Improve early bailout test in resolve_vars_if_possible.

nnethercote · nnethercote · commit f08a3371b01f · 2023-02-06T08:52:04.000+11:00
`!t.has_non_region_infer()` is the test used in
`OpportunisticVarResolver`, and catches a few cases that
`!t.needs_infer()` misses.
diff --git a/compiler/rustc_infer/src/infer/mod.rs b/compiler/rustc_infer/src/infer/mod.rs
@@ -1389,8 +1389,8 @@ impl<'tcx> InferCtxt<'tcx> {
     where
         T: TypeFoldable<'tcx>,
     {
-        if !value.needs_infer() {
-            return value; // Avoid duplicated subst-folding.
+        if !value.has_non_region_infer() {
+            return value;
         }
         let mut r = resolve::OpportunisticVarResolver::new(self);
         value.fold_with(&mut r)

Original file line number	Diff line number	Diff line change
`@@ -1389,8 +1389,8 @@ impl<'tcx> InferCtxt<'tcx> {`
`1389`	`1389`	`where`
`1390`	`1390`	`T: TypeFoldable<'tcx>,`
`1391`	`1391`	`{`
`1392`		`- if !value.needs_infer() {`
`1393`		`- return value; // Avoid duplicated subst-folding.`
	`1392`	`+ if !value.has_non_region_infer() {`
	`1393`	`+ return value;`
`1394`	`1394`	`}`
`1395`	`1395`	`let mut r = resolve::OpportunisticVarResolver::new(self);`
`1396`	`1396`	`value.fold_with(&mut r)`