Don't enable USE_GLFW by default

This changes the default behaviour to match that of STRICT mode
and MINIMAL_RUNTIME node.

We made a similar change for USE_SDL back in #18443.

As part of this change I also updated the code that maps `-l` flags
to JS libraries.  In some cases we also want these to set the
corresponding `-sUSE_XXX` setting.

Author: sbc100

ChangeLog.md

@@ -24,6 +24,10 @@ See docs/process.md for more on how version tagging works.
 - The `--minify=0` commnad line flag will now preserve comments as well as
   whitespace.  This means the resulting output can then be run though closure
   compiler or some other tool that gives comments semantic meaning. (#20121)
+- The `USE_GLFW` settings now defaults to 0 rather than 2.  This matches other
+  other settings such as `USE_SDL` that default to 0 these days and also is
+  inline the the behaviour under `MINIMAL_RUNTIME`.  If you use glfw you now
+  need to explictly opt into it using `-sUSE_GLFW`.
 
 3.1.45 - 08/23/23
 -----------------

emcc.py

@@ -54,7 +54,7 @@
 from tools import webassembly
 from tools import config
 from tools import cache
-from tools.settings import user_settings, settings, MEM_SIZE_SETTINGS, COMPILE_TIME_SETTINGS
+from tools.settings import default_setting, user_settings, settings, MEM_SIZE_SETTINGS, COMPILE_TIME_SETTINGS
 from tools.utils import read_file, write_file, read_binary, delete_file, removeprefix
 
 logger = logging.getLogger('emcc')
@@ -409,11 +409,6 @@ def expand_byte_size_suffixes(value):
   return value
 
 
-def default_setting(name, new_default):
-  if name not in user_settings:
-    setattr(settings, name, new_default)
-
-
 def apply_user_settings():
   """Take a map of users settings {NAME: VALUE} and apply them to the global
   settings object.
@@ -2027,15 +2022,13 @@ def phase_linker_setup(options, state, newargs):
     default_setting('AUTO_JS_LIBRARIES', 0)
     # When using MINIMAL_RUNTIME, symbols should only be exported if requested.
     default_setting('EXPORT_KEEPALIVE', 0)
-    default_setting('USE_GLFW', 0)
 
   if settings.STRICT_JS and (settings.MODULARIZE or settings.EXPORT_ES6):
     exit_with_error("STRICT_JS doesn't work with MODULARIZE or EXPORT_ES6")
 
   if settings.STRICT:
     if not settings.MODULARIZE and not settings.EXPORT_ES6:
       default_setting('STRICT_JS', 1)
-    default_setting('USE_GLFW', 0)
     default_setting('AUTO_JS_LIBRARIES', 0)
     default_setting('AUTO_NATIVE_LIBRARIES', 0)
     default_setting('AUTO_ARCHIVE_INDEXES', 0)

src/settings.js

@@ -1306,9 +1306,8 @@ var EMSCRIPTEN_TRACING = false;
 // Specify the GLFW version that is being linked against.  Only relevant, if you
 // are linking against the GLFW library.  Valid options are 2 for GLFW2 and 3
 // for GLFW3.
-// This defaults to 0 in either MINIMAL_RUNTIME or STRICT modes.
 // [link]
-var USE_GLFW = 2;
+var USE_GLFW = 0;
 
 // Whether to use compile code to WebAssembly. Set this to 0 to compile to JS
 // instead of wasm.

test/test_browser.py

@@ -1621,6 +1621,7 @@ def test_sdl_fog_linear(self):
   @requires_graphics_hardware
   def test_glfw(self):
     self.btest_exit('browser/test_glfw.c', args=['-sLEGACY_GL_EMULATION', '-lglfw', '-lGL'])
+    self.btest_exit('browser/test_glfw.c', args=['-sLEGACY_GL_EMULATION', '-sUSE_GLFW=2', '-lGL'])
     self.btest_exit('browser/test_glfw.c', args=['-sLEGACY_GL_EMULATION', '-sUSE_GLFW=2', '-lglfw', '-lGL'])
 
   def test_glfw_minimal(self):

tools/building.py

@@ -32,7 +32,7 @@
 from .shared import LLVM_DWARFDUMP, demangle_c_symbol_name
 from .shared import get_emscripten_temp_dir, exe_suffix, is_c_symbol
 from .utils import WINDOWS
-from .settings import settings
+from .settings import settings, default_setting
 
 logger = logging.getLogger('building')
 
@@ -1114,12 +1114,21 @@ def map_to_js_libs(library_name, emit_tsd):
     'embind': 'libembind',
     'GL': 'libGL',
   }
+  settings_map = {
+    'glfw': {'USE_GLFW': 2},
+    'glfw3': {'USE_GLFW': 3},
+    'SDL': {'USE_SDL': 2},
+  }
 
   if library_name in library_map:
     libs = library_map[library_name]
     logger.debug('Mapping library `%s` to JS libraries: %s' % (library_name, libs))
     return (libs, native_library_map.get(library_name))
 
+  if library_name in settings_map:
+    for key, value in settings_map[library_name].items():
+      default_setting(key, value)
+
   if library_name.endswith('.js') and os.path.isfile(path_from_root('src', f'library_{library_name}')):
     return ([f'library_{library_name}'], None)
 

tools/settings.py

@@ -95,6 +95,11 @@
 user_settings: Dict[str, str] = {}
 
 
+def default_setting(name, new_default):
+  if name not in user_settings:
+    setattr(settings, name, new_default)
+
+
 class SettingsManager:
   attrs: Dict[str, Any] = {}
   types: Dict[str, Any] = {}