Fix an ICE with uninhabited consts

Author: varkor

src/librustc/ty/inhabitedness/mod.rs

@@ -97,7 +97,7 @@ impl<'tcx> TyCtxt<'tcx> {
         self.ty_inhabitedness_forest(ty).contains(self, module)
     }
 
-    pub fn is_ty_uninhabited_from_all_modules(self, ty: Ty<'tcx>) -> bool {
+    pub fn is_ty_uninhabited_from_any_module(self, ty: Ty<'tcx>) -> bool {
         !self.ty_inhabitedness_forest(ty).is_empty()
     }
 

src/librustc_mir/interpret/terminator.rs

@@ -388,12 +388,10 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpretCx<'mir, 'tcx, M> {
                             ));
                         }
                     } else {
-                        let callee_layout =
-                            self.layout_of_local(self.frame(), mir::RETURN_PLACE, None)?;
-                        if !callee_layout.abi.is_uninhabited() {
-                            return err!(FunctionRetMismatch(
-                                self.tcx.types.never, callee_layout.ty
-                            ));
+                        let local = mir::RETURN_PLACE;
+                        let ty = self.frame().body.local_decls[local].ty;
+                        if !self.tcx.is_ty_uninhabited_from_any_module(ty) {
+                            return err!(FunctionRetMismatch(self.tcx.types.never, ty));
                         }
                     }
                     Ok(())

src/test/ui/consts/uninhabited-const-issue-61744.rs

@@ -0,0 +1,19 @@
+// compile-fail
+
+pub const unsafe fn fake_type<T>() -> T {
+    hint_unreachable()
+}
+
+pub const unsafe fn hint_unreachable() -> ! {
+    fake_type() //~ ERROR any use of this value will cause an error
+}
+
+trait Const {
+    const CONSTANT: i32 = unsafe { fake_type() };
+}
+
+impl <T> Const for T {}
+
+pub fn main() -> () {
+    dbg!(i32::CONSTANT); //~ ERROR erroneous constant used
+}

src/test/ui/consts/uninhabited-const-issue-61744.stderr

@@ -0,0 +1,24 @@
+error: any use of this value will cause an error
+  --> $DIR/uninhabited-const-issue-61744.rs:8:5
+   |
+LL |     fake_type()
+   |     ^^^^^^^^^^^
+   |     |
+   |     tried to call a function with return type T passing return place of type !
+   |     inside call to `hint_unreachable` at $DIR/uninhabited-const-issue-61744.rs:4:5
+   |     inside call to `fake_type::<i32>` at $DIR/uninhabited-const-issue-61744.rs:12:36
+...
+LL |     const CONSTANT: i32 = unsafe { fake_type() };
+   |     ---------------------------------------------
+   |
+   = note: #[deny(const_err)] on by default
+
+error[E0080]: erroneous constant used
+  --> $DIR/uninhabited-const-issue-61744.rs:18:10
+   |
+LL |     dbg!(i32::CONSTANT);
+   |          ^^^^^^^^^^^^^ referenced constant has errors
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0080`.