This is prohibited by the GLSL ES spec:
"In addition, all identifiers containing two consecutive underscores (__) are reserved for use by underlying
software layers. Defining such a name in a shader does not itself result in an error, but may result in
unintended behaviors that stem from having multiple definitions of the same name."
(https://registry.khronos.org/OpenGL/specs/es/3.1/GLSL_ES_Specification_3.10.withchanges.pdf, section 3.7).
However, while glslang validation will not give an error on this, NVidia
ES drivers will. So I've added a Dawn end2end test instead of a WGSL test.
Bug: tint:1944
Change-Id: I4b965af00039ca7a232bc11be884483f8e02ccf6
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/134140
Reviewed-by: Ben Clayton <bclayton@google.com>
Commit-Queue: Stephen White <senorblanco@chromium.org>
Kokoro: Kokoro <noreply+kokoro@google.com>
0c7a99f894