Use delay_span_bug in validate-mir.

Author: cjgillot

compiler/rustc_mir_transform/src/validate.rs

@@ -11,12 +11,12 @@ use rustc_infer::traits::{Obligation, ObligationCause};
 use rustc_middle::mir::coverage::CoverageKind;
 use rustc_middle::mir::visit::{MutatingUseContext, NonUseContext, PlaceContext, Visitor};
 use rustc_middle::mir::*;
+use rustc_middle::span_bug;
 use rustc_middle::ty::adjustment::PointerCoercion;
 use rustc_middle::ty::print::with_no_trimmed_paths;
 use rustc_middle::ty::{
     self, CoroutineArgsExt, InstanceKind, ScalarInt, Ty, TyCtxt, TypeVisitableExt, Upcast, Variance,
 };
-use rustc_middle::{bug, span_bug};
 use rustc_mir_dataflow::debuginfo::debuginfo_locals;
 use rustc_trait_selection::traits::ObligationCtxt;
 
@@ -122,18 +122,17 @@ struct CfgChecker<'a, 'tcx> {
 
 impl<'a, 'tcx> CfgChecker<'a, 'tcx> {
     #[track_caller]
-    fn fail(&self, location: Location, msg: impl AsRef<str>) {
+    fn fail(&self, location: Location, msg: impl std::fmt::Display) {
         // We might see broken MIR when other errors have already occurred.
-        if self.tcx.dcx().has_errors().is_none() {
-            span_bug!(
-                self.body.source_info(location).span,
+        // But we may have some cases of errors happening *after* MIR construction,
+        // for instance because of generic constants or coroutines.
+        self.tcx.dcx().span_delayed_bug(
+            self.body.source_info(location).span,
+            format!(
                 "broken MIR in {:?} ({}) at {:?}:\n{}",
-                self.body.source.instance,
-                self.when,
-                location,
-                msg.as_ref(),
-            );
-        }
+                self.body.source.instance, self.when, location, msg,
+            ),
+        );
     }
 
     fn check_edge(&mut self, location: Location, bb: BasicBlock, edge_kind: EdgeKind) {
@@ -1637,7 +1636,11 @@ impl<'a, 'tcx> Visitor<'tcx> for TypeChecker<'a, 'tcx> {
                     ty::Int(int) => int.normalize(target_width).bit_width().unwrap(),
                     ty::Char => 32,
                     ty::Bool => 1,
-                    other => bug!("unhandled type: {:?}", other),
+                    other => {
+                        self.fail(location, format!("unhandled type in SwitchInt {other:?}"));
+                        // Magic number to avoid ICEing.
+                        1
+                    }
                 });
 
                 for (value, _) in targets.iter() {

tests/crashes/140850.rs

@@ -1,6 +1,6 @@
 //@ known-bug: #140850
 //@ compile-flags: -Zvalidate-mir
-fn A() -> impl {
+fn A() -> impl Copy {
     while A() {}
     loop {}
 }

tests/crashes/137916.rs renamed to tests/ui/coroutine/non-send-dyn-send-ice.rs

@@ -1,9 +1,11 @@
-//@ known-bug: #137916
+//! Regression test for ICE #137916
 //@ edition: 2021
+//@ compile-flags: -Zvalidate-mir
+
 use std::ptr::null;
 
 async fn a() -> Box<dyn Send> {
-    Box::new(async {
+    Box::new(async { //~ ERROR future cannot be sent between threads safely
         let non_send = null::<()>();
         &non_send;
         async {}.await

tests/ui/coroutine/non-send-dyn-send-ice.stderr

@@ -0,0 +1,23 @@
+error: future cannot be sent between threads safely
+  --> $DIR/non-send-dyn-send-ice.rs:8:5
+   |
+LL | /     Box::new(async {
+LL | |         let non_send = null::<()>();
+LL | |         &non_send;
+LL | |         async {}.await
+LL | |     })
+   | |______^ future created by async block is not `Send`
+   |
+   = help: within `{async block@$DIR/non-send-dyn-send-ice.rs:8:14: 8:19}`, the trait `Send` is not implemented for `*const ()`
+note: future is not `Send` as this value is used across an await
+  --> $DIR/non-send-dyn-send-ice.rs:11:18
+   |
+LL |         let non_send = null::<()>();
+   |             -------- has type `*const ()` which is not `Send`
+LL |         &non_send;
+LL |         async {}.await
+   |                  ^^^^^ await occurs here, with `non_send` maybe used later
+   = note: required for the cast from `Box<{async block@$DIR/non-send-dyn-send-ice.rs:8:14: 8:19}>` to `Box<dyn Send>`
+
+error: aborting due to 1 previous error
+

tests/crashes/126680.rs renamed to tests/ui/type-alias-impl-trait/branch-closure-parameter.rs

@@ -1,5 +1,6 @@
-//@ known-bug: rust-lang/rust#126680
+//! Regression test for #126680
 //@ compile-flags: -Zvalidate-mir
+
 #![feature(type_alias_impl_trait)]
 type Bar = impl std::fmt::Display;
 
@@ -10,7 +11,7 @@ struct A {
 }
 
 #[define_opaque(Bar)]
-fn foo() -> A {
+fn foo() -> A { //~ ERROR item does not constrain `Bar::{opaque#0}`
     A {
         func: |check, b| {
             if check {

tests/ui/type-alias-impl-trait/branch-closure-parameter.stderr

@@ -0,0 +1,15 @@
+error: item does not constrain `Bar::{opaque#0}`
+  --> $DIR/branch-closure-parameter.rs:14:4
+   |
+LL | fn foo() -> A {
+   |    ^^^
+   |
+   = note: consider removing `#[define_opaque]` or adding an empty `#[define_opaque()]`
+note: this opaque type is supposed to be constrained
+  --> $DIR/branch-closure-parameter.rs:5:12
+   |
+LL | type Bar = impl std::fmt::Display;
+   |            ^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 1 previous error
+