Auto merge of #99798 - JulianKnodt:ac1, r=BoxyUwU

Add `ConstKind::Expr`

Starting to implement `ty::ConstKind::Abstract`, most of the match cases are stubbed out, some I was unsure what to add, others I didn't want to add until a more complete implementation was ready.

r? `@lcnr`

9 files changed, 115 insertions, 6 deletions

diff --git a/src/test/ui/const-generics/generic_const_exprs/assoc_const_unification/const_equate_assoc_consts.rs b/src/test/ui/const-generics/generic_const_exprs/assoc_const_unification/const_equate_assoc_consts.rs
new file mode 100644
index 00000000000..e8f89cb1aa2
--- /dev/null
+++ b/src/test/ui/const-generics/generic_const_exprs/assoc_const_unification/const_equate_assoc_consts.rs
@@ -0,0 +1,27 @@
+// check-pass
+#![feature(generic_const_exprs)]
+#![allow(incomplete_features)]
+
+trait Trait {
+    const ASSOC: usize;
+}
+impl<T> Trait for T {
+    const ASSOC: usize = std::mem::size_of::<T>();
+}
+
+struct Foo<T: Trait>([u8; T::ASSOC])
+where
+    [(); T::ASSOC]:;
+
+fn bar<T: Trait>()
+where
+    [(); T::ASSOC]:,
+{
+    let _: Foo<T> = Foo::<_>(make());
+}
+
+fn make() -> ! {
+    todo!()
+}
+
+fn main() {}
diff --git a/src/test/ui/const-generics/generic_const_exprs/assoc_const_unification/doesnt_unify_evaluatable.rs b/src/test/ui/const-generics/generic_const_exprs/assoc_const_unification/doesnt_unify_evaluatable.rs
new file mode 100644
index 00000000000..c8f7553da79
--- /dev/null
+++ b/src/test/ui/const-generics/generic_const_exprs/assoc_const_unification/doesnt_unify_evaluatable.rs
@@ -0,0 +1,15 @@
+#![feature(generic_const_exprs)]
+#![allow(incomplete_features)]
+
+trait Trait {
+    const ASSOC: usize;
+}
+
+fn foo<T: Trait, U: Trait>() where [(); U::ASSOC]:, {
+    bar::<{ T::ASSOC }>();
+    //~^ ERROR: unconstrained generic constant
+}
+
+fn bar<const N: usize>() {}
+
+fn main() {}
diff --git a/src/test/ui/const-generics/generic_const_exprs/assoc_const_unification/doesnt_unify_evaluatable.stderr b/src/test/ui/const-generics/generic_const_exprs/assoc_const_unification/doesnt_unify_evaluatable.stderr
new file mode 100644
index 00000000000..e4a0cabe572
--- /dev/null
+++ b/src/test/ui/const-generics/generic_const_exprs/assoc_const_unification/doesnt_unify_evaluatable.stderr
@@ -0,0 +1,10 @@
+error: unconstrained generic constant
+  --> $DIR/doesnt_unify_evaluatable.rs:9:11
+   |
+LL |     bar::<{ T::ASSOC }>();
+   |           ^^^^^^^^^^^^
+   |
+   = help: try adding a `where` bound using this expression: `where [(); { T::ASSOC }]:`
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/const-generics/generic_const_exprs/assoc_const_unification/dropck_unifies_assoc_consts.rs b/src/test/ui/const-generics/generic_const_exprs/assoc_const_unification/dropck_unifies_assoc_consts.rs
new file mode 100644
index 00000000000..274caa1e993
--- /dev/null
+++ b/src/test/ui/const-generics/generic_const_exprs/assoc_const_unification/dropck_unifies_assoc_consts.rs
@@ -0,0 +1,20 @@
+// check-pass
+#![feature(generic_const_exprs)]
+#![allow(incomplete_features)]
+
+trait Trait {
+    const ASSOC: usize;
+}
+
+struct Foo<T: Trait>(T)
+where
+    [(); T::ASSOC]:;
+
+impl<T: Trait> Drop for Foo<T>
+where
+    [(); T::ASSOC]:,
+{
+    fn drop(&mut self) {}
+}
+
+fn main() {}
diff --git a/src/test/ui/const-generics/generic_const_exprs/assoc_const_unification/unifies_evaluatable.rs b/src/test/ui/const-generics/generic_const_exprs/assoc_const_unification/unifies_evaluatable.rs
new file mode 100644
index 00000000000..6597b9f2b3f
--- /dev/null
+++ b/src/test/ui/const-generics/generic_const_exprs/assoc_const_unification/unifies_evaluatable.rs
@@ -0,0 +1,18 @@
+// check-pass
+
+#![feature(generic_const_exprs)]
+#![allow(incomplete_features)]
+
+trait Trait {
+    const ASSOC: usize;
+}
+
+fn foo<T: Trait, U: Trait>() where [(); T::ASSOC]:, {
+    bar::<{ T::ASSOC }>();
+}
+
+fn bar<const N: usize>() -> [(); N] {
+    [(); N]
+}
+
+fn main() {}
diff --git a/src/test/ui/const-generics/invariant.rs b/src/test/ui/const-generics/invariant.rs
index ee191b65c2c..39d658be67d 100644
--- a/src/test/ui/const-generics/invariant.rs
+++ b/src/test/ui/const-generics/invariant.rs
@@ -24,7 +24,8 @@ where
 fn covariant(
     v: &'static Foo<for<'a> fn(&'a ())>
 ) -> &'static Foo<fn(&'static ())> {
-    v //~ ERROR mismatched types
+    v
+    //~^ ERROR mismatched types
 }
 
 fn main() {
diff --git a/src/test/ui/const-generics/issues/issue-83765.stderr b/src/test/ui/const-generics/issues/issue-83765.stderr
index 4becf3a364c..d7b2b006c2a 100644
--- a/src/test/ui/const-generics/issues/issue-83765.stderr
+++ b/src/test/ui/const-generics/issues/issue-83765.stderr
@@ -1,15 +1,15 @@
-error[E0391]: cycle detected when resolving instance `<LazyUpdim<'_, T, { T::DIM }, DIM> as TensorDimension>::DIM`
+error[E0391]: cycle detected when resolving instance `<LazyUpdim<'_, T, <T as TensorDimension>::DIM, DIM> as TensorDimension>::DIM`
   --> $DIR/issue-83765.rs:5:5
    |
 LL |     const DIM: usize;
    |     ^^^^^^^^^^^^^^^^
    |
-note: ...which requires computing candidate for `<LazyUpdim<'_, T, { T::DIM }, DIM> as TensorDimension>`...
+note: ...which requires computing candidate for `<LazyUpdim<'_, T, <T as TensorDimension>::DIM, DIM> as TensorDimension>`...
   --> $DIR/issue-83765.rs:4:1
    |
 LL | trait TensorDimension {
    | ^^^^^^^^^^^^^^^^^^^^^
-   = note: ...which again requires resolving instance `<LazyUpdim<'_, T, { T::DIM }, DIM> as TensorDimension>::DIM`, completing the cycle
+   = note: ...which again requires resolving instance `<LazyUpdim<'_, T, <T as TensorDimension>::DIM, DIM> as TensorDimension>::DIM`, completing the cycle
 note: cycle used when computing candidate for `<LazyUpdim<'_, T, { T::DIM }, DIM> as TensorDimension>`
   --> $DIR/issue-83765.rs:4:1
    |
diff --git a/src/test/incremental/const-generics/try_unify_abstract_const_regression_tests/issue-85031-2.rs b/src/test/ui/const-generics/issues/issue-85031-2.rs
index db1e2fc2af4..4908fb29692 100644
--- a/src/test/incremental/const-generics/try_unify_abstract_const_regression_tests/issue-85031-2.rs
+++ b/src/test/ui/const-generics/issues/issue-85031-2.rs
@@ -1,4 +1,8 @@
-// revisions: cfail
+// check-pass
+// known-bug
+
+// This should not compile, as the compiler should not know
+// `A - 0` is satisfied `?x - 0` if `?x` is inferred to `A`.
 #![allow(incomplete_features)]
 #![feature(generic_const_exprs)]
 
@@ -6,8 +10,8 @@ pub struct Ref<'a>(&'a i32);
 
 impl<'a> Ref<'a> {
     pub fn foo<const A: usize>() -> [(); A - 0] {
+        //~^ WARN function cannot
         Self::foo()
-        //~^ error: type annotations needed
     }
 }
 
diff --git a/src/test/ui/const-generics/issues/issue-85031-2.stderr b/src/test/ui/const-generics/issues/issue-85031-2.stderr
new file mode 100644
index 00000000000..fc690576875
--- /dev/null
+++ b/src/test/ui/const-generics/issues/issue-85031-2.stderr
@@ -0,0 +1,14 @@
+warning: function cannot return without recursing
+  --> $DIR/issue-85031-2.rs:12:5
+   |
+LL |     pub fn foo<const A: usize>() -> [(); A - 0] {
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ cannot return without recursing
+LL |
+LL |         Self::foo()
+   |         ----------- recursive call site
+   |
+   = help: a `loop` may express intention better if this is on purpose
+   = note: `#[warn(unconditional_recursion)]` on by default
+
+warning: 1 warning emitted
+