Only have one source of truth for keywords.

`rustc_symbol` is the source of truth for keywords.

rustdoc has its own implicit definition of keywords, via the
`is_doc_keyword`. It (presumably) intends to include all keywords, but
it omits `yeet`.

rustfmt has its own explicit list of Rust keywords. It also (presumably)
intends to include all keywords, but it omits `await`, `builtin`, `gen`,
`macro_rules`, `raw`, `reuse`, `safe`, and `yeet`. Also, it does linear
searches through this list, which is inefficient.

This commit fixes all of the above problems by introducing a new
predicate `is_any_keyword` in rustc and using it in rustdoc and rustfmt.
It documents that it's not the right predicate in most cases.

1 files changed, 2 insertions, 2 deletions

diff --git a/compiler/rustc_parse/src/parser/diagnostics.rs b/compiler/rustc_parse/src/parser/diagnostics.rs
index 9b335df6c0f..8417701ac0c 100644
--- a/compiler/rustc_parse/src/parser/diagnostics.rs
+++ b/compiler/rustc_parse/src/parser/diagnostics.rs
@@ -815,8 +815,8 @@ impl<'a> Parser<'a> {
 
             // Otherwise, check the previous token with all the keywords as possible candidates.
             // This handles code like `Struct Human;` and `While a < b {}`.
-            // We check the previous token only when the current token is an identifier to avoid false
-            // positives like suggesting keyword `for` for `extern crate foo {}`.
+            // We check the previous token only when the current token is an identifier to avoid
+            // false positives like suggesting keyword `for` for `extern crate foo {}`.
             if let Some(misspelled_kw) = find_similar_kw(prev_ident, &all_keywords) {
                 err.subdiagnostic(misspelled_kw);
                 // We don't want other suggestions to be added as they are most likely meaningless