Currently there's no conversion (at last for the D3D11/12 backend), so if for eg the input state is declaring a int4 for position and the shader is taking a vec4 it does not work.

Should the conversion be done automatically? That's what happens in WebGL (in Angle: https://source.chromium.org/chromium/chromium/src/+/master:third_party/angle/src/libANGLE/renderer/d3d/DynamicHLSL.cpp;l=1202)

[EDIT] Note however that it does work when the data in the buffer are flagged as normalized (so there must be a conversion path somewhere already existing - still speaking about D3D11/12 backend) [/EDIT]