[PaserDiagnostics] Improve '#if is not allowed' diagnostics

'#if' and '#endif' can be in the same node

Author: rintaro

Sources/SwiftParserDiagnostics/ParseDiagnosticsGenerator.swift

@@ -482,21 +482,36 @@ public class ParseDiagnosticsGenerator: SyntaxAnyVisitor {
       otherNode.lastToken(viewMode: .sourceAccurate)?.tokenKind == .poundEndif
     {
       let diagnoseOn = parent.parent ?? parent
-      addDiagnostic(
-        diagnoseOn,
-        IfConfigDeclNotAllowedInContext(context: diagnoseOn),
-        highlights: [Syntax(node), Syntax(otherNode)],
-        fixIts: [
-          FixIt(
-            message: RemoveNodesFixIt([Syntax(node), Syntax(otherNode)]),
-            changes: [
-              .makeMissing([Syntax(node)], transferTrivia: false),
-              .makeMissing([Syntax(otherNode)], transferTrivia: false),
-            ]
-          )
-        ],
-        handledNodes: [node.id, otherNode.id]
-      )
+      if node == otherNode {
+        addDiagnostic(
+          diagnoseOn,
+          IfConfigDeclNotAllowedInContext(context: diagnoseOn),
+          highlights: [Syntax(node)],
+          fixIts: [
+            FixIt(
+              message: RemoveNodesFixIt([Syntax(node)]),
+              changes: .makeMissing([Syntax(node)], transferTrivia: false),
+            )
+          ],
+          handledNodes: [node.id]
+        )
+      } else {
+        addDiagnostic(
+          diagnoseOn,
+          IfConfigDeclNotAllowedInContext(context: diagnoseOn),
+          highlights: [Syntax(node), Syntax(otherNode)],
+          fixIts: [
+            FixIt(
+              message: RemoveNodesFixIt([Syntax(node), Syntax(otherNode)]),
+              changes: [
+                .makeMissing([Syntax(node)], transferTrivia: false),
+                .makeMissing([Syntax(otherNode)], transferTrivia: false),
+              ]
+            )
+          ],
+          handledNodes: [node.id, otherNode.id]
+        )
+      }
     } else {
       addDiagnostic(node, UnexpectedNodesError(unexpectedNodes: node), highlights: [Syntax(node)])
     }

Tests/SwiftParserTest/AttributeTests.swift

@@ -1402,15 +1402,35 @@ final class AttributeTests: ParserTestCase {
   }
 
   func testAttributeParsable() {
-    let source = """
-      #if true
+    assertParse(
+      """
+      1️⃣#if true
       @discardableResult
       #endif
-      """
-    var parser = Parser(source)
-    let attr = AttributeSyntax.parse(from: &parser)
-
-    XCTAssertTrue(attr.description == source)
-    XCTAssertTrue(attr.tokens(viewMode: .fixedUp).allSatisfy({ $0.presence == .missing }))
+      """,
+      { AttributeSyntax.parse(from: &$0) },
+      substructure: AttributeSyntax(
+        atSign: .atSignToken(presence: .missing),
+        attributeName: TypeSyntax(MissingTypeSyntax(placeholder: .identifier("<#type#>", presence: .missing))),
+        UnexpectedNodesSyntax([
+          TokenSyntax.poundIfToken(),
+          TokenSyntax.keyword(.true),
+          TokenSyntax.atSignToken(),
+          TokenSyntax.identifier("discardableResult"),
+          TokenSyntax.poundEndifToken(),
+        ])
+      ),
+      diagnostics: [
+        DiagnosticSpec(message: "expected '@' and name in attribute", fixIts: ["insert '@' and name"]),
+        DiagnosticSpec(message: "conditional compilation not permitted in attribute", fixIts: ["""
+          remove '#if true
+          @discardableResult
+          #endif'
+          """])
+      ],
+      fixedSource: """
+        @<#type#>
+        """
+    )
   }
 }