Add pretty-printing for const generics

Co-Authored-By: Gabriel Smith <[email protected]>

Author: varkor

src/librustc_save_analysis/sig.rs

@@ -646,6 +646,11 @@ impl Sig for ast::Generics {
                         param_text.push_str(&pprust::bounds_to_string(&param.bounds));
                         // FIXME descend properly into bounds.
                     }
+                    ast::GenericParamKind::Const { ref ty } => {
+                        param_text.push_str(&pprust::bounds_to_string(&param.bounds));
+                        param_text.push_str("= ");
+                        param_text.push_str(&pprust::ty_to_string(&ty));
+                    }
                 }
             }
             text.push_str(&param_text);

src/libsyntax/print/pprust.rs

@@ -1025,6 +1025,7 @@ impl<'a> State<'a> {
         match generic_arg {
             GenericArg::Lifetime(lt) => self.print_lifetime(*lt),
             GenericArg::Type(ty) => self.print_type(ty),
+            GenericArg::Const(ct) => self.print_expr(&ct.value),
         }
     }
 
@@ -2929,7 +2930,7 @@ impl<'a> State<'a> {
                     s.print_outer_attributes_inline(&param.attrs)?;
                     let lt = ast::Lifetime { id: param.id, ident: param.ident };
                     s.print_lifetime_bounds(lt, &param.bounds)
-                },
+                }
                 ast::GenericParamKind::Type { ref default } => {
                     s.print_outer_attributes_inline(&param.attrs)?;
                     s.print_ident(param.ident)?;
@@ -2943,6 +2944,15 @@ impl<'a> State<'a> {
                         _ => Ok(())
                     }
                 }
+                ast::GenericParamKind::Const { ref ty } => {
+                    s.print_outer_attributes_inline(&param.attrs)?;
+                    s.word_space("const")?;
+                    s.print_ident(param.ident)?;
+                    s.s.space()?;
+                    s.word_space(":")?;
+                    s.print_type(ty)?;
+                    s.print_type_bounds(":", &param.bounds)
+                }
             }
         })?;