Diagnose || being used to join platforms in an availability condition

Author: ahoppen

Sources/SwiftParser/Availability.swift

@@ -32,10 +32,18 @@ extension Parser {
           entry = self.parseAvailabilitySpec()
         }
 
+        let unexpectedBeforeKeepGoing: RawUnexpectedNodesSyntax?
         keepGoing = self.consume(if: .comma)
+        if keepGoing == nil, let orOperator = self.consume(if: .spacedBinaryOperator, where: { $0.tokenText == "||" }) {
+          unexpectedBeforeKeepGoing = RawUnexpectedNodesSyntax([orOperator], arena: self.arena)
+          keepGoing = missingToken(.comma)
+        } else {
+          unexpectedBeforeKeepGoing = nil
+        }
         elements.append(
           RawAvailabilityArgumentSyntax(
             entry: entry,
+            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: AvailabilityArgumentSyntax) -> SyntaxVisitorContinueKind {
+    if shouldSkip(node) {
+      return .skipChildren
+    }
+    if let trailingComma = node.trailingComma {
+      exchangeTokens(
+        unexpected: node.unexpectedBetweenEntryAndTrailingComma,
+        unexpectedTokenCondition: { $0.text == "||" },
+        correctTokens: [node.trailingComma],
+        message: { _ in .joinPlatformsUsingComma },
+        moveFixIt: { ReplaceTokensFixIt(replaceTokens: $0, replacement: trailingComma) }
+      )
+    }
+    return .visitChildren
+  }
+
   public override func visit(_ node: ConditionElementSyntax) -> SyntaxVisitorContinueKind {
     if shouldSkip(node) {
       return .skipChildren

Sources/SwiftParserDiagnostics/ParserDiagnosticMessages.swift

@@ -137,6 +137,9 @@ extension DiagnosticMessage where Self == StaticParserError {
   public static var joinConditionsUsingComma: Self {
     .init("expected ',' joining parts of a multi-clause condition")
   }
+  public static var joinPlatformsUsingComma: Self {
+    .init("expected ',' joining platforms in availability condition")
+  }
   public static var missingColonAndExprInTernaryExpr: Self {
     .init("expected ':' and expression after '? ...' in ternary expression")
   }

Tests/SwiftParserTest/translated/AvailabilityQueryTests.swift

@@ -389,9 +389,12 @@ final class AvailabilityQueryTests: XCTestCase {
       }
       """,
       diagnostics: [
-        // TODO: Old parser expected error on line 1: '||' cannot be used in an availability condition
-        DiagnosticSpec(message: "unexpected code '|| iOS 8.0' in availability condition")
-      ]
+        DiagnosticSpec(message: "expected ',' joining platforms in availability condition", fixIts: ["replace '||' by ','"])
+      ],
+      fixedSource: """
+        if #available(OSX 10.51 , iOS 8.0) {
+        }
+        """
     )
   }
 

Tests/SwiftParserTest/translated/AvailabilityQueryUnavailabilityTests.swift

@@ -360,8 +360,7 @@ final class AvailabilityQueryUnavailabilityTests: XCTestCase {
       }
       """,
       diagnostics: [
-        // TODO: Old parser expected error on line 1: '||' cannot be used in an availability condition
-        DiagnosticSpec(message: "unexpected code '|| iOS 8.0' in availability condition")
+        DiagnosticSpec(message: "expected ',' joining platforms in availability condition")
       ]
     )
   }