[Piglit] [RFC PATCH] Test that in/out qualifiers are required when redeclaring gl_ClipDistance.

[Jordan Justen]

On Tue, Oct 8, 2013 at 11:29 AM, Paul Berry <stereotype441 at gmail.com> wrote:
> Although it is not explicitly stated in the GLSL spec, all examples of
> redeclaring built-in in/out variables (such as gl_ClipDistance)
> include the "in" or "out" qualifier, so it seems like failure to do so
> should cause a compile error.
>
> At present:
>
> - Mesa (as of commit a50c5f8) does not generate an error.
>
> - The NVIDIA proprietary driver for Linux (version 313.18) does not
>   generate an error; however, if gl_ClipDistance is redeclared in the
>   fragment shader without specifying the "in" keyword, it fails to
>   work properly.

By 'fails to work properly', do you mean that it is unlikely that an
app could be relying on this behavior? If so, it seems fine to add
this test and make mesa generate a compile error.

Regarding 'out' with the VS, do you think you've tested it enough to
be sure that an app also could not accidentally be relying on this
behavior?

If we are pretty confident that apps won't break, then
Reviewed-by: Jordan Justen <jordan.l.justen at intel.com>

Also, perhaps we should log a spec bug to ask the spec to clarify this?

-Jordan

> ---
>  .../clip-distance-redeclare-without-inout.frag      | 21 +++++++++++++++++++++
>  .../clip-distance-redeclare-without-inout.vert      | 21 +++++++++++++++++++++
>  2 files changed, 42 insertions(+)
>  create mode 100644 tests/spec/glsl-1.30/compiler/clipping/clip-distance-redeclare-without-inout.frag
>  create mode 100644 tests/spec/glsl-1.30/compiler/clipping/clip-distance-redeclare-without-inout.vert
>
> diff --git a/tests/spec/glsl-1.30/compiler/clipping/clip-distance-redeclare-without-inout.frag b/tests/spec/glsl-1.30/compiler/clipping/clip-distance-redeclare-without-inout.frag
> new file mode 100644
> index 0000000..60f0650
> --- /dev/null
> +++ b/tests/spec/glsl-1.30/compiler/clipping/clip-distance-redeclare-without-inout.frag
> @@ -0,0 +1,21 @@
> +/* [config]
> + * expect_result: fail
> + * glsl_version: 1.30
> + * check_link: true
> + * [end config]
> + *
> + * Although it is not explicitly stated in the GLSL spec, in all
> + * examples, redeclarations of built-in variables (such as
> + * gl_ClipDistance) preserve the in/out qualifiers.
> + *
> + * This test verifies that a shader is rejected if it tries to
> + * redeclare gl_ClipDistance without an in/out qualifier.
> + */
> +#version 130
> +
> +float gl_ClipDistance[3];
> +
> +void main()
> +{
> +  gl_FragColor = vec4(0.0);
> +}
> diff --git a/tests/spec/glsl-1.30/compiler/clipping/clip-distance-redeclare-without-inout.vert b/tests/spec/glsl-1.30/compiler/clipping/clip-distance-redeclare-without-inout.vert
> new file mode 100644
> index 0000000..d385cc7
> --- /dev/null
> +++ b/tests/spec/glsl-1.30/compiler/clipping/clip-distance-redeclare-without-inout.vert
> @@ -0,0 +1,21 @@
> +/* [config]
> + * expect_result: fail
> + * glsl_version: 1.30
> + * check_link: true
> + * [end config]
> + *
> + * Although it is not explicitly stated in the GLSL spec, in all
> + * examples, redeclarations of built-in variables (such as
> + * gl_ClipDistance) preserve the in/out qualifiers.
> + *
> + * This test verifies that a shader is rejected if it tries to
> + * redeclare gl_ClipDistance without an in/out qualifier.
> + */
> +#version 130
> +
> +float gl_ClipDistance[3];
> +
> +void main()
> +{
> +  gl_Position = vec4(0.0);
> +}
> --
> 1.8.4
>
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