Remove windows-specific console coloring

Windows 10 and above support ANSI coloring and there should be very few
emscripten users on older version of windows at this point (if any?).

The downside is that windows 7 will no longer have nice colored error
messages, but the upside is that we can cleanup and refactor this code
now (see emscripten-core#25495).

Author: sbc100

ChangeLog.md

@@ -20,6 +20,8 @@ See docs/process.md for more on how version tagging works.
 
 4.0.16 (in development)
 -----------------------
+- Colored console output for error messages and logging is not longer supported
+  on Windows 8 and older. (#25502)
 - A warning was added about usage of embind without C++17 or above. (#25424)
 - The minimum supported versions of Node, Chrome and Firefox were bumped
   enabling the removal of the `globalThis` polyfill and universally enabling

test/test_other.py

@@ -11607,21 +11607,11 @@ def test_color_diagnostics_disable(self, flag):
   })
   def test_color_diagnostics_force(self, flag):
     create_file('src.c', 'int main() {')
-    # -fansi-escape-codes is needed here to make this test work on windows, which doesn't
-    # use ansi codes by default
-    output = self.expect_fail([EMCC, '-fansi-escape-codes', flag, 'src.c'])
+    output = self.expect_fail([EMCC, flag, 'src.c'])
     self.assertIn("\x1b[1msrc.c:1:13: \x1b[0m\x1b[0;1;31merror: \x1b[0m\x1b[1mexpected '}'\x1b[0m", output)
     # Verify that emcc errors show up as red and bold
     self.assertIn('emcc: \x1b[31m\x1b[1m', output)
 
-    if WINDOWS:
-      # Also test without -fansi-escape-codes on windows.
-      # In those mode the code will use kernel calls such as SetConsoleTextAttribute to
-      # change the output color.  We cannot detect this in the output, but we can at least
-      # get coverage of the code path in the diagnositics.py.
-      output = self.expect_fail([EMCC, flag, 'src.c'])
-      self.assertNotIn('\x1b', output)
-
   def test_sanitizer_color(self):
     create_file('src.c', '''
       #include <emscripten.h>

tools/cmdline.py

@@ -514,7 +514,7 @@ def consume_arg_file():
     elif arg in ('-fno-color-diagnostics', '-fdiagnostics-color=never'):
       diagnostics.color_enabled = False
     elif arg == '-fansi-escape-codes':
-      diagnostics.force_ansi = True
+      diagnostics.color_enabled = True
     elif arg == '-fno-exceptions':
       settings.DISABLE_EXCEPTION_CATCHING = 1
       settings.DISABLE_EXCEPTION_THROWING = 1

tools/colored_logger.py

@@ -11,88 +11,25 @@
 import logging
 
 
-def add_coloring_to_emit_windows(fn):
+def ansi_color_available():
+  if not sys.platform.startswith('win'):
+    return sys.stderr.isatty()
+
   # Constants from the Windows API
   STD_OUTPUT_HANDLE = -11
+  ENABLE_VIRTUAL_TERMINAL_PROCESSING = 0x0004
 
-  def _get_color():
-    SHORT = ctypes.c_short
-    WORD = ctypes.c_ushort
-
-    class COORD(ctypes.Structure):
-      _fields_ = [
-        ("X", SHORT),
-        ("Y", SHORT)]
-
-    class SMALL_RECT(ctypes.Structure):
-      _fields_ = [
-        ("Left", SHORT),
-        ("Top", SHORT),
-        ("Right", SHORT),
-        ("Bottom", SHORT)]
-
-    class CONSOLE_SCREEN_BUFFER_INFO(ctypes.Structure):
-      _fields_ = [
-        ("dwSize", COORD),
-        ("dwCursorPosition", COORD),
-        ("wAttributes", WORD),
-        ("srWindow", SMALL_RECT),
-        ("dwMaximumWindowSize", COORD)]
+  kernel32 = ctypes.windll.kernel32
+  stdout_handle = kernel32.GetStdHandle(STD_OUTPUT_HANDLE)
 
-    hdl = ctypes.windll.kernel32.GetStdHandle(STD_OUTPUT_HANDLE)
-    csbi = CONSOLE_SCREEN_BUFFER_INFO()
-    ctypes.windll.kernel32.GetConsoleScreenBufferInfo(hdl, ctypes.byref(csbi))
-    return csbi.wAttributes
+  # Get the current console mode
+  console_mode = ctypes.c_uint()
+  if not kernel32.GetConsoleMode(stdout_handle, ctypes.byref(console_mode)):
+    # Handle error if GetConsoleMode fails
+    return False
 
-  def _set_color(code):
-    hdl = ctypes.windll.kernel32.GetStdHandle(STD_OUTPUT_HANDLE)
-    ctypes.windll.kernel32.SetConsoleTextAttribute(hdl, code)
-
-  def new(*args):
-    # wincon.h
-    FOREGROUND_BLACK     = 0x0000 # noqa
-    FOREGROUND_BLUE      = 0x0001 # noqa
-    FOREGROUND_GREEN     = 0x0002 # noqa
-    FOREGROUND_CYAN      = 0x0003 # noqa
-    FOREGROUND_RED       = 0x0004 # noqa
-    FOREGROUND_MAGENTA   = 0x0005 # noqa
-    FOREGROUND_YELLOW    = 0x0006 # noqa
-    FOREGROUND_GREY      = 0x0007 # noqa
-    FOREGROUND_INTENSITY = 0x0008 # foreground color is intensified.
-
-    FOREGROUND_WHITE     = FOREGROUND_BLUE|FOREGROUND_GREEN |FOREGROUND_RED # noqa
-
-    BACKGROUND_BLACK     = 0x0000 # noqa
-    BACKGROUND_BLUE      = 0x0010 # noqa
-    BACKGROUND_GREEN     = 0x0020 # noqa
-    BACKGROUND_CYAN      = 0x0030 # noqa
-    BACKGROUND_RED       = 0x0040 # noqa
-    BACKGROUND_MAGENTA   = 0x0050 # noqa
-    BACKGROUND_YELLOW    = 0x0060 # noqa
-    BACKGROUND_GREY      = 0x0070 # noqa
-    BACKGROUND_INTENSITY = 0x0080 # background color is intensified.
-    levelno = args[1].levelno
-    if (levelno >= 50):
-        color = BACKGROUND_YELLOW | FOREGROUND_RED | FOREGROUND_INTENSITY | BACKGROUND_INTENSITY
-    elif (levelno >= 40):
-        color = FOREGROUND_RED | FOREGROUND_INTENSITY
-    elif (levelno >= 30):
-        color = FOREGROUND_YELLOW | FOREGROUND_INTENSITY
-    elif (levelno >= 20):
-        color = FOREGROUND_GREEN
-    elif (levelno >= 10):
-        color = FOREGROUND_MAGENTA
-    else:
-        color = FOREGROUND_WHITE
-
-    old_color = _get_color()
-    _set_color(color)
-    ret = fn(*args)
-    _set_color(old_color)
-    return ret
-
-  new.orig_func = fn
-  return new
+  # Check if the flag is set in the current console mode
+  return (console_mode.value & ENABLE_VIRTUAL_TERMINAL_PROCESSING) != 0
 
 
 def add_coloring_to_emit_ansi(fn):
@@ -117,11 +54,8 @@ def new(*args):
 
 
 def enable():
-  if sys.stderr.isatty():
-    if sys.platform.startswith('win'):
-      logging.StreamHandler.emit = add_coloring_to_emit_windows(logging.StreamHandler.emit)
-    else:
-      logging.StreamHandler.emit = add_coloring_to_emit_ansi(logging.StreamHandler.emit)
+  if ansi_color_available():
+    logging.StreamHandler.emit = add_coloring_to_emit_ansi(logging.StreamHandler.emit)
 
 
 def disable():

tools/diagnostics.py

@@ -6,24 +6,22 @@
 """Simple color-enabled diagnositics reporting functions.
 """
 
-import ctypes
 import logging
 import os
 import sys
 from typing import Dict
 
-WINDOWS = sys.platform.startswith('win')
+from . import colored_logger
 
+color_enabled = colored_logger.ansi_color_available()
 logger = logging.getLogger('diagnostics')
-color_enabled = sys.stderr.isatty()
 tool_name = os.path.splitext(os.path.basename(sys.argv[0]))[0]
-force_ansi = False
 
 # diagnostic levels
 WARN = 1
 ERROR = 2
 
-# available colors
+# available (ANSI) colors
 RED = 1
 GREEN = 2
 YELLOW = 3
@@ -43,94 +41,19 @@
     ERROR: 'error: ',
 }
 
-# Constants from the Windows API
-STD_OUTPUT_HANDLE = -11
-
-
-def output_color_windows(color):
-  assert not force_ansi
-  # TODO(sbc): This code is duplicated in colored_logger.py.  Refactor.
-  # wincon.h
-  FOREGROUND_BLACK     = 0x0000 # noqa
-  FOREGROUND_BLUE      = 0x0001 # noqa
-  FOREGROUND_GREEN     = 0x0002 # noqa
-  FOREGROUND_CYAN      = 0x0003 # noqa
-  FOREGROUND_RED       = 0x0004 # noqa
-  FOREGROUND_MAGENTA   = 0x0005 # noqa
-  FOREGROUND_YELLOW    = 0x0006 # noqa
-  FOREGROUND_GREY      = 0x0007 # noqa
-
-  color_map = {
-    RED: FOREGROUND_RED,
-    GREEN: FOREGROUND_GREEN,
-    YELLOW: FOREGROUND_YELLOW,
-    BLUE: FOREGROUND_BLUE,
-    MAGENTA: FOREGROUND_MAGENTA,
-    CYAN: FOREGROUND_CYAN,
-    WHITE: FOREGROUND_BLUE | FOREGROUND_GREEN | FOREGROUND_RED,
-  }
-
-  sys.stderr.flush()
-  hdl = ctypes.windll.kernel32.GetStdHandle(STD_OUTPUT_HANDLE)
-  ctypes.windll.kernel32.SetConsoleTextAttribute(hdl, color_map[color])
-
-
-def get_color_windows():
-  assert not force_ansi
-  SHORT = ctypes.c_short
-  WORD = ctypes.c_ushort
-
-  class COORD(ctypes.Structure):
-    _fields_ = [
-      ("X", SHORT),
-      ("Y", SHORT)]
-
-  class SMALL_RECT(ctypes.Structure):
-    _fields_ = [
-      ("Left", SHORT),
-      ("Top", SHORT),
-      ("Right", SHORT),
-      ("Bottom", SHORT)]
-
-  class CONSOLE_SCREEN_BUFFER_INFO(ctypes.Structure):
-    _fields_ = [
-      ("dwSize", COORD),
-      ("dwCursorPosition", COORD),
-      ("wAttributes", WORD),
-      ("srWindow", SMALL_RECT),
-      ("dwMaximumWindowSize", COORD)]
-
-  hdl = ctypes.windll.kernel32.GetStdHandle(STD_OUTPUT_HANDLE)
-  csbi = CONSOLE_SCREEN_BUFFER_INFO()
-  ctypes.windll.kernel32.GetConsoleScreenBufferInfo(hdl, ctypes.byref(csbi))
-  return csbi.wAttributes
-
-
-def reset_color_windows():
-  assert not force_ansi
-  sys.stderr.flush()
-  hdl = ctypes.windll.kernel32.GetStdHandle(STD_OUTPUT_HANDLE)
-  ctypes.windll.kernel32.SetConsoleTextAttribute(hdl, default_color)
-
 
 def output_color(color):
-  if WINDOWS and not force_ansi:
-    output_color_windows(color)
-    return ''
+  assert color_enabled
   return '\033[3%sm' % color
 
 
 def bold():
-  if WINDOWS and not force_ansi:
-    # AFAICT there is no way to enable bold output on windows
-    return ''
+  assert color_enabled
   return '\033[1m'
 
 
 def reset_color():
-  if WINDOWS and not force_ansi:
-    reset_color_windows()
-    return ''
+  assert color_enabled
   return '\033[0m'
 
 
@@ -260,7 +183,4 @@ def capture_warnings(argv):
   return manager.capture_warnings(argv)
 
 
-if WINDOWS:
-  default_color = get_color_windows()
-
 manager = WarningManager()