MSL: Regression in Metal shader compilation tests

[billhollings]

df234e8 introduced the following test shaders:

shaders-msl-no-opt/asm/frag/barycentric-centroid-noperspective.msl22.asm.frag
shaders-msl-no-opt/asm/frag/barycentric-centroid-perspective.msl22.asm.frag
shaders-msl-no-opt/asm/frag/barycentric-sample-noperspective.msl22.asm.frag
shaders-msl-no-opt/asm/frag/barycentric-sample-perspective.msl22.asm.frag

These are failing Metal compilation with:

reference/shaders-msl-no-opt/asm/frag/barycentric-centroid-perspective.msl22.asm.frag:13:30: error: 'barycentric_coord' and 'centroid_perspective' attributes are not compatible
    float3 gl_BaryCoordEXT [[barycentric_coord, centroid_perspective]];
                             ^~~~~~~~~~~~~~~~~
reference/shaders-msl-no-opt/asm/frag/barycentric-centroid-perspective.msl22.asm.frag:16:26: error: type 'main0_in' is not valid for attribute 'stage_in'
fragment main0_out main0(main0_in in [[stage_in]])
                         ^             ~~~~~~~~
2 errors generated.
Error compiling Metal shader: reference/shaders-msl-no-opt/asm/frag/barycentric-centroid-perspective.msl22.asm.frag
Error: Failed to compile Metal shader

These tests seem to be violating this restriction from the MSL spec:

A fragment function input declared with the [[barycentric_coord]] attribute can only be declared with either the center_perspective (default) or center_no_perspective

[HansKristian-Work]

Why are we passing CI then?

[HansKristian-Work]

12: Testing MSL shader: /Users/runner/work/SPIRV-Cross/SPIRV-Cross/shaders-msl-no-opt/asm/frag/barycentric-centroid-noperspective.msl22.asm.frag
12: Reference shader path: /Users/runner/work/SPIRV-Cross/SPIRV-Cross/reference/shaders-msl-no-opt/asm/frag/barycentric-centroid-noperspective.msl22.asm.frag
12: Skipping validation for /Users/runner/work/SPIRV-Cross/SPIRV-Cross/shaders-msl-no-opt/asm/frag/barycentric-centroid-noperspective.msl22.asm.frag due to lack of toolchain support.

uh ... but logs also say

 19: Current SDK supports MSL -std=macos-metal2.2. Enabling validation for MSL -std=macos-metal2.2 shaders.
19: Current SDK supports MSL -std=macos-metal2.3. Enabling validation for MSL -std=macos-metal2.3 shaders.
19: Current SDK supports MSL -std=macos-metal2.4. Enabling validation for MSL -std=macos-metal2.4 shaders.
19: Current SDK supports MSL -std=metal3.0. Enabling validation for MSL -std=metal3.0 shaders.
19: Current SDK supports MSL -std=metal3.1. Enabling validation for MSL -std=metal3.1 shaders.

sigh ...