Rollup merge of rust-lang#134744 - compiler-errors:transmute-non-wf, r=lcnr

Don't ice on bad transmute in typeck in new solver

Old trait solver ends up getting its infcx tainted because we try to normalize the type, but the new trait solver doesn't. This means we try to compute the stalled transmute obligations, which tries to normalize a type an ICEs. Let's make this a delayed bug.

r? lcnr

Author: jhpratt

compiler/rustc_hir_typeck/src/intrinsicck.rs

@@ -40,13 +40,25 @@ fn unpack_option_like<'tcx>(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> Ty<'tcx> {
 }
 
 impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
+    /// FIXME: Move this check out of typeck, since it'll easily cycle when revealing opaques,
+    /// and we shouldn't need to check anything here if the typeck results are tainted.
     pub(crate) fn check_transmute(&self, from: Ty<'tcx>, to: Ty<'tcx>, hir_id: HirId) {
         let tcx = self.tcx;
         let dl = &tcx.data_layout;
         let span = tcx.hir().span(hir_id);
         let normalize = |ty| {
             let ty = self.resolve_vars_if_possible(ty);
-            self.tcx.normalize_erasing_regions(self.typing_env(self.param_env), ty)
+            if let Ok(ty) =
+                self.tcx.try_normalize_erasing_regions(self.typing_env(self.param_env), ty)
+            {
+                ty
+            } else {
+                Ty::new_error_with_message(
+                    tcx,
+                    span,
+                    "tried to normalize non-wf type in check_transmute",
+                )
+            }
         };
         let from = normalize(from);
         let to = normalize(to);

tests/ui/traits/next-solver/dont-ice-on-bad-transmute-in-typeck.rs

@@ -0,0 +1,17 @@
+//@ compile-flags: -Znext-solver
+
+trait Trait<'a> {
+    type Assoc;
+}
+
+fn foo(x: for<'a> fn(<() as Trait<'a>>::Assoc)) {
+    //~^ ERROR the trait bound `for<'a> (): Trait<'a>` is not satisfied
+    //~| ERROR the trait bound `for<'a> (): Trait<'a>` is not satisfied
+    //~| ERROR the trait bound `for<'a> (): Trait<'a>` is not satisfied
+    unsafe { std::mem::transmute::<_, ()>(x); }
+    //~^ ERROR the trait bound `for<'a> (): Trait<'a>` is not satisfied
+    //~| ERROR the trait bound `for<'a> (): Trait<'a>` is not satisfied
+    //~| ERROR the trait bound `for<'a> (): Trait<'a>` is not satisfied
+}
+
+fn main() {}

tests/ui/traits/next-solver/dont-ice-on-bad-transmute-in-typeck.stderr

@@ -0,0 +1,75 @@
+error[E0277]: the trait bound `for<'a> (): Trait<'a>` is not satisfied
+  --> $DIR/dont-ice-on-bad-transmute-in-typeck.rs:7:11
+   |
+LL | fn foo(x: for<'a> fn(<() as Trait<'a>>::Assoc)) {
+   |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `for<'a> Trait<'a>` is not implemented for `()`
+   |
+help: this trait has no implementations, consider adding one
+  --> $DIR/dont-ice-on-bad-transmute-in-typeck.rs:3:1
+   |
+LL | trait Trait<'a> {
+   | ^^^^^^^^^^^^^^^
+
+error[E0277]: the trait bound `for<'a> (): Trait<'a>` is not satisfied
+  --> $DIR/dont-ice-on-bad-transmute-in-typeck.rs:7:8
+   |
+LL | fn foo(x: for<'a> fn(<() as Trait<'a>>::Assoc)) {
+   |        ^ the trait `for<'a> Trait<'a>` is not implemented for `()`
+   |
+help: this trait has no implementations, consider adding one
+  --> $DIR/dont-ice-on-bad-transmute-in-typeck.rs:3:1
+   |
+LL | trait Trait<'a> {
+   | ^^^^^^^^^^^^^^^
+
+error[E0277]: the trait bound `for<'a> (): Trait<'a>` is not satisfied
+  --> $DIR/dont-ice-on-bad-transmute-in-typeck.rs:11:14
+   |
+LL |     unsafe { std::mem::transmute::<_, ()>(x); }
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `for<'a> Trait<'a>` is not implemented for `()`
+   |
+help: this trait has no implementations, consider adding one
+  --> $DIR/dont-ice-on-bad-transmute-in-typeck.rs:3:1
+   |
+LL | trait Trait<'a> {
+   | ^^^^^^^^^^^^^^^
+
+error[E0277]: the trait bound `for<'a> (): Trait<'a>` is not satisfied
+  --> $DIR/dont-ice-on-bad-transmute-in-typeck.rs:11:36
+   |
+LL |     unsafe { std::mem::transmute::<_, ()>(x); }
+   |                                    ^ the trait `for<'a> Trait<'a>` is not implemented for `()`
+   |
+help: this trait has no implementations, consider adding one
+  --> $DIR/dont-ice-on-bad-transmute-in-typeck.rs:3:1
+   |
+LL | trait Trait<'a> {
+   | ^^^^^^^^^^^^^^^
+
+error[E0277]: the trait bound `for<'a> (): Trait<'a>` is not satisfied
+  --> $DIR/dont-ice-on-bad-transmute-in-typeck.rs:11:43
+   |
+LL |     unsafe { std::mem::transmute::<_, ()>(x); }
+   |                                           ^ the trait `for<'a> Trait<'a>` is not implemented for `()`
+   |
+help: this trait has no implementations, consider adding one
+  --> $DIR/dont-ice-on-bad-transmute-in-typeck.rs:3:1
+   |
+LL | trait Trait<'a> {
+   | ^^^^^^^^^^^^^^^
+
+error[E0277]: the trait bound `for<'a> (): Trait<'a>` is not satisfied
+  --> $DIR/dont-ice-on-bad-transmute-in-typeck.rs:7:1
+   |
+LL | fn foo(x: for<'a> fn(<() as Trait<'a>>::Assoc)) {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `for<'a> Trait<'a>` is not implemented for `()`
+   |
+help: this trait has no implementations, consider adding one
+  --> $DIR/dont-ice-on-bad-transmute-in-typeck.rs:3:1
+   |
+LL | trait Trait<'a> {
+   | ^^^^^^^^^^^^^^^
+
+error: aborting due to 6 previous errors
+
+For more information about this error, try `rustc --explain E0277`.