[gtk/wip/otte/conic: 1/3] glrenderer: Emit more useful error messages

[Benjamin Otte <otte src gnome org>]

commit c907ad83b0f5d7b32a04e9cbd0949e8da0143bf6
Author: Benjamin Otte <otte redhat com>
Date:   Thu Dec 3 05:33:30 2020 +0100

    glrenderer: Emit more useful error messages
    
    Catch the error when it happens, so that we can emit a specific and more
    helpful error message.
    
    Also verify that all branches in the code now do indeed set a proper
    GError when they fail, so that the final catch-all is no longer needed.
    Instead, assert that the error is set so that we catch future code
    additions early that do not set the GError.

 gsk/gl/gskglrenderer.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)
---
diff --git a/gsk/gl/gskglrenderer.c b/gsk/gl/gskglrenderer.c
index bb09be8bdd..57b0767772 100644
--- a/gsk/gl/gskglrenderer.c
+++ b/gsk/gl/gskglrenderer.c
@@ -54,6 +54,8 @@
                               glGetUniformLocation(programs->program_name ## _program.id, "u_" 
#uniform_basename);\
                 if (programs->program_name ## _program.program_name.uniform_basename ## _location == -1) \
                   { \
+                    g_set_error (error, GDK_GL_ERROR, GDK_GL_ERROR_LINK_FAILED, \
+                                 "Failed to find variable \"u_%s\" in shader program \"%s\"", 
#uniform_basename, #program_name); \
                     g_clear_pointer (&programs, gsk_gl_renderer_programs_unref); \
                     goto out; \
                   } \
@@ -3361,9 +3363,8 @@ gsk_gl_renderer_create_programs (GskGLRenderer  *self,
 out:
   gsk_gl_shader_builder_finish (&shader_builder);
 
-  if (error && !(*error) && !programs)
-    g_set_error (error, GDK_GL_ERROR, GDK_GL_ERROR_COMPILATION_FAILED,
-                 "Failed to compile all shader programs"); /* Probably, eh. */
+  /* Check we indeed emitted an error if there was one */
+  g_assert (programs || !error || *error);
 
   return programs;
 }