Fix XED runtime always defaulting to /MT

dependencies/XEDConfig.cmake.in

@@ -1,4 +1,4 @@
-# /Users/admin/Projects/cxx-common/ports/xed/XEDConfig.cmake
+# Reference: https://github.com/lifting-bits/cxx-common/blob/e0063b2f5986582ed8dcab0c2863abf0893b3082/ports/xed/XEDConfig.cmake
 
 if(XED_FOUND)
     return()

dependencies/xed.cmake

@@ -23,6 +23,37 @@ set(MFILE_ARGS
     "--compiler=${compiler}"
 )
 
+# XED is built by mbuild, not CMake, so it does not honor
+# CMAKE_MSVC_RUNTIME_LIBRARY. mbuild also ties "--static" to /MT by default.
+# Dna.LLVMInterop and the CMake-built dependencies use the DLL CRT (/MD), so
+# disable mbuild's implicit CRT flag and pass the matching MSVC runtime flag
+# explicitly. Without this, xed.lib/xed-ild.lib embed /DEFAULTLIB:libcmt.lib
+# and the Dna.LLVMInterop link emits LNK4098.
+if(CMAKE_SYSTEM_NAME STREQUAL "Windows" AND MSVC)
+    set(xed_msvc_runtime_flag "")
+    if(DEFINED CMAKE_MSVC_RUNTIME_LIBRARY AND NOT CMAKE_MSVC_RUNTIME_LIBRARY STREQUAL "")
+        if(CMAKE_MSVC_RUNTIME_LIBRARY MATCHES "DebugDLL$")
+            set(xed_msvc_runtime_flag "/MDd")
+        elseif(CMAKE_MSVC_RUNTIME_LIBRARY MATCHES "DLL$")
+            set(xed_msvc_runtime_flag "/MD")
+        elseif(CMAKE_MSVC_RUNTIME_LIBRARY MATCHES "Debug$")
+            set(xed_msvc_runtime_flag "/MTd")
+        else()
+            set(xed_msvc_runtime_flag "/MT")
+        endif()
+    elseif(CMAKE_BUILD_TYPE STREQUAL "Debug")
+        set(xed_msvc_runtime_flag "/MDd")
+    else()
+        set(xed_msvc_runtime_flag "/MD")
+    endif()
+
+    list(APPEND MFILE_ARGS
+        "--no-mscrt"
+        "--extra-ccflags=${xed_msvc_runtime_flag}"
+        "--extra-cxxflags=${xed_msvc_runtime_flag}"
+    )
+endif()
+
 if(CMAKE_OSX_SYSROOT)
     list(APPEND MFILE_ARGS "--extra-ccflags=-isysroot ${CMAKE_OSX_SYSROOT}")
     list(APPEND MFILE_ARGS "--extra-cxxflags=-isysroot ${CMAKE_OSX_SYSROOT}")