Use OUT_DIR for hermes_parser build script

Summary:
Same as D53502298, we need to use the OUT_DIR for generated files in build.rs to make internal infra happy.

Original Author: [email protected]
Original Git: 61f1f52
Original Reviewed By: alunyov
Original Revision: D53545692

Reviewed By: avp

Differential Revision: D54092034

fbshipit-source-id: 339a60a5987650971a64b6f897865548e599f6b0

unsupported/hermes/crates/hermes_estree_codegen/src/codegen.rs

@@ -64,6 +64,25 @@ pub fn estree_hermes() -> String {
     )
 }
 
+/// Returns estree_herems that can be included indirectly
+pub fn estree_hermes_mod() -> String {
+    let src = include_str!("./ecmascript.json");
+    let grammar: Grammar = serde_json::from_str(src).unwrap();
+    let raw = grammar.codegen_hermes();
+    let in_mod = quote! {
+        pub mod generated {
+            #raw
+        }
+    };
+
+    let parsed = syn::parse_file(&in_mod.to_string()).unwrap();
+    format!(
+        "// {}generated\n{}",
+        '\u{0040}',
+        prettyplease::unparse(&parsed)
+    )
+}
+
 #[derive(Serialize, Deserialize, Debug)]
 #[serde(deny_unknown_fields)]
 pub struct Grammar {

unsupported/hermes/crates/hermes_estree_codegen/src/lib.rs

@@ -9,4 +9,5 @@ mod codegen;
 
 pub use codegen::estree;
 pub use codegen::estree_hermes;
+pub use codegen::estree_hermes_mod;
 pub use codegen::estree_mod;

unsupported/hermes/crates/hermes_parser/build.rs

@@ -5,7 +5,10 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-use hermes_estree_codegen::estree_hermes;
+use std::env;
+use std::path::Path;
+
+use hermes_estree_codegen::estree_hermes_mod;
 
 // Example custom build script.
 fn main() {
@@ -15,6 +18,8 @@ fn main() {
     println!("cargo:rerun-if-changed=../hermes_estree_codegen/src/ecmascript.json");
     println!("cargo:rerun-if-changed=../hermes_estree_codegen");
 
-    let src = estree_hermes();
-    std::fs::write("src/generated.rs", src).unwrap();
+    let src = estree_hermes_mod();
+    let out_dir = env::var("OUT_DIR").unwrap();
+    let dest_path = Path::new(&out_dir).join("generated.rs");
+    std::fs::write(dest_path, src).unwrap();
 }