Print `ParamTy` and `ParamConst` instead of displaying them Display for `ParamTy` and `ParamConst` is implemented in terms of print. Using print avoids creating a new `FmtPrinter` just to display the parameter name. r? `@Mark-Simulacrum`
opt_def_kind
&mut DiagnosticBuilder
&mut Diagnostic
Const
DiagnosticBuilder::emit