From d6c97a32b4f5e38c0e85010df4438dc7205c44f4 Mon Sep 17 00:00:00 2001
From: Nicholas Nethercote <n.nethercote@gmail.com>
Date: Tue, 8 Nov 2022 15:59:19 +1100
Subject: [PATCH] Simplify `unescape_{char,byte}`.

The `usize` isn't needed in the error case.
---
 compiler/rustc_lexer/src/unescape.rs       | 14 +++++---------
 compiler/rustc_lexer/src/unescape/tests.rs | 12 ++++--------
 2 files changed, 9 insertions(+), 17 deletions(-)

diff --git a/compiler/rustc_lexer/src/unescape.rs b/compiler/rustc_lexer/src/unescape.rs
index 674bbff0878ce..e405013dcabf8 100644
--- a/compiler/rustc_lexer/src/unescape.rs
+++ b/compiler/rustc_lexer/src/unescape.rs
@@ -94,19 +94,15 @@ where
 }
 
 /// Takes a contents of a char literal (without quotes), and returns an
-/// unescaped char or an error
-pub fn unescape_char(src: &str) -> Result<char, (usize, EscapeError)> {
-    let mut chars = src.chars();
-    unescape_char_or_byte(&mut chars, false).map_err(|err| (src.len() - chars.as_str().len(), err))
+/// unescaped char or an error.
+pub fn unescape_char(src: &str) -> Result<char, EscapeError> {
+    unescape_char_or_byte(&mut src.chars(), false)
 }
 
 /// Takes a contents of a byte literal (without quotes), and returns an
 /// unescaped byte or an error.
-pub fn unescape_byte(src: &str) -> Result<u8, (usize, EscapeError)> {
-    let mut chars = src.chars();
-    unescape_char_or_byte(&mut chars, true)
-        .map(byte_from_char)
-        .map_err(|err| (src.len() - chars.as_str().len(), err))
+pub fn unescape_byte(src: &str) -> Result<u8, EscapeError> {
+    unescape_char_or_byte(&mut src.chars(), true).map(byte_from_char)
 }
 
 /// What kind of literal do we parse.
diff --git a/compiler/rustc_lexer/src/unescape/tests.rs b/compiler/rustc_lexer/src/unescape/tests.rs
index 00c8401efdfe4..c7ca8fd16ae47 100644
--- a/compiler/rustc_lexer/src/unescape/tests.rs
+++ b/compiler/rustc_lexer/src/unescape/tests.rs
@@ -3,8 +3,7 @@ use super::*;
 #[test]
 fn test_unescape_char_bad() {
     fn check(literal_text: &str, expected_error: EscapeError) {
-        let actual_result = unescape_char(literal_text).map_err(|(_offset, err)| err);
-        assert_eq!(actual_result, Err(expected_error));
+        assert_eq!(unescape_char(literal_text), Err(expected_error));
     }
 
     check("", EscapeError::ZeroChars);
@@ -68,8 +67,7 @@ fn test_unescape_char_bad() {
 #[test]
 fn test_unescape_char_good() {
     fn check(literal_text: &str, expected_char: char) {
-        let actual_result = unescape_char(literal_text);
-        assert_eq!(actual_result, Ok(expected_char));
+        assert_eq!(unescape_char(literal_text), Ok(expected_char));
     }
 
     check("a", 'a');
@@ -149,8 +147,7 @@ fn test_unescape_str_good() {
 #[test]
 fn test_unescape_byte_bad() {
     fn check(literal_text: &str, expected_error: EscapeError) {
-        let actual_result = unescape_byte(literal_text).map_err(|(_offset, err)| err);
-        assert_eq!(actual_result, Err(expected_error));
+        assert_eq!(unescape_byte(literal_text), Err(expected_error));
     }
 
     check("", EscapeError::ZeroChars);
@@ -219,8 +216,7 @@ fn test_unescape_byte_bad() {
 #[test]
 fn test_unescape_byte_good() {
     fn check(literal_text: &str, expected_byte: u8) {
-        let actual_result = unescape_byte(literal_text);
-        assert_eq!(actual_result, Ok(expected_byte));
+        assert_eq!(unescape_byte(literal_text), Ok(expected_byte));
     }
 
     check("a", b'a');