[Mesa-dev] [PATCH] glsl: Allow ES2 function parameters to be hidden by variable declarations.

[Ian Romanick]

On 07/16/2018 02:46 PM, Eric Anholt wrote:
> This fixes dEQP case:
> 
> dEQP-GLES2.functional.shaders.scoping.valid.local_variable_hides_function_parameter_fragment

Are we sure that test is correct?  I'm sure I already know the answer,
but does the test contain any justification or spec references?  I just
re-read section 4.2 (Scoping) of the ESSL 1.00 spec, and I don't see
anything to support this.  Did I miss something?

In fact, the grammar says:

function_definition:
        function_prototype compound_statement_no_new_scope

So... I think this test is just wrong.

> without breaking
> 
> dEQP-GLES3.functional.shaders.scoping.invalid.local_variable_hides_function_parameter_fragment
> ---
>  src/compiler/glsl/ast_to_hir.cpp | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/src/compiler/glsl/ast_to_hir.cpp b/src/compiler/glsl/ast_to_hir.cpp
> index dd60a2a87fd5..28f074ca8a39 100644
> --- a/src/compiler/glsl/ast_to_hir.cpp
> +++ b/src/compiler/glsl/ast_to_hir.cpp
> @@ -6180,10 +6180,19 @@ ast_function_definition::hir(exec_list *instructions,
>        }
>     }
>  
> +   /* On ES2, function parameters may be redeclared to be hidden within the
> +    * function.  Do this by creating a new scope inside the function.
> +    */
> +   if (state->is_version(0, 100) && !state->is_version(0, 300))
> +      state->symbols->push_scope();
> +
>     /* Convert the body of the function to HIR. */
>     this->body->hir(&signature->body, state);
>     signature->is_defined = true;
>  
> +   if (state->is_version(0, 100) && !state->is_version(0, 300))
> +      state->symbols->pop_scope();
> +
>     state->symbols->pop_scope();
>  
>     assert(state->current_function == signature);
>