Rollup merge of rust-lang#68913 - Areredify:gat_pretty, r=cramertj

Pretty-print generic params and where clauses on associated types

closes rust-lang#67509

Author: Dylan-DPC

src/librustc_ast_pretty/pprust.rs

@@ -1074,12 +1074,15 @@ impl<'a> State<'a> {
     fn print_associated_type(
         &mut self,
         ident: ast::Ident,
+        generics: &ast::Generics,
         bounds: &ast::GenericBounds,
         ty: Option<&ast::Ty>,
     ) {
         self.word_space("type");
         self.print_ident(ident);
+        self.print_generic_params(&generics.params);
         self.print_type_bounds(":", bounds);
+        self.print_where_clause(&generics.where_clause);
         if let Some(ty) = ty {
             self.s.space();
             self.word_space("=");
@@ -1474,7 +1477,7 @@ impl<'a> State<'a> {
                 self.print_fn_full(sig, item.ident, &item.generics, &item.vis, body, &item.attrs);
             }
             ast::AssocItemKind::TyAlias(bounds, ty) => {
-                self.print_associated_type(item.ident, bounds, ty.as_deref());
+                self.print_associated_type(item.ident, &item.generics, bounds, ty.as_deref());
             }
             ast::AssocItemKind::Macro(mac) => {
                 self.print_mac(mac);

src/librustc_hir/print.rs

@@ -454,14 +454,17 @@ impl<'a> State<'a> {
     fn print_associated_type(
         &mut self,
         ident: ast::Ident,
+        generics: &hir::Generics<'_>,
         bounds: Option<hir::GenericBounds<'_>>,
         ty: Option<&hir::Ty<'_>>,
     ) {
         self.word_space("type");
         self.print_ident(ident);
+        self.print_generic_params(&generics.params);
         if let Some(bounds) = bounds {
             self.print_bounds(":", bounds);
         }
+        self.print_where_clause(&generics.where_clause);
         if let Some(ty) = ty {
             self.s.space();
             self.word_space("=");
@@ -902,6 +905,7 @@ impl<'a> State<'a> {
             hir::TraitItemKind::Type(ref bounds, ref default) => {
                 self.print_associated_type(
                     ti.ident,
+                    &ti.generics,
                     Some(bounds),
                     default.as_ref().map(|ty| &**ty),
                 );
@@ -930,7 +934,7 @@ impl<'a> State<'a> {
                 self.ann.nested(self, Nested::Body(body));
             }
             hir::ImplItemKind::TyAlias(ref ty) => {
-                self.print_associated_type(ii.ident, None, Some(ty));
+                self.print_associated_type(ii.ident, &ii.generics, None, Some(ty));
             }
             hir::ImplItemKind::OpaqueTy(bounds) => {
                 self.word_space("type");

src/test/pretty/gat-bounds.pp

@@ -0,0 +1,25 @@
+// Check that associated types print generic parameters and where clauses.
+// See issue #67509.
+
+// pretty-compare-only
+// pp-exact:gat-bounds.pp
+
+#![feature(generic_associated_types)]
+
+trait X {
+    type
+    Y<T>: Trait
+    where
+    Self: Sized;
+}
+
+impl X for () {
+    type
+    Y<T>
+    where
+    Self: Sized
+    =
+    u32;
+}
+
+fn main() { }

src/test/pretty/gat-bounds.rs

@@ -0,0 +1,17 @@
+// Check that associated types print generic parameters and where clauses.
+// See issue #67509.
+
+// pretty-compare-only
+// pp-exact:gat-bounds.pp
+
+#![feature(generic_associated_types)]
+
+trait X {
+    type Y<T>: Trait where Self: Sized;
+}
+
+impl X for () {
+    type Y<T> where Self: Sized = u32;
+}
+
+fn main() { }