shift no characters when using raw string literals

remove `find_skips`

remove unnecessary variables

compiler/rustc_parse_format/src/lib.rs

@@ -818,13 +818,18 @@ fn find_skips_from_snippet(
         _ => return (vec![], false),
     };
 
-    fn find_skips(snippet: &str, is_raw: bool) -> Vec<usize> {
+    if str_style.is_some() {
+        return (vec![], true);
+    }
+
+    let snippet = &snippet[1..snippet.len() - 1];
+
     let mut s = snippet.char_indices();
     let mut skips = vec![];
     while let Some((pos, c)) = s.next() {
         match (c, s.clone().next()) {
             // skip whitespace and empty lines ending in '\\'
-                ('\\', Some((next_pos, '\n'))) if !is_raw => {
+            ('\\', Some((next_pos, '\n'))) => {
                 skips.push(pos);
                 skips.push(next_pos);
                 let _ = s.next();
@@ -842,7 +847,7 @@ fn find_skips_from_snippet(
                 skips.push(next_pos);
                 let _ = s.next();
             }
-                ('\\', Some((_, 'x'))) if !is_raw => {
+            ('\\', Some((_, 'x'))) => {
                 for _ in 0..3 {
                     // consume `\xAB` literal
                     if let Some((pos, _)) = s.next() {
@@ -852,7 +857,7 @@ fn find_skips_from_snippet(
                     }
                 }
             }
-                ('\\', Some((_, 'u'))) if !is_raw => {
+            ('\\', Some((_, 'u'))) => {
                 if let Some((pos, _)) = s.next() {
                     skips.push(pos);
                 }
@@ -873,8 +878,7 @@ fn find_skips_from_snippet(
                         // exclude as many digits as it is greater than 1 byte
                         //
                         // So for a 3 byte character, exclude 2 digits
-                            let required_skips =
+                        let required_skips = digits_len.saturating_sub(len_utf8.saturating_sub(1));
-                                digits_len.saturating_sub(len_utf8.saturating_sub(1));
 
                         // skip '{' and '}' also
                         for pos in (next_pos..).take(required_skips + 2) {
@@ -901,13 +905,7 @@ fn find_skips_from_snippet(
             _ => {}
         }
     }
-        skips
+    (skips, true)
-    }
-
-    let r_start = str_style.map_or(0, |r| r + 1);
-    let r_end = str_style.unwrap_or(0);
-    let s = &snippet[r_start + 1..snippet.len() - r_end - 1];
-    (find_skips(s, str_style.is_some()), true)
 }
 
 #[cfg(test)]

src/test/ui/fmt/format-raw-string-error.rs

@@ -0,0 +1,3 @@
+fn main() {
+    println!(r#"\'\'\'\'\'\'\'\'\'\'\'\'\'\'}"#); //~ ERROR invalid format string: unmatched `}` found
+}

src/test/ui/fmt/format-raw-string-error.stderr

@@ -0,0 +1,10 @@
+error: invalid format string: unmatched `}` found
+  --> $DIR/format-raw-string-error.rs:2:45
+   |
+LL |     println!(r#"\'\'\'\'\'\'\'\'\'\'\'\'\'\'}"#);
+   |                                             ^ unmatched `}` in format string
+   |
+   = note: if you intended to print `}`, you can escape it using `}}`
+
+error: aborting due to previous error
+

src/test/ui/fmt/issue-104142.rs

@@ -0,0 +1,6 @@
+fn main() {
+    println!(
+        r#"
+    \"\'}､"# //~ ERROR invalid format string: unmatched `}` found
+    );
+}

src/test/ui/fmt/issue-104142.stderr

@@ -0,0 +1,10 @@
+error: invalid format string: unmatched `}` found
+  --> $DIR/issue-104142.rs:4:9
+   |
+LL |     \"\'}､"#
+   |         ^ unmatched `}` in format string
+   |
+   = note: if you intended to print `}`, you can escape it using `}}`
+
+error: aborting due to previous error
+