Make --debug-gl have zero runtime cost when absent

__main__.py

@@ -2,6 +2,8 @@
 # vim:fileencoding=utf-8
 # License: GPL v3 Copyright: 2015, Kovid Goyal <kovid at kovidgoyal.net>
 
+import sys
+sys.debug_gl = '--debug-kitty-gl' in sys.argv
 
-from kitty.main import main
+from kitty.main import main  # noqa
 main()

kitty/data-types.c

@@ -100,6 +100,7 @@ extern bool init_fontconfig_library(PyObject*);
 extern bool init_glfw(PyObject *m);
 extern bool init_sprites(PyObject *module);
 extern bool init_shaders(PyObject *module);
+extern bool init_shaders_debug(PyObject *module);
 #ifdef __APPLE__
 extern int init_CoreText(PyObject *);
 extern bool init_cocoa(PyObject *module);
@@ -125,7 +126,11 @@ PyInit_fast_data_types(void) {
         if (!add_module_gl_constants(m)) return NULL;
         if (!init_glfw(m)) return NULL;
         if (!init_sprites(m)) return NULL;
-        if (!init_shaders(m)) return NULL;
+        if (PySys_GetObject("debug_gl") == Py_True) {
+            if (!init_shaders_debug(m)) return NULL;
+        } else { 
+            if (!init_shaders(m)) return NULL;
+        }
         if (!init_Window(m)) return NULL;
 #ifdef __APPLE__
         if (!init_CoreText(m)) return NULL;

kitty/main.py

@@ -17,13 +17,13 @@ from .constants import (
     appname, config_dir, isosx, logo_data_file, str_version, viewport_size
 )
 from .fast_data_types import (
-    GL_COLOR_BUFFER_BIT, GLFW_CONTEXT_VERSION_MAJOR, GL_VERSION_REQUIRED,
+    GL_COLOR_BUFFER_BIT, GL_VERSION_REQUIRED, GLFW_CONTEXT_VERSION_MAJOR,
     GLFW_CONTEXT_VERSION_MINOR, GLFW_DECORATED, GLFW_OPENGL_CORE_PROFILE,
     GLFW_OPENGL_FORWARD_COMPAT, GLFW_OPENGL_PROFILE, GLFW_SAMPLES,
-    GLFW_STENCIL_BITS, Window, change_wcwidth, check_for_extensions,
-    enable_automatic_opengl_error_checking, glClear, glClearColor, glewInit,
-    glfw_init, glfw_init_hint_string, glfw_set_error_callback,
-    glfw_swap_interval, glfw_terminate, glfw_window_hint
+    GLFW_STENCIL_BITS, Window, change_wcwidth, check_for_extensions, glClear,
+    glClearColor, glewInit, glfw_init, glfw_init_hint_string,
+    glfw_set_error_callback, glfw_swap_interval, glfw_terminate,
+    glfw_window_hint
 )
 from .layout import all_layouts
 from .utils import detach, safe_print
@@ -109,7 +109,7 @@ def option_parser():
                ' child process. Useful for debugging.')
     )
     a(
-        '--debug-gl',
+        '--debug-kitty-gl',
         action='store_true',
         default=False,
         help=_('Debug OpenGL commands. This will cause all OpenGL calls'
@@ -294,7 +294,6 @@ def main():
     opts = load_config(*config, overrides=overrides)
     change_wcwidth(not opts.use_system_wcwidth)
     glfw_set_error_callback(on_glfw_error)
-    enable_automatic_opengl_error_checking(args.debug_gl)
     if GLFW_X11_WM_CLASS_CLASS is not None:
         glfw_init_hint_string(GLFW_X11_WM_CLASS_CLASS, opts.cls)
     if not glfw_init():

kitty/shaders.c

@@ -34,6 +34,7 @@ static char glbuf[4096];
 #define fatal(...) { fprintf(stderr, __VA_ARGS__); fprintf(stderr, "\n"); exit(EXIT_FAILURE); }
 #define fatal_msg(msg) fatal("%s", msg);
 
+#ifdef ENABLE_DEBUG_GL
 static void
 check_for_gl_error(int line) {
 #define f(msg) fatal("%s (at line: %d)", msg, line); break;
@@ -60,8 +61,10 @@ check_for_gl_error(int line) {
     }
 }
 
-static bool _enable_error_checking = false;
-#define check_gl() { if (_enable_error_checking) check_for_gl_error(__LINE__); }
+#define check_gl() { check_for_gl_error(__LINE__); }
+#else
+#define check_gl() {}
+#endif
 
 static PyObject* 
 glew_init(PyObject UNUSED *self) {
@@ -582,12 +585,6 @@ send_borders_rects(GLuint vw, GLuint vh) {
 // }}}
 
 // Python API {{{
-static PyObject*
-enable_automatic_opengl_error_checking(PyObject UNUSED *self, PyObject *val) {
-    _enable_error_checking = PyObject_IsTrue(val) ? true : false;
-    Py_RETURN_NONE;
-}
-
 static PyObject*
 compile_program(PyObject UNUSED *self, PyObject *args) {
     const char *vertex_shader, *fragment_shader;
@@ -686,7 +683,6 @@ PYWRAP1(draw_cells) {
 #define M(name, arg_type) {#name, (PyCFunction)name, arg_type, NULL}
 #define MW(name, arg_type) {#name, (PyCFunction)py##name, arg_type, NULL}
 static PyMethodDef module_methods[] = {
-    M(enable_automatic_opengl_error_checking, METH_O),
     {"glewInit", (PyCFunction)glew_init, METH_NOARGS, NULL}, 
     M(compile_program, METH_VARARGS),
     MW(create_vao, METH_NOARGS),
@@ -711,7 +707,11 @@ static PyMethodDef module_methods[] = {
 };
 
 bool
+#ifdef ENABLE_DEBUG_GL
+init_shaders_debug(PyObject *module) {
+#else
 init_shaders(PyObject *module) {
+#endif
 #define C(x) if (PyModule_AddIntConstant(module, #x, x) != 0) { PyErr_NoMemory(); return false; }
     C(CELL_PROGRAM); C(CURSOR_PROGRAM); C(BORDERS_PROGRAM);
     C(GLSL_VERSION);

setup.py

@@ -194,6 +194,7 @@ def run_tool(cmd):
 
 SPECIAL_SOURCES = {
     'kitty/parser_dump.c': ('kitty/parser.c', ['DUMP_COMMANDS']),
+    'kitty/shaders_debug.c': ('kitty/shaders.c', ['ENABLE_DEBUG_GL']),
 }
 
 
@@ -287,6 +288,7 @@ def find_c_files():
         key=lambda x: os.path.getmtime(os.path.join(base, x)), reverse=True
     )
     ans.append('kitty/parser_dump.c')
+    ans.append('kitty/shaders_debug.c')
     return tuple(ans), tuple(headers)