Tentatively derive pest::Parser normally

If it still creates spurious recompilations, I'll revert that

3 files changed, 7 insertions, 20 deletions

diff --git a/dhall_generated_parser/Cargo.toml b/dhall_generated_parser/Cargo.toml
index 0730f60..b1f0d02 100644
--- a/dhall_generated_parser/Cargo.toml
+++ b/dhall_generated_parser/Cargo.toml
@@ -12,8 +12,7 @@ doctest = false
 
 [build-dependencies]
 abnf_to_pest = { version = "0.1.1", path = "../abnf_to_pest" }
-pest_generator = "2.1"
-quote = "1.0.2"
 
 [dependencies]
 pest = "2.1"
+pest_derive = "2.1"
diff --git a/dhall_generated_parser/build.rs b/dhall_generated_parser/build.rs
index c562fad..68895dd 100644
--- a/dhall_generated_parser/build.rs
+++ b/dhall_generated_parser/build.rs
@@ -1,7 +1,5 @@
-use std::env;
 use std::fs::File;
 use std::io::{BufRead, BufReader, Read, Write};
-use std::path::Path;
 
 use abnf_to_pest::render_rules_to_pest;
 
@@ -90,20 +88,5 @@ fn main() -> std::io::Result<()> {
     writeln!(&mut file)?;
     writeln!(&mut file, "{}", render_rules_to_pest(rules).pretty(80))?;
 
-    // Generate pest parser manually to avoid spurious recompilations
-    let derived = {
-        let pest_path = "dhall.pest";
-        let pest = quote::quote! {
-            #[grammar = #pest_path]
-            pub struct DhallParser;
-        };
-        pest_generator::derive_parser(pest, false)
-    };
-
-    let out_dir = env::var("OUT_DIR").unwrap();
-    let grammar_path = Path::new(&out_dir).join("grammar.rs");
-    let mut file = File::create(grammar_path)?;
-    writeln!(file, "pub struct DhallParser;\n{}", derived,)?;
-
     Ok(())
 }
diff --git a/dhall_generated_parser/src/lib.rs b/dhall_generated_parser/src/lib.rs
index 280b75e..fbb9ccd 100644
--- a/dhall_generated_parser/src/lib.rs
+++ b/dhall_generated_parser/src/lib.rs
@@ -14,4 +14,9 @@
 // additional overrides are done in ../build.rs.
 // The lines that are commented out in ./dhall.pest.visibility are marked as
 // silent (see pest docs for what that means) in the generated pest file.
-include!(concat!(env!("OUT_DIR"), "/grammar.rs"));
+
+use pest_derive::Parser;
+
+#[derive(Parser)]
+#[grammar = "dhall.pest"]
+pub struct DhallParser;