Don't ICE when encountering placeholders in layout computation

Author: compiler-errors

compiler/rustc_ty_utils/src/layout.rs

@@ -611,7 +611,7 @@ fn layout_of_uncached<'tcx>(
         }
 
         // Types with no meaningful known layout.
-        ty::Param(_) => {
+        ty::Param(_) | ty::Placeholder(..) => {
             return Err(error(cx, LayoutError::TooGeneric(ty)));
         }
 
@@ -628,11 +628,7 @@ fn layout_of_uncached<'tcx>(
             return Err(error(cx, err));
         }
 
-        ty::Placeholder(..)
-        | ty::Bound(..)
-        | ty::CoroutineWitness(..)
-        | ty::Infer(_)
-        | ty::Error(_) => {
+        ty::Bound(..) | ty::CoroutineWitness(..) | ty::Infer(_) | ty::Error(_) => {
             // `ty::Error` is handled at the top of this function.
             bug!("layout_of: unexpected type `{ty}`")
         }

tests/ui/consts/too_generic_eval_ice.stderr renamed to tests/ui/consts/too_generic_eval_ice.current.stderr

@@ -1,29 +1,29 @@
 error: constant expression depends on a generic parameter
-  --> $DIR/too_generic_eval_ice.rs:7:13
+  --> $DIR/too_generic_eval_ice.rs:11:13
    |
 LL |         [5; Self::HOST_SIZE] == [6; 0]
    |             ^^^^^^^^^^^^^^^
    |
    = note: this may fail depending on what value the parameter takes
 
 error: constant expression depends on a generic parameter
-  --> $DIR/too_generic_eval_ice.rs:7:9
+  --> $DIR/too_generic_eval_ice.rs:11:9
    |
 LL |         [5; Self::HOST_SIZE] == [6; 0]
    |         ^^^^^^^^^^^^^^^^^^^^
    |
    = note: this may fail depending on what value the parameter takes
 
 error: constant expression depends on a generic parameter
-  --> $DIR/too_generic_eval_ice.rs:7:30
+  --> $DIR/too_generic_eval_ice.rs:11:30
    |
 LL |         [5; Self::HOST_SIZE] == [6; 0]
    |                              ^^
    |
    = note: this may fail depending on what value the parameter takes
 
 error[E0277]: can't compare `[{integer}; Self::HOST_SIZE]` with `[{integer}; 0]`
-  --> $DIR/too_generic_eval_ice.rs:7:30
+  --> $DIR/too_generic_eval_ice.rs:11:30
    |
 LL |         [5; Self::HOST_SIZE] == [6; 0]
    |                              ^^ no implementation for `[{integer}; Self::HOST_SIZE] == [{integer}; 0]`

tests/ui/consts/too_generic_eval_ice.next.stderr

@@ -0,0 +1,9 @@
+error[E0284]: type annotations needed: cannot satisfy `the constant `Self::HOST_SIZE` can be evaluated`
+  --> $DIR/too_generic_eval_ice.rs:11:13
+   |
+LL |         [5; Self::HOST_SIZE] == [6; 0]
+   |             ^^^^^^^^^^^^^^^ cannot satisfy `the constant `Self::HOST_SIZE` can be evaluated`
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0284`.

tests/ui/consts/too_generic_eval_ice.rs

@@ -1,14 +1,19 @@
+//@ revisions: current next
+//@ ignore-compare-mode-next-solver (explicit revisions)
+//@[next] compile-flags: -Znext-solver
+
 pub struct Foo<A, B>(A, B);
 
 impl<A, B> Foo<A, B> {
     const HOST_SIZE: usize = std::mem::size_of::<B>();
 
     pub fn crash() -> bool {
         [5; Self::HOST_SIZE] == [6; 0]
-        //~^ ERROR constant expression depends on a generic parameter
-        //~| ERROR constant expression depends on a generic parameter
-        //~| ERROR constant expression depends on a generic parameter
-        //~| ERROR can't compare `[{integer}; Self::HOST_SIZE]` with `[{integer}; 0]`
+        //[current]~^ ERROR constant expression depends on a generic parameter
+        //[current]~| ERROR constant expression depends on a generic parameter
+        //[current]~| ERROR constant expression depends on a generic parameter
+        //[current]~| ERROR can't compare `[{integer}; Self::HOST_SIZE]` with `[{integer}; 0]`
+        //[next]~^^^^^ ERROR type annotations needed
     }
 }