Merge pull request #1821 from kishikawakatsumi/literal-59

[5.9]Fixes wrong escape when creating a string literal where a pound sign follows a sequence of double quotes or backslashes

Author: ahoppen

Sources/SwiftSyntaxBuilder/ConvenienceInitializers.swift

@@ -262,6 +262,8 @@ extension StringLiteralExprSyntax {
       case (true, _) where c.unicodeScalars.contains("#"):
         consecutivePounds += 1
         maxPounds = max(maxPounds, consecutivePounds)
+      case (true, "\""), (true, "\\"):
+        continue
       case (true, _):
         countingPounds = false
         consecutivePounds = 0

Tests/SwiftSyntaxBuilderTest/StringLiteralExprSyntaxTests.swift

@@ -71,6 +71,24 @@ final class StringLiteralExprSyntaxTests: XCTestCase {
     )
   }
 
+  func testEscapePoundsAfterConsecutiveQuotes() {
+    assertBuildResult(
+      StringLiteralExprSyntax(content: ##"foobar""#"##),
+      """
+      ##"foobar""#"##
+      """
+    )
+  }
+
+  func testEscapePoundsAfterConsecutiveBackslashes() {
+    assertBuildResult(
+      StringLiteralExprSyntax(content: ##"foobar\\#"##),
+      ##"""
+      ##"foobar\\#"##
+      """##
+    )
+  }
+
   func testEscapePoundEmojis() {
     assertBuildResult(
       StringLiteralExprSyntax(content: ##"foo"#️⃣"bar"##),