From 5d944e1e65b7bd0e5290da300e74f1c0dbb2e372 Mon Sep 17 00:00:00 2001
From: Adwin White <adwinw01@gmail.com>
Date: Mon, 5 Aug 2024 10:59:17 +0800
Subject: [PATCH] check type error recursively in typeck

---
 compiler/rustc_hir_typeck/src/lib.rs      | 44 ++++++++++++++++++++++-
 tests/ui/typeck/wide_ptr_transmute.rs     | 13 +++++++
 tests/ui/typeck/wide_ptr_transmute.stderr | 19 ++++++++++
 3 files changed, 75 insertions(+), 1 deletion(-)
 create mode 100644 tests/ui/typeck/wide_ptr_transmute.rs
 create mode 100644 tests/ui/typeck/wide_ptr_transmute.stderr

diff --git a/compiler/rustc_hir_typeck/src/lib.rs b/compiler/rustc_hir_typeck/src/lib.rs
index fa78b9ced1282..3bd67b18cdda3 100644
--- a/compiler/rustc_hir_typeck/src/lib.rs
+++ b/compiler/rustc_hir_typeck/src/lib.rs
@@ -42,8 +42,11 @@ mod typeck_root_ctxt;
 mod upvar;
 mod writeback;
 
+use core::ops::ControlFlow;
+
 pub use coercion::can_coerce;
 use fn_ctxt::FnCtxt;
+use rustc_data_structures::fx::FxHashSet;
 use rustc_data_structures::unord::UnordSet;
 use rustc_errors::codes::*;
 use rustc_errors::{struct_span_code_err, Applicability, ErrorGuaranteed};
@@ -55,7 +58,7 @@ use rustc_hir_analysis::check::check_abi;
 use rustc_hir_analysis::hir_ty_lowering::HirTyLowerer;
 use rustc_infer::traits::{ObligationCauseCode, ObligationInspector, WellFormedLoc};
 use rustc_middle::query::Providers;
-use rustc_middle::ty::{self, Ty, TyCtxt};
+use rustc_middle::ty::{self, Ty, TyCtxt, TypeSuperVisitable, TypeVisitable, TypeVisitor};
 use rustc_middle::{bug, span_bug};
 use rustc_session::config;
 use rustc_span::def_id::LocalDefId;
@@ -116,6 +119,40 @@ pub fn inspect_typeck<'tcx>(
     typeck_with_fallback(tcx, def_id, fallback, Some(inspect))
 }
 
+struct RecursiveHasErrorVisitor<'tcx> {
+    tcx: TyCtxt<'tcx>,
+    // To avoid cycle when visiting recursive types.
+    visited_tys: FxHashSet<Ty<'tcx>>,
+}
+
+impl<'tcx> RecursiveHasErrorVisitor<'tcx> {
+    fn new(tcx: TyCtxt<'tcx>) -> Self {
+        RecursiveHasErrorVisitor { tcx, visited_tys: Default::default() }
+    }
+}
+
+impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for RecursiveHasErrorVisitor<'tcx> {
+    type Result = ControlFlow<ErrorGuaranteed>;
+
+    fn visit_ty(&mut self, t: Ty<'tcx>) -> Self::Result {
+        if self.visited_tys.insert(t.clone()) {
+            if let ty::Adt(def, args) = t.kind() {
+                let field_tys: Vec<_> = def.all_fields().map(|f| f.ty(self.tcx, args)).collect();
+                for field_ty in field_tys {
+                    field_ty.visit_with(self)?;
+                }
+            }
+            t.super_visit_with(self)
+        } else {
+            ControlFlow::Continue(())
+        }
+    }
+
+    fn visit_error(&mut self, guar: ErrorGuaranteed) -> Self::Result {
+        ControlFlow::Break(guar)
+    }
+}
+
 #[instrument(level = "debug", skip(tcx, fallback, inspector), ret)]
 fn typeck_with_fallback<'tcx>(
     tcx: TyCtxt<'tcx>,
@@ -168,6 +205,11 @@ fn typeck_with_fallback<'tcx>(
 
         let expected_type = fcx.normalize(body.value.span, expected_type);
 
+        let mut error_visitor = RecursiveHasErrorVisitor::new(tcx);
+        if let ControlFlow::Break(guar) = expected_type.visit_with(&mut error_visitor) {
+            fcx.set_tainted_by_errors(guar);
+        }
+
         let wf_code = ObligationCauseCode::WellFormed(Some(WellFormedLoc::Ty(def_id)));
         fcx.register_wf_obligation(expected_type.into(), body.value.span, wf_code);
 
diff --git a/tests/ui/typeck/wide_ptr_transmute.rs b/tests/ui/typeck/wide_ptr_transmute.rs
new file mode 100644
index 0000000000000..64a72ebcdce1e
--- /dev/null
+++ b/tests/ui/typeck/wide_ptr_transmute.rs
@@ -0,0 +1,13 @@
+// issue #127742
+struct Vtable(dyn Cap);
+//~^ ERROR missing lifetime specifier
+
+trait Cap<'a> {}
+
+union Transmute {
+    t: u64,
+    u: &'static Vtable,
+}
+
+const G: &'static Vtable = unsafe { Transmute { t: 1 }.u };
+fn main() {}
diff --git a/tests/ui/typeck/wide_ptr_transmute.stderr b/tests/ui/typeck/wide_ptr_transmute.stderr
new file mode 100644
index 0000000000000..5f28cf93417d2
--- /dev/null
+++ b/tests/ui/typeck/wide_ptr_transmute.stderr
@@ -0,0 +1,19 @@
+error[E0106]: missing lifetime specifier
+  --> $DIR/wide_ptr_transmute.rs:2:19
+   |
+LL | struct Vtable(dyn Cap);
+   |                   ^^^ expected named lifetime parameter
+   |
+   = note: for more information on higher-ranked polymorphism, visit https://doc.rust-lang.org/nomicon/hrtb.html
+help: consider making the bound lifetime-generic with a new `'a` lifetime
+   |
+LL | struct Vtable(dyn for<'a> Cap<'a>);
+   |                   +++++++    ++++
+help: consider introducing a named lifetime parameter
+   |
+LL | struct Vtable<'a>(dyn Cap<'a>);
+   |              ++++        ++++
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0106`.