Rollup merge of #97967 - BoxyUwU:at_docs_mention_trace, r=compiler-er…

…rors

Mention `infer::Trace` methods on `infer::At` methods' docs

I missed that you could do `infcx.at(...).trace(...).eq(a, b)` when `a` and `b` dont implement `ToTrace` but does implement `Relate` these docs would have helped see that 😅

compiler/rustc_infer/src/infer/at.rs

@@ -111,6 +111,9 @@ impl<'a, 'tcx> At<'a, 'tcx> {
     }
 
     /// Makes `a <: b`, where `a` may or may not be expected.
+    ///
+    /// See [`At::trace_exp`] and [`Trace::sub`] for a version of
+    /// this method that only requires `T: Relate<'tcx>`
     pub fn sub_exp<T>(self, a_is_expected: bool, a: T, b: T) -> InferResult<'tcx, ()>
     where
         T: ToTrace<'tcx>,
@@ -122,6 +125,9 @@ impl<'a, 'tcx> At<'a, 'tcx> {
     /// call like `foo(x)`, where `foo: fn(i32)`, you might have
     /// `sup(i32, x)`, since the "expected" type is the type that
     /// appears in the signature.
+    ///
+    /// See [`At::trace`] and [`Trace::sub`] for a version of
+    /// this method that only requires `T: Relate<'tcx>`
     pub fn sup<T>(self, expected: T, actual: T) -> InferResult<'tcx, ()>
     where
         T: ToTrace<'tcx>,
@@ -130,6 +136,9 @@ impl<'a, 'tcx> At<'a, 'tcx> {
     }
 
     /// Makes `expected <: actual`.
+    ///
+    /// See [`At::trace`] and [`Trace::sub`] for a version of
+    /// this method that only requires `T: Relate<'tcx>`
     pub fn sub<T>(self, expected: T, actual: T) -> InferResult<'tcx, ()>
     where
         T: ToTrace<'tcx>,
@@ -138,6 +147,9 @@ impl<'a, 'tcx> At<'a, 'tcx> {
     }
 
     /// Makes `expected <: actual`.
+    ///
+    /// See [`At::trace_exp`] and [`Trace::eq`] for a version of
+    /// this method that only requires `T: Relate<'tcx>`
     pub fn eq_exp<T>(self, a_is_expected: bool, a: T, b: T) -> InferResult<'tcx, ()>
     where
         T: ToTrace<'tcx>,
@@ -146,6 +158,9 @@ impl<'a, 'tcx> At<'a, 'tcx> {
     }
 
     /// Makes `expected <: actual`.
+    ///
+    /// See [`At::trace`] and [`Trace::eq`] for a version of
+    /// this method that only requires `T: Relate<'tcx>`
     pub fn eq<T>(self, expected: T, actual: T) -> InferResult<'tcx, ()>
     where
         T: ToTrace<'tcx>,
@@ -176,6 +191,9 @@ impl<'a, 'tcx> At<'a, 'tcx> {
     /// this can result in an error (e.g., if asked to compute LUB of
     /// u32 and i32), it is meaningful to call one of them the
     /// "expected type".
+    ///
+    /// See [`At::trace`] and [`Trace::lub`] for a version of
+    /// this method that only requires `T: Relate<'tcx>`
     pub fn lub<T>(self, expected: T, actual: T) -> InferResult<'tcx, T>
     where
         T: ToTrace<'tcx>,
@@ -186,6 +204,9 @@ impl<'a, 'tcx> At<'a, 'tcx> {
     /// Computes the greatest-lower-bound, or mutual subtype, of two
     /// values. As with `lub` order doesn't matter, except for error
     /// cases.
+    ///
+    /// See [`At::trace`] and [`Trace::glb`] for a version of
+    /// this method that only requires `T: Relate<'tcx>`
     pub fn glb<T>(self, expected: T, actual: T) -> InferResult<'tcx, T>
     where
         T: ToTrace<'tcx>,