Rollup merge of rust-lang#154752 - theemathas:comment, r=lcnr

matthiaskrgr · web-flow · commit 70b05beb84a6 · 2026-04-03T20:47:39.000+02:00
Add comment to borrow-checker As requested by @lcnr r? @lcnr
diff --git a/compiler/rustc_borrowck/src/type_check/mod.rs b/compiler/rustc_borrowck/src/type_check/mod.rs
@@ -447,6 +447,8 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
         let tcx = self.infcx.tcx;
 
         for proj in &user_ty.projs {
+            // Necessary for non-trivial patterns whose user-type annotation is an opaque type,
+            // e.g. `let (_a,): Tait = whatever`, see #105897
             if !self.infcx.next_trait_solver()
                 && let ty::Alias(ty::Opaque, ..) = curr_projected_ty.ty.kind()
             {

Original file line number	Diff line number	Diff line change
`@@ -447,6 +447,8 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {`
`447`	`447`	`let tcx = self.infcx.tcx;`
`448`	`448`
`449`	`449`	`for proj in &user_ty.projs {`
	`450`	`+ // Necessary for non-trivial patterns whose user-type annotation is an opaque type,`
	`451`	+ // e.g. `let (_a,): Tait = whatever`, see #105897
`450`	`452`	`if !self.infcx.next_trait_solver()`
`451`	`453`	`&& let ty::Alias(ty::Opaque, ..) = curr_projected_ty.ty.kind()`
`452`	`454`	`{`