fix type of const params in assoc fn.

Author: lcnr

src/librustc_typeck/collect/type_of.rs

@@ -256,10 +256,10 @@ pub(super) fn type_of(tcx: TyCtxt<'_>, def_id: DefId) -> Ty<'_> {
                         // figure out which generic parameter it corresponds to and return
                         // the relevant type.
                         let generics = match path.res {
-                            Res::Def(DefKind::Ctor(..), def_id)
-                            | Res::Def(DefKind::AssocTy, def_id) => {
-                                tcx.generics_of(tcx.parent(def_id).unwrap())
-                            }
+                            Res::Def(
+                                DefKind::Ctor(..) | DefKind::AssocTy | DefKind::AssocFn,
+                                def_id,
+                            ) => tcx.generics_of(tcx.parent(def_id).unwrap()),
                             Res::Def(_, def_id) => tcx.generics_of(def_id),
                             res => {
                                 tcx.sess.delay_span_bug(
@@ -291,8 +291,8 @@ pub(super) fn type_of(tcx: TyCtxt<'_>, def_id: DefId) -> Ty<'_> {
                                 tcx.sess.delay_span_bug(
                                     DUMMY_SP,
                                     &format!(
-                                        "missing generic parameter for `AnonConst`, parent {:?}",
-                                        parent_node
+                                        "missing generic parameter for `AnonConst`, parent: {:?}, path.res: {:?}",
+                                        parent_node, path.res
                                     ),
                                 );
                                 tcx.types.err

src/librustc_typeck/lib.rs

@@ -62,6 +62,7 @@ This API is completely unstable and subject to change.
 #![feature(crate_visibility_modifier)]
 #![feature(in_band_lifetimes)]
 #![feature(nll)]
+#![feature(or_patterns)]
 #![feature(try_blocks)]
 #![feature(never_type)]
 #![feature(slice_partition_dedup)]

src/test/ui/const-generics/issues/issue70273-assoc-fn.rs

@@ -0,0 +1,17 @@
+// check-pass
+
+#![feature(const_generics)]
+//~^ WARN the feature `const_generics` is incomplete and may cause the compiler to crash
+
+trait T<const A: usize> {
+    fn f();
+}
+struct S;
+
+impl T<0usize> for S {
+    fn f() {}
+}
+
+fn main() {
+    let _err = <S as T<0usize>>::f();
+}

src/test/ui/const-generics/issues/issue70273-assoc-fn.stderr

@@ -0,0 +1,8 @@
+warning: the feature `const_generics` is incomplete and may cause the compiler to crash
+  --> $DIR/issue70273-assoc-fn.rs:3:12
+   |
+LL | #![feature(const_generics)]
+   |            ^^^^^^^^^^^^^^
+   |
+   = note: `#[warn(incomplete_features)]` on by default
+