added comments - related to #21

doctest/doctest.h

@@ -663,6 +663,7 @@ namespace detail
 
 #ifdef _MSC_VER
 #pragma warning(push)
+// http://stackoverflow.com/questions/39479163 what's the difference between C4018 and C4389
 #pragma warning(disable : 4389) // 'operator' : signed/unsigned mismatch
 #pragma warning(disable : 4018) // 'expression' : signed/unsigned mismatch
 //#pragma warning(disable : 4805) // 'operation' : unsafe mix of type 'type' and type 'type' in operation

doctest/parts/doctest_fwd.h

@@ -660,6 +660,7 @@ namespace detail
 
 #ifdef _MSC_VER
 #pragma warning(push)
+// http://stackoverflow.com/questions/39479163 what's the difference between C4018 and C4389
 #pragma warning(disable : 4389) // 'operator' : signed/unsigned mismatch
 #pragma warning(disable : 4018) // 'expression' : signed/unsigned mismatch
 //#pragma warning(disable : 4805) // 'operation' : unsafe mix of type 'type' and type 'type' in operation

examples/exe_with_static_libs/doctest_force_link_static_lib_in_target.cmake

@@ -28,6 +28,10 @@ function(doctest_include_file_in_sources header sources)
 endfunction()
 
 # this is the magic function - forces every object file from the library to be linked into the target (dll or executable)
+# it doesn't work in 2 scenarios:
+# - either the target or the library uses a precompiled header - see the end of this issue for details: https://github.com/onqtam/doctest/issues/21
+# - either the target or the library is an imported target (pre-built) and not built within the current cmake tree
+# - for an alternative you can checkout this repository: https://github.com/pthom/doctest_registerlibrary
 function(doctest_force_link_static_lib_in_target target lib)
     # check if the library has generated dummy headers
     get_target_property(DDH ${lib} DOCTEST_DUMMY_HEADER)