Dont ICE when encountering post-mono layout cycle error

Author: compiler-errors

compiler/rustc_codegen_llvm/src/context.rs

@@ -1187,10 +1187,11 @@ impl<'tcx> FnAbiOfHelpers<'tcx> for CodegenCx<'_, 'tcx> {
 span:Span,
 fn_abi_request:FnAbiRequest<'tcx>,
 ) -> ! {
-ifletFnAbiError::Layout(LayoutError::SizeOverflow(_)) = err {
-self.tcx.dcx().emit_fatal(Spanned{ span,node: err })
-}else{
-match fn_abi_request {
+match err {
+FnAbiError::Layout(LayoutError::SizeOverflow(_) | LayoutError::Cycle(_)) => {
+self.tcx.dcx().emit_fatal(Spanned{ span,node: err });
+}
+ _ => match fn_abi_request {
 FnAbiRequest::OfFnPtr{ sig, extra_args } => {
 span_bug!(span,"`fn_abi_of_fn_ptr({sig}, {extra_args:?})` failed: {err:?}",);
 }
@@ -1200,7 +1201,7 @@ impl<'tcx> FnAbiOfHelpers<'tcx> for CodegenCx<'_, 'tcx> {
 "`fn_abi_of_instance({instance}, {extra_args:?})` failed: {err:?}",
 );
 }
-}
+},
 }
 }
 }

tests/ui/layout/post-mono-layout-cycle-2.rs

@@ -0,0 +1,59 @@
+//@ build-fail
+//@ edition: 2021
+
+#![feature(async_closure, noop_waker)]
+
+use std::future::Future;
+use std::pin::pin;
+use std::task::*;
+
+pubfnblock_on<T>(fut:implFuture<Output = T>) -> T{
+letmut fut = pin!(fut);
+// Poll loop, just to test the future...
+let ctx = &mutContext::from_waker(Waker::noop());
+
+loop{
+match fut.as_mut().poll(ctx){
+Poll::Pending => {}
+Poll::Ready(t) => break t,
+}
+}
+}
+
+traitBlah{
+asyncfniter<T>(&mutself,iterator:T)
+where
+T:IntoIterator<Item = ()>;
+}
+
+implBlahfor(){
+asyncfniter<T>(&mutself,iterator:T)
+//~^ ERROR recursion in an async fn requires boxing
+where
+T:IntoIterator<Item = ()>,
+{
+Blah::iter(self, iterator).await
+}
+}
+
+structWrap<T:Blah>{
+t:T,
+}
+
+impl<T:Blah>Wrap<T>
+where
+T:Blah,
+{
+asyncfnice(&mutself){
+//~^ ERROR a cycle occurred during layout computation
+let arr:[();0] = [];
+self.t.iter(arr.into_iter()).await;
+}
+}
+
+fnmain(){
+block_on(async{
+letmut t = Wrap{t:()};
+ t.ice();
+})
+}

tests/ui/layout/post-mono-layout-cycle-2.stderr

@@ -0,0 +1,23 @@
+error[E0733]: recursion in an async fn requires boxing
+ --> $DIR/post-mono-layout-cycle-2.rs:30:5
+ |
+LL | / async fn iter<T>(&mut self, iterator: T)
+LL | |
+LL | | where
+LL | | T: IntoIterator<Item = ()>,
+ | |___________________________________^
+LL | {
+LL | Blah::iter(self, iterator).await
+ | -------------------------------- recursive call here
+ |
+ = note: a recursive `async fn` call must introduce indirection such as `Box::pin` to avoid an infinitely sized future
+
+error: a cycle occurred during layout computation
+ --> $DIR/post-mono-layout-cycle-2.rs:47:5
+ |
+LL | async fn ice(&mut self) {
+ | ^^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0733`.

tests/ui/layout/post-mono-layout-cycle.rs

@@ -0,0 +1,25 @@
+//@ build-fail
+//~^ cycle detected when computing layout of `Wrapper<()>`
+
+traitTrait{
+typeAssoc;
+}
+
+implTraitfor(){
+typeAssoc = Wrapper<()>;
+}
+
+structWrapper<T:Trait>{
+_x: <TasTrait>::Assoc,
+}
+
+fnabi<T:Trait>(_:Option<Wrapper<T>>){}
+//~^ ERROR a cycle occurred during layout computation
+
+fnindirect<T:Trait>(){
+abi::<T>(None);
+}
+
+fnmain(){
+indirect::<()>();
+}

tests/ui/layout/post-mono-layout-cycle.stderr

@@ -0,0 +1,16 @@
+error[E0391]: cycle detected when computing layout of `Wrapper<()>`
+ |
+ = note: ...which requires computing layout of `<() as Trait>::Assoc`...
+ = note: ...which again requires computing layout of `Wrapper<()>`, completing the cycle
+ = note: cycle used when computing layout of `core::option::Option<Wrapper<()>>`
+ = note: see https://rustc-dev-guide.rust-lang.org/overview.html#queries and https://rustc-dev-guide.rust-lang.org/query.html for more information
+
+error: a cycle occurred during layout computation
+ --> $DIR/post-mono-layout-cycle.rs:16:1
+ |
+LL | fn abi<T: Trait>(_: Option<Wrapper<T>>) {}
+ | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0391`.