Taint the type of ill-formed (unsized) statics

compiler/rustc_hir_analysis/src/check/check.rs

@@ -767,7 +767,6 @@ pub(crate) fn check_item_type(tcx: TyCtxt<'_>, def_id: LocalDefId) -> Result<(),
                 DefKind::Static { .. } => {
                     check_static_inhabited(tcx, def_id);
                     check_static_linkage(tcx, def_id);
-                    res = res.and(wfcheck::check_static_item(tcx, def_id));
                 }
                 DefKind::Const => res = res.and(wfcheck::check_const_item(tcx, def_id)),
                 _ => unreachable!(),

compiler/rustc_hir_analysis/src/check/wfcheck.rs

@@ -1180,12 +1180,12 @@ fn check_item_fn(
 }
 
 #[instrument(level = "debug", skip(tcx))]
-pub(super) fn check_static_item(
-    tcx: TyCtxt<'_>,
+pub(crate) fn check_static_item<'tcx>(
+    tcx: TyCtxt<'tcx>,
     item_id: LocalDefId,
+    ty: Ty<'tcx>,
 ) -> Result<(), ErrorGuaranteed> {
     enter_wf_checking_ctxt(tcx, item_id, |wfcx| {
-        let ty = tcx.type_of(item_id).instantiate_identity();
         let span = tcx.ty_span(item_id);
         let item_ty = wfcx.deeply_normalize(span, Some(WellFormedLoc::Ty(item_id)), ty);
 

compiler/rustc_hir_analysis/src/collect/type_of.rs

@@ -14,6 +14,7 @@ use rustc_middle::{bug, span_bug};
 use rustc_span::{DUMMY_SP, Ident, Span};
 
 use super::{HirPlaceholderCollector, ItemCtxt, bad_placeholder};
+use crate::check::wfcheck::check_static_item;
 use crate::errors::TypeofReservedKeywordUsed;
 use crate::hir_ty_lowering::HirTyLowerer;
 
@@ -217,7 +218,13 @@ pub(super) fn type_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::EarlyBinder<'_
                         "static variable",
                     )
                 } else {
-                    icx.lower_ty(ty)
+                    let ty = icx.lower_ty(ty);
+                    // MIR relies on references to statics being scalars.
+                    // Verify that here to avoid ill-formed MIR.
+                    match check_static_item(tcx, def_id, ty) {
+                        Ok(()) => ty,
+                        Err(guar) => Ty::new_error(tcx, guar),
+                    }
                 }
             }
             ItemKind::Const(ident, _, ty, body_id) => {
@@ -275,7 +282,15 @@ pub(super) fn type_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::EarlyBinder<'_
                 let args = ty::GenericArgs::identity_for_item(tcx, def_id);
                 Ty::new_fn_def(tcx, def_id.to_def_id(), args)
             }
-            ForeignItemKind::Static(t, _, _) => icx.lower_ty(t),
+            ForeignItemKind::Static(ty, _, _) => {
+                let ty = icx.lower_ty(ty);
+                // MIR relies on references to statics being scalars.
+                // Verify that here to avoid ill-formed MIR.
+                match check_static_item(tcx, def_id, ty) {
+                    Ok(()) => ty,
+                    Err(guar) => Ty::new_error(tcx, guar),
+                }
+            }
             ForeignItemKind::Type => Ty::new_foreign(tcx, def_id.to_def_id()),
         },
 

tests/ui/consts/const-unsized.rs

@@ -10,14 +10,10 @@ const CONST_FOO: str = *"foo";
 
 static STATIC_1: dyn Debug + Sync = *(&1 as &(dyn Debug + Sync));
 //~^ ERROR the size for values of type
-//~| ERROR cannot move out of a shared reference
 
 static STATIC_BAR: str = *"bar";
 //~^ ERROR the size for values of type
-//~| ERROR cannot move out of a shared reference
 
 fn main() {
     println!("{:?} {:?} {:?} {:?}", &CONST_0, &CONST_FOO, &STATIC_1, &STATIC_BAR);
-    //~^ ERROR: cannot move a value of type `str`
-    //~| ERROR: cannot move a value of type `dyn Debug + Sync`
 }

tests/ui/consts/const-unsized.stderr

@@ -26,7 +26,7 @@ LL | static STATIC_1: dyn Debug + Sync = *(&1 as &(dyn Debug + Sync));
    = note: statics and constants must have a statically known size
 
 error[E0277]: the size for values of type `str` cannot be known at compilation time
-  --> $DIR/const-unsized.rs:15:1
+  --> $DIR/const-unsized.rs:14:1
    |
 LL | static STATIC_BAR: str = *"bar";
    | ^^^^^^^^^^^^^^^^^^^^^^ doesn't have a size known at compile-time
@@ -46,31 +46,7 @@ error[E0507]: cannot move out of a shared reference
 LL | const CONST_FOO: str = *"foo";
    |                        ^^^^^^ move occurs because value has type `str`, which does not implement the `Copy` trait
 
-error[E0507]: cannot move out of a shared reference
-  --> $DIR/const-unsized.rs:11:37
-   |
-LL | static STATIC_1: dyn Debug + Sync = *(&1 as &(dyn Debug + Sync));
-   |                                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ move occurs because value has type `dyn Debug + Sync`, which does not implement the `Copy` trait
-
-error[E0507]: cannot move out of a shared reference
-  --> $DIR/const-unsized.rs:15:26
-   |
-LL | static STATIC_BAR: str = *"bar";
-   |                          ^^^^^^ move occurs because value has type `str`, which does not implement the `Copy` trait
-
-error[E0161]: cannot move a value of type `dyn Debug + Sync`
-  --> $DIR/const-unsized.rs:20:38
-   |
-LL |     println!("{:?} {:?} {:?} {:?}", &CONST_0, &CONST_FOO, &STATIC_1, &STATIC_BAR);
-   |                                      ^^^^^^^ the size of `dyn Debug + Sync` cannot be statically determined
-
-error[E0161]: cannot move a value of type `str`
-  --> $DIR/const-unsized.rs:20:48
-   |
-LL |     println!("{:?} {:?} {:?} {:?}", &CONST_0, &CONST_FOO, &STATIC_1, &STATIC_BAR);
-   |                                                ^^^^^^^^^ the size of `str` cannot be statically determined
-
-error: aborting due to 10 previous errors
+error: aborting due to 6 previous errors
 
-Some errors have detailed explanations: E0161, E0277, E0507.
-For more information about an error, try `rustc --explain E0161`.
+Some errors have detailed explanations: E0277, E0507.
+For more information about an error, try `rustc --explain E0277`.

tests/ui/coroutine/layout-error.rs

@@ -17,6 +17,7 @@ impl<F: Future> Task<F> {
 }
 
 pub type F = impl Future;
+
 #[define_opaque(F)]
 fn foo()
 where
@@ -31,5 +32,7 @@ where
 
 // Check that statics are inhabited computes they layout.
 static POOL: Task<F> = Task::new();
+//~^ ERROR cycle detected when computing type of `POOL`
+//~| ERROR cycle detected when computing type of `POOL`
 
 fn main() {}

tests/ui/coroutine/layout-error.stderr

@@ -1,9 +1,97 @@
 error[E0425]: cannot find value `Foo` in this scope
-  --> $DIR/layout-error.rs:26:17
+  --> $DIR/layout-error.rs:27:17
    |
 LL |         let a = Foo;
    |                 ^^^ not found in this scope
 
-error: aborting due to 1 previous error
+error[E0391]: cycle detected when computing type of `POOL`
+  --> $DIR/layout-error.rs:34:14
+   |
+LL | static POOL: Task<F> = Task::new();
+   |              ^^^^^^^
+   |
+   = note: ...which requires evaluating trait selection obligation `Task<F>: core::marker::Sync`...
+note: ...which requires computing type of opaque `F::{opaque#0}`...
+  --> $DIR/layout-error.rs:19:14
+   |
+LL | pub type F = impl Future;
+   |              ^^^^^^^^^^^
+note: ...which requires borrow-checking `foo`...
+  --> $DIR/layout-error.rs:22:1
+   |
+LL | / fn foo()
+LL | | where
+LL | |     F:,
+   | |_______^
+note: ...which requires promoting constants in MIR for `foo`...
+  --> $DIR/layout-error.rs:22:1
+   |
+LL | / fn foo()
+LL | | where
+LL | |     F:,
+   | |_______^
+note: ...which requires checking if `foo` contains FFI-unwind calls...
+  --> $DIR/layout-error.rs:22:1
+   |
+LL | / fn foo()
+LL | | where
+LL | |     F:,
+   | |_______^
+note: ...which requires building MIR for `foo`...
+  --> $DIR/layout-error.rs:22:1
+   |
+LL | / fn foo()
+LL | | where
+LL | |     F:,
+   | |_______^
+note: ...which requires match-checking `foo`...
+  --> $DIR/layout-error.rs:22:1
+   |
+LL | / fn foo()
+LL | | where
+LL | |     F:,
+   | |_______^
+note: ...which requires type-checking `foo`...
+  --> $DIR/layout-error.rs:22:1
+   |
+LL | / fn foo()
+LL | | where
+LL | |     F:,
+   | |_______^
+   = note: ...which again requires computing type of `POOL`, completing the cycle
+note: cycle used when checking that `POOL` is well-formed
+  --> $DIR/layout-error.rs:34:1
+   |
+LL | static POOL: Task<F> = Task::new();
+   | ^^^^^^^^^^^^^^^^^^^^
+   = 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[E0391]: cycle detected when computing type of `POOL`
+  --> $DIR/layout-error.rs:34:14
+   |
+LL | static POOL: Task<F> = Task::new();
+   |              ^^^^^^^
+   |
+   = note: ...which requires evaluating trait selection obligation `Task<F>: core::marker::Sync`...
+note: ...which requires computing type of opaque `F::{opaque#0}`...
+  --> $DIR/layout-error.rs:19:14
+   |
+LL | pub type F = impl Future;
+   |              ^^^^^^^^^^^
+note: ...which requires computing the opaque types defined by `POOL`...
+  --> $DIR/layout-error.rs:34:1
+   |
+LL | static POOL: Task<F> = Task::new();
+   | ^^^^^^^^^^^^^^^^^^^^
+   = note: ...which again requires computing type of `POOL`, completing the cycle
+note: cycle used when checking that `POOL` is well-formed
+  --> $DIR/layout-error.rs:34:1
+   |
+LL | static POOL: Task<F> = Task::new();
+   | ^^^^^^^^^^^^^^^^^^^^
+   = 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: aborting due to 3 previous errors
 
-For more information about this error, try `rustc --explain E0425`.
+Some errors have detailed explanations: E0391, E0425.
+For more information about an error, try `rustc --explain E0391`.

tests/ui/coroutine/metadata-sufficient-for-layout.rs

@@ -4,7 +4,6 @@
 // Regression test for #80998.
 //
 //@ aux-build:metadata-sufficient-for-layout.rs
-//@ check-pass
 
 #![feature(type_alias_impl_trait, rustc_attrs)]
 #![feature(coroutine_trait)]
@@ -23,5 +22,6 @@ mod helper {
 
 // Static queries the layout of the coroutine.
 static A: Option<helper::F> = None;
+//~^ ERROR cycle detected when computing type of `A`
 
 fn main() {}

tests/ui/coroutine/metadata-sufficient-for-layout.stderr

@@ -0,0 +1,38 @@
+error[E0391]: cycle detected when computing type of `A`
+  --> $DIR/metadata-sufficient-for-layout.rs:24:11
+   |
+LL | static A: Option<helper::F> = None;
+   |           ^^^^^^^^^^^^^^^^^
+   |
+   = note: ...which requires evaluating trait selection obligation `core::option::Option<helper::F>: core::marker::Sync`...
+note: ...which requires computing type of opaque `helper::F::{opaque#0}`...
+  --> $DIR/metadata-sufficient-for-layout.rs:15:18
+   |
+LL |     pub type F = impl Coroutine<(), Yield = (), Return = ()>;
+   |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+note: ...which requires borrow-checking `helper::f`...
+  --> $DIR/metadata-sufficient-for-layout.rs:18:5
+   |
+LL |     fn f() -> F {
+   |     ^^^^^^^^^^^
+note: ...which requires computing type of opaque `helper::F::{opaque#0}` via HIR typeck...
+  --> $DIR/metadata-sufficient-for-layout.rs:15:18
+   |
+LL |     pub type F = impl Coroutine<(), Yield = (), Return = ()>;
+   |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+note: ...which requires computing the opaque types defined by `A`...
+  --> $DIR/metadata-sufficient-for-layout.rs:24:1
+   |
+LL | static A: Option<helper::F> = None;
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   = note: ...which again requires computing type of `A`, completing the cycle
+note: cycle used when checking that `A` is well-formed
+  --> $DIR/metadata-sufficient-for-layout.rs:24:1
+   |
+LL | static A: Option<helper::F> = None;
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   = 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: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0391`.

tests/ui/dyn-compatibility/taint-const-eval.rs

@@ -6,6 +6,5 @@ trait Qux {
 
 static FOO: &(dyn Qux + Sync) = "desc";
 //~^ ERROR the trait `Qux` is not dyn compatible
-//~| ERROR the trait `Qux` is not dyn compatible
 
 fn main() {}

tests/ui/dyn-compatibility/taint-const-eval.stderr

@@ -21,30 +21,6 @@ help: alternatively, consider constraining `bar` so it does not apply to trait o
 LL |     fn bar() where Self: Sized;
    |              +++++++++++++++++
 
-error[E0038]: the trait `Qux` is not dyn compatible
-  --> $DIR/taint-const-eval.rs:7:15
-   |
-LL | static FOO: &(dyn Qux + Sync) = "desc";
-   |               ^^^^^^^^^^^^^^ `Qux` is not dyn compatible
-   |
-note: for a trait to be dyn compatible it needs to allow building a vtable
-      for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>
-  --> $DIR/taint-const-eval.rs:4:8
-   |
-LL | trait Qux {
-   |       --- this trait is not dyn compatible...
-LL |     fn bar();
-   |        ^^^ ...because associated function `bar` has no `self` parameter
-   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
-help: consider turning `bar` into a method by giving it a `&self` argument
-   |
-LL |     fn bar(&self);
-   |            +++++
-help: alternatively, consider constraining `bar` so it does not apply to trait objects
-   |
-LL |     fn bar() where Self: Sized;
-   |              +++++++++++++++++
-
-error: aborting due to 2 previous errors
+error: aborting due to 1 previous error
 
 For more information about this error, try `rustc --explain E0038`.

tests/ui/extern/issue-36122-accessing-externed-dst.rs

@@ -3,5 +3,4 @@ fn main() {
         static symbol: [usize]; //~ ERROR: the size for values of type
     }
     println!("{}", symbol[0]);
-    //~^ ERROR: extern static is unsafe
 }

tests/ui/extern/issue-36122-accessing-externed-dst.stderr

@@ -7,15 +7,6 @@ LL |         static symbol: [usize];
    = help: the trait `Sized` is not implemented for `[usize]`
    = note: statics and constants must have a statically known size
 
-error[E0133]: use of extern static is unsafe and requires unsafe function or block
-  --> $DIR/issue-36122-accessing-externed-dst.rs:5:20
-   |
-LL |     println!("{}", symbol[0]);
-   |                    ^^^^^^ use of extern static
-   |
-   = note: extern statics are not controlled by the Rust type system: invalid data, aliasing violations or data races will cause undefined behavior
-
-error: aborting due to 2 previous errors
+error: aborting due to 1 previous error
 
-Some errors have detailed explanations: E0133, E0277.
-For more information about an error, try `rustc --explain E0133`.
+For more information about this error, try `rustc --explain E0277`.