Resolve prelude redundant import warnings in nightly

    error: the item `syn` is imported redundantly
      --> derive_builder_core/src/block.rs:5:11
       |
    5  | use syn::{self, spanned::Spanned, Block, LitStr};
       |           ^^^^
       |
      ::: derive_builder_core/src/lib.rs:27:1
       |
    27 | extern crate syn;
       | ----------------- the item `syn` is already imported here
       |
    note: the lint level is defined here
      --> derive_builder_core/src/lib.rs:18:9
       |
    18 | #![deny(warnings, missing_docs)]
       |         ^^^^^^^^
       = note: `#[deny(unused_imports)]` implied by `#[deny(warnings)]`

    error: the item `syn` is imported redundantly
      --> derive_builder_core/src/builder.rs:6:11
       |
    6  | use syn::{self, Path, TraitBound, TraitBoundModifier, TypeParamBound};
       |           ^^^^
       |
      ::: derive_builder_core/src/lib.rs:27:1
       |
    27 | extern crate syn;
       | ----------------- the item `syn` is already imported here

    error: the item `darling` is imported redundantly
      --> derive_builder_core/src/macro_options/darling_opts.rs:6:15
       |
    6  | use darling::{self, Error, FromMeta};
       |               ^^^^
       |
      ::: derive_builder_core/src/lib.rs:22:1
       |
    22 | extern crate darling;
       | --------------------- the item `darling` is already imported here

    error: the item `syn` is imported redundantly
      --> derive_builder_core/src/macro_options/darling_opts.rs:9:11
       |
    9  | use syn::{self, spanned::Spanned, Attribute, Generics, Ident, Path};
       |           ^^^^
       |
      ::: derive_builder_core/src/lib.rs:27:1
       |
    27 | extern crate syn;
       | ----------------- the item `syn` is already imported here

derive_builder/tests/try_setter.rs

@@ -4,7 +4,6 @@ extern crate derive_builder;
 use std::convert::TryFrom;
 use std::net::{AddrParseError, IpAddr};
 use std::str::FromStr;
-use std::string::ToString;
 
 #[derive(Debug, Clone, PartialEq)]
 pub struct MyAddr(IpAddr);

derive_builder_core/src/block.rs

@@ -2,7 +2,7 @@ use std::convert::TryFrom;
 
 use proc_macro2::{Span, TokenStream};
 use quote::ToTokens;
-use syn::{self, spanned::Spanned, Block, LitStr};
+use syn::{spanned::Spanned, Block, LitStr};
 
 /// A wrapper for expressions/blocks which automatically adds the start and end
 /// braces.
@@ -76,7 +76,6 @@ mod test {
     use std::convert::TryInto;
 
     use super::*;
-    use proc_macro2::Span;
 
     fn parse(s: &str) -> Result<BlockContents, syn::Error> {
         (&LitStr::new(s, Span::call_site())).try_into()

derive_builder_core/src/builder.rs

@@ -3,7 +3,7 @@ use std::borrow::Cow;
 use proc_macro2::TokenStream;
 use quote::{format_ident, ToTokens, TokenStreamExt};
 use syn::punctuated::Punctuated;
-use syn::{self, Path, TraitBound, TraitBoundModifier, TypeParamBound};
+use syn::{Path, TraitBound, TraitBoundModifier, TypeParamBound};
 
 use crate::{
     doc_comment_from, BuildMethod, BuilderField, BuilderPattern, DeprecationNotes, Setter,
@@ -405,7 +405,6 @@ macro_rules! default_builder {
 mod tests {
     #[allow(unused_imports)]
     use super::*;
-    use proc_macro2::TokenStream;
     use syn::Ident;
 
     fn add_simple_foo_builder(result: &mut TokenStream) {

derive_builder_core/src/macro_options/darling_opts.rs

@@ -3,10 +3,9 @@ use std::{borrow::Cow, vec::IntoIter};
 use crate::BuildMethod;
 
 use darling::util::{Flag, PathList, SpannedValue};
-use darling::{self, Error, FromMeta};
+use darling::{Error, FromMeta};
 use proc_macro2::Span;
-use syn::Meta;
-use syn::{self, spanned::Spanned, Attribute, Generics, Ident, Path};
+use syn::{spanned::Spanned, Attribute, Generics, Ident, Meta, Path};
 
 use crate::{
     BlockContents, Builder, BuilderField, BuilderFieldType, BuilderPattern, DefaultExpression,