Rollup merge of rust-lang#94178 - est31:tolerant_lines_check, r=Mark-Simulacrum

tidy: fire less "ignoring file length unneccessarily" warnings

This avoids a situation where a file is at the border of the limit,
and alternates between hitting the limit and not hitting it, causing
a back and forth of addition of the ignore-tidy-linelength directive.

As an example, consider the ignore-tidy-filelength of compiler/rustc_typeck/src/collect.rs.

It was added in 2ca4964, removed in
37354eb (a revert of the earlier commit), added again in 448d076,
removed in 3171bd5, added in 438826f,
and removed in bb0a2f9.

To avoid this back and forth, we exempt files from the unneccessary
ignoring warning that have length of at least 70% of the limit.

Author: matthiaskrgr

src/tools/tidy/src/style.rs

@@ -395,6 +395,9 @@ pub fn check(path: &Path, bad: &mut bool) {
                 );
             };
             suppressible_tidy_err!(err, skip_file_length, "");
+        } else if lines > (LINES * 7) / 10 {
+            // Just set it to something that doesn't trigger the "unneccessarily ignored" warning.
+            skip_file_length = Directive::Ignore(true);
         }
 
         if let Directive::Ignore(false) = skip_cr {