1 files changed, 177 insertions, 0 deletions
diff --git a/third_party/rust/syn/src/macros.rs b/third_party/rust/syn/src/macros.rs
new file mode 100644
index 0000000000..da10a1a550
--- /dev/null
+++ b/third_party/rust/syn/src/macros.rs
@@ -0,0 +1,177 @@
+#[cfg_attr(
+    not(any(feature = "full", feature = "derive")),
+    allow(unknown_lints, unused_macro_rules)
+)]
+macro_rules! ast_struct {
+    (
+        [$($attrs_pub:tt)*]
+        struct $name:ident #full $($rest:tt)*
+    ) => {
+        #[cfg(feature = "full")]
+        $($attrs_pub)* struct $name $($rest)*
+
+        #[cfg(not(feature = "full"))]
+        $($attrs_pub)* struct $name {
+            _noconstruct: ::std::marker::PhantomData<::proc_macro2::Span>,
+        }
+
+        #[cfg(all(not(feature = "full"), feature = "printing"))]
+        impl ::quote::ToTokens for $name {
+            fn to_tokens(&self, _: &mut ::proc_macro2::TokenStream) {
+                unreachable!()
+            }
+        }
+    };
+
+    (
+        [$($attrs_pub:tt)*]
+        struct $name:ident $($rest:tt)*
+    ) => {
+        $($attrs_pub)* struct $name $($rest)*
+    };
+
+    ($($t:tt)*) => {
+        strip_attrs_pub!(ast_struct!($($t)*));
+    };
+}
+
+macro_rules! ast_enum {
+    // Drop the `#no_visit` attribute, if present.
+    (
+        [$($attrs_pub:tt)*]
+        enum $name:ident #no_visit $($rest:tt)*
+    ) => (
+        ast_enum!([$($attrs_pub)*] enum $name $($rest)*);
+    );
+
+    (
+        [$($attrs_pub:tt)*]
+        enum $name:ident $($rest:tt)*
+    ) => (
+        $($attrs_pub)* enum $name $($rest)*
+    );
+
+    ($($t:tt)*) => {
+        strip_attrs_pub!(ast_enum!($($t)*));
+    };
+}
+
+macro_rules! ast_enum_of_structs {
+    (
+        $(#[$enum_attr:meta])*
+        $pub:ident $enum:ident $name:ident $body:tt
+        $($remaining:tt)*
+    ) => {
+        ast_enum!($(#[$enum_attr])* $pub $enum $name $body);
+        ast_enum_of_structs_impl!($pub $enum $name $body $($remaining)*);
+    };
+}
+
+macro_rules! ast_enum_of_structs_impl {
+    (
+        $pub:ident $enum:ident $name:ident {
+            $(
+                $(#[cfg $cfg_attr:tt])*
+                $(#[doc $($doc_attr:tt)*])*
+                $variant:ident $( ($($member:ident)::+) )*,
+            )*
+        }
+
+        $($remaining:tt)*
+    ) => {
+        check_keyword_matches!(pub $pub);
+        check_keyword_matches!(enum $enum);
+
+        $($(
+            ast_enum_from_struct!($name::$variant, $($member)::+);
+        )*)*
+
+        #[cfg(feature = "printing")]
+        generate_to_tokens! {
+            $($remaining)*
+            ()
+            tokens
+            $name {
+                $(
+                    $(#[cfg $cfg_attr])*
+                    $(#[doc $($doc_attr)*])*
+                    $variant $($($member)::+)*,
+                )*
+            }
+        }
+    };
+}
+
+macro_rules! ast_enum_from_struct {
+    // No From<TokenStream> for verbatim variants.
+    ($name:ident::Verbatim, $member:ident) => {};
+
+    ($name:ident::$variant:ident, $member:ident) => {
+        impl From<$member> for $name {
+            fn from(e: $member) -> $name {
+                $name::$variant(e)
+            }
+        }
+    };
+}
+
+#[cfg(feature = "printing")]
+#[cfg_attr(
+    not(any(feature = "full", feature = "derive")),
+    allow(unknown_lints, unused_macro_rules)
+)]
+macro_rules! generate_to_tokens {
+    (do_not_generate_to_tokens $($foo:tt)*) => ();
+
+    (
+        ($($arms:tt)*) $tokens:ident $name:ident {
+            $(#[cfg $cfg_attr:tt])*
+            $(#[doc $($doc_attr:tt)*])*
+            $variant:ident,
+            $($next:tt)*
+        }
+    ) => {
+        generate_to_tokens!(
+            ($($arms)* $(#[cfg $cfg_attr])* $name::$variant => {})
+            $tokens $name { $($next)* }
+        );
+    };
+
+    (
+        ($($arms:tt)*) $tokens:ident $name:ident {
+            $(#[cfg $cfg_attr:tt])*
+            $(#[doc $($doc_attr:tt)*])*
+            $variant:ident $member:ident,
+            $($next:tt)*
+        }
+    ) => {
+        generate_to_tokens!(
+            ($($arms)* $(#[cfg $cfg_attr])* $name::$variant(_e) => _e.to_tokens($tokens),)
+            $tokens $name { $($next)* }
+        );
+    };
+
+    (($($arms:tt)*) $tokens:ident $name:ident {}) => {
+        #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+        impl ::quote::ToTokens for $name {
+            fn to_tokens(&self, $tokens: &mut ::proc_macro2::TokenStream) {
+                match self {
+                    $($arms)*
+                }
+            }
+        }
+    };
+}
+
+macro_rules! strip_attrs_pub {
+    ($mac:ident!($(#[$m:meta])* $pub:ident $($t:tt)*)) => {
+        check_keyword_matches!(pub $pub);
+
+        $mac!([$(#[$m])* $pub] $($t)*);
+    };
+}
+
+macro_rules! check_keyword_matches {
+    (enum enum) => {};
+    (pub pub) => {};
+}