Update to syn 2

Cargo.toml

@@ -29,7 +29,7 @@ proc-macro = true
 [dependencies]
 proc-macro2 = "1.0"
 quote = "1.0"
-syn = "1.0.3"
+syn = "2"
 convert_case = { version = "0.4", optional = true}
 
 [build-dependencies]

src/display.rs

@@ -1,10 +1,12 @@
 use std::{fmt::Display, str::FromStr as _};
 
+use crate::syn_compat::{AttributeExt as _, NestedMeta, ParsedMeta};
 use proc_macro2::{Ident, Span, TokenStream};
 use quote::{quote, quote_spanned};
 use syn::{
  parse::Parser as _, punctuated::Punctuated, spanned::Spanned as _, Error, Result,
 };
+use syn::{Expr, ExprLit};
 
 use crate::utils;
 use utils::{HashMap, HashSet};
@@ -220,21 +222,20 @@ impl<'a, 'b> State<'a, 'b> {
  &self,
  attrs: &[syn::Attribute],
  meta_key: &str,
- ) -> Result<Option<syn::Meta>> {
+ ) -> Result<Option<ParsedMeta>> {
  let mut metas = Vec::new();
  for meta in attrs.iter().filter_map(|attr| attr.parse_meta().ok()) {
  let meta_list = match &meta {
- syn::Meta::List(meta) => meta,
+ ParsedMeta::List(meta) => meta,
  _ => continue,
  };
 
  if !meta_list.path.is_ident(self.trait_attr) {
  continue;
  }
 
- use syn::{Meta, NestedMeta};
  let meta_nv = match meta_list.nested.first() {
- Some(NestedMeta::Meta(Meta::NameValue(meta_nv))) => meta_nv,
+ Some(NestedMeta::Meta(ParsedMeta::NameValue(meta_nv))) => meta_nv,
  _ => {
  // If the given attribute is not MetaNameValue, it most likely implies that the
  // user is writing an incorrect format. For example:
@@ -337,20 +338,24 @@ impl<'a, 'b> State<'a, 'b> {
  }
  fn parse_meta_fmt(
  &self,
- meta: &syn::Meta,
+ meta: &ParsedMeta,
  outer_enum: bool,
  ) -> Result<(TokenStream, bool)> {
  let list = match meta {
- syn::Meta::List(list) => list,
+ ParsedMeta::List(list) => list,
  _ => {
  return Err(Error::new(meta.span(), self.get_proper_fmt_syntax()));
  }
  };
 
  match &list.nested[0] {
- syn::NestedMeta::Meta(syn::Meta::NameValue(syn::MetaNameValue {
+ NestedMeta::Meta(ParsedMeta::NameValue(syn::MetaNameValue {
  path,
- lit: syn::Lit::Str(fmt),
+ value:
+ Expr::Lit(ExprLit {
+ lit: syn::Lit::Str(fmt),
+ ..
+ }),
  ..
  })) => match path {
  op if op.segments.first().expect("path shouldn't be empty").ident
@@ -366,10 +371,14 @@ impl<'a, 'b> State<'a, 'b> {
  }
  // TODO: Check for a single `Display` group?
  let fmt_string = match &list.nested[0] {
- syn::NestedMeta::Meta(syn::Meta::NameValue(
+ NestedMeta::Meta(ParsedMeta::NameValue(
  syn::MetaNameValue {
  path,
- lit: syn::Lit::Str(s),
+ value:
+ Expr::Lit(ExprLit {
+ lit: syn::Lit::Str(s),
+ ..
+ }),
  ..
  },
  )) if path
@@ -403,8 +412,8 @@ impl<'a, 'b> State<'a, 'b> {
  .skip(1) // skip fmt = "..."
  .try_fold(TokenStream::new(), |args, arg| {
  let arg = match arg {
- syn::NestedMeta::Lit(syn::Lit::Str(s)) => s,
- syn::NestedMeta::Meta(syn::Meta::Path(i)) => {
+ NestedMeta::Lit(syn::Lit::Str(s)) => s,
+ NestedMeta::Meta(ParsedMeta::Path(i)) => {
  return Ok(quote_spanned!(list.span()=> #args #i,));
  }
  _ => {
@@ -586,7 +595,7 @@ impl<'a, 'b> State<'a, 'b> {
  let span = meta.span();
 
  let meta = match meta {
- syn::Meta::List(meta) => meta.nested,
+ ParsedMeta::List(meta) => meta.nested,
  _ => return Err(Error::new(span, self.get_proper_bound_syntax())),
  };
 
@@ -595,12 +604,15 @@ impl<'a, 'b> State<'a, 'b> {
  }
 
  let meta = match &meta[0] {
- syn::NestedMeta::Meta(syn::Meta::NameValue(meta)) => meta,
+ NestedMeta::Meta(ParsedMeta::NameValue(meta)) => meta,
  _ => return Err(Error::new(span, self.get_proper_bound_syntax())),
  };
 
- let extra_bounds = match &meta.lit {
- syn::Lit::Str(extra_bounds) => extra_bounds,
+ let extra_bounds = match &meta.value {
+ Expr::Lit(ExprLit {
+ lit: syn::Lit::Str(extra_bounds),
+ ..
+ }) => extra_bounds,
  _ => return Err(Error::new(span, self.get_proper_bound_syntax())),
  };
 
@@ -615,7 +627,7 @@ impl<'a, 'b> State<'a, 'b> {
  fn get_used_type_params_bounds(
  &self,
  fields: &syn::Fields,
- meta: &syn::Meta,
+ meta: &ParsedMeta,
  ) -> HashMap<syn::Type, HashSet<syn::TraitBound>> {
  if self.type_params.is_empty() {
  return HashMap::default();
@@ -645,7 +657,7 @@ impl<'a, 'b> State<'a, 'b> {
  }
 
  let list = match meta {
- syn::Meta::List(list) => list,
+ ParsedMeta::List(list) => list,
  // This one has been checked already in get_meta_fmt() method.
  _ => unreachable!(),
  };
@@ -655,10 +667,10 @@ impl<'a, 'b> State<'a, 'b> {
  .skip(1) // skip fmt = "..."
  .enumerate()
  .filter_map(|(i, arg)| match arg {
- syn::NestedMeta::Lit(syn::Lit::Str(ref s)) => {
+ NestedMeta::Lit(syn::Lit::Str(ref s)) => {
  syn::parse_str(&s.value()).ok().map(|id| (i, id))
  }
- syn::NestedMeta::Meta(syn::Meta::Path(ref id)) => Some((i, id.clone())),
+ NestedMeta::Meta(ParsedMeta::Path(ref id)) => Some((i, id.clone())),
  // This one has been checked already in get_meta_fmt() method.
  _ => unreachable!(),
  })
@@ -667,9 +679,13 @@ impl<'a, 'b> State<'a, 'b> {
  return HashMap::default();
  }
  let fmt_string = match &list.nested[0] {
- syn::NestedMeta::Meta(syn::Meta::NameValue(syn::MetaNameValue {
+ NestedMeta::Meta(ParsedMeta::NameValue(syn::MetaNameValue {
  path,
- lit: syn::Lit::Str(s),
+ value:
+ Expr::Lit(ExprLit {
+ lit: syn::Lit::Str(s),
+ ..
+ }),
  ..
  })) if path
  .segments

src/lib.rs

@@ -190,6 +190,7 @@ extern crate proc_macro;
 use proc_macro::TokenStream;
 use syn::parse::Error as ParseError;
 
+mod syn_compat;
 mod utils;
 
 #[cfg(any(feature = "add_assign", feature = "mul_assign"))]