feat: Add -Zcache-all-derive-macros to use/bypass cache

Author: futile

compiler/rustc_expand/src/proc_macro.rs

@@ -147,9 +147,12 @@ impl MultiItemModifier for DeriveProcMacro {
             assert_eq!(invoc_id.expn_data().call_site, span);
 
             let res = crate::derive_macro_expansion::enter_context((ecx, self.client), move || {
-                let res =
-                    tcx.derive_macro_expansion((invoc_id, proc_macro_crate_hash, input)).cloned();
-                res
+                let key = (invoc_id, proc_macro_crate_hash, input);
+                if tcx.sess.opts.unstable_opts.cache_all_derive_macros {
+                    tcx.derive_macro_expansion(key).cloned()
+                } else {
+                    crate::derive_macro_expansion::provide_derive_macro_expansion(tcx, key).cloned()
+                }
             });
 
             res

compiler/rustc_session/src/options.rs

@@ -1637,6 +1637,8 @@ options! {
         "emit noalias metadata for box (default: yes)"),
     branch_protection: Option<BranchProtection> = (None, parse_branch_protection, [TRACKED],
         "set options for branch target identification and pointer authentication on AArch64"),
+    cache_all_derive_macros: bool = (false, parse_bool, [UNTRACKED],
+        "cache the results of ALL derive macro invocations (potentially unsound!) (default: no)"),
     cf_protection: CFProtection = (CFProtection::None, parse_cfprotection, [TRACKED],
         "instrument control-flow architecture protection"),
     check_cfg_all_expected: bool = (false, parse_bool, [UNTRACKED],