skip_binder to instantiate_identity

lcnr · lcnr · commit dbc2cc8717dd · 2023-10-02T13:19:37.000+02:00
diff --git a/compiler/rustc_middle/src/ty/instance.rs b/compiler/rustc_middle/src/ty/instance.rs
@@ -617,12 +617,17 @@ impl<'tcx> Instance<'tcx> {
         v: EarlyBinder<T>,
     ) -> Result<T, NormalizationError<'tcx>>
     where
-        T: TypeFoldable<TyCtxt<'tcx>> + Clone,
+        T: TypeFoldable<TyCtxt<'tcx>>,
     {
         if let Some(args) = self.args_for_mir_body() {
             tcx.try_instantiate_and_normalize_erasing_regions(args, param_env, v)
         } else {
-            tcx.try_normalize_erasing_regions(param_env, v.skip_binder())
+            // We're using `instantiate_identity` as e.g.
+            // `FnPtrShim` is separately generated for every
+            // instantiation of the `FnDef`, so the MIR body
+            // is already instantiated. Any generic parameters it
+            // contains are generic parameters from the caller.
+            tcx.try_normalize_erasing_regions(param_env, v.instantiate_identity())
         }
     }
 

Original file line number	Diff line number	Diff line change
`@@ -617,12 +617,17 @@ impl<'tcx> Instance<'tcx> {`
`617`	`617`	`v: EarlyBinder<T>,`
`618`	`618`	`) -> Result<T, NormalizationError<'tcx>>`
`619`	`619`	`where`
`620`		`- T: TypeFoldable<TyCtxt<'tcx>> + Clone,`
	`620`	`+ T: TypeFoldable<TyCtxt<'tcx>>,`
`621`	`621`	`{`
`622`	`622`	`if let Some(args) = self.args_for_mir_body() {`
`623`	`623`	`tcx.try_instantiate_and_normalize_erasing_regions(args, param_env, v)`
`624`	`624`	`} else {`
`625`		`- tcx.try_normalize_erasing_regions(param_env, v.skip_binder())`
	`625`	+ // We're using `instantiate_identity` as e.g.
	`626`	+ // `FnPtrShim` is separately generated for every
	`627`	+ // instantiation of the `FnDef`, so the MIR body
	`628`	`+ // is already instantiated. Any generic parameters it`
	`629`	`+ // contains are generic parameters from the caller.`
	`630`	`+ tcx.try_normalize_erasing_regions(param_env, v.instantiate_identity())`
`626`	`631`	`}`
`627`	`632`	`}`
`628`	`633`