Is your feature request related to a problem? Please describe.
DXC tries to guess the format of storage images and storage texel buffers from the type of the resource. For example, for RWTexture<float4> DXC will set the format to Rgba32. Recent Vulkan validation throws a warning if the format in SPIR-V doesn't match the format of the VkImage.

So developers really have two choices. Either decorate the resource with [[vk::format(...)]] or ignore the validation warning. Both solutions are not ideal. The 1st solution means touching a potentially huge set of shader code and the 2nd solution might not be possible if validation runs through some tool that can't filter messages.

According to https://vulkan.gpuinfo.org the vast majority of GPUs (90%+) nowadays support reading and writing from Unknown.

Describe the solution you'd like
To avoid breaking existing code DXC could add a command line option that stops it from guessing the format and always sets it to Unknown.