glsl: invariant qualifier is not valid for shader inputs in GLSL ES 3.00

GLSL ES 3.00 spec, chapter 4.6.1 "The Invariant Qualifier",

    Only variables output from a shader can be candidates for invariance. This
    includes user-defined output variables and the built-in output variables.
    As only outputs can be declared as invariant, an invariant output from one
    shader stage will still match an input of a subsequent stage without the
    input being declared as invariant.

This patch fixes the following dEQP tests:

dEQP-GLES3.functional.shaders.qualification_order.variables.valid.invariant_interp_storage_precision
dEQP-GLES3.functional.shaders.qualification_order.variables.valid.invariant_interp_storage
dEQP-GLES3.functional.shaders.qualification_order.variables.valid.invariant_storage_precision
dEQP-GLES3.functional.shaders.qualification_order.variables.valid.invariant_storage
dEQP-GLES3.functional.shaders.qualification_order.variables.invalid.invariant_interp_storage_precision_invariant_input
dEQP-GLES3.functional.shaders.qualification_order.variables.invalid.invariant_interp_storage_invariant_input
dEQP-GLES3.functional.shaders.qualification_order.variables.invalid.invariant_storage_precision_invariant_input
dEQP-GLES3.functional.shaders.qualification_order.variables.invalid.invariant_storage_invariant_input

No piglit regressions observed.

v2:
- Add spec content in the code

Signed-off-by: Samuel Iglesias Gonsalvez <[email protected]>
Reviewed-by: Ian Romanick <[email protected]>

1 files changed, 11 insertions, 0 deletions

diff --git a/src/glsl/glsl_parser.yy b/src/glsl/glsl_parser.yy
index 6a55a4e6bf6..7fb8c38abe3 100644
--- a/src/glsl/glsl_parser.yy
+++ b/src/glsl/glsl_parser.yy
@@ -1602,6 +1602,17 @@ type_qualifier:
 
       $$ = $2;
       $$.flags.q.invariant = 1;
+
+      /* GLSL ES 3.00 spec, section 4.6.1 "The Invariant Qualifier":
+       *
+       * "Only variables output from a shader can be candidates for invariance.
+       * This includes user-defined output variables and the built-in output
+       * variables. As only outputs can be declared as invariant, an invariant
+       * output from one shader stage will still match an input of a subsequent
+       * stage without the input being declared as invariant."
+       */
+      if (state->es_shader && state->language_version >= 300 && $$.flags.q.in)
+         _mesa_glsl_error(&@1, state, "invariant qualifiers cannot be used with shader inputs");
    }
    | interpolation_qualifier type_qualifier
    {