Diagnose && used to separte multiple availability conditions

Author: ahoppen

Sources/SwiftParser/Statements.swift

@@ -213,10 +213,18 @@ extension Parser {
     var loopProgress = LoopProgressCondition()
     repeat {
       let condition = self.parseConditionElement()
+      let unexpectedBeforeKeepGoing: RawUnexpectedNodesSyntax?
       keepGoing = self.consume(if: .comma)
+      if keepGoing == nil, let andOperator = self.consume(if: .spacedBinaryOperator, where: { $0.tokenText == "&&" }) {
+        unexpectedBeforeKeepGoing = RawUnexpectedNodesSyntax([andOperator], arena: self.arena)
+        keepGoing = missingToken(.comma)
+      } else {
+        unexpectedBeforeKeepGoing = nil
+      }
       elements.append(
         RawConditionElementSyntax(
           condition: condition,
+          unexpectedBeforeKeepGoing,
           trailingComma: keepGoing,
           arena: self.arena
         )

Sources/SwiftParserDiagnostics/ParseDiagnosticsGenerator.swift

@@ -312,6 +312,22 @@ public class ParseDiagnosticsGenerator: SyntaxAnyVisitor {
     return .visitChildren
   }
 
+  public override func visit(_ node: ConditionElementSyntax) -> SyntaxVisitorContinueKind {
+    if shouldSkip(node) {
+      return .skipChildren
+    }
+    if let trailingComma = node.trailingComma {
+      exchangeTokens(
+        unexpected: node.unexpectedBetweenConditionAndTrailingComma,
+        unexpectedTokenCondition: { $0.text == "&&" },
+        correctTokens: [node.trailingComma],
+        message: { _ in .joinConditionsUsingComma },
+        moveFixIt: { ReplaceTokensFixIt(replaceTokens: $0, replacement: trailingComma) }
+      )
+    }
+    return .visitChildren
+  }
+
   public override func visit(_ node: ClosureExprSyntax) -> SyntaxVisitorContinueKind {
     if shouldSkip(node) {
       return .skipChildren

Sources/SwiftParserDiagnostics/ParserDiagnosticMessages.swift

@@ -134,6 +134,9 @@ extension DiagnosticMessage where Self == StaticParserError {
   public static var invalidWhitespaceAfterPeriod: Self {
     .init("extraneous whitespace after '.' is not permitted")
   }
+  public static var joinConditionsUsingComma: Self {
+    .init("expected ',' joining parts of a multi-clause condition")
+  }
   public static var missingColonAndExprInTernaryExpr: Self {
     .init("expected ':' and expression after '? ...' in ternary expression")
   }

Tests/SwiftParserTest/translated/AvailabilityQueryTests.swift

@@ -93,9 +93,12 @@ final class AvailabilityQueryTests: XCTestCase {
       }
       """,
       diagnostics: [
-        // TODO: Old parser expected error on line 1: expected ',' joining parts of a multi-clause condition, Fix-It replacements: 28 - 31 = ','
-        DiagnosticSpec(message: "unexpected code '&& #available(OSX 10.52, *)' in 'if' statement")
-      ]
+        DiagnosticSpec(message: "expected ',' joining parts of a multi-clause condition", fixIts: ["replace '&&' by ','"])
+      ],
+      fixedSource: """
+        if #available(OSX 10.51, *) , #available(OSX 10.52, *) {
+        }
+        """
     )
   }
 

Tests/SwiftParserTest/translated/AvailabilityQueryUnavailabilityTests.swift

@@ -78,8 +78,7 @@ final class AvailabilityQueryUnavailabilityTests: XCTestCase {
       }
       """,
       diagnostics: [
-        // TODO: Old parser expected error on line 1: expected ',' joining parts of a multi-clause condition, Fix-It replacements: 27 - 30 = ','
-        DiagnosticSpec(message: "unexpected code '&& #unavailable(OSX 10.52)' in 'if' statement")
+        DiagnosticSpec(message: "expected ',' joining parts of a multi-clause condition", fixIts: ["replace '&&' by ','"])
       ]
     )
   }