Fix wrong foratting of multiline string literal

Author: kimdv

Sources/SwiftBasicFormat/BasicFormat.swift

@@ -171,9 +171,31 @@ open class BasicFormat: SyntaxRewriter {
       }
     }
 
-    return false
+    let syntaxToken: Syntax = Syntax(token)
+    switch syntaxToken.keyPathInParent {
+    case \StringLiteralExprSyntax.closeQuote:
+      return token.tokenKind == .multilineStringQuote
+    default:
+      return false
+    }
   }
 
+    /// Whether a trailing newline on `token` should be added.
+    open func requiresTrailingNewline(_ token: TokenSyntax) -> Bool {
+        // We don't want to add newlines inside string interpolation
+        if isInsideStringInterpolation(token) {
+            return false
+        }
+
+        let syntaxToken: Syntax = Syntax(token)
+        switch syntaxToken.keyPathInParent {
+        case \StringLiteralExprSyntax.openQuote:
+            return token.tokenKind == .multilineStringQuote
+        default:
+            return false
+        }
+    }
+
   open func requiresWhitespace(between first: TokenSyntax?, and second: TokenSyntax?) -> Bool {
     switch (first?.tokenKind, second?.tokenKind) {
     case (.atSign, _),
@@ -356,6 +378,12 @@ open class BasicFormat: SyntaxRewriter {
       }
     }
 
+    if requiresTrailingNewline(token) {
+      if !trailingTrivia.endsWithNewline && !nextTokenWillStartWithNewline {
+        trailingTrivia += .newline
+      }
+    }
+
     if leadingTrivia.indentation(isOnNewline: previousTokenWillEndWithNewline) == [] {
       // If the token starts on a new line and does not have indentation, this
       // is the last non-indented token. Store its indentation level

Sources/SwiftParserDiagnostics/DiagnosticExtensions.swift

@@ -167,7 +167,7 @@ extension FixIt.MultiNodeChange {
       }
     }
 
-    if let previousToken = node.previousToken(viewMode: .all),
+    if let previousToken = node.previousToken(viewMode: .fixedUp),
       previousToken.presence == .present,
       let firstToken = node.firstToken(viewMode: .all),
       previousToken.trailingTrivia.allSatisfy({ $0.isWhitespace }),

Sources/SwiftParserDiagnostics/ParseDiagnosticsGenerator.swift

@@ -1174,12 +1174,10 @@ public class ParseDiagnosticsGenerator: SyntaxAnyVisitor {
     }
     if case .stringSegment(let segment) = node.segments.last {
       if let invalidContent = segment.unexpectedBeforeContent?.onlyToken(where: { $0.trailingTrivia.contains(where: { $0.isBackslash }) }) {
-        let leadingTrivia = segment.content.leadingTrivia
-        let trailingTrivia = segment.content.trailingTrivia
         let fixIt = FixIt(
           message: .removeBackslash,
           changes: [
-            .makePresent(segment.content, leadingTrivia: leadingTrivia, trailingTrivia: trailingTrivia),
+            .makePresent(segment.content),
             .makeMissing(invalidContent, transferTrivia: false),
           ]
         )

Tests/SwiftParserTest/ExpressionTests.swift

@@ -577,7 +577,8 @@ final class ExpressionTests: XCTestCase {
         )
       ],
       fixedSource: ##"""
-        """""""
+        """"
+        """
         """##
     )
 
@@ -589,7 +590,8 @@ final class ExpressionTests: XCTestCase {
         DiagnosticSpec(message: #"expected '"""' to end string literal"#, fixIts: [#"insert '"""'"#])
       ],
       fixedSource: ##"""
-        """"""""
+        """""
+        """
         """##
     )
 
@@ -626,7 +628,8 @@ final class ExpressionTests: XCTestCase {
         DiagnosticSpec(message: ##"expected '"""#' to end string literal"##, fixIts: [##"insert '"""#'"##])
       ],
       fixedSource: ##"""
-        #""""""#
+        #"""
+        """#
         """##
     )
 
@@ -638,7 +641,8 @@ final class ExpressionTests: XCTestCase {
         DiagnosticSpec(message: ##"expected '"""#' to end string literal"##, fixIts: [##"insert '"""#'"##])
       ],
       fixedSource: ##"""
-        #"""a"""#
+        #"""a
+        """#
         """##
     )
 

Tests/SwiftParserTest/translated/AvailabilityQueryTests.swift

@@ -100,7 +100,7 @@ final class AvailabilityQueryTests: XCTestCase {
         DiagnosticSpec(message: "expected ',' joining parts of a multi-clause condition", fixIts: ["replace '&&' with ','"])
       ],
       fixedSource: """
-        if #available(OSX 10.51, *) , #available(OSX 10.52, *) {
+        if #available(OSX 10.51, *), #available(OSX 10.52, *) {
         }
         """
     )
@@ -433,7 +433,7 @@ final class AvailabilityQueryTests: XCTestCase {
         DiagnosticSpec(message: "expected ',' joining platforms in availability condition", fixIts: ["replace '||' with ','"])
       ],
       fixedSource: """
-        if #available(OSX 10.51 , iOS 8.0) {
+        if #available(OSX 10.51, iOS 8.0) {
         }
         """
     )

Tests/SwiftParserTest/translated/AvailabilityQueryUnavailabilityTests.swift

@@ -103,7 +103,7 @@ final class AvailabilityQueryUnavailabilityTests: XCTestCase {
         )
       ],
       fixedSource: """
-        if #unavailable(OSX 10.51) , #unavailable(OSX 10.52) {
+        if #unavailable(OSX 10.51), #unavailable(OSX 10.52) {
         }
         """
     )
@@ -446,7 +446,7 @@ final class AvailabilityQueryUnavailabilityTests: XCTestCase {
         )
       ],
       fixedSource: """
-        if #unavailable(OSX 10.51 , iOS 8.0) {
+        if #unavailable(OSX 10.51, iOS 8.0) {
         }
         """
     )

Tests/SwiftParserTest/translated/MultilineErrorsTests.swift

@@ -603,7 +603,8 @@ final class MultilineErrorsTests: XCTestCase {
       ],
       fixedSource: ##"""
         _ = """
-          foo\"""
+          foo\
+        """
         """##
     )
   }

Tests/SwiftParserTest/translated/MultilinePoundDiagnosticArgRdar41154797Tests.swift

@@ -25,7 +25,8 @@ final class MultilinePoundDiagnosticArgRdar41154797Tests: XCTestCase {
         DiagnosticSpec(message: "expected ')' to end macro expansion", fixIts: ["insert ')'"]),
       ],
       fixedSource: ##"""
-        #error("""""")
+        #error("""
+        """)
         """##
     )
   }

Tests/SwiftParserTest/translated/MultilineStringTests.swift

@@ -411,6 +411,14 @@ final class MultilineStringTests: XCTestCase {
     )
   }
 
+    func testMultilineString47() {
+        assertParse(
+      #"""
+      _ = """"""
+      """#
+        )
+    }
+
   func testEscapeNewlineInRawString() {
     assertParse(
       ##"""

Tests/SwiftParserTest/translated/StringLiteralEofTests.swift

@@ -106,7 +106,8 @@ final class StringLiteralEofTests: XCTestCase {
       fixedSource: #"""
         // NOTE: DO NOT add a newline at EOF.
         _ = """
-            foo"""
+            foo
+        """
         """#
     )
   }
@@ -126,7 +127,8 @@ final class StringLiteralEofTests: XCTestCase {
       fixedSource: ##"""
         _ = """
             foo
-            \(<#expression#>)"""
+            \(<#expression#>)
+        """
         """##
       // FIXME: The closing delimiter should be put on the new line
     )
@@ -148,7 +150,8 @@ final class StringLiteralEofTests: XCTestCase {
       fixedSource: ##"""
         _ = """
             foo
-            \("bar")"""
+            \("bar")
+        """
         """##
     )
   }
@@ -169,7 +172,8 @@ final class StringLiteralEofTests: XCTestCase {
       fixedSource: ##"""
         _ = """
             \("bar"
-            baz)"""
+            baz)
+        """
         """##
     )
   }