cmake: support static runtime linking

Author: jtattermusch

CMakeLists.txt

@@ -90,6 +90,7 @@ endif()
 set(CMAKE_POSITION_INDEPENDENT_CODE TRUE)
 
 if (MSVC)
+  include(cmake/msvc_static_runtime.cmake)
   add_definitions(-D_WIN32_WINNT=0x600 -D_SCL_SECURE_NO_WARNINGS -D_CRT_SECURE_NO_WARNINGS -D_WINSOCK_DEPRECATED_NO_WARNINGS)
   # needed to compile protobuf
   add_definitions(/wd4065 /wd4506)

cmake/msvc_static_runtime.cmake

@@ -0,0 +1,14 @@
+option(gRPC_MSVC_STATIC_RUNTIME "Link with static msvc runtime libraries" OFF)
+
+if(gRPC_MSVC_STATIC_RUNTIME)
+  # switch from dynamic to static linking of msvcrt
+  foreach(flag_var
+    CMAKE_CXX_FLAGS CMAKE_CXX_FLAGS_DEBUG CMAKE_CXX_FLAGS_RELEASE
+    CMAKE_CXX_FLAGS_MINSIZEREL CMAKE_CXX_FLAGS_RELWITHDEBINFO)
+
+    if(${flag_var} MATCHES "/MD")
+    string(REGEX REPLACE "/MD" "/MT" ${flag_var} "${${flag_var}}")
+    endif(${flag_var} MATCHES "/MD")
+  endforeach(flag_var)
+endif()
+

templates/CMakeLists.txt.template

@@ -134,6 +134,7 @@
   set(CMAKE_POSITION_INDEPENDENT_CODE TRUE)
 
   if (MSVC)
+    include(cmake/msvc_static_runtime.cmake)
     add_definitions(-D_WIN32_WINNT=0x600 -D_SCL_SECURE_NO_WARNINGS -D_CRT_SECURE_NO_WARNINGS -D_WINSOCK_DEPRECATED_NO_WARNINGS)
     # needed to compile protobuf
     add_definitions(/wd4065 /wd4506)