Rollup merge of #125750 - compiler-errors:expect, r=lcnr

Align `Term` methods with `GenericArg` methods, add `Term::expect_*`

* `Term::ty` -> `Term::as_type`.
* `Term::ct` -> `Term::as_const`.
* Adds `Term::expect_type` and `Term::expect_const`, and uses them in favor of `.ty().unwrap()`, etc.

I could also shorten these to `as_ty` and then do `GenericArg::as_ty` as well, but I do think the `as_` is important to signal that this is a conversion method, and not a getter, like `Const::ty` is.

r? types

2 files changed, 13 insertions, 5 deletions

diff --git a/compiler/rustc_middle/src/ty/mod.rs b/compiler/rustc_middle/src/ty/mod.rs
index 2643ce976de..3fdcb966960 100644
--- a/compiler/rustc_middle/src/ty/mod.rs
+++ b/compiler/rustc_middle/src/ty/mod.rs
@@ -624,14 +624,22 @@ impl<'tcx> Term<'tcx> {
         }
     }
 
-    pub fn ty(&self) -> Option<Ty<'tcx>> {
+    pub fn as_type(&self) -> Option<Ty<'tcx>> {
         if let TermKind::Ty(ty) = self.unpack() { Some(ty) } else { None }
     }
 
-    pub fn ct(&self) -> Option<Const<'tcx>> {
+    pub fn expect_type(&self) -> Ty<'tcx> {
+        self.as_type().expect("expected a type, but found a const")
+    }
+
+    pub fn as_const(&self) -> Option<Const<'tcx>> {
         if let TermKind::Const(c) = self.unpack() { Some(c) } else { None }
     }
 
+    pub fn expect_const(&self) -> Const<'tcx> {
+        self.as_const().expect("expected a const, but found a type")
+    }
+
     pub fn into_arg(self) -> GenericArg<'tcx> {
         match self.unpack() {
             TermKind::Ty(ty) => ty.into(),
diff --git a/compiler/rustc_middle/src/ty/print/pretty.rs b/compiler/rustc_middle/src/ty/print/pretty.rs
index 8fb4367d3b5..af7784d6b8e 100644
--- a/compiler/rustc_middle/src/ty/print/pretty.rs
+++ b/compiler/rustc_middle/src/ty/print/pretty.rs
@@ -1077,7 +1077,7 @@ pub trait PrettyPrinter<'tcx>: Printer<'tcx> + fmt::Write {
                         }
 
                         p!(")");
-                        if let Some(ty) = return_ty.skip_binder().ty() {
+                        if let Some(ty) = return_ty.skip_binder().as_type() {
                             if !ty.is_unit() {
                                 p!(" -> ", print(return_ty));
                             }
@@ -1144,7 +1144,7 @@ pub trait PrettyPrinter<'tcx>: Printer<'tcx> + fmt::Write {
                     for (assoc_item_def_id, term) in assoc_items {
                         // Skip printing `<{coroutine@} as Coroutine<_>>::Return` from async blocks,
                         // unless we can find out what coroutine return type it comes from.
-                        let term = if let Some(ty) = term.skip_binder().ty()
+                        let term = if let Some(ty) = term.skip_binder().as_type()
                             && let ty::Alias(ty::Projection, proj) = ty.kind()
                             && let Some(assoc) = tcx.opt_associated_item(proj.def_id)
                             && assoc.trait_container(tcx) == tcx.lang_items().coroutine_trait()
@@ -1322,7 +1322,7 @@ pub trait PrettyPrinter<'tcx>: Printer<'tcx> + fmt::Write {
                             p!(pretty_fn_sig(
                                 tys,
                                 false,
-                                proj.skip_binder().term.ty().expect("Return type was a const")
+                                proj.skip_binder().term.as_type().expect("Return type was a const")
                             ));
                             resugared = true;
                         }