Avoid ICE when suggestion span is at Eof

src/librustc_errors/lib.rs

@@ -229,7 +229,8 @@ impl CodeSuggestion {
                         }
                     }
                     if let Some(cur_line) = fm.get_line(cur_lo.line - 1) {
-                        buf.push_str(&cur_line[..cur_lo.col.to_usize()]);
+                        let end = std::cmp::min(cur_line.len(), cur_lo.col.to_usize());
+                        buf.push_str(&cur_line[..end]);
                     }
                 }
                 buf.push_str(&part.snippet);

src/test/ui/parser/issue-62973.rs

@@ -0,0 +1,8 @@
+// ignore-tidy-trailing-newlines
+// error-pattern: aborting due to 6 previous errors
+
+fn main() {}
+
+fn p() { match s { v, E { [) {) }
+
+

src/test/ui/parser/issue-62973.stderr

@@ -0,0 +1,61 @@
+error: this file contains an un-closed delimiter
+  --> $DIR/issue-62973.rs:8:2
+   |
+LL | fn p() { match s { v, E { [) {) }
+   |        -         - un-closed delimiter
+   |        |
+   |        un-closed delimiter
+LL | 
+LL | 
+   |  ^
+
+error: expected one of `,` or `}`, found `{`
+  --> $DIR/issue-62973.rs:6:25
+   |
+LL | fn p() { match s { v, E { [) {) }
+   |                -        ^ expected one of `,` or `}` here
+   |                |
+   |                while parsing this struct
+
+error: struct literals are not allowed here
+  --> $DIR/issue-62973.rs:6:16
+   |
+LL |   fn p() { match s { v, E { [) {) }
+   |  ________________^
+LL | |
+LL | |
+   | |_^
+help: surround the struct literal with parentheses
+   |
+LL | fn p() { match (s { v, E { [) {) }
+LL | 
+LL | )
+   |
+
+error: expected one of `.`, `?`, `{`, or an operator, found `}`
+  --> $DIR/issue-62973.rs:8:1
+   |
+LL | fn p() { match s { v, E { [) {) }
+   |          ----- while parsing this match expression
+LL | 
+LL | 
+   | ^ expected one of `.`, `?`, `{`, or an operator here
+
+error: incorrect close delimiter: `)`
+  --> $DIR/issue-62973.rs:6:28
+   |
+LL | fn p() { match s { v, E { [) {) }
+   |                           -^ incorrect close delimiter
+   |                           |
+   |                           un-closed delimiter
+
+error: incorrect close delimiter: `)`
+  --> $DIR/issue-62973.rs:6:31
+   |
+LL | fn p() { match s { v, E { [) {) }
+   |                              -^ incorrect close delimiter
+   |                              |
+   |                              un-closed delimiter
+
+error: aborting due to 6 previous errors
+

src/tools/tidy/src/style.rs

@@ -152,6 +152,8 @@ pub fn check(path: &Path, bad: &mut bool) {
         let mut skip_file_length = contains_ignore_directive(can_contain, &contents, "filelength");
         let mut skip_end_whitespace =
             contains_ignore_directive(can_contain, &contents, "end-whitespace");
+        let mut skip_trailing_newlines =
+            contains_ignore_directive(can_contain, &contents, "trailing-newlines");
         let mut skip_copyright = contains_ignore_directive(can_contain, &contents, "copyright");
         let mut leading_new_lines = false;
         let mut trailing_new_lines = 0;
@@ -214,10 +216,17 @@ pub fn check(path: &Path, bad: &mut bool) {
         if leading_new_lines {
             tidy_error!(bad, "{}: leading newline", file.display());
         }
+        let mut err = |msg: &str| {
+            tidy_error!(bad, "{}: {}", file.display(), msg);
+        };
         match trailing_new_lines {
-            0 => tidy_error!(bad, "{}: missing trailing newline", file.display()),
+            0 => suppressible_tidy_err!(err, skip_trailing_newlines, "missing trailing newline"),
             1 => {}
-            n => tidy_error!(bad, "{}: too many trailing newlines ({})", file.display(), n),
+            n => suppressible_tidy_err!(
+                err,
+                skip_trailing_newlines,
+                &format!("too many trailing newlines ({})", n)
+            ),
         };
         if lines > LINES {
             let mut err = |_| {
@@ -247,6 +256,9 @@ pub fn check(path: &Path, bad: &mut bool) {
         if let Directive::Ignore(false) = skip_end_whitespace {
             tidy_error!(bad, "{}: ignoring trailing whitespace unnecessarily", file.display());
         }
+        if let Directive::Ignore(false) = skip_trailing_newlines {
+            tidy_error!(bad, "{}: ignoring trailing newlines unnecessarily", file.display());
+        }
         if let Directive::Ignore(false) = skip_copyright {
             tidy_error!(bad, "{}: ignoring copyright unnecessarily", file.display());
         }