+_mesa_init_image_units(struct gl_context *ctx);
+
+/**
+ * Return GL_TRUE if the state of the image unit passed as argument is valid
+ * and access from the shader is allowed. Otherwise loads from this unit
+ * should return zero and stores should have no effect.
+ *
+ * The result depends on context state other than the passed image unit, part
+ * of the _NEW_TEXTURE_OBJECT set.
+ */
+GLboolean
+_mesa_is_image_unit_valid(struct gl_context *ctx, struct gl_image_unit *u);
+
+void GLAPIENTRY
+_mesa_BindImageTexture_no_error(GLuint unit, GLuint texture, GLint level,
+ GLboolean layered, GLint layer, GLenum access,
+ GLenum format);