \"dynamic\"")
     endif()
-    
+
     macro(check_both_vars_are_set var1 var2)
         if((NOT DEFINED ${var1} OR NOT DEFINED ${var2}) AND (DEFINED ${var1} OR DEFINED ${var2}))
             message(FATAL_ERROR "Both ${var1} and ${var2} must be set.")
         endif()
     endmacro()
-    
+
     check_both_vars_are_set(VCPKG_CXX_FLAGS_DEBUG VCPKG_C_FLAGS_DEBUG)
     check_both_vars_are_set(VCPKG_CXX_FLAGS_RELEASE VCPKG_C_FLAGS_RELEASE)
     check_both_vars_are_set(VCPKG_CXX_FLAGS VCPKG_C_FLAGS)
@@ -204,6 +204,8 @@ function(vcpkg_configure_cmake)
             set(VCPKG_CHAINLOAD_TOOLCHAIN_FILE "${SCRIPTS}/toolchains/osx.cmake")
         elseif(VCPKG_CMAKE_SYSTEM_NAME STREQUAL "FreeBSD")
             set(VCPKG_CHAINLOAD_TOOLCHAIN_FILE "${SCRIPTS}/toolchains/freebsd.cmake")
+        elseif(VCPKG_CMAKE_SYSTEM_NAME STREQUAL "MinGW")
+            set(VCPKG_CHAINLOAD_TOOLCHAIN_FILE "${SCRIPTS}/toolchains/mingw.cmake")
         endif()
     endif()