CFI: Erase regions when projecting ADT to its transparent non-1zst field

compiler/rustc_sanitizers/src/cfi/typeid/itanium_cxx_abi/transform.rs

@@ -146,7 +146,7 @@ impl<'tcx> TypeFolder<TyCtxt<'tcx>> for TransformTy<'tcx> {
                         !is_zst
                     });
                     if let Some(field) = field {
-                        let ty0 = self.tcx.type_of(field.did).instantiate(self.tcx, args);
+                        let ty0 = self.tcx.erase_regions(field.ty(self.tcx, args));
                         // Generalize any repr(transparent) user-defined type that is either a
                         // pointer or reference, and either references itself or any other type that
                         // contains or references itself, to avoid a reference cycle.

tests/ui/sanitizer/cfi/transparent-has-regions.rs

@@ -0,0 +1,18 @@
+//@ needs-sanitizer-cfi
+//@ compile-flags: -Ccodegen-units=1 -Clto -Ctarget-feature=-crt-static -Zsanitizer=cfi
+//@ no-prefer-dynamic
+//@ only-x86_64-unknown-linux-gnu
+//@ build-pass
+
+pub trait Trait {}
+
+impl Trait for i32 {}
+
+#[repr(transparent)]
+struct BoxedTrait(Box<dyn Trait + 'static>);
+
+fn hello(x: BoxedTrait) {}
+
+fn main() {
+    hello(BoxedTrait(Box::new(1)));
+}