Skip parsing trailing closures after literals

Postfix parsing should skip trailing closure if the base expression is
a literal (which is not callable).

Author: bnbarham

Sources/SwiftParser/Expressions.swift

@@ -790,7 +790,7 @@ extension Parser {
       }
 
       // Check for a trailing closure, if allowed.
-      if self.at(.leftBrace) && self.withLookahead({ $0.atValidTrailingClosure(flavor: flavor) }) {
+      if self.at(.leftBrace) && !leadingExpr.raw.kind.isLiteral && self.withLookahead({ $0.atValidTrailingClosure(flavor: flavor) }) {
         // FIXME: if Result has a trailing closure, break out.
         // Add dummy blank argument list to the call expression syntax.
         let list = RawLabeledExprListSyntax(elements: [], arena: self.arena)
@@ -2543,3 +2543,14 @@ extension Parser.Lookahead {
     }
   }
 }
+
+extension SyntaxKind {
+  fileprivate var isLiteral: Bool {
+    switch self {
+    case .arrayExpr, .booleanLiteralExpr, .dictionaryExpr, .floatLiteralExpr, .integerLiteralExpr, .nilLiteralExpr, .regexLiteralExpr, .stringLiteralExpr:
+      return true
+    default:
+      return false
+    }
+  }
+}

Tests/SwiftParserTest/DeclarationTests.swift

@@ -3059,4 +3059,11 @@ final class DeclarationTests: ParserTestCase {
       """
     )
   }
+
+  func testLiteralInitializerWithTrailingClosure() {
+    assertParse(
+      "let foo = 1 { return 1 }",
+      substructure: AccessorBlockSyntax(accessors: .getter([CodeBlockItemSyntax("return 1")]))
+    )
+  }
 }

Tests/SwiftParserTest/ExpressionTests.swift

@@ -1463,12 +1463,86 @@ final class ExpressionTests: ParserTestCase {
     )
   }
 
-  func testNulCharacterInSourceFile() {
+  func testLiteralWithTrailingClosure() {
+    let expectedDiagnostics = [
+      DiagnosticSpec(
+        message: "consecutive statements on a line must be separated by newline or ';'",
+        fixIts: ["insert newline", "insert ';'"]
+      )
+    ]
+
     assertParse(
-      "let a = 1️⃣\u{0}1",
-      diagnostics: [
-        DiagnosticSpec(message: "nul character embedded in middle of file", severity: .warning)
-      ]
+      "_ = true1️⃣ { return true }",
+      diagnostics: expectedDiagnostics,
+      fixedSource: """
+        _ = true
+        { return true }
+        """
+    )
+    assertParse(
+      "_ = nil1️⃣ { return nil }",
+      diagnostics: expectedDiagnostics,
+      fixedSource: """
+        _ = nil
+        { return nil }
+        """
+    )
+    assertParse(
+      "_ = 11️⃣ { return 1 }",
+      diagnostics: expectedDiagnostics,
+      fixedSource: """
+        _ = 1
+        { return 1 }
+        """
+    )
+    assertParse(
+      "_ = 1.01️⃣ { return 1.0 }",
+      diagnostics: expectedDiagnostics,
+      fixedSource: """
+        _ = 1.0
+        { return 1.0 }
+        """
+    )
+    assertParse(
+      #"_ = "foo"1️⃣ { return "foo" }"#,
+      diagnostics: expectedDiagnostics,
+      fixedSource: """
+        _ = "foo"
+        { return "foo" }
+        """
+    )
+    assertParse(
+      "_ = /foo/1️⃣ { return /foo/ }",
+      diagnostics: expectedDiagnostics,
+      fixedSource: """
+        _ = /foo/
+        { return /foo/ }
+        """
+    )
+    assertParse(
+      "_ = [1]1️⃣ { return [1] }",
+      diagnostics: expectedDiagnostics,
+      fixedSource: """
+        _ = [1]
+        { return [1] }
+        """
+    )
+    assertParse(
+      "_ = [1: 1]1️⃣ { return [1: 1] }",
+      diagnostics: expectedDiagnostics,
+      fixedSource: """
+        _ = [1: 1]
+        { return [1: 1] }
+        """
+    )
+
+    assertParse(
+      "_ = 1 + 11️⃣ { return 1 }",
+      diagnostics: expectedDiagnostics,
+      fixedSource: """
+        _ = 1 + 1
+        { return 1 }
+        """
     )
   }
 }

Tests/SwiftParserTest/LexerTests.swift

@@ -1495,4 +1495,13 @@ public class LexerTests: ParserTestCase {
       ]
     )
   }
+
+  func testNulCharacterInSourceFile() {
+    assertParse(
+      "let a = 1️⃣\u{0}1",
+      diagnostics: [
+        DiagnosticSpec(message: "nul character embedded in middle of file", severity: .warning)
+      ]
+    )
+  }
 }

Tests/SwiftParserTest/translated/RecoveryTests.swift

@@ -1810,14 +1810,14 @@ final class RecoveryTests: ParserTestCase {
     assertParse(
       """
       struct ErrorInFunctionSignatureResultArrayType2 1️⃣{
-        func foo() -> Int2️⃣[0 {
+        func foo() -> Int2️⃣[0 3️⃣{
           return [0]
-        }3️⃣
-      4️⃣}
+        }4️⃣
+      5️⃣}
       """,
       diagnostics: [
-        // TODO: Old parser expected error on line 2: expected ']' in array type
-        // TODO: Old parser expected note on line 2: to match this opening '['
+        // TODO: Old parser expected error to add `]` on line 2, but we should just recover to
+        //       `{` with `[0` becoming unexpected.
         DiagnosticSpec(
           locationMarker: "2️⃣",
           message: "expected '}' to end struct",
@@ -1826,19 +1826,24 @@ final class RecoveryTests: ParserTestCase {
         ),
         DiagnosticSpec(
           locationMarker: "3️⃣",
+          message: "expected ',' in array element",
+          fixIts: ["insert ','"]
+        ),
+        DiagnosticSpec(
+          locationMarker: "4️⃣",
           message: "expected ']' to end array",
           notes: [NoteSpec(locationMarker: "2️⃣", message: "to match this opening '['")],
           fixIts: ["insert ']'"]
         ),
         DiagnosticSpec(
-          locationMarker: "4️⃣",
+          locationMarker: "5️⃣",
           message: "extraneous brace at top level"
         ),
       ],
       fixedSource: """
         struct ErrorInFunctionSignatureResultArrayType2 {
           func foo() -> Int
-        }[0 {
+        }[0, {
             return [0]
           }]
         }
@@ -1895,11 +1900,12 @@ final class RecoveryTests: ParserTestCase {
     assertParse(
       """
       struct ErrorInFunctionSignatureResultArrayType11 ℹ️{
-        func foo() -> Int1️⃣[(a){a++}] {
+        func foo() -> Int1️⃣[(a){a++}]2️⃣ {
         }
-      2️⃣}
+      3️⃣}
       """,
       diagnostics: [
+        // TODO: We should just recover to `{` with `[(a){a++}]` becoming unexpected.
         DiagnosticSpec(
           locationMarker: "1️⃣",
           message: "expected '}' to end struct",
@@ -1908,13 +1914,19 @@ final class RecoveryTests: ParserTestCase {
         ),
         DiagnosticSpec(
           locationMarker: "2️⃣",
+          message: "consecutive statements on a line must be separated by newline or ';'",
+          fixIts: ["insert newline", "insert ';'"]
+        ),
+        DiagnosticSpec(
+          locationMarker: "3️⃣",
           message: "extraneous brace at top level"
         ),
       ],
       fixedSource: """
         struct ErrorInFunctionSignatureResultArrayType11 {
           func foo() -> Int
-        }[(a){a++}] {
+        }[(a){a++}]
+          {
           }
         }
         """