cgen: remove the need for [console] for gg or ui programs on windows (#15912)

doc/docs.md

@@ -6175,9 +6175,11 @@ fn C.DefWindowProc(hwnd int, msg int, lparam int, wparam int)
 type FastFn = fn (int) bool
 
 // Windows only:
-// If a default graphics library is imported (ex. gg, ui), then the graphical window takes
+// Without this attribute all graphical apps will have the following behavior on Windows:
-// priority and no console window is created, effectively disabling println() statements.
+// If run from a console or terminal; keep the terminal open so all (e)println statements can be viewed.
-// Use to explicitly create console window. Valid before main() only.
+// If run from e.g. Explorer, by double-click; app is opened, but no terminal is opened, and no (e)println output can be seen.
+// Use it to force-open a terminal to view output in, even if the app is started from Explorer.
+// Valid before main() only.
 [console]
 fn main() {
 }

examples/clock/clock.v

@@ -147,8 +147,6 @@ fn on_init(mut app App) {
 	app.resize()
 }
 
-// is needed for easier diagnostics on windows
-[console]
 fn main() {
 	println("Press 'q' to quit.")
 	mut font_path := os.resource_abs_path(os.join_path('..', 'assets', 'fonts', 'RobotoMono-Regular.ttf'))

examples/fireworks/fireworks.v

@@ -93,8 +93,6 @@ fn (mut app App) resize() {
 	app.ui.height = size.height
 }
 
-// is needed for easier diagnostics on windows
-[console]
 fn main() {
 	mut font_path := os.resource_abs_path(os.join_path('..', 'assets', 'fonts', 'RobotoMono-Regular.ttf'))
 	$if android {

examples/gg/mandelbrot.v

@@ -222,7 +222,6 @@ fn graphics_keydown(code gg.KeyCode, mod gg.Modifier, mut state AppState) {
 	}
 }
 
-[console]
 fn main() {
 	mut state := &AppState{}
 	state.gg = gg.new_context(

examples/sokol/01_cubes/cube.v

@@ -403,8 +403,6 @@ fn my_event_manager(mut ev gg.Event, mut app App) {
 * Main
 *
 ******************************************************************************/
-// is needed for easier diagnostics on windows
-[console]
 fn main() {
 	// App init
 	mut app := &App{

examples/sokol/02_cubes_glsl/cube_glsl.v

@@ -577,7 +577,6 @@ fn my_event_manager(mut ev gg.Event, mut app App) {
 * Main
 *
 ******************************************************************************/
-[console] // is needed for easier diagnostics on windows
 fn main() {
 	// App init
 	mut app := &App{

examples/sokol/03_march_tracing_glsl/rt_glsl.v

@@ -392,7 +392,6 @@ fn my_event_manager(mut ev gg.Event, mut app App) {
 /******************************************************************************
 * Main
 ******************************************************************************/
-[console] // is needed for easier diagnostics on windows
 fn main() {
 	// App init
 	mut app := &App{

examples/sokol/04_multi_shader_glsl/rt_glsl.v

@@ -586,7 +586,6 @@ fn my_event_manager(mut ev gg.Event, mut app App) {
 /******************************************************************************
 * Main
 ******************************************************************************/
-[console] // is needed for easier diagnostics on windows
 fn main() {
 	// App init
 	mut app := &App{

examples/sokol/05_instancing_glsl/rt_glsl.v

@@ -475,7 +475,6 @@ fn my_event_manager(mut ev gg.Event, mut app App) {
 /******************************************************************************
 * Main
 ******************************************************************************/
-[console] // is needed for easier diagnostics on windows
 fn main(){
 	// App init
 	mut app := &App{

examples/sokol/06_obj_viewer/show_obj.v

@@ -265,8 +265,6 @@ fn my_event_manager(mut ev gg.Event, mut app App) {
 /******************************************************************************
 * Main
 ******************************************************************************/
-// is needed for easier diagnostics on windows
-[console]
 fn main() {
 	/*
 	obj.tst()

examples/sokol/fonts.v

@@ -13,7 +13,6 @@ mut:
 	font_normal  int
 }
 
-[console]
 fn main() {
 	mut color_action := gfx.ColorAttachmentAction{
 		action: .clear

examples/sokol/freetype_raven.v

@@ -61,7 +61,6 @@ mut:
 	inited      bool
 }
 
-[console]
 fn main() {
 	mut color_action := gfx.ColorAttachmentAction{
 		action: .clear

examples/ttf_font/example_ttf.v

@@ -116,7 +116,6 @@ fn my_event_manager(mut ev gg.Event, mut app App_data) {
 	}
 }
 
-[console]
 fn main() {
 	mut app := &App_data{
 		gg: 0

examples/viewer/view.v

@@ -761,8 +761,6 @@ fn load_and_show(file_list []string, mut app App) {
 * Main
 *
 ******************************************************************************/
-// is needed for easier diagnostics on windows
-[console]
 fn main() {
 	// mut font_path := os.resource_abs_path(os.join_path('../assets/fonts/', 'RobotoMono-Regular.ttf'))
 	font_name := 'RobotoMono-Regular.ttf'

vlib/gg/testdata/draw_simple_polygons.vv

@@ -10,7 +10,6 @@ mut:
 	edge     int = 3
 }
 
-[console]
 fn main() {
 	println('rotation: left arrow key, right arrow key')
 	println('center polygon edge: up arrow key, down arrow key')

vlib/gg/testdata/remove_image_from_cache.vv

@@ -3,7 +3,6 @@ module main
 import gg
 import sokol.gfx
 
-[console]
 fn main() {
 	mut context := gg.new_context(
 		frame_fn: frame

vlib/v/fmt/tests/attrs_expected.vv

@@ -3,7 +3,7 @@
 [direct_array_access; inline; unsafe]
 fn heavily_tagged() {}
 
-// console attribute for easier diagnostics on windows
+// console attribute to force-open a console for easier diagnostics on windows
 // also it's not safe to use
 [console; unsafe]
 fn dangerous_console() {}

vlib/v/fmt/tests/attrs_input.vv

@@ -5,6 +5,6 @@
 [tom: 'jerry']
 fn heavily_tagged() {}
 
-[console] // console attribute for easier diagnostics on windows
+[console] // console attribute to force-open a console for easier diagnostics on windows
 [unsafe] // also it's not safe to use
 fn dangerous_console() {}

vlib/v/gen/c/cmain.v

@@ -69,6 +69,20 @@ fn (mut g Gen) gen_c_main_function_only_header() {
 			g.writeln('\tcmd_line_to_argv CommandLineToArgvW = (cmd_line_to_argv)GetProcAddress(shell32_module, "CommandLineToArgvW");')
 			g.writeln('\tint ___argc;')
 			g.writeln('\twchar_t** ___argv = CommandLineToArgvW(full_cmd_line, &___argc);')
+
+			g.writeln('BOOL con_valid = FALSE;')
+			if g.force_main_console {
+				g.writeln('con_valid = AllocConsole();')
+			} else {
+				g.writeln('con_valid = AttachConsole(ATTACH_PARENT_PROCESS);')
+			}
+			g.writeln('if (con_valid) {')
+			g.writeln('\tFILE* res_fp = 0;')
+			g.writeln('\terrno_t err;')
+			g.writeln('\terr = freopen_s(&res_fp, "CON", "w", stdout);')
+			g.writeln('\terr = freopen_s(&res_fp, "CON", "w", stderr);')
+			g.writeln('\t(void)err;')
+			g.writeln('}')
 			return
 		}
 		// Console application

vlib/v/tests/skip_unused/gg_code.vv

@@ -3,7 +3,6 @@ module main
 import gg
 import gx
 
-[console]
 fn main() {
 	x := gg.new_context(
 		bg_color: gx.rgb(174, 198, 255)

vlib/x/ttf/README.md

@@ -57,7 +57,6 @@ Let's start with a simple snippet of code:
 import os
 import x.ttf
 
-[console]
 fn main() {
 	mut ttf_font := ttf.TTF_File{}
 	ttf_font.buf = os.read_bytes('arial.ttf') or { panic(err) }
@@ -75,7 +74,6 @@ At this point we can render a simple text:
 import os
 import x.ttf
 
-[console]
 fn main() {
 	mut ttf_font := ttf.TTF_File{}
 	ttf_font.buf = os.read_bytes('arial.ttf') or { panic(err) }
@@ -139,7 +137,6 @@ Draw text block draw a justified and indented block of multiline text in the bit
 import os
 import x.ttf
 
-[console]
 fn main() {
 	mut ttf_font := ttf.TTF_File{}
 	ttf_font.buf = os.read_bytes('arial.ttf') or { panic(err) }
@@ -268,7 +265,6 @@ fn draw_frame(mut app App_data) {
 	app.gg.end()
 }
 
-[console]
 fn main() {
 	mut app := &App_data{
 		gg: 0