Add more tests that exercise the well-formedness checking of lazy type aliases

Author: fmease

tests/ui/lazy-type-alias/def-site-body-wf.rs

@@ -0,0 +1,18 @@
+// Test that we check the body at the definition site for well-formedness.
+
+#![feature(lazy_type_alias)]
+
+// unsatisified trait bounds
+type _A<T> = <T as std::ops::Mul>::Output; //~ ERROR cannot multiply `T` by `T`
+type _B = Vec<str>; //~ ERROR the size for values of type `str` cannot be known at compilation time
+
+// unsatisfied outlives-bounds
+type _C<'a> = &'static &'a (); //~ ERROR reference has a longer lifetime than the data it references
+
+// diverging const exprs
+type _D = [(); panic!()]; //~ ERROR evaluation panicked
+
+// dyn incompatibility
+type _E = dyn Sized; //~ ERROR the trait `Sized` is not dyn compatible
+
+fn main() {}

tests/ui/lazy-type-alias/def-site-body-wf.stderr

@@ -0,0 +1,54 @@
+error[E0277]: cannot multiply `T` by `T`
+  --> $DIR/def-site-body-wf.rs:6:14
+   |
+LL | type _A<T> = <T as std::ops::Mul>::Output;
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ no implementation for `T * T`
+   |
+help: consider restricting type parameter `T` with trait `Mul`
+   |
+LL | type _A<T: std::ops::Mul> = <T as std::ops::Mul>::Output;
+   |          +++++++++++++++
+
+error[E0277]: the size for values of type `str` cannot be known at compilation time
+  --> $DIR/def-site-body-wf.rs:7:11
+   |
+LL | type _B = Vec<str>;
+   |           ^^^^^^^^ doesn't have a size known at compile-time
+   |
+   = help: the trait `Sized` is not implemented for `str`
+note: required by an implicit `Sized` bound in `Vec`
+  --> $SRC_DIR/alloc/src/vec/mod.rs:LL:COL
+
+error[E0491]: in type `&'static &'a ()`, reference has a longer lifetime than the data it references
+  --> $DIR/def-site-body-wf.rs:10:1
+   |
+LL | type _C<'a> = &'static &'a ();
+   | ^^^^^^^^^^^
+   |
+   = note: the pointer is valid for the static lifetime
+note: but the referenced data is only valid for the lifetime `'a` as defined here
+  --> $DIR/def-site-body-wf.rs:10:9
+   |
+LL | type _C<'a> = &'static &'a ();
+   |         ^^
+
+error[E0080]: evaluation panicked: explicit panic
+  --> $DIR/def-site-body-wf.rs:13:16
+   |
+LL | type _D = [(); panic!()];
+   |                ^^^^^^^^ evaluation of `_D::{constant#0}` failed here
+
+error[E0038]: the trait `Sized` is not dyn compatible
+  --> $DIR/def-site-body-wf.rs:16:11
+   |
+LL | type _E = dyn Sized;
+   |           ^^^^^^^^^ `Sized` is not dyn compatible
+   |
+   = note: the trait is not dyn compatible because it requires `Self: Sized`
+   = 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>
+
+error: aborting due to 5 previous errors
+
+Some errors have detailed explanations: E0038, E0080, E0277, E0491.
+For more information about an error, try `rustc --explain E0038`.

tests/ui/lazy-type-alias/unsatisfied-bounds-type-alias-body.rs

@@ -0,0 +1,16 @@
+// Test that we check usage sites of lazy type aliases, aka free alias types, for well-formedness.
+// We check trailing where-clauses separately in `trailing-where-clause.rs`.
+
+#![feature(lazy_type_alias)]
+
+type B<T: Copy> = T;
+
+fn b<X>(_: B<X>) {}
+//~^ ERROR the trait bound `X: Copy` is not satisfied
+//~| ERROR the trait bound `X: Copy` is not satisfied
+
+type A<'a: 'static> = &'a ();
+
+fn a<'r>(_: A<'r>) {} //~ ERROR lifetime bound not satisfied
+
+fn main() {}

tests/ui/lazy-type-alias/unsatisfied-bounds-type-alias-body.stderr

@@ -0,0 +1,50 @@
+error[E0277]: the trait bound `X: Copy` is not satisfied
+  --> $DIR/use-site-wf.rs:8:12
+   |
+LL | fn b<X>(_: B<X>) {}
+   |            ^^^^ the trait `Copy` is not implemented for `X`
+   |
+note: required by a bound on the type alias `B`
+  --> $DIR/use-site-wf.rs:6:11
+   |
+LL | type B<T: Copy> = T;
+   |           ^^^^ required by this bound
+help: consider restricting type parameter `X` with trait `Copy`
+   |
+LL | fn b<X: std::marker::Copy>(_: B<X>) {}
+   |       +++++++++++++++++++
+
+error[E0478]: lifetime bound not satisfied
+  --> $DIR/use-site-wf.rs:14:13
+   |
+LL | fn a<'r>(_: A<'r>) {}
+   |             ^^^^^
+   |
+note: lifetime parameter instantiated with the lifetime `'r` as defined here
+  --> $DIR/use-site-wf.rs:14:6
+   |
+LL | fn a<'r>(_: A<'r>) {}
+   |      ^^
+   = note: but lifetime parameter must outlive the static lifetime
+
+error[E0277]: the trait bound `X: Copy` is not satisfied
+  --> $DIR/use-site-wf.rs:8:12
+   |
+LL | fn b<X>(_: B<X>) {}
+   |            ^^^^ the trait `Copy` is not implemented for `X`
+   |
+note: required by a bound on the type alias `B`
+  --> $DIR/use-site-wf.rs:6:11
+   |
+LL | type B<T: Copy> = T;
+   |           ^^^^ required by this bound
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
+help: consider restricting type parameter `X` with trait `Copy`
+   |
+LL | fn b<X: std::marker::Copy>(_: B<X>) {}
+   |       +++++++++++++++++++
+
+error: aborting due to 3 previous errors
+
+Some errors have detailed explanations: E0277, E0478.
+For more information about an error, try `rustc --explain E0277`.