From 56bf28d4f4236f19f962868f181b15b174d041c4 Mon Sep 17 00:00:00 2001
From: Michael Goulet <michael@errs.io>
Date: Tue, 7 Feb 2023 20:22:42 +0000
Subject: [PATCH] Expand const-if-const trait bounds correctly

---
 compiler/rustc_ast_pretty/src/pprust/state.rs  | 14 ++++++++++++--
 tests/ui/macros/stringify.rs                   |  6 +++---
 tests/ui/unpretty/ast-const-trait-bound.rs     |  4 ++++
 tests/ui/unpretty/ast-const-trait-bound.stdout |  4 ++++
 4 files changed, 23 insertions(+), 5 deletions(-)
 create mode 100644 tests/ui/unpretty/ast-const-trait-bound.rs
 create mode 100644 tests/ui/unpretty/ast-const-trait-bound.stdout

diff --git a/compiler/rustc_ast_pretty/src/pprust/state.rs b/compiler/rustc_ast_pretty/src/pprust/state.rs
index d7767efa984..cd621bc67a1 100644
--- a/compiler/rustc_ast_pretty/src/pprust/state.rs
+++ b/compiler/rustc_ast_pretty/src/pprust/state.rs
@@ -1567,8 +1567,18 @@ pub fn print_type_bounds(&mut self, bounds: &[ast::GenericBound]) {
 
             match bound {
                 GenericBound::Trait(tref, modifier) => {
-                    if modifier == &TraitBoundModifier::Maybe {
-                        self.word("?");
+                    match modifier {
+                        TraitBoundModifier::None => {}
+                        TraitBoundModifier::Maybe => {
+                            self.word("?");
+                        }
+                        TraitBoundModifier::MaybeConst => {
+                            self.word_space("~const");
+                        }
+                        TraitBoundModifier::MaybeConstMaybe => {
+                            self.word_space("~const");
+                            self.word("?");
+                        }
                     }
                     self.print_poly_trait_ref(tref);
                 }
diff --git a/tests/ui/macros/stringify.rs b/tests/ui/macros/stringify.rs
index 5cd217df6fc..fdc2a7666d6 100644
--- a/tests/ui/macros/stringify.rs
+++ b/tests/ui/macros/stringify.rs
@@ -626,7 +626,7 @@ impl<T> const Trait for T {}
         stringify_item!(
             impl ~const Struct {}
         ),
-        "impl Struct {}", // FIXME
+        "impl ~const Struct {}",
     );
 
     // ItemKind::MacCall
@@ -838,7 +838,7 @@ fn test_ty() {
     assert_eq!(stringify_ty!(dyn Send + 'a), "dyn Send + 'a");
     assert_eq!(stringify_ty!(dyn 'a + Send), "dyn 'a + Send");
     assert_eq!(stringify_ty!(dyn ?Sized), "dyn ?Sized");
-    assert_eq!(stringify_ty!(dyn ~const Clone), "dyn Clone"); // FIXME
+    assert_eq!(stringify_ty!(dyn ~const Clone), "dyn ~const Clone");
     assert_eq!(stringify_ty!(dyn for<'a> Send), "dyn for<'a> Send");
 
     // TyKind::ImplTrait
@@ -846,7 +846,7 @@ fn test_ty() {
     assert_eq!(stringify_ty!(impl Send + 'a), "impl Send + 'a");
     assert_eq!(stringify_ty!(impl 'a + Send), "impl 'a + Send");
     assert_eq!(stringify_ty!(impl ?Sized), "impl ?Sized");
-    assert_eq!(stringify_ty!(impl ~const Clone), "impl Clone"); // FIXME
+    assert_eq!(stringify_ty!(impl ~const Clone), "impl ~const Clone");
     assert_eq!(stringify_ty!(impl for<'a> Send), "impl for<'a> Send");
 
     // TyKind::Paren
diff --git a/tests/ui/unpretty/ast-const-trait-bound.rs b/tests/ui/unpretty/ast-const-trait-bound.rs
new file mode 100644
index 00000000000..dbcba7871ec
--- /dev/null
+++ b/tests/ui/unpretty/ast-const-trait-bound.rs
@@ -0,0 +1,4 @@
+// compile-flags: -Zunpretty=normal
+// check-pass
+
+fn foo() where T: ~const Bar {}
diff --git a/tests/ui/unpretty/ast-const-trait-bound.stdout b/tests/ui/unpretty/ast-const-trait-bound.stdout
new file mode 100644
index 00000000000..dbcba7871ec
--- /dev/null
+++ b/tests/ui/unpretty/ast-const-trait-bound.stdout
@@ -0,0 +1,4 @@
+// compile-flags: -Zunpretty=normal
+// check-pass
+
+fn foo() where T: ~const Bar {}
-- 
2.44.0