shader IR vs. application IR

I have a question for Myles. From the minutes of 2017-08-16:


   -

   *MM: the language that the author writes their shader in should match
   the languages they use the API in. If we add / remove features from SPIRV,
   we’ll need to make it match more the language the API is used in..*
   -

   JK: For Vulkan having multiple high level languages is a strength, no
   one complained about it.
   -

   *MM: not trying to restrict to using a particular high level language.
   but if we’re using a set of features from an IR, that set of features has
   to be applied to the high-level language the author would be writing in.*


I disagree with this assertion about how closely the shader IR should match
the language in which the API is used. I'd like to know more about why you
think this is important.
There are many scenarios with good results that don't hold to this
requirement, e.g. any current scenario where SPIR-V is used. I *can* see
that some things might be more convenient with the constraint, but
definitely not a requirement.

Or have I misjudged the force of your statement?

thanks
david