From 755dedb7dd0be4d5717d774d8982be5595f753ea Mon Sep 17 00:00:00 2001
From: Andrew Devasia <andrew.devasia@gmail.com>
Date: Sun, 1 Feb 2026 15:03:40 +0530
Subject: [PATCH] Ensure FormatRawStringLiteral returns valid swift syntax

---
 .../FormatRawStringLiteral.swift              | 20 ++++++-------------
 .../FormatRawStringLiteral.swift              |  9 ++++++---
 2 files changed, 12 insertions(+), 17 deletions(-)

diff --git a/Sources/SwiftRefactor/FormatRawStringLiteral.swift b/Sources/SwiftRefactor/FormatRawStringLiteral.swift
index c8208b56ec3..366e402a0ff 100644
--- a/Sources/SwiftRefactor/FormatRawStringLiteral.swift
+++ b/Sources/SwiftRefactor/FormatRawStringLiteral.swift
@@ -32,18 +32,16 @@ import SwiftSyntax
 /// ```swift
 /// ##"The # of values is \(count)"##
 /// ##"Hello \#(world)"##
-/// "Hello World"
+/// #"Hello World"#
 /// ```
 public struct FormatRawStringLiteral: SyntaxRefactoringProvider {
   public static func refactor(syntax lit: StringLiteralExprSyntax, in context: Void) -> StringLiteralExprSyntax {
     var maximumHashes = 0
     for segment in lit.segments {
       switch segment {
-      case .expressionSegment(let expr):
-        if let rawStringDelimiter = expr.pounds {
-          // Pick up any delimiters in interpolation segments \#...#(...)
-          maximumHashes = max(maximumHashes, rawStringDelimiter.text.longestRun(of: "#"))
-        }
+      case .expressionSegment:
+        // Valid string interpolations require matching the delimiter count
+        return lit
       case .stringSegment(let string):
         // Find the longest run of # characters in the content of the literal.
         maximumHashes = max(maximumHashes, string.content.text.longestRun(of: "#"))
@@ -54,14 +52,8 @@ public struct FormatRawStringLiteral: SyntaxRefactoringProvider {
       }
     }
 
-    guard maximumHashes > 0 else {
-      return
-        lit
-        .with(\.openingPounds, lit.openingPounds?.with(\.tokenKind, .rawStringPoundDelimiter("")))
-        .with(\.closingPounds, lit.closingPounds?.with(\.tokenKind, .rawStringPoundDelimiter("")))
-    }
-
-    let delimiters = String(repeating: "#", count: maximumHashes + 1)
+    // Ensure at least one delimiter for raw string literals
+    let delimiters = String(repeating: "#", count: max(1, maximumHashes + 1))
     return
       lit
       .with(\.openingPounds, lit.openingPounds?.with(\.tokenKind, .rawStringPoundDelimiter(delimiters)))
diff --git a/Tests/SwiftRefactorTest/FormatRawStringLiteral.swift b/Tests/SwiftRefactorTest/FormatRawStringLiteral.swift
index 59d5f3e8012..053c077afc5 100644
--- a/Tests/SwiftRefactorTest/FormatRawStringLiteral.swift
+++ b/Tests/SwiftRefactorTest/FormatRawStringLiteral.swift
@@ -21,8 +21,7 @@ final class FormatRawStringLiteralTest: XCTestCase {
   func testDelimiterPlacement() throws {
     let tests = [
       (#line, literal: #" "Hello World" "#, expectation: #" "Hello World" "#),
-      (#line, literal: ##" #"Hello World" "##, expectation: #" "Hello World" "#),
-      (#line, literal: ##" #"Hello World"# "##, expectation: #" "Hello World" "#),
+      (#line, literal: ##" #"Hello World"# "##, expectation: ##" #"Hello World"# "##),
       (#line, literal: #####" "####" "#####, expectation: #####" "####" "#####),
       (#line, literal: #####" #"####"# "#####, expectation: ######" #####"####"##### "######),
       (#line, literal: #####" #"\####(hello)"# "#####, expectation: ######" #####"\####(hello)"##### "######),
@@ -30,7 +29,11 @@ final class FormatRawStringLiteralTest: XCTestCase {
         #line, literal: #######" #"###### \####(hello) ##"# "#######,
         expectation: ########" #######"###### \####(hello) ##"####### "########
       ),
-      (#line, literal: ########" #######"hello \(world) "####### "########, expectation: #" "hello \(world) " "#),
+      (#line, literal: ########" #######"hello \(world) "####### "########, expectation: ##" #"hello \(world) "# "##),
+      (#line, literal: ###" ##"""## "###, expectation: ##" #"""# "##),
+      (#line, literal: ####" ###"C:\Users\swift"### "####, expectation: ##" #"C:\Users\swift"# "##),
+      (#line, literal: #####" ####"He said "Hi""#### "#####, expectation: ##" #"He said "Hi""# "##),
+      (#line, literal: #####" ###"Value: \###(count)"### "#####, expectation: ####" ###"Value: \###(count)"### "####),
     ]
 
     for (line, literal, expectation) in tests {