[Mesa-dev] [PATCH 7/8] glsl: Don't emit spurious errors for constant indexes of the wrong type

[Kenneth Graunke]

On 04/01/2013 11:25 AM, Ian Romanick wrote:
> From: Ian Romanick <ian.d.romanick at intel.com>
>
> Previously the shader
>
> uniform float x[6];
> void main() { gl_Position.x = x[1.0]; }
>
> would have generated the errors
>
> 0:2(33): error: array index must be integer type
> 0:2(36): error: array index must be < 6
>
> Now only
>
> 0:2(33): error: array index must be integer type
>
> will be generated.
>
> Signed-off-by: Ian Romanick <ian.d.romanick at intel.com>
> ---
>   src/glsl/ast_array_index.cpp | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/src/glsl/ast_array_index.cpp b/src/glsl/ast_array_index.cpp
> index 486ff55..c7ebcbd 100644
> --- a/src/glsl/ast_array_index.cpp
> +++ b/src/glsl/ast_array_index.cpp
> @@ -58,7 +58,7 @@ _mesa_ast_array_index_to_hir(void *mem_ctx,
>       * declared size.
>       */
>      ir_constant *const const_index = idx->constant_expression_value();
> -   if (const_index != NULL) {
> +   if (const_index != NULL && idx->type->is_integer()) {
>         const int idx = const_index->value.i[0];
>         const char *type_name = "error";
>         unsigned bound = 0;
> @@ -118,7 +118,7 @@ _mesa_ast_array_index_to_hir(void *mem_ctx,
>   	    check_builtin_array_max_size(v->name, idx+1, loc, state);
>   	 }
>         }
> -   } else if (array->type->is_array()) {
> +   } else if (const_index == NULL && array->type->is_array()) {
>         if (array->type->array_size() == 0) {
>   	 _mesa_glsl_error(&loc, state, "unsized array index must be constant");
>         } else if (array->type->fields.array->is_interface()) {

Aww.  Patch 6 cleaned this up so nicely, and now it's getting a bit 
uglier again.

How about simply doing an early-return above:

    if (!idx->type->is_integer()) {
       _mesa_glsl_error(& idx_loc, state, "array index must be integer 
type");
       return result;
    } else if (!idx->type->is_scalar()) {
       _mesa_glsl_error(& idx_loc, state, "array index must be scalar");
       return result;
    }

Basically, if you hit those errors, you don't want to continue checking 
for more of them.