WGSL requires that runtime-sized arrays appear only as the last member of a
structure in in the `storage` storage class. It seems to me that Naga should
enforce this restriction on its own IR as well.
The `apply_common_default_interpolation` helper function would panic if bindings
were missing, but missing bindings should be something that front ends can count
on validation to detect, so the helper should just return silently.
The validator returned `InvalidType` errors for missing bindings, apparently
because variables without bindings must be structs that do have bindings. But
this is unhelpful when you've just forgotten to label an argument. So this patch
adds a new, more specific, `VaryingError` variant.
* Add support for int8, int16, and int64 as well as null constant structs
* Add support for OpArrayLength to the spirv frontend
* Add hacky OpCopyMemory support to spirv frontend
* Add OpInBoundsAccessChain to spirv frontend
* Add OpLogical(Not)Equal to spirv frontend
* Fix several of the issues raised in the pr
* Fix the Op::ArrayLength match
* Validate accessing structs through pointers
* Remove extraneous type check
When validating IR, verify that all `Binding`s for vertex shader outputs and
fragment shader inputs, whether directly in the argument or result, or applied
to a struct member, has specified an interpolation and sampling, not `None`.
This ensures that front ends explicitly state their policies, rather than
coasting through on back ends' default behavior.
In practice, all our front ends have very similar defaults, so provide a utility
function on `Module` to apply these rules. Use this utility function in the
SPIR-V and WGSL front ends; GLSL seems to already fill in interpolation as
required.
