Merge pull request #391 from matt-phylum/needless-lifetimes

suppress needless_lifetimes lints from clippy 0.1.83

Author: dtolnay

impl/src/expand.rs

@@ -197,7 +197,7 @@ 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)]
+            #[allow(unused_qualifications, clippy::needless_lifetimes)]
             #[automatically_derived]
             impl #impl_generics ::core::convert::From<#from> for #ty #ty_generics #where_clause {
                 #[allow(deprecated)]
@@ -462,7 +462,7 @@ 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)]
+            #[allow(unused_qualifications, clippy::needless_lifetimes)]
             #[automatically_derived]
             impl #impl_generics ::core::convert::From<#from> for #ty #ty_generics #where_clause {
                 #[allow(deprecated)]

tests/test_lints.rs

@@ -18,3 +18,18 @@ fn test_unused_qualifications() {
 
     let _: MyError;
 }
+
+#[test]
+fn test_needless_lifetimes() {
+    #![allow(dead_code)]
+    #![deny(clippy::needless_lifetimes)]
+
+    #[derive(Debug, Error)]
+    #[error("...")]
+    pub enum MyError<'a> {
+        A(#[from] std::io::Error),
+        B(&'a ()),
+    }
+
+    let _: MyError;
+}