stage1: override cmake's default compilation flags to statically link the CRT on windows

we want to use /MT instead of /MD for a fully static executable

Author: Sahnvour

CMakeLists.txt

@@ -10,10 +10,14 @@ if(NOT CMAKE_INSTALL_PREFIX)
       "Directory to install zig to" FORCE)
 endif()
 
+set(CMAKE_USER_MAKE_RULES_OVERRIDE
+   ${CMAKE_CURRENT_SOURCE_DIR}/cmake/c_flag_overrides.cmake)
+set(CMAKE_USER_MAKE_RULES_OVERRIDE_CXX
+   ${CMAKE_CURRENT_SOURCE_DIR}/cmake/cxx_flag_overrides.cmake)
+
 project(zig C CXX)
 set(CMAKE_MODULE_PATH ${CMAKE_SOURCE_DIR}/cmake ${CMAKE_MODULE_PATH})
 
-
 set(ZIG_VERSION_MAJOR 0)
 set(ZIG_VERSION_MINOR 5)
 set(ZIG_VERSION_PATCH 0)

cmake/c_flag_overrides.cmake

@@ -0,0 +1,13 @@
+if(MSVC)
+    set(CMAKE_C_FLAGS_DEBUG_INIT
+        "/D_DEBUG /MTd /Zi /Ob0 /Od /RTC1")
+
+    set(CMAKE_C_FLAGS_MINSIZEREL_INIT
+        "/MT /O1 /Ob1 /D NDEBUG")
+
+    set(CMAKE_C_FLAGS_RELEASE_INIT
+        "/MT /O2 /Ob2 /D NDEBUG")
+
+    set(CMAKE_C_FLAGS_RELWITHDEBINFO_INIT
+        "/MT /Zi /O2 /Ob1 /D NDEBUG")
+endif()

cmake/cxx_flag_overrides.cmake

@@ -0,0 +1,13 @@
+if(MSVC)
+    set(CMAKE_CXX_FLAGS_DEBUG_INIT
+        "/D_DEBUG /MTd /Zi /Ob0 /Od /RTC1")
+
+    set(CMAKE_CXX_FLAGS_MINSIZEREL_INIT
+        "/MT /O1 /Ob1 /D NDEBUG")
+
+    set(CMAKE_CXX_FLAGS_RELEASE_INIT
+        "/MT /O2 /Ob2 /D NDEBUG")
+
+    set(CMAKE_CXX_FLAGS_RELWITHDEBINFO_INIT
+        "/MT /Zi /O2 /Ob1 /D NDEBUG")
+endif()