[Webkit-unassigned] [Bug 205756] REGRESSION: [ Mac ] webgl/2.0.0/conformance2/glsl3/no-attribute-vertex-shader.html is failing

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=205756

--- Comment #3 from Dean Jackson <dino at apple.com> ---
I'm now very confused. I did revert this test to what it was before the ANGLE default. There clearly is a bug in Apple's OpenGL where, on some hardware, gl_VertexID 0 doesn't exist.

This is also mentioned in the ANGLE code:

// This flag works around a inconsistent behavior in Mac AMD driver where gl_VertexID doesn't
// include base vertex value. It replaces gl_VertexID with (gl_VertexID + angle_BaseVertex)
// when angle_BaseVertex is available.
const ShCompileOptions SH_ADD_BASE_VERTEX_TO_VERTEX_ID = UINT64_C(1) << 48;

So it makes sense that this would fail on hardware without ANGLE (which is now the expected result). And maybe this bot doesn't have the bug, so passes the test (not expected).

But what doesn't make sense is how this only just started happening on the bots. I didn't change anything in TestExpectations about this.

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