From 2ce39494c7050654096731011a9d7afbec6149b0 Mon Sep 17 00:00:00 2001
From: pinkjuice66 <pinkjuice66@gmail.com>
Date: Wed, 6 Dec 2023 01:36:44 +0900
Subject: [PATCH 1/2] Fix error message StartsWith parser throws

---
 Sources/Parsing/ParserPrinters/StartsWith.swift |  2 +-
 Sources/Parsing/ParsingError.swift              |  3 +++
 Tests/ParsingTests/StartsWithTests.swift        | 15 +++++++++++++++
 3 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/Sources/Parsing/ParserPrinters/StartsWith.swift b/Sources/Parsing/ParserPrinters/StartsWith.swift
index d21568f005..e0f9245dba 100644
--- a/Sources/Parsing/ParserPrinters/StartsWith.swift
+++ b/Sources/Parsing/ParserPrinters/StartsWith.swift
@@ -63,7 +63,7 @@ public struct StartsWith<Input: Collection>: Parser where Input.SubSequence == I
   @inlinable
   public func parse(_ input: inout Input) throws {
     guard self.startsWith(input) else {
-      throw ParsingError.expectedInput(formatValue(self.possiblePrefix), at: input)
+      throw ParsingError.expectedInput("\"\(formatValue(self.possiblePrefix))\"", at: input)
     }
     input.removeFirst(self.count)
   }
diff --git a/Sources/Parsing/ParsingError.swift b/Sources/Parsing/ParsingError.swift
index 5c03dbc674..9f71b8455f 100644
--- a/Sources/Parsing/ParsingError.swift
+++ b/Sources/Parsing/ParsingError.swift
@@ -415,6 +415,9 @@ func formatValue<Input>(
 
   case let input as Substring.UTF8View:
     return Substring(input).debugDescription
+    
+  case let input as AnyCollection<UInt8>:
+    return String(bytes: input, encoding: .utf8) ?? "\(input)"
 
   default:
     return "\(input)"
diff --git a/Tests/ParsingTests/StartsWithTests.swift b/Tests/ParsingTests/StartsWithTests.swift
index 00310b564a..1eff9a6092 100644
--- a/Tests/ParsingTests/StartsWithTests.swift
+++ b/Tests/ParsingTests/StartsWithTests.swift
@@ -7,4 +7,19 @@ final class StartsWithTests: XCTestCase {
     XCTAssertNoThrow(try StartsWith("Hello".utf8).parse(&str))
     XCTAssertEqual(", world!", Substring(str))
   }
+  
+  func testParseFailure() {
+    var input = "Goodnight, Blob!"[...].utf8
+    XCTAssertThrowsError(try StartsWith("Hello, ".utf8).parse(&input)) { error in
+      XCTAssertEqual(
+        """
+        error: unexpected input
+         --> input:1:1
+        1 | Goodnight, Blob!
+          | ^ expected "Hello, "
+        """,
+        "\(error)"
+      )
+    }
+  }
 }

From 824425b01cd69ad8e1031e29a467e1dcfdfe7023 Mon Sep 17 00:00:00 2001
From: pinkjuice66 <pinkjuice66@gmail.com>
Date: Wed, 6 Dec 2023 03:56:37 +0900
Subject: [PATCH 2/2] preserve possiblePrefix value with original type

---
 Sources/Parsing/ParserPrinters/StartsWith.swift | 4 +++-
 Sources/Parsing/ParsingError.swift              | 3 ---
 2 files changed, 3 insertions(+), 4 deletions(-)

diff --git a/Sources/Parsing/ParserPrinters/StartsWith.swift b/Sources/Parsing/ParserPrinters/StartsWith.swift
index e0f9245dba..22e24816d1 100644
--- a/Sources/Parsing/ParserPrinters/StartsWith.swift
+++ b/Sources/Parsing/ParserPrinters/StartsWith.swift
@@ -39,6 +39,7 @@
 public struct StartsWith<Input: Collection>: Parser where Input.SubSequence == Input {
   public let count: Int
   public let possiblePrefix: AnyCollection<Input.Element>
+  public let originalPossiblePrefix: Any
   public let startsWith: (Input) -> Bool
 
   /// Initializes a parser that successfully returns `Void` when the initial elements of its input
@@ -57,13 +58,14 @@ public struct StartsWith<Input: Collection>: Parser where Input.SubSequence == I
   where PossiblePrefix.Element == Input.Element {
     self.count = possiblePrefix.count
     self.possiblePrefix = AnyCollection(possiblePrefix)
+    self.originalPossiblePrefix = possiblePrefix
     self.startsWith = { input in input.starts(with: possiblePrefix, by: areEquivalent) }
   }
 
   @inlinable
   public func parse(_ input: inout Input) throws {
     guard self.startsWith(input) else {
-      throw ParsingError.expectedInput("\"\(formatValue(self.possiblePrefix))\"", at: input)
+      throw ParsingError.expectedInput(formatValue(self.originalPossiblePrefix), at: input)
     }
     input.removeFirst(self.count)
   }
diff --git a/Sources/Parsing/ParsingError.swift b/Sources/Parsing/ParsingError.swift
index 9f71b8455f..5c03dbc674 100644
--- a/Sources/Parsing/ParsingError.swift
+++ b/Sources/Parsing/ParsingError.swift
@@ -415,9 +415,6 @@ func formatValue<Input>(
 
   case let input as Substring.UTF8View:
     return Substring(input).debugDescription
-    
-  case let input as AnyCollection<UInt8>:
-    return String(bytes: input, encoding: .utf8) ?? "\(input)"
 
   default:
     return "\(input)"