Improve error message on invalid legacy settings. NFC.

Author: sbc100

src/settings.js

@@ -2147,8 +2147,8 @@ var LEGACY_SETTINGS = [
   ['BINARYEN_MEM_MAX', 'MAXIMUM_MEMORY'],
   ['BINARYEN_PASSES', [''], 'Use BINARYEN_EXTRA_PASSES to add additional passes'],
   ['SWAPPABLE_ASM_MODULE', [0], 'Fully swappable asm modules are no longer supported'],
-  ['ASM_JS', [1], 'asm.js output is not supported any more'],
-  ['FINALIZE_ASM_JS', [0, 1], 'asm.js output is not supported any more'],
+  ['ASM_JS', [1], 'asm.js output is not supported anymore'],
+  ['FINALIZE_ASM_JS', [0, 1], 'asm.js output is not supported anymore'],
   ['ASYNCIFY_WHITELIST', 'ASYNCIFY_ONLY'],
   ['ASYNCIFY_BLACKLIST', 'ASYNCIFY_REMOVE'],
   ['EXCEPTION_CATCHING_WHITELIST', 'EXCEPTION_CATCHING_ALLOWED'],

test/test_other.py

@@ -10635,7 +10635,7 @@ def test_c_preprocessor(self):
   # Test that legacy settings that have been fixed to a specific value and their value can no longer be changed,
   def test_legacy_settings_forbidden_to_change(self):
     stderr = self.expect_fail([EMCC, '-sMEMFS_APPEND_TO_TYPED_ARRAYS=0', test_file('hello_world.c')])
-    self.assertContained('MEMFS_APPEND_TO_TYPED_ARRAYS=0 is no longer supported', stderr)
+    self.assertContained('emcc: error: invalid command line setting `-sMEMFS_APPEND_TO_TYPED_ARRAYS=0`: Starting from Emscripten 1.38.26, MEMFS_APPEND_TO_TYPED_ARRAYS=0 is no longer supported', stderr)
 
     self.run_process([EMCC, '-sMEMFS_APPEND_TO_TYPED_ARRAYS', test_file('hello_world.c')])
     self.run_process([EMCC, '-sPRECISE_I64_MATH=2', test_file('hello_world.c')])

tools/settings.py

@@ -207,7 +207,7 @@ def __setattr__(self, name, value):
         exit_with_error('legacy setting used in strict mode: %s', name)
       fixed_values, error_message = self.legacy_settings[name]
       if fixed_values and value not in fixed_values:
-        exit_with_error('Invalid command line option -s ' + name + '=' + str(value) + ': ' + error_message)
+        exit_with_error(f'invalid command line setting `-s{name}={value}`: {error_message}')
       diagnostics.warning('legacy-settings', 'use of legacy setting: %s (%s)', name, error_message)
 
     if name in self.alt_names: