docs: Update MinGW + MSYS2 documentation and setup (#239)

README.md

@@ -115,6 +115,26 @@ or use it on the command line.
 [cmake]: https://cmake.org/cmake/help/latest/
 [cmake guide]: https://developer.android.com/ndk/guides/cmake
 
+**MinGW**:
+
+64-bits is the only platform supported for now.
+LLVM + Clang are mandatory here : they are required to generate .pdb files, used by Crashpad for the report generation.
+
+For your application to generate the appropriate .pdb output, you need to activate CodeView file format generation on your application target. To do so, update your own CMakeLists.txt with something like `target_compile_options(${yourApplicationTarget} PRIVATE -gcodeview)`.
+
+If you use a MSYS2 environement to compile with MinGW, make sure to :
+
+-   Create an environement variable `MINGW_ROOT` (ex : `C:/msys64/mingw64`)
+-   Run from `mingw64.exe` : `pacman -S --needed - < ./toolchains/msys2-mingw64-pkglist.txt`
+-   Build as :
+
+```sh
+# Configure with Ninja as generator and use the MSYS2 toolchain file
+$ cmake -GNinja -Bbuild -H. -DCMAKE_TOOLCHAIN_FILE=toolchains/msys2.cmake
+# build with Ninja
+$ ninja -C build
+```
+
 ### Compile-Time Options
 
 The following options can be set when running the cmake generator, for example

tests/unit/CMakeLists.txt

@@ -49,7 +49,8 @@ target_link_libraries(sentry_test_unit PRIVATE
 
 if(MINGW)
 	if(CMAKE_CXX_COMPILER_ID STREQUAL "Clang")
-		target_link_options(sentry_test_unit PRIVATE -Wl,-pdb=) # IMPORTANT ! MUST generate pdb files
+		target_link_options(sentry_test_unit PRIVATE -Wl,-pdb=) # IMPORTANT ! LLD must generate pdb files
+		target_compile_options(sentry_test_unit PRIVATE -gcodeview) # IMPORTANT ! Clang must generate pdb to CodeView format
 	else()
 		message(FATAL_ERROR "Tests will not pass on MinGW if your compiler cannot generate .pdb files ! Please use Clang instead")
 	endif()

toolchains/msys2-mingw64-pkglist.txt

@@ -0,0 +1,5 @@
+mingw64/mingw-w64-x86_64-uasm
+mingw64/mingw-w64-x86_64-clang
+mingw64/mingw-w64-x86_64-lld
+mingw64/mingw-w64-x86_64-ninja
+mingw64/mingw-w64-x86_64-cmake

toolchains/msys2.cmake

@@ -0,0 +1,33 @@
+if(NOT DEFINED MINGW_ROOT)
+    if(DEFINED ENV{MINGW_ROOT})
+        SET(MINGW_ROOT $ENV{MINGW_ROOT})
+    elseif(DEFINED ENV{MINGW64_ROOT})
+        SET(MINGW_ROOT $ENV{MINGW64_ROOT})
+    elseif(DEFINED ENV{MINGW32_ROOT})
+        SET(MINGW_ROOT $ENV{MINGW32_ROOT})
+    else()
+        message(FATAL_ERROR "Required variable MINGW_ROOT is not defined. Please check README.md for more details !")
+    endif()
+endif()
+
+# search for programs in the build host directories
+set (CMAKE_FIND_ROOT_PATH_MODE_PROGRAM ONLY)
+
+# for libraries and headers in the target directories
+set (CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
+set (CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
+set (CMAKE_FIND_ROOT_PATH_MODE_PACKAGE ONLY)
+
+list(APPEND CMAKE_PREFIX_PATH
+    ${MINGW_ROOT}
+)
+
+SET (CMAKE_ASM_MASM_COMPILER    "uasm")
+SET (CMAKE_C_COMPILER           "clang")
+SET (CMAKE_CXX_COMPILER         "clang++")
+
+SET (CMAKE_C_FLAGS              "-fuse-ld=lld")
+SET (CMAKE_CXX_FLAGS            ${CMAKE_C_FLAGS})
+
+SET (CMAKE_C_FLAGS_DEBUG        "-O0 -g")
+SET (CMAKE_CXX_FLAGS_DEBUG      ${CMAKE_C_FLAGS_DEBUG})