Introduce type aliases in syntax tree

macro/src/expand.rs

@@ -55,6 +55,7 @@ fn expand(namespace: &Namespace, ffi: ItemMod, apis: &[Api], types: &Types) -> T
             Api::RustFunction(efn) => {
                 hidden.extend(expand_rust_function_shim(namespace, efn, types))
             }
+            Api::TypeAlias(_alias) => unimplemented!(),
         }
     }
 

syntax/ident.rs

@@ -42,6 +42,7 @@ pub(crate) fn check_all(cx: &mut Check, namespace: &Namespace, apis: &[Api]) {
                     check(cx, &arg.ident);
                 }
             }
+            Api::TypeAlias(_alias) => unimplemented!(),
         }
     }
 }

syntax/mod.rs

@@ -20,7 +20,7 @@ use self::parse::kw;
 use proc_macro2::{Ident, Span};
 use syn::punctuated::Punctuated;
 use syn::token::{Brace, Bracket, Paren};
-use syn::{Lifetime, LitStr, Token};
+use syn::{Lifetime, LitStr, Token, Type as RustType};
 
 pub use self::atom::Atom;
 pub use self::doc::Doc;
@@ -35,6 +35,7 @@ pub enum Api {
     CxxFunction(ExternFn),
     RustType(ExternType),
     RustFunction(ExternFn),
+    TypeAlias(TypeAlias),
 }
 
 pub struct ExternType {
@@ -68,6 +69,14 @@ pub struct ExternFn {
     pub semi_token: Token![;],
 }
 
+pub struct TypeAlias {
+    pub type_token: Token![type],
+    pub ident: Ident,
+    pub eq_token: Token![=],
+    pub ty: RustType,
+    pub semi_token: Token![;],
+}
+
 pub struct Signature {
     pub fn_token: Token![fn],
     pub receiver: Option<Receiver>,

syntax/tokens.rs

@@ -1,6 +1,7 @@
 use crate::syntax::atom::Atom::*;
 use crate::syntax::{
-    Derive, Enum, ExternFn, ExternType, Receiver, Ref, Signature, Slice, Struct, Ty1, Type, Var,
+    Derive, Enum, ExternFn, ExternType, Receiver, Ref, Signature, Slice, Struct, Ty1, Type,
+    TypeAlias, Var,
 };
 use proc_macro2::{Ident, Span, TokenStream};
 use quote::{quote_spanned, ToTokens};
@@ -86,6 +87,14 @@ impl ToTokens for ExternType {
     }
 }
 
+impl ToTokens for TypeAlias {
+    fn to_tokens(&self, tokens: &mut TokenStream) {
+        // Notional token range for error reporting purposes.
+        self.type_token.to_tokens(tokens);
+        self.ident.to_tokens(tokens);
+    }
+}
+
 impl ToTokens for Struct {
     fn to_tokens(&self, tokens: &mut TokenStream) {
         // Notional token range for error reporting purposes.

syntax/types.rs

@@ -96,6 +96,7 @@ impl<'a> Types<'a> {
                         visit(&mut all, ret);
                     }
                 }
+                Api::TypeAlias(_alias) => unimplemented!(),
             }
         }