Print function pointer type for function pointer const generics

Author: oli-obk

src/librustc/ty/print/pretty.rs

@@ -1009,7 +1009,11 @@ pub trait PrettyPrinter<'tcx>:
                     let alloc_map = self.tcx().alloc_map.lock();
                     alloc_map.unwrap_fn(ptr.alloc_id)
                 };
-                p!(print_value_path(instance.def_id(), instance.substs));
+                self = self.typed_value(
+                    |this| this.print_value_path(instance.def_id(), instance.substs),
+                    |this| this.print_type(ty),
+                    true,
+                )?;
             }
             // For function type zsts just printing the type is enough
             (Scalar::Raw { size: 0, .. }, ty::FnDef(..)) => p!(print(ty)),

src/test/ui/const-generics/fn-const-param-infer.stderr

@@ -10,12 +10,12 @@ error[E0308]: mismatched types
   --> $DIR/fn-const-param-infer.rs:16:31
    |
 LL |     let _: Checked<not_one> = Checked::<not_two>;
-   |            ----------------   ^^^^^^^^^^^^^^^^^^ expected `not_one`, found `not_two`
+   |            ----------------   ^^^^^^^^^^^^^^^^^^ expected `{not_one as fn(usize) -> bool}`, found `{not_two as fn(usize) -> bool}`
    |            |
    |            expected due to this
    |
-   = note: expected struct `Checked<not_one>`
-              found struct `Checked<not_two>`
+   = note: expected struct `Checked<{not_one as fn(usize) -> bool}>`
+              found struct `Checked<{not_two as fn(usize) -> bool}>`
 
 error[E0308]: mismatched types
   --> $DIR/fn-const-param-infer.rs:20:24
@@ -36,12 +36,12 @@ error[E0308]: mismatched types
   --> $DIR/fn-const-param-infer.rs:25:40
    |
 LL |     let _: Checked<{generic::<u32>}> = Checked::<{generic::<u16>}>;
-   |            -------------------------   ^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `generic::<u32>`, found `generic::<u16>`
+   |            -------------------------   ^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `{generic::<u32> as fn(usize) -> bool}`, found `{generic::<u16> as fn(usize) -> bool}`
    |            |
    |            expected due to this
    |
-   = note: expected struct `Checked<generic::<u32>>`
-              found struct `Checked<generic::<u16>>`
+   = note: expected struct `Checked<{generic::<u32> as fn(usize) -> bool}>`
+              found struct `Checked<{generic::<u16> as fn(usize) -> bool}>`
 
 error: aborting due to 4 previous errors