patches/syn-2.patch

diff --git a/src/generator.rs b/src/generator.rs
index 87d1f00..0dbcaa3 100644
--- a/src/generator.rs
+++ b/src/generator.rs
@@ -22,7 +22,7 @@ use crate::docs::DocComment;
 pub(crate) fn generate(
     name: Ident,
     generics: &Generics,
-    path: Option<PathBuf>,
+    paths: Vec<PathBuf>,
     rules: Vec<OptimizedRule>,
     defaults: Vec<&str>,
     doc_comment: &DocComment,
@@ -32,10 +32,7 @@ pub(crate) fn generate(
 
     let builtins = generate_builtin_rules();
     let include_fix = if include_grammar {
-        match path {
-            Some(ref path) => generate_include(&name, path.to_str().expect("non-Unicode path")),
-            None => quote!(),
-        }
+        generate_include(&name, paths)
     } else {
         quote!()
     };
@@ -170,17 +167,33 @@ fn generate_builtin_rules() -> Vec<(&'static str, TokenStream)> {
     builtins
 }
 
-// Needed because Cargo doesn't watch for changes in grammars.
-fn generate_include(name: &Ident, path: &str) -> TokenStream {
+/// Generate Rust `include_str!` for grammar files, then Cargo will watch changes in grammars.
+fn generate_include(name: &Ident, paths: Vec<PathBuf>) -> TokenStream {
     let const_name = format_ident!("_PEST_GRAMMAR_{}", name);
     // Need to make this relative to the current directory since the path to the file
     // is derived from the CARGO_MANIFEST_DIR environment variable
-    let mut current_dir = std::env::current_dir().expect("Unable to get current directory");
-    current_dir.push(path);
-    let relative_path = current_dir.to_str().expect("path contains invalid unicode");
+    let current_dir = std::env::current_dir().expect("Unable to get current directory");
+
+    let include_tokens = paths.iter().map(|path| {
+        let path = path.to_str().expect("non-Unicode path");
+
+        let relative_path = current_dir
+            .join(path)
+            .to_str()
+            .expect("path contains invalid unicode")
+            .to_string();
+
+        quote! {
+            include_str!(#relative_path)
+        }
+    });
+
+    let len = include_tokens.len();
     quote! {
         #[allow(non_upper_case_globals)]
-        const #const_name: &'static str = include_str!(#relative_path);
+        const #const_name: [&'static str; #len] = [
+            #(#include_tokens),*
+        ];
     }
 }
 
@@ -1016,14 +1029,16 @@ mod tests {
         let defaults = vec!["ANY"];
         let result = result_type();
         let box_ty = box_type();
-        let mut current_dir = std::env::current_dir().expect("Unable to get current directory");
-        current_dir.push("test.pest");
-        let test_path = current_dir.to_str().expect("path contains invalid unicode");
+        let current_dir = std::env::current_dir().expect("Unable to get current directory");
+
+        let base_path = current_dir.join("base.pest").to_str().unwrap().to_string();
+        let test_path = current_dir.join("test.pest").to_str().unwrap().to_string();
+
         assert_eq!(
-            generate(name, &generics, Some(PathBuf::from("test.pest")), rules, defaults, doc_comment, true).to_string(),
+            generate(name, &generics, vec![PathBuf::from("base.pest"), PathBuf::from("test.pest")], rules, defaults, doc_comment, true).to_string(),
             quote! {
                 #[allow(non_upper_case_globals)]
-                const _PEST_GRAMMAR_MyParser: &'static str = include_str!(#test_path);
+                const _PEST_GRAMMAR_MyParser: [&'static str; 2usize] = [include_str!(#base_path), include_str!(#test_path)];
 
                 #[doc = "This is Rule doc\nThis is second line"]
                 #[allow(dead_code, non_camel_case_types, clippy::upper_case_acronyms)]
diff --git a/src/lib.rs b/src/lib.rs
index f808987..7aed193 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -27,7 +27,7 @@ use std::io::{self, Read};
 use std::path::Path;
 
 use proc_macro2::TokenStream;
-use syn::{Attribute, DeriveInput, Generics, Ident, Lit, Meta};
+use syn::{Attribute, DeriveInput, Expr, ExprLit, Generics, Ident, Lit, Meta};
 
 #[macro_use]
 mod macros;
@@ -45,7 +45,7 @@ pub fn derive_parser(input: TokenStream, include_grammar: bool) -> TokenStream {
     let (name, generics, contents) = parse_derive(ast);
 
     let mut data = String::new();
-    let mut path = None;
+    let mut paths = vec![];
 
     for content in contents {
         let (_data, _path) = match content {
@@ -81,8 +81,9 @@ pub fn derive_parser(input: TokenStream, include_grammar: bool) -> TokenStream {
         };
 
         data.push_str(&_data);
-        if _path.is_some() {
-            path = _path;
+        match _path {
+            Some(path) => paths.push(path),
+            None => (),
         }
     }
 
@@ -99,7 +100,7 @@ pub fn derive_parser(input: TokenStream, include_grammar: bool) -> TokenStream {
     generator::generate(
         name,
         &generics,
-        path,
+        paths,
         optimized,
         defaults,
         &doc_comment,
@@ -127,11 +128,9 @@ fn parse_derive(ast: DeriveInput) -> (Ident, Generics, Vec<GrammarSource>) {
     let grammar: Vec<&Attribute> = ast
         .attrs
         .iter()
-        .filter(|attr| match attr.parse_meta() {
-            Ok(Meta::NameValue(name_value)) => {
-                name_value.path.is_ident("grammar") || name_value.path.is_ident("grammar_inline")
-            }
-            _ => false,
+        .filter(|attr| {
+            let path = attr.meta.path();
+            path.is_ident("grammar") || path.is_ident("grammar_inline")
         })
         .collect();
 
@@ -148,9 +147,12 @@ fn parse_derive(ast: DeriveInput) -> (Ident, Generics, Vec<GrammarSource>) {
 }
 
 fn get_attribute(attr: &Attribute) -> GrammarSource {
-    match attr.parse_meta() {
-        Ok(Meta::NameValue(name_value)) => match name_value.lit {
-            Lit::Str(string) => {
+    match &attr.meta {
+        Meta::NameValue(name_value) => match &name_value.value {
+            Expr::Lit(ExprLit {
+                lit: Lit::Str(string),
+                ..
+            }) => {
                 if name_value.path.is_ident("grammar") {
                     GrammarSource::File(string.value())
                 } else {