terminateRayEXT & ignoreIntersectionEXT not recognized in GLSL compatibility mode

[juliusikkala]

When attempting to compile the following any-hit shader in GLSL compatibility mode (e.g. slangc -allow-glsl -target spirv -entry main -O2 test.rahit -o test.spv), the terminateRayEXT and ignoreIntersectionEXT keywords are not recognized by slangc.

// test.rahit
#version 460
#extension GL_EXT_ray_tracing : require

void main()
{
    terminateRayEXT;
    ignoreIntersectionEXT;
}

Output:

test.rahit(7): error 30015: undefined identifier 'terminateRayEXT'.
    terminateRayEXT;
    ^~~~~~~~~~~~~~~
test.rahit(8): error 30015: undefined identifier 'ignoreIntersectionEXT'.
    ignoreIntersectionEXT;
    ^~~~~~~~~~~~~~~~~~~~~

[juliusikkala]

These two are conspicuously missing from glsl.meta.slang, probably because they're statement keywords and not functions.

Based on a quick look at the internals, the options are:

1. Add #define terminateRayEXT AcceptHitAndEndSearch() to glsl.meta.slang
2. Expand parseSyntaxDecl to allow a new keyword to map to a function call, then add syntax terminateRayEXT = AcceptHitAndEndSearch; to glsl.meta.slang
3. Add new AST nodes and parse in Parser::ParseStatement similar to discard

Considering terminateRayEXT and ignoreIntersectionEXT map directly to function calls (AcceptHitAndEndSearch() & IgnoreHit()) and this is just a compatibility feature, the third option seems a bit overkill. Option 1 is trivial to implement but would leak terminateRayEXT to all shader stages. To me, option 2 seems fairly clean and could be useful for other stuff as well.

I'm pretty confident I can fix this myself and submit a PR with any of the three options, but I'm not sure which one's the best from your POV.

[csyonghe]

I believe you should be able to (ab)use global property for this:

property int terminateRayEXT { [ForceInline] get { AcceptHitAndEndSearch(); return 0; } }

void test()
{
     terminateRayEXT;
}