Merge #8327

8327: Move `Ty` creation methods out of `Ty` (Chalk move preparation) r=flodiebold a=flodiebold

When we'll move to using `chalk_ir::Ty` (#8313), we won't be able to have our own inherent methods on `Ty` anymore, so we need to move the helpers elsewhere.
This adds a `TyBuilder` that allows easily constructing `Ty` and related types (`TraitRef`, `ProjectionTy`, `Substitution`). It also replaces `SubstsBuilder`. `TyBuilder` can construct different things based on its type parameter; e.g. if it has an `AdtId`, we're constructing an ADT type, but if it has a `TraitId`, we're constructing a `TraitRef`. The common thing for all of them is that we need to build a `Substitution`, so the API stays the same for all of them except at the beginning and end.

We also use `TyBuilder` to house various one-shot methods for constructing types, e.g. `TyBuilder::unit()`.

Co-authored-by: Florian Diebold <[email protected]>

1 files changed, 13 insertions, 0 deletions

diff --git a/crates/hir_ty/src/chalk_ext.rs b/crates/hir_ty/src/chalk_ext.rs
new file mode 100644
index 000000000..b7463366b
--- /dev/null
+++ b/crates/hir_ty/src/chalk_ext.rs
@@ -0,0 +1,13 @@
+//! Various extensions traits for Chalk types.
+
+use crate::{Interner, Ty, TyKind};
+
+pub trait TyExt {
+    fn is_unit(&self) -> bool;
+}
+
+impl TyExt for Ty {
+    fn is_unit(&self) -> bool {
+        matches!(self.kind(&Interner), TyKind::Tuple(0, _))
+    }
+}