Improve recovery if variable or subscript is missing brace wrapping getter and setter

Author: ahoppen

Sources/SwiftParser/Declarations.swift

@@ -1690,7 +1690,7 @@ extension Parser {
 
     // Parse getter and setter.
     let accessor: RawSyntax?
-    if self.at(.leftBrace) {
+    if self.at(any: [.leftBrace], contextualKeywords: ["get", "set"]) {
       accessor = self.parseGetSet()
     } else {
       accessor = nil
@@ -1786,7 +1786,7 @@ extension Parser {
         }
 
         let accessor: RawSyntax?
-        if self.at(.leftBrace) {
+        if self.at(any: [.leftBrace], contextualKeywords: ["get", "set"]) {
           accessor = self.parseGetSet()
         } else {
           accessor = nil
@@ -1921,7 +1921,14 @@ extension Parser {
   @_spi(RawSyntax)
   public mutating func parseGetSet() -> RawSyntax {
     // Parse getter and setter.
-    let (unexpectedBeforeLBrace, lbrace) = self.expect(.leftBrace)
+    let unexpectedBeforeLBrace: RawUnexpectedNodesSyntax?
+    let lbrace: RawTokenSyntax
+    if self.at(any: [], contextualKeywords: ["get", "set"]) {
+      unexpectedBeforeLBrace = nil
+      lbrace = missingToken(.leftBrace, text: nil)
+    } else {
+      (unexpectedBeforeLBrace, lbrace) = self.expect(.leftBrace)
+    }
     // Collect all explicit accessors to a list.
     var elements = [RawAccessorDeclSyntax]()
     do {

Tests/SwiftParserTest/Declarations.swift

@@ -1141,6 +1141,42 @@ final class DeclarationTests: XCTestCase {
       """
     )
   }
+
+  func testVariableDeclWithGetSetButNoBrace() {
+    AssertParse(
+      """
+      var x: Int 1️⃣
+        get {
+          4
+        }
+        set {
+          x = newValue
+        }
+      }
+      """,
+      diagnostics: [
+        DiagnosticSpec(message: "expected '{' in variable")
+      ]
+    )
+  }
+
+  func testVariableDeclWithSetGetButNoBrace() {
+    AssertParse(
+      """
+      var x: Int 1️⃣
+        set {
+          x = newValue
+        }
+        get {
+          4
+        }
+      }
+      """,
+      diagnostics: [
+        DiagnosticSpec(message: "expected '{' in variable")
+      ]
+    )
+  }
 }
 
 extension Parser.DeclAttributes {

Tests/SwiftParserTest/translated/SubscriptingTests.swift

@@ -362,20 +362,18 @@ final class SubscriptingTests: XCTestCase {
     AssertParse(
       """
       struct A8 {
-        subscript(i : Int) -> Int
-          1️⃣get 2️⃣{
+        subscript(i : Int) -> Int1️⃣
+          get {
             return stored
           }
-          3️⃣set 4️⃣{
+          set {
             stored = value
           }
-        }
+        }2️⃣
       """,
       diagnostics: [
-        DiagnosticSpec(locationMarker: "1️⃣", message: "expected 'func' in function"),
-        DiagnosticSpec(locationMarker: "2️⃣", message: "expected parameter clause in function signature"),
-        DiagnosticSpec(locationMarker: "3️⃣", message: "expected 'func' in function"),
-        DiagnosticSpec(locationMarker: "4️⃣", message: "expected parameter clause in function signature"),
+        DiagnosticSpec(locationMarker: "1️⃣", message: "expected '{' in subscript"),
+        DiagnosticSpec(locationMarker: "2️⃣", message: "expected '}' to end struct"),
       ]
     )
   }