glsl non-empty case statements must have break or return for ANGLE

[sotaroikeda]

ps_border.fs.glsl and ps_border.vs.glsl has non-empty case statements must have break or return, it causes failures of compiling the shaders. I faced the problem on gecko webrender on graphics branch on Windows. When I tested on windows, "discard;" also seemed to request break/return

The following are actual error log.

C:\fakepath(4586,1): error X3533: non-empty case statements must have break or return
C:\fakepath(4589,1): error X3533: non-empty case statements must have break or return

[sotaroikeda]

#749 fixed the same problem in the past.

[emilio]

didn't we have angle running in CI for this?

[kvark]

Yes, it was added in #713, and CI still passes successfully: https://travis-ci.org/servo/webrender/jobs/217127497#L626
I also checked cd webrender && cargo test locally and got:

Shader translated succesfully: ps_border.vs
Shader translated succesfully: ps_border.vs

So either we are not setting Angle up correctly, or it just behaves differently on Linux vs Windows?..

[sotaroikeda]

It seems like Windows specific.

[sotaroikeda]

I faced the problem during investigating https://bugzilla.mozilla.org/show_bug.cgi?id=1352287

[sotaroikeda]

The following are actual log out when the problem happened.

WebRender - OpenGL version new OpenGL ES 3.0 (ANGLE 2.1.0.2a250c8a0e15)
[Child 2468] WARNING: pipe error: 109: file c:/quantum_gfx_src_1/graphics/ipc/chromium/src/chrome/common/ipc_channel_win.cc, line 346
[Child 2468] WARNING: pipe error: 109: file c:/quantum_gfx_src_1/graphics/ipc/chromium/src/chrome/common/ipc_channel_win.cc, line 346
WebRender - OpenGL version new OpenGL ES 3.0 (ANGLE 2.1.0.2a250c8a0e15)
Failed to link shader program: C:\fakepath(889,25-35): warning X3556: integer modulus may be much slower, try using uints if possible.
C:\fakepath(889,41-51): warning X3556: integer divides may be much slower, try using uints if possible.
C:\fakepath(914,24-35): warning X3556: integer modulus may be much slower, try using uints if possible.
C:\fakepath(914,41-52): warning X3556: integer divides may be much slower, try using uints if possible.
C:\fakepath(964,24-35): warning X3556: integer modulus may be much slower, try using uints if possible.
C:\fakepath(964,41-52): warning X3556: integer divides may be much slower, try using uints if possible.
C:\fakepath(864,20-31): warning X3556: integer modulus may be much slower, try using uints if possible.
C:\fakepath(864,37-48): warning X3556: integer divides may be much slower, try using uints if possible.

C:\fakepath(976,1): error X3533: non-empty case statements must have break or return
C:\fakepath(979,1): error X3533: non-empty case statements must have break or return
C:\fakepath(977,8): 
thread '<unnamed>' panicked at 'called `Result::unwrap()` on an `Err` value: Link("C:\\fakepath(889,25-35): warning X3556: integer modulus may be much slower, try using uints if possible.
C:\\fakepath(889,41-51): warning X3556: integer divides may be much slower, try using uints if possible.
C:\\fakepath(914,24-35): warning X3556: integer modulus may be much slower, try using uints if possible.
C:\\fakepath(914,41-52): warning X3556: integer divides may be much slower, try using uints if possible.
C:\\fakepath(964,24-35): warning X3556: integer modulus may be much slower, try using uints if possible.
C:\\fakepath(964,41-52): warning X3556: integer divides may be much slower, try using uints if possible.
C:\\fakepath(864,20-31): warning X3556: integer modulus may be much slower, try using uints if possible.
C:\\fakepath(864,37-48): warning X3556: integer divides may be much slower, try using uints if possible.

C:\\fakepath(976,1): error X3533: non-empty case statements must have break or return
C:\\fakepath(979,1): error X3533: non-empty case statements must have break or return
C:\\fakepath(977,8): ")', src\libcore\result.rs:860
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.
stack backtrace:
   0: gleam::gl::{{impl}}::draw_elements_instanced
             at ./third_party\rust\gleam\src\gles_fns.rs:723

[sotaroikeda]

The following did not work on windows

   case BORDER_STYLE_HIDDEN:
     discard;

The following works on windows, but it did not work on linux

   case BORDER_STYLE_HIDDEN:
     discard;
     break;

[staktrace]

See also https://bugzilla.mozilla.org/show_bug.cgi?id=1352878 (note the unwrap_failed<webrender::device::ShaderError> in comment 0 of that bug)