Merge #578

578: Prepare for syn v2 r=jonasbb a=jonasbb

Update darling to v0.20 and syn to v2, require serde v1.0.157 (first using syn v2).
This moves all direct dependencies to crates using syn v2.

syn v2 has problems with the `#[serde_as(as = "..")]` style of attributes, since `as` is a keyword and keywords are not allowed in meta attributes. Instead pre-process the token stream to replace all `as` with `r#as` which can be parsed.

Bump thiserror and cxx in the lock file.
Not all crates are using syn v2 yet.

Co-authored-by: Jonas Bushart <jonas@bushart.org>

Author: bors[bot]

Cargo.lock

@@ -7,6 +7,12 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 ## [Unreleased]
 
+### Changed
+
+* Update `syn` to v2 and `darling` to v0.20 (#578)
+    Update proc-macro dependencies.
+    This change should have no impact on users, but now uses the same dependency as `serde_derive`.
+
 ## [2.3.2] - 2023-04-05
 
 ### Changed

serde_with/CHANGELOG.md

@@ -67,7 +67,7 @@ hex = {version = "0.4.3", optional = true, default-features = false}
 indexmap_1 = {package = "indexmap", version = "1.8", optional = true, default-features = false, features = ["serde-1"]}
 # The derive feature is needed for the flattened_maybe macro.
 # https://github.com/jonasbb/serde_with/blob/eb1965a74a3be073ecd13ec05f02a01bc1c44309/serde_with/src/flatten_maybe.rs#L67
-serde = {version = "1.0.139", default-features = false, features = ["derive"] }
+serde = {version = "1.0.157", default-features = false, features = ["derive"] }
 serde_json = {version = "1.0.45", optional = true, default-features = false}
 serde_with_macros = {path = "../serde_with_macros", version = "=2.3.2", optional = true}
 time_0_3 = {package = "time", version = "~0.3.11", optional = true, default-features = false}

serde_with/Cargo.toml

@@ -50,7 +50,7 @@
 /// ```
 #[macro_export]
 macro_rules! flattened_maybe {
-    ($fn:ident, $field:literal) => {
+    ($fn:ident, $field:tt) => {
         fn $fn<'de, T, D>(deserializer: D) -> $crate::__private__::Result<T, D::Error>
         where
             T: $crate::serde::Deserialize<'de>,

serde_with/src/flatten_maybe.rs

@@ -7,6 +7,12 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 ## [Unreleased]
 
+### Changed
+
+* Update `syn` to v2 and `darling` to v0.20 (#578)
+    Update proc-macro dependencies.
+    This change should have no impact on users, but now uses the same dependency as `serde_derive`.
+
 ## [2.3.2] - 2023-04-05
 
 No changes.

serde_with_macros/CHANGELOG.md

@@ -30,7 +30,7 @@ proc-macro = true
 maintenance = {status = "actively-developed"}
 
 [dependencies]
-darling = "0.14.0"
+darling = "0.20.0"
 proc-macro2 = "1.0.1"
 quote = "1.0.0"
 
@@ -40,13 +40,13 @@ features = [
     "full",
     "parsing",
 ]
-version = "1.0.3"
+version = "2.0.0"
 
 [dev-dependencies]
 expect-test = "1.4.0"
 pretty_assertions = "1.0.0"
 rustversion = "1.0.0"
-serde = {version = "1.0.75", features = ["derive"]}
+serde = {version = "1.0.157", features = ["derive"]}
 serde_json = "1.0.25"
 trybuild = "1.0.80"
 version-sync = "0.9.1"

serde_with_macros/Cargo.toml

@@ -1,11 +1,11 @@
-use darling::{Error as DarlingError, FromMeta};
+use darling::{ast::NestedMeta, Error as DarlingError, FromMeta};
 use proc_macro::TokenStream;
 use quote::ToTokens as _;
 use syn::{
     parse::{Parse, ParseStream},
     punctuated::Punctuated,
-    Attribute, Error, Field, NestedMeta, Path, Token, Type, TypeArray, TypeGroup, TypeParen,
-    TypePath, TypePtr, TypeReference, TypeSlice, TypeTuple,
+    Attribute, Error, Field, Path, Token, Type, TypeArray, TypeGroup, TypeParen, TypePath, TypePtr,
+    TypeReference, TypeSlice, TypeTuple,
 };
 
 /// Parsed form of a single rule in the `#[apply(...)]` attribute.
@@ -53,7 +53,7 @@ impl Parse for ApplyInput {
         }
 
         let rules: Punctuated<AddAttributesRule, Token![,]> =
-            input.parse_terminated(AddAttributesRule::parse)?;
+            input.parse_terminated(AddAttributesRule::parse, Token![,])?;
         Ok(Self { metas, rules })
     }
 }