}
+/**
+ * Looks up the array object for the given ID.
+ *
+ * Unlike _mesa_lookup_vao, this function generates a GL_INVALID_OPERATION
+ * error if the array object does not exist. It also returns the default
+ * array object when ctx is a compatibility profile context and id is zero.
+ */
+struct gl_vertex_array_object *
+_mesa_lookup_vao_err(struct gl_context *ctx, GLuint id, const char *caller)
+{
+ /* The ARB_direct_state_access specification says:
+ *
+ * "<vaobj> is [compatibility profile:
+ * zero, indicating the default vertex array object, or]
+ * the name of the vertex array object."
+ */
+ if (id == 0) {
+ if (ctx->API == API_OPENGL_CORE) {
+ _mesa_error(ctx, GL_INVALID_OPERATION,
+ "%s(zero is not valid vaobj name in a core profile "
+ "context)", caller);
+ return NULL;
+ }
+
+ return ctx->Array.DefaultVAO;
+ } else {
+ struct gl_vertex_array_object *vao =
+ (struct gl_vertex_array_object *)
+ _mesa_HashLookup(ctx->Array.Objects, id);
+
+ /* The ARB_direct_state_access specification says:
+ *
+ * "An INVALID_OPERATION error is generated if <vaobj> is not
+ * [compatibility profile: zero or] the name of an existing
+ * vertex array object."
+ */
+ if (!vao || !vao->EverBound) {
+ _mesa_error(ctx, GL_INVALID_OPERATION,
+ "%s(non-existent vaobj=%u)", caller, id);
+ return NULL;
+ }
+
+ return vao;
+ }
+}
+
+
/**
* For all the vertex binding points in the array object, unbind any pointers
* to any buffer objects (VBOs).
extern struct gl_vertex_array_object *
_mesa_lookup_vao(struct gl_context *ctx, GLuint id);
+extern struct gl_vertex_array_object *
+_mesa_lookup_vao_err(struct gl_context *ctx, GLuint id, const char *caller);
+
extern struct gl_vertex_array_object *
_mesa_new_vao(struct gl_context *ctx, GLuint name);