[front_end] Convert an error message to use named arguments.

Modifies the scanner logic that reports the `AsciiControlCharacter`
error message so that it invokes it using `withArguments` (which
accepts named arguments) rather than the old `withArgumentsOld` (which
accepts positional arguments). The name of the parameter accepted by
this error message has been changed to `character`, to reflect its
usage, and parameter documentation has been added.

This is an exercise to verify that the front end's new `withArguments`
error reporting infrastructure is fully functional. In follow-up CLs,
I plan to introduce some tools to partially automate the process of
updating front end code to use `withArguments` rather than
`withArgumentsOld`.

However, if anyone wishes to start migrating error reporting to the
new scheme before that, they are welcome to do so.

Change-Id: I6a6a6964fc87d6bf551ec4891c56e6106dd9c098
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/448239
Commit-Queue: Paul Berry <[email protected]>
Reviewed-by: Johnni Winther <[email protected]>

Author: stereotype441

pkg/_fe_analyzer_shared/lib/src/messages/codes_generated.dart

@@ -211,32 +211,32 @@ const MessageCode codeAnonymousContinueTargetOutsideFunction =
 
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
 const Template<
-  Message Function(int unicode),
-  Message Function({required int unicode})
+  Message Function(int character),
+  Message Function({required int character})
 >
 codeAsciiControlCharacter = const Template(
   "AsciiControlCharacter",
   problemMessageTemplate:
-      r"""The control character #unicode can only be used in strings and comments.""",
+      r"""The control character #character can only be used in strings and comments.""",
   withArgumentsOld: _withArgumentsOldAsciiControlCharacter,
   withArguments: _withArgumentsAsciiControlCharacter,
   analyzerCodes: <String>["ILLEGAL_CHARACTER"],
 );
 
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
-Message _withArgumentsAsciiControlCharacter({required int unicode}) {
-  var unicode_0 = conversions.codePointToUnicode(unicode);
+Message _withArgumentsAsciiControlCharacter({required int character}) {
+  var character_0 = conversions.codePointToUnicode(character);
   return new Message(
     codeAsciiControlCharacter,
     problemMessage:
-        """The control character ${unicode_0} can only be used in strings and comments.""",
-    arguments: {'unicode': unicode},
+        """The control character ${character_0} can only be used in strings and comments.""",
+    arguments: {'character': character},
   );
 }
 
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
-Message _withArgumentsOldAsciiControlCharacter(int unicode) =>
-    _withArgumentsAsciiControlCharacter(unicode: unicode);
+Message _withArgumentsOldAsciiControlCharacter(int character) =>
+    _withArgumentsAsciiControlCharacter(character: character);
 
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
 const MessageCode codeAssertAsExpression = const MessageCode(

pkg/_fe_analyzer_shared/lib/src/scanner/error_token.dart

@@ -160,7 +160,7 @@ class AsciiControlCharacterToken extends ErrorToken {
 
   @override
   Message get assertionMessage =>
-      codeAsciiControlCharacter.withArgumentsOld(character);
+      codeAsciiControlCharacter.withArguments(character: character);
 }
 
 /// Denotes an operator that is not supported in the Dart language.

pkg/front_end/messages.yaml

@@ -146,8 +146,8 @@
 
 AsciiControlCharacter:
   parameters:
-    Unicode unicode: undocumented
-  problemMessage: "The control character #unicode can only be used in strings and comments."
+    Unicode character: the unexpected control character.
+  problemMessage: "The control character #character can only be used in strings and comments."
   analyzerCode: ILLEGAL_CHARACTER
   expression: "\x1b 1"