Suppress deprecation warning on generated From impls

Author: dtolnay

impl/src/expand.rs

@@ -170,10 +170,9 @@ fn impl_struct(input: Struct) -> TokenStream {
         let source_var = Ident::new("source", span);
         let body = from_initializer(from_field, backtrace_field, &source_var);
         quote_spanned! {span=>
-            #[allow(unused_qualifications, clippy::needless_lifetimes)]
+            #[allow(deprecated, unused_qualifications, clippy::needless_lifetimes)]
             #[automatically_derived]
             impl #impl_generics ::core::convert::From<#from> for #ty #ty_generics #where_clause {
-                #[allow(deprecated)]
                 fn from(#source_var: #from) -> Self {
                     #ty #body
                 }
@@ -435,10 +434,9 @@ fn impl_enum(input: Enum) -> TokenStream {
         let source_var = Ident::new("source", span);
         let body = from_initializer(from_field, backtrace_field, &source_var);
         Some(quote_spanned! {span=>
-            #[allow(unused_qualifications, clippy::needless_lifetimes)]
+            #[allow(deprecated, unused_qualifications, clippy::needless_lifetimes)]
             #[automatically_derived]
             impl #impl_generics ::core::convert::From<#from> for #ty #ty_generics #where_clause {
-                #[allow(deprecated)]
                 fn from(#source_var: #from) -> Self {
                     #ty::#variant #body
                 }