diff --git a/gen/build/Cargo.toml b/gen/build/Cargo.toml
index 0added962..9b74255bf 100644
--- a/gen/build/Cargo.toml
+++ b/gen/build/Cargo.toml
@@ -25,7 +25,7 @@ once_cell = "1.9"
 proc-macro2 = { version = "1.0.39", default-features = false, features = ["span-locations"] }
 quote = { version = "1.0", default-features = false }
 scratch = "1.0"
-syn = { version = "2.0.0", default-features = false, features = ["parsing", "printing", "clone-impls", "full"] }
+syn = { version = "2.0.1", default-features = false, features = ["parsing", "printing", "clone-impls", "full"] }
 
 [dev-dependencies]
 cxx = { version = "1.0", path = "../.." }
diff --git a/gen/cmd/Cargo.toml b/gen/cmd/Cargo.toml
index 99f32a4cd..0026a5317 100644
--- a/gen/cmd/Cargo.toml
+++ b/gen/cmd/Cargo.toml
@@ -25,7 +25,7 @@ clap = { version = "4", default-features = false, features = ["error-context", "
 codespan-reporting = "0.11"
 proc-macro2 = { version = "1.0.39", default-features = false, features = ["span-locations"] }
 quote = { version = "1.0", default-features = false }
-syn = { version = "2.0.0", default-features = false, features = ["parsing", "printing", "clone-impls", "full"] }
+syn = { version = "2.0.1", default-features = false, features = ["parsing", "printing", "clone-impls", "full"] }
 
 [package.metadata.docs.rs]
 targets = ["x86_64-unknown-linux-gnu"]
diff --git a/gen/lib/Cargo.toml b/gen/lib/Cargo.toml
index 6bc89f87f..b4f45b6bf 100644
--- a/gen/lib/Cargo.toml
+++ b/gen/lib/Cargo.toml
@@ -15,7 +15,7 @@ rust-version = "1.60"
 codespan-reporting = "0.11"
 proc-macro2 = { version = "1.0.39", default-features = false, features = ["span-locations"] }
 quote = { version = "1.0", default-features = false }
-syn = { version = "2.0.0", default-features = false, features = ["parsing", "printing", "clone-impls", "full"] }
+syn = { version = "2.0.1", default-features = false, features = ["parsing", "printing", "clone-impls", "full"] }
 
 [lib]
 doc-scrape-examples = false
diff --git a/macro/Cargo.toml b/macro/Cargo.toml
index 1380c2529..89d97022d 100644
--- a/macro/Cargo.toml
+++ b/macro/Cargo.toml
@@ -23,7 +23,7 @@ experimental-enum-variants-from-header = ["clang-ast", "flate2", "memmap", "serd
 [dependencies]
 proc-macro2 = "1.0.39"
 quote = "1.0.4"
-syn = { version = "2.0.0", features = ["full"] }
+syn = { version = "2.0.1", features = ["full"] }
 
 # optional dependencies:
 clang-ast = { version = "0.1", optional = true }
diff --git a/syntax/attrs.rs b/syntax/attrs.rs
index 1b8e579bd..4ff700a84 100644
--- a/syntax/attrs.rs
+++ b/syntax/attrs.rs
@@ -146,7 +146,7 @@ pub fn parse(cx: &mut Errors, attrs: Vec<Attribute>, mut parser: Parser) -> Othe
         } else if attr_path.is_ident("variants_from_header")
             && cfg!(feature = "experimental-enum-variants-from-header")
         {
-            if let Err(err) = require_empty_attribute(&attr.meta) {
+            if let Err(err) = attr.meta.require_path_only() {
                 cx.push(err);
             }
             if let Some(variants_from_header) = &mut parser.variants_from_header {
@@ -310,12 +310,3 @@ impl ToTokens for OtherAttrs {
         }
     }
 }
-
-fn require_empty_attribute(meta: &Meta) -> Result<()> {
-    let error_span = match meta {
-        Meta::Path(_) => return Ok(()),
-        Meta::List(meta) => meta.delimiter.span().open(),
-        Meta::NameValue(meta) => meta.eq_token.span,
-    };
-    Err(Error::new(error_span, "unexpected token in cxx attribute"))
-}
diff --git a/third-party/BUCK b/third-party/BUCK
index 56c9c897f..cb756ae7f 100644
--- a/third-party/BUCK
+++ b/third-party/BUCK
@@ -378,68 +378,68 @@ third_party_rust_library(
 
 alias(
     name = "syn",
-    actual = ":syn-2.0.0",
+    actual = ":syn-2.0.1",
     visibility = ["PUBLIC"],
 )
 
 third_party_rust_library(
-    name = "syn-2.0.0",
+    name = "syn-2.0.1",
     srcs = [
-        "vendor/syn-2.0.0/src/attr.rs",
-        "vendor/syn-2.0.0/src/bigint.rs",
-        "vendor/syn-2.0.0/src/buffer.rs",
-        "vendor/syn-2.0.0/src/custom_keyword.rs",
-        "vendor/syn-2.0.0/src/custom_punctuation.rs",
-        "vendor/syn-2.0.0/src/data.rs",
-        "vendor/syn-2.0.0/src/derive.rs",
-        "vendor/syn-2.0.0/src/discouraged.rs",
-        "vendor/syn-2.0.0/src/drops.rs",
-        "vendor/syn-2.0.0/src/error.rs",
-        "vendor/syn-2.0.0/src/export.rs",
-        "vendor/syn-2.0.0/src/expr.rs",
-        "vendor/syn-2.0.0/src/ext.rs",
-        "vendor/syn-2.0.0/src/file.rs",
-        "vendor/syn-2.0.0/src/gen/clone.rs",
-        "vendor/syn-2.0.0/src/gen/debug.rs",
-        "vendor/syn-2.0.0/src/gen/eq.rs",
-        "vendor/syn-2.0.0/src/gen/fold.rs",
-        "vendor/syn-2.0.0/src/gen/hash.rs",
-        "vendor/syn-2.0.0/src/gen/visit.rs",
-        "vendor/syn-2.0.0/src/gen/visit_mut.rs",
-        "vendor/syn-2.0.0/src/gen_helper.rs",
-        "vendor/syn-2.0.0/src/generics.rs",
-        "vendor/syn-2.0.0/src/group.rs",
-        "vendor/syn-2.0.0/src/ident.rs",
-        "vendor/syn-2.0.0/src/item.rs",
-        "vendor/syn-2.0.0/src/lib.rs",
-        "vendor/syn-2.0.0/src/lifetime.rs",
-        "vendor/syn-2.0.0/src/lit.rs",
-        "vendor/syn-2.0.0/src/lookahead.rs",
-        "vendor/syn-2.0.0/src/mac.rs",
-        "vendor/syn-2.0.0/src/macros.rs",
-        "vendor/syn-2.0.0/src/meta.rs",
-        "vendor/syn-2.0.0/src/op.rs",
-        "vendor/syn-2.0.0/src/parse.rs",
-        "vendor/syn-2.0.0/src/parse_macro_input.rs",
-        "vendor/syn-2.0.0/src/parse_quote.rs",
-        "vendor/syn-2.0.0/src/pat.rs",
-        "vendor/syn-2.0.0/src/path.rs",
-        "vendor/syn-2.0.0/src/print.rs",
-        "vendor/syn-2.0.0/src/punctuated.rs",
-        "vendor/syn-2.0.0/src/restriction.rs",
-        "vendor/syn-2.0.0/src/sealed.rs",
-        "vendor/syn-2.0.0/src/span.rs",
-        "vendor/syn-2.0.0/src/spanned.rs",
-        "vendor/syn-2.0.0/src/stmt.rs",
-        "vendor/syn-2.0.0/src/thread.rs",
-        "vendor/syn-2.0.0/src/token.rs",
-        "vendor/syn-2.0.0/src/tt.rs",
-        "vendor/syn-2.0.0/src/ty.rs",
-        "vendor/syn-2.0.0/src/verbatim.rs",
-        "vendor/syn-2.0.0/src/whitespace.rs",
+        "vendor/syn-2.0.1/src/attr.rs",
+        "vendor/syn-2.0.1/src/bigint.rs",
+        "vendor/syn-2.0.1/src/buffer.rs",
+        "vendor/syn-2.0.1/src/custom_keyword.rs",
+        "vendor/syn-2.0.1/src/custom_punctuation.rs",
+        "vendor/syn-2.0.1/src/data.rs",
+        "vendor/syn-2.0.1/src/derive.rs",
+        "vendor/syn-2.0.1/src/discouraged.rs",
+        "vendor/syn-2.0.1/src/drops.rs",
+        "vendor/syn-2.0.1/src/error.rs",
+        "vendor/syn-2.0.1/src/export.rs",
+        "vendor/syn-2.0.1/src/expr.rs",
+        "vendor/syn-2.0.1/src/ext.rs",
+        "vendor/syn-2.0.1/src/file.rs",
+        "vendor/syn-2.0.1/src/gen/clone.rs",
+        "vendor/syn-2.0.1/src/gen/debug.rs",
+        "vendor/syn-2.0.1/src/gen/eq.rs",
+        "vendor/syn-2.0.1/src/gen/fold.rs",
+        "vendor/syn-2.0.1/src/gen/hash.rs",
+        "vendor/syn-2.0.1/src/gen/visit.rs",
+        "vendor/syn-2.0.1/src/gen/visit_mut.rs",
+        "vendor/syn-2.0.1/src/gen_helper.rs",
+        "vendor/syn-2.0.1/src/generics.rs",
+        "vendor/syn-2.0.1/src/group.rs",
+        "vendor/syn-2.0.1/src/ident.rs",
+        "vendor/syn-2.0.1/src/item.rs",
+        "vendor/syn-2.0.1/src/lib.rs",
+        "vendor/syn-2.0.1/src/lifetime.rs",
+        "vendor/syn-2.0.1/src/lit.rs",
+        "vendor/syn-2.0.1/src/lookahead.rs",
+        "vendor/syn-2.0.1/src/mac.rs",
+        "vendor/syn-2.0.1/src/macros.rs",
+        "vendor/syn-2.0.1/src/meta.rs",
+        "vendor/syn-2.0.1/src/op.rs",
+        "vendor/syn-2.0.1/src/parse.rs",
+        "vendor/syn-2.0.1/src/parse_macro_input.rs",
+        "vendor/syn-2.0.1/src/parse_quote.rs",
+        "vendor/syn-2.0.1/src/pat.rs",
+        "vendor/syn-2.0.1/src/path.rs",
+        "vendor/syn-2.0.1/src/print.rs",
+        "vendor/syn-2.0.1/src/punctuated.rs",
+        "vendor/syn-2.0.1/src/restriction.rs",
+        "vendor/syn-2.0.1/src/sealed.rs",
+        "vendor/syn-2.0.1/src/span.rs",
+        "vendor/syn-2.0.1/src/spanned.rs",
+        "vendor/syn-2.0.1/src/stmt.rs",
+        "vendor/syn-2.0.1/src/thread.rs",
+        "vendor/syn-2.0.1/src/token.rs",
+        "vendor/syn-2.0.1/src/tt.rs",
+        "vendor/syn-2.0.1/src/ty.rs",
+        "vendor/syn-2.0.1/src/verbatim.rs",
+        "vendor/syn-2.0.1/src/whitespace.rs",
     ],
     crate = "syn",
-    crate_root = "vendor/syn-2.0.0/src/lib.rs",
+    crate_root = "vendor/syn-2.0.1/src/lib.rs",
     edition = "2021",
     features = [
         "clone-impls",
diff --git a/third-party/Cargo.lock b/third-party/Cargo.lock
index c426a1ef2..fd14b8182 100644
--- a/third-party/Cargo.lock
+++ b/third-party/Cargo.lock
@@ -81,9 +81,9 @@ checksum = "1792db035ce95be60c3f8853017b3999209281c24e2ba5bc8e59bf97a0c590c1"
 
 [[package]]
 name = "syn"
-version = "2.0.0"
+version = "2.0.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4cff13bb1732bccfe3b246f3fdb09edfd51c01d6f5299b7ccd9457c2e4e37774"
+checksum = "55ee2415bee46ba26eac9cd8e52966995c46bf0e842b6304eb8fcf99826548ed"
 dependencies = [
  "proc-macro2",
  "quote",
diff --git a/third-party/Cargo.toml b/third-party/Cargo.toml
index ce3fc01e2..5a069811c 100644
--- a/third-party/Cargo.toml
+++ b/third-party/Cargo.toml
@@ -15,4 +15,4 @@ once_cell = "1.9"
 proc-macro2 = { version = "1.0.39", features = ["span-locations"] }
 quote = "1.0.4"
 scratch = "1"
-syn = { version = "2.0.0", features = ["full"] }
+syn = { version = "2.0.1", features = ["full"] }
diff --git a/third-party/bazel/BUILD.bazel b/third-party/bazel/BUILD.bazel
index 642c762fe..d35ae840e 100644
--- a/third-party/bazel/BUILD.bazel
+++ b/third-party/bazel/BUILD.bazel
@@ -69,6 +69,6 @@ alias(
 
 alias(
     name = "syn",
-    actual = "@vendor__syn-2.0.0//:syn",
+    actual = "@vendor__syn-2.0.1//:syn",
     tags = ["manual"],
 )
diff --git a/third-party/bazel/BUILD.syn-2.0.0.bazel b/third-party/bazel/BUILD.syn-2.0.1.bazel
similarity index 98%
rename from third-party/bazel/BUILD.syn-2.0.0.bazel
rename to third-party/bazel/BUILD.syn-2.0.1.bazel
index 9eba98722..42cdf3184 100644
--- a/third-party/bazel/BUILD.syn-2.0.0.bazel
+++ b/third-party/bazel/BUILD.syn-2.0.1.bazel
@@ -47,7 +47,7 @@ rust_library(
         "noclippy",
         "norustfmt",
     ],
-    version = "2.0.0",
+    version = "2.0.1",
     deps = [
         "@vendor__proc-macro2-1.0.52//:proc_macro2",
         "@vendor__quote-1.0.26//:quote",
diff --git a/third-party/bazel/defs.bzl b/third-party/bazel/defs.bzl
index b295fd32b..e799b0e9d 100644
--- a/third-party/bazel/defs.bzl
+++ b/third-party/bazel/defs.bzl
@@ -298,7 +298,7 @@ _NORMAL_DEPENDENCIES = {
             "proc-macro2": "@vendor__proc-macro2-1.0.52//:proc_macro2",
             "quote": "@vendor__quote-1.0.26//:quote",
             "scratch": "@vendor__scratch-1.0.5//:scratch",
-            "syn": "@vendor__syn-2.0.0//:syn",
+            "syn": "@vendor__syn-2.0.1//:syn",
         },
     },
 }
@@ -472,12 +472,12 @@ def crate_repositories():
 
     maybe(
         http_archive,
-        name = "vendor__syn-2.0.0",
-        sha256 = "4cff13bb1732bccfe3b246f3fdb09edfd51c01d6f5299b7ccd9457c2e4e37774",
+        name = "vendor__syn-2.0.1",
+        sha256 = "55ee2415bee46ba26eac9cd8e52966995c46bf0e842b6304eb8fcf99826548ed",
         type = "tar.gz",
-        urls = ["https://crates.io/api/v1/crates/syn/2.0.0/download"],
-        strip_prefix = "syn-2.0.0",
-        build_file = Label("@cxx.rs//third-party/bazel:BUILD.syn-2.0.0.bazel"),
+        urls = ["https://crates.io/api/v1/crates/syn/2.0.1/download"],
+        strip_prefix = "syn-2.0.1",
+        build_file = Label("@cxx.rs//third-party/bazel:BUILD.syn-2.0.1.bazel"),
     )
 
     maybe(