Rollup merge of #89558 - lcnr:query-stable-lint, r=estebank

Add rustc lint, warning when iterating over hashmaps

r? rust-lang/wg-incr-comp

compiler/rustc_span/src/lib.rs

@@ -21,6 +21,7 @@
 #![feature(nll)]
 #![feature(min_specialization)]
 #![feature(thread_local_const_init)]
+#![cfg_attr(not(bootstrap), allow(rustc::potential_query_instability))]
 
 #[macro_use]
 extern crate rustc_macros;

compiler/rustc_span/src/symbol.rs

@@ -1114,6 +1114,7 @@ symbols! {
         rustc_layout_scalar_valid_range_end,
         rustc_layout_scalar_valid_range_start,
         rustc_legacy_const_generics,
+        rustc_lint_query_instability,
         rustc_macro_transparency,
         rustc_main,
         rustc_mir,