[analyzer] trim trailing whitespace from diagnostic messages.

This is something the CFE already does as part of its diagnostic
message code generation; the analyzer should do it too.

Making this change to the analyzer now paves the way for unifying the
analyzer and CFE code for reading and interpreting `messages.yaml`
files.

Change-Id: I6a6a6964b04ef0a67f8077becb3726bafc40a5cb
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/448228
Reviewed-by: Konstantin Shcheglov <[email protected]>
Commit-Queue: Paul Berry <[email protected]>
Reviewed-by: Brian Wilkerson <[email protected]>

Author: stereotype441

pkg/analyzer/lib/src/manifest/manifest_warning_code.g.dart

@@ -57,7 +57,7 @@ class ManifestWarningCode extends DiagnosticCodeWithExpectedTypes {
   noTouchscreenFeature = ManifestWarningWithoutArguments(
     'NO_TOUCHSCREEN_FEATURE',
     "The default \"android.hardware.touchscreen\" needs to be optional for "
-        "Chrome OS. ",
+        "Chrome OS.",
     correctionMessage:
         "Consider adding <uses-feature "
         "android:name=\"android.hardware.touchscreen\" android:required=\"false\" "
@@ -76,7 +76,7 @@ class ManifestWarningCode extends DiagnosticCodeWithExpectedTypes {
   permissionImpliesUnsupportedHardware = ManifestWarningTemplate(
     'PERMISSION_IMPLIES_UNSUPPORTED_HARDWARE',
     "Permission makes app incompatible for Chrome OS, consider adding optional "
-        "{0} feature tag, ",
+        "{0} feature tag,",
     correctionMessage:
         " Try adding `<uses-feature android:name=\"{0}\"  "
         "android:required=\"false\">`.",

pkg/analyzer/tool/messages/error_code_info.dart

@@ -656,13 +656,13 @@ abstract class ErrorCodeInfo {
   ErrorCodeInfo.fromYaml(Map<Object?, Object?> yaml)
     : this(
         comment: yaml['comment'] as String?,
-        correctionMessage: yaml['correctionMessage'] as String?,
+        correctionMessage: _decodeMessage(yaml['correctionMessage']),
         deprecatedMessage: yaml['deprecatedMessage'] as String?,
         documentation: yaml['documentation'] as String?,
         hasPublishedDocs: yaml['hasPublishedDocs'] as bool?,
         isUnresolvedIdentifier:
             yaml['isUnresolvedIdentifier'] as bool? ?? false,
-        problemMessage: yaml['problemMessage'] as String? ?? '',
+        problemMessage: _decodeMessage(yaml['problemMessage']) ?? '',
         sharedName: yaml['sharedName'] as String?,
         removedIn: yaml['removedIn'] as String?,
         previousName: yaml['previousName'] as String?,
@@ -887,6 +887,20 @@ static LocatableDiagnostic $withArgumentsName({$withArgumentsParams}) {
     }
   }
 
+  static String? _decodeMessage(Object? rawMessage) {
+    switch (rawMessage) {
+      case null:
+        return null;
+      case String():
+        // Remove trailing whitespace. This is necessary for templates defined
+        // with `|` (verbatim) as they always contain a trailing newline that we
+        // don't want.
+        return rawMessage.trimRight();
+      default:
+        throw 'Bad message type: ${rawMessage.runtimeType}';
+    }
+  }
+
   static List<ErrorCodeParameter>? _decodeParameters(Object? yaml) {
     if (yaml == null) return null;
     if (yaml == 'none') return const [];