Rollup merge of rust-lang#109444 - WaffleLapkin:undeprecate_todos, r=jyn514

Change tidy error message for TODOs

Blocked on rust-lang#109440 (first few commits are from where)

IMO "deprecated" doesn't really explain anything, I've tried to highlight the actual reason we error on TODOs. The message is not at all perfect, maybe someone has ideas how to phrase it better?

Author: matthiaskrgr

src/tools/tidy/src/style.rs

@@ -385,10 +385,12 @@ pub fn check(path: &Path, bad: &mut bool) {
             }
             if filename != "style.rs" {
                 if trimmed.contains("TODO") {
-                    err("TODO is deprecated; use FIXME")
+                    err(
+                        "TODO is used for tasks that should be done before merging a PR; If you want to leave a message in the codebase use FIXME",
+                    )
                 }
                 if trimmed.contains("//") && trimmed.contains(" XXX") {
-                    err("XXX is deprecated; use FIXME")
+                    err("Instead of XXX use FIXME")
                 }
                 if any_problematic_line {
                     for s in problematic_consts_strings.iter() {