Add diagnostic for @\nAttribute typo (WIP)

Author: TiagoMaiaL

Sources/SwiftParser/Attributes.swift

@@ -169,7 +169,7 @@ extension Parser {
     var (unexpectedBeforeAtSign, atSign) = self.expect(.atSign)
     let attributeName = self.parseType()
 
-    if !atSign.trailingTriviaPieces.isEmpty {
+    if atSign.trailingTriviaByteLength != 0 {
       unexpectedBeforeAtSign = RawUnexpectedNodesSyntax(
         combining: unexpectedBeforeAtSign, atSign,
         arena: self.arena
@@ -181,11 +181,12 @@ extension Parser {
         presence: .missing,
         arena: self.arena
       )
-    } else if let attributeTokenView = attributeName.raw.tokenView, attributeTokenView.leadingRawTriviaPieces.isEmpty {
+    } else if attributeName.raw.leadingTriviaByteLength != 0 {
       unexpectedBeforeAtSign = RawUnexpectedNodesSyntax(
         combining: unexpectedBeforeAtSign, attributeName.as(RawTokenSyntax.self),
         arena: self.arena
       )
+      // TODO: Synthesize fixed attributeName (RawTypeSyntax)
     }
 
     let shouldParseArgument: Bool

Sources/SwiftParserDiagnostics/ParseDiagnosticsGenerator.swift

@@ -459,28 +459,47 @@ public class ParseDiagnosticsGenerator: SyntaxAnyVisitor {
     }
     if node.hasError,
        let unexpectedBeforeAtSignTokens = node.unexpectedBeforeAtSignToken,
-       let unexpectedBeforeAtSign = unexpectedBeforeAtSignTokens.lastToken(viewMode: .sourceAccurate),
-       unexpectedBeforeAtSign.tokenKind == .atSign,
-       !unexpectedBeforeAtSign.trailingTrivia.isEmpty {
+       let unexpectedBeforeAtSign = unexpectedBeforeAtSignTokens.lastToken(viewMode: .sourceAccurate) {
       let tokensToDiscard = unexpectedBeforeAtSignTokens.compactMap { $0.as(TokenSyntax.self) }
-      addDiagnostic(
-        unexpectedBeforeAtSign,
-        StaticParserError.invalidWhitespaceBetweenAttributeAtSignAndIdentifier,
-        fixIts: [
-          FixIt(
-            message: StaticParserFixIt.removeExtraneousWhitespace,
-            changes: [
-              .makeMissing(tokensToDiscard, transferTrivia: false),
-              .makePresent(node.atSignToken),
-            ]
-          )
-        ],
-        handledNodes: [
-          node.id,
-          unexpectedBeforeAtSignTokens.id,
-          node.atSignToken.id
-        ]
-      )
+      if unexpectedBeforeAtSign.tokenKind == .atSign, !unexpectedBeforeAtSign.trailingTrivia.isEmpty {
+        addDiagnostic(
+          unexpectedBeforeAtSign,
+          StaticParserError.invalidWhitespaceBetweenAttributeAtSignAndIdentifier,
+          fixIts: [
+            FixIt(
+              message: StaticParserFixIt.removeExtraneousWhitespace,
+              changes: [
+                .makeMissing(tokensToDiscard, transferTrivia: false),
+                .makePresent(node.atSignToken),
+              ]
+            )
+          ],
+          handledNodes: [
+            node.id,
+            unexpectedBeforeAtSignTokens.id,
+            node.atSignToken.id
+          ]
+        )
+      } else if unexpectedBeforeAtSign.tokenKind == .identifier(unexpectedBeforeAtSign.text) {
+        addDiagnostic(
+          unexpectedBeforeAtSign,
+          StaticParserError.invalidWhitespaceBetweenAttributeAtSignAndIdentifier,
+          fixIts: [
+            FixIt(
+              message: StaticParserFixIt.removeExtraneousWhitespace,
+              changes: [
+                .makeMissing(tokensToDiscard, transferTrivia: false),
+                .makePresent(node.attributeName), // TODO: Provide synthesized attributeName as a replacement.
+              ]
+            )
+          ],
+          handledNodes: [
+            node.id,
+            unexpectedBeforeAtSignTokens.id,
+            node.attributeName.id
+          ]
+        )
+      }
     }
     return .visitChildren
   }