glsl/linker: always validate explicit locations for first and last interfaces

Until now, we were only doing this when linking a SSO
program. However, nothing avoids linking a non SSO program which
doesn't have both a VS and FS. In those cases, we also need to report
the usual linking errors, if happening.

v2: Use a better name for the renamed function (Timothy).

Signed-off-by: Andres Gomez <agomez@igalia.com>
Reviewed-by: Timothy Arceri <tarceri@itsqueeze.com>

src/compiler/glsl/link_varyings.cpp

@@ -678,17 +678,15 @@ validate_explicit_variable_location(struct gl_context *ctx,
 
 /**
  * Validate explicit locations for the inputs to the first stage and the
- * outputs of the last stage in an SSO program (everything in between is
- * validated in cross_validate_outputs_to_inputs).
+ * outputs of the last stage in a program, if those are not the VS and FS
+ * shaders.
  */
 void
-validate_sso_explicit_locations(struct gl_context *ctx,
-                                struct gl_shader_program *prog,
-                                gl_shader_stage first_stage,
-                                gl_shader_stage last_stage)
+validate_first_and_last_interface_explicit_locations(struct gl_context *ctx,
+                                                     struct gl_shader_program *prog,
+                                                     gl_shader_stage first_stage,
+                                                     gl_shader_stage last_stage)
 {
-   assert(prog->SeparateShader);
-
    /* VS inputs and FS outputs are validated in
     * assign_attribute_or_color_locations()
     */

src/compiler/glsl/link_varyings.h

@@ -276,10 +276,10 @@ link_varyings(struct gl_shader_program *prog, unsigned first, unsigned last,
               struct gl_context *ctx, void *mem_ctx);
 
 void
-validate_sso_explicit_locations(struct gl_context *ctx,
-                                struct gl_shader_program *prog,
-                                gl_shader_stage first,
-                                gl_shader_stage last);
+validate_first_and_last_interface_explicit_locations(struct gl_context *ctx,
+                                                     struct gl_shader_program *prog,
+                                                     gl_shader_stage first,
+                                                     gl_shader_stage last);
 
 void
 cross_validate_outputs_to_inputs(struct gl_context *ctx,

src/compiler/glsl/linker.cpp

@@ -5141,15 +5141,14 @@ link_shaders(struct gl_context *ctx, struct gl_shader_program *prog)
       prev = i;
    }
 
-   /* The cross validation of outputs/inputs above validates explicit locations
-    * but for SSO programs we need to do this also for the inputs in the
-    * first stage and outputs of the last stage included in the program, since
-    * there is no cross validation for these.
+   /* The cross validation of outputs/inputs above validates interstage
+    * explicit locations. We need to do this also for the inputs in the first
+    * stage and outputs of the last stage included in the program, since there
+    * is no cross validation for these.
     */
-   if (prog->SeparateShader)
-      validate_sso_explicit_locations(ctx, prog,
-                                      (gl_shader_stage) first,
-                                      (gl_shader_stage) last);
+   validate_first_and_last_interface_explicit_locations(ctx, prog,
+                                                        (gl_shader_stage) first,
+                                                        (gl_shader_stage) last);
 
    /* Cross-validate uniform blocks between shader stages */
    validate_interstage_uniform_blocks(prog, prog->_LinkedShaders);