Update to syn 2 where possible (#30387)

* Update to syn 2 where possible

* Cleanups

* Better no_trace comment

Co-authored-by: Martin Robinson <mrobinson@igalia.com>

---------

Co-authored-by: Martin Robinson <mrobinson@igalia.com>

Cargo.lock

@@ -1275,8 +1275,8 @@ dependencies = [
 name = "deny_public_fields"
 version = "0.0.1"
 dependencies = [
- "syn 1.0.103",
- "synstructure",
+ "syn 2.0.32",
+ "synstructure 0.13.0",
 ]
 
 [[package]]
@@ -1294,7 +1294,7 @@ dependencies = [
  "proc-macro2",
  "quote",
  "syn 1.0.103",
- "synstructure",
+ "synstructure 0.12.6",
 ]
 
 [[package]]
@@ -1408,7 +1408,7 @@ name = "dom_struct"
 version = "0.0.1"
 dependencies = [
  "quote",
- "syn 1.0.103",
+ "syn 2.0.32",
 ]
 
 [[package]]
@@ -1417,7 +1417,7 @@ version = "0.0.1"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 1.0.103",
+ "syn 2.0.32",
 ]
 
 [[package]]
@@ -2981,8 +2981,8 @@ name = "jstraceable_derive"
 version = "0.0.1"
 dependencies = [
  "proc-macro2",
- "syn 1.0.103",
- "synstructure",
+ "syn 2.0.32",
+ "synstructure 0.13.0",
 ]
 
 [[package]]
@@ -3449,7 +3449,7 @@ checksum = "632647502a8bfa82458c07134791fffa7a719f00427d1afd79c3cb6d4960a982"
 dependencies = [
  "proc-macro2",
  "syn 1.0.103",
- "synstructure",
+ "synstructure 0.12.6",
 ]
 
 [[package]]
@@ -4239,7 +4239,7 @@ dependencies = [
  "proc-macro2",
  "quote",
  "syn 1.0.103",
- "synstructure",
+ "synstructure 0.12.6",
  "unicode-xid",
 ]
 
@@ -5376,7 +5376,7 @@ dependencies = [
  "itertools",
  "proc-macro2",
  "quote",
- "syn 1.0.103",
+ "syn 2.0.32",
 ]
 
 [[package]]
@@ -5840,7 +5840,7 @@ dependencies = [
  "proc-macro2",
  "quote",
  "syn 1.0.103",
- "synstructure",
+ "synstructure 0.12.6",
 ]
 
 [[package]]
@@ -5969,6 +5969,18 @@ dependencies = [
  "unicode-xid",
 ]
 
+[[package]]
+name = "synstructure"
+version = "0.13.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "285ba80e733fac80aa4270fbcdf83772a79b80aa35c97075320abfee4a915b06"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn 2.0.32",
+ "unicode-xid",
+]
+
 [[package]]
 name = "take_mut"
 version = "0.2.2"
@@ -6169,7 +6181,7 @@ dependencies = [
  "proc-macro2",
  "quote",
  "syn 1.0.103",
- "synstructure",
+ "synstructure 0.12.6",
 ]
 
 [[package]]

Cargo.toml

@@ -75,8 +75,8 @@ string_cache = "0.8"
 string_cache_codegen = "0.5"
 # NOTE: the sm-angle feature only enables ANGLE on Windows, not other platforms!
 surfman = { version = "0.8", features = ["chains", "sm-angle", "sm-angle-default"] }
-syn = { version = "1", default-features = false, features = ["clone-impls", "derive", "parsing"] }
-synstructure = "0.12"
+syn = { version = "2", default-features = false, features = ["clone-impls", "derive", "parsing"] }
+synstructure = "0.13"
 time = "0.1.41"
 tokio = "1"
 tokio-rustls = "0.24"

components/config_plugins/lib.rs

@@ -13,10 +13,7 @@ use proc_macro2::{Span, TokenStream};
 use quote::*;
 use syn::parse::Result;
 use syn::spanned::Spanned;
-use syn::{
-    parse_macro_input, Attribute, Ident, Lit, LitStr, Meta, MetaList, MetaNameValue, NestedMeta,
-    Path,
-};
+use syn::{parse_macro_input, Attribute, Ident, LitStr, Path};
 
 mod parse;
 use parse::*;
@@ -199,23 +196,19 @@ impl Field {
 }
 
 fn attr_to_pref_name(attr: &Attribute) -> Option<LitStr> {
-    attr.parse_meta().ok().and_then(|meta| {
-        if let Meta::List(MetaList { path, nested, .. }) = meta {
-            if path.is_ident("serde") {
-                if let Some(NestedMeta::Meta(Meta::NameValue(MetaNameValue {
-                    ref path,
-                    lit: Lit::Str(val),
-                    ..
-                }))) = nested.iter().next()
-                {
-                    if path.is_ident("rename") {
-                        return Some(val.clone());
-                    }
-                }
+    if attr.path().is_ident("serde") {
+        // If `parse_nested_meta()` fails, `result` will remain None.
+        let mut result = None;
+        let _ = attr.parse_nested_meta(|meta| {
+            if meta.path.is_ident("rename") {
+                result = Some(meta.value()?.parse()?);
             }
-        }
+            Ok(())
+        });
+        result
+    } else {
         None
-    })
+    }
 }
 
 fn err<S: Spanned>(s: S, msg: &str) -> syn::Error {

components/config_plugins/parse.rs

@@ -56,7 +56,8 @@ pub struct RootTypeDef {
 
 impl Parse for MacroInput {
     fn parse(input: ParseStream<'_>) -> Result<Self> {
-        let fields: Punctuated<MacroArg, Token![, ]> = input.parse_terminated(MacroArg::parse)?;
+        let fields: Punctuated<MacroArg, Token![, ]> =
+            Punctuated::parse_terminated_with(input, MacroArg::parse)?;
         let mut gen_accessors = None;
         let mut type_def = None;
         let mut accessor_type = None;
@@ -134,7 +135,7 @@ impl Parse for NewTypeDef {
         #[allow(clippy::eval_order_dependence)]
         Ok(NewTypeDef {
             _braces: braced!(content in input),
-            fields: content.parse_terminated(Field::parse)?,
+            fields: Punctuated::parse_terminated_with(&content, Field::parse)?,
         })
     }
 }

components/derive_common/Cargo.toml

@@ -13,5 +13,5 @@ path = "lib.rs"
 darling = { workspace = true }
 proc-macro2 = { workspace = true }
 quote = { workspace = true }
-syn = { workspace = true }
-synstructure = { workspace = true }
+syn = { version = "1", default-features = false, features = ["clone-impls", "derive", "parsing"] }
+synstructure = "0.12"

components/jstraceable_derive/lib.rs

@@ -149,21 +149,15 @@ fn js_traceable_derive(s: synstructure::Structure) -> proc_macro2::TokenStream {
     let mut asserts = quote!();
     let match_body = s.each(|binding| {
         for attr in binding.ast().attrs.iter() {
-            match attr.parse_meta().unwrap() {
-                syn::Meta::Path(ref path) | syn::Meta::List(syn::MetaList { ref path, .. }) => {
-                    if path.is_ident("no_trace") {
-                        asserts.extend(assert_not_impl_traceable(&binding.ast().ty));
-                        return None;
-                    } else if path.is_ident("custom_trace") {
-                        return Some(quote!(<crate::dom::bindings::trace::CustomTraceable>::trace(#binding, tracer);));
-                    }
-                },
-                syn::Meta::NameValue(syn::MetaNameValue { ref path, .. }) => {
-                    // if reason provided we can skip JSTraceable check
-                    if path.is_ident("no_trace") {
-                        return None;
-                    }
-                },
+            if attr.path().is_ident("no_trace") {
+                // If no reason argument is provided to `no_trace` (ie `#[no_trace="This types does not need..."]`),
+                // assert that the type in this bound field does not implement traceable.
+                if !matches!(attr.meta, syn::Meta::NameValue(_)) {
+                    asserts.extend(assert_not_impl_traceable(&binding.ast().ty));
+                }
+                return None;
+            } else if attr.path().is_ident("custom_trace") {
+                return Some(quote!(<crate::dom::bindings::trace::CustomTraceable>::trace(#binding, tracer);));
             }
         }
         Some(quote!(#binding.trace(tracer);))

components/to_shmem_derive/Cargo.toml

@@ -15,5 +15,5 @@ darling = { workspace = true }
 derive_common = { path = "../derive_common" }
 proc-macro2 = { workspace = true }
 quote = { workspace = true }
-syn = { workspace = true }
-synstructure = { workspace = true }
+syn = { version = "1", default-features = false, features = ["clone-impls", "derive", "parsing"] }
+synstructure = "0.12"

servo-tidy.toml

@@ -67,7 +67,10 @@ packages = [
     "foreign-types-shared",
     "metal",
     "paste",
+
+    # Duplicated by Gecko crates that haven't been updated yet (style, shmem, derive_common, ...).
     "syn",
+    "synstructure",
 
     # style/webxr (0.62) vs. mozjs_sys (0.66)
     "bindgen",