Access qualifiers aren't supported yet, and some of the image handling
is a bit messy (currently tied to glsl when it should be general), but
the basics are there. However, now I've got to sort out the execution
model (need Fragment or GLCompute for ImplicitLod).
I decided to not mess with actual casts. In retrospect, this is probably
for the best as it avoids any bit-cast conflicts, but should allow for
block initializers with a few tweaks. `@construct (type, args...)` in
Ruamoko follows the same path as `type(args...)` in glsl.
Because the symbol tables for generic functions are ephemeral (as such),
they need to be easily removed from the scope chain, it's easiest if
definitions are never added to them (instead, they get added to the
parent symbol table). This keeps handling of function declarations or
definitions and their parameter scopes simple as the function gets put
in the global scope still, and the parameter scope simply gets
reconnected to the global scope (really, the generic scope's parent)
when the parameter scope is popped within a generic scope.
Because the glsl front-end uses Ruamoko to compile its builtins, it
needs to switch languages, and the cleanest way to do so is to use a
context object that gets passed around. This removes not only the
current_language global, but also (as a bonus) any real references to
flex's scanner object (there's still a pointer in rua_ctx_t, but it's no
longer a parameter (which caused some pain in the change)).
Unfortunately, it turns out that generic functions are over-grouped so
all functions with the same name get the last definition, so `mix` with
a float (which should get GLSLstd450FMix) gets the bool version instead
(SpvOpSelect).
I think I need to come up with a better way of defining glsl builtins
and the strings are rather ugly (and I don't want to use qfcc system
header files).
iqm.vert now compiles, but doesn't pass validation yet (matrix bugs).
While I'm not happy with the module "creation" (at least it's limited to
two places), setting it up with spir-v capabilities and memory model
seems quite nice and should play nicely with being set up from within
source code, though using uint constant expressions might be overkill.
Attributes seem appropriate as GLSL's qualifiers affect variables rather
than types (since there's no typedef).
Not much is done with the attributes yet other than some basic error
checking (duplicates of non-layout attributes) and debug output, but
most (if not all) declarations get to the declaration code with
attributes intact.
The version directive really does only some error checking, and
only GL_EXT_multiview and GL_GOOGLE_include_directive are supported for
extensions, but enable/disable work (but not yet warn for multiview).
There's no direct support for namespaces in Ruamoko yet, nor even in
qfcc, but glsl's blocks bring in a bit of foundation for them, even the
concept of "using" (for blocks with no instance name).
The members don't get locations allocated to them yet, but
fstrianglest.vert compiles and links correctly otherwise.
Also, there's no error checking yet.
