script: copy include! files from script_bindings to script's OUT_DIR (#36384)

copy generated `include!`d files from script_bindings's OUT_DIR, to
script's OUT_DIR to allow Rust Analyzer to load them.
This is done to bypass limitation of Rust Analyzer:
https://github.com/rust-lang/rust-analyzer/issues/17040

Also build script will now be rerun only when there are actual changes
to concrete bindings due to emitted `cargo::rerun-if-changed` (not for
each change in script crate).

Testing: It compiles so it works, I tested manually and RA now works as
expected (although we need to from type alias to concrete union-types
definitions)
Fixes:
https://servo.zulipchat.com/#narrow/channel/263398-general/topic/rust-analyzer.20failed.20to.20include.20codes.20in.20script_bindings

---------

Signed-off-by: sagudev <16504129+sagudev@users.noreply.github.com>

components/script/build.rs

@@ -3,10 +3,54 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 use std::env;
+use std::path::{Path, PathBuf};
 
 fn main() {
+    // copy include! files from script_bindings's OUT_DIR, to script's OUT_DIR
+    // this is done to bypass limitation of Rust Analyzer: https://github.com/rust-lang/rust-analyzer/issues/17040
+    let script_bindings_out_dir =
+        PathBuf::from(env::var_os("DEP_SCRIPT_BINDINGS_CRATE_OUT_DIR").unwrap());
+    let out_dir = PathBuf::from(env::var_os("OUT_DIR").unwrap());
+    // copy concrete files
+    [
+        "InterfaceTypes.rs",
+        "DomTypeHolder.rs",
+        "InterfaceObjectMap.rs",
+        "ConcreteInheritTypes.rs",
+        "UnionTypes.rs",
+        "InterfaceObjectMapPhf.rs",
+    ]
+    .iter()
+    .map(Path::new)
+    .for_each(|file| {
+        println!(
+            "cargo::rerun-if-changed={}",
+            script_bindings_out_dir.join(file).display()
+        );
+        std::fs::copy(
+            script_bindings_out_dir.join(file),
+            out_dir.join(file.file_name().unwrap()),
+        )
+        .unwrap();
+    });
+    // copy ConcreteBindings folder
+    let _ = std::fs::create_dir(out_dir.join("ConcreteBindings"));
+    let script_concrete_bindings_out_dir = script_bindings_out_dir.join("ConcreteBindings");
     println!(
-        "cargo:rustc-env=BINDINGS_OUT_DIR={}",
-        env::var("DEP_SCRIPT_BINDINGS_CRATE_OUT_DIR").unwrap(),
+        "cargo::rerun-if-changed={}",
+        script_concrete_bindings_out_dir.display()
     );
+    std::fs::read_dir(script_concrete_bindings_out_dir)
+        .unwrap()
+        .filter_map(|res| res.map(|e| e.path()).ok())
+        .filter(|path| path.is_file())
+        .for_each(|file| {
+            std::fs::copy(
+                &file,
+                out_dir
+                    .join("ConcreteBindings")
+                    .join(file.file_name().unwrap()),
+            )
+            .unwrap();
+        });
 }

components/script/dom/bindings/mod.rs

@@ -166,28 +166,22 @@ pub(crate) use script_bindings::{callback, iterable, num};
 #[allow(missing_docs, non_snake_case)]
 pub(crate) mod codegen {
     pub(crate) mod DomTypeHolder {
-        include!(concat!(env!("BINDINGS_OUT_DIR"), "/DomTypeHolder.rs"));
+        include!(concat!(env!("OUT_DIR"), "/DomTypeHolder.rs"));
     }
     pub(crate) use script_bindings::codegen::GenericBindings;
     #[allow(dead_code)]
     pub(crate) mod Bindings {
-        include!(concat!(
-            env!("BINDINGS_OUT_DIR"),
-            "/ConcreteBindings/mod.rs"
-        ));
+        include!(concat!(env!("OUT_DIR"), "/ConcreteBindings/mod.rs"));
     }
     pub(crate) mod InterfaceObjectMap {
-        include!(concat!(env!("BINDINGS_OUT_DIR"), "/InterfaceObjectMap.rs"));
+        include!(concat!(env!("OUT_DIR"), "/InterfaceObjectMap.rs"));
     }
     pub(crate) mod ConcreteInheritTypes {
-        include!(concat!(
-            env!("BINDINGS_OUT_DIR"),
-            "/ConcreteInheritTypes.rs"
-        ));
+        include!(concat!(env!("OUT_DIR"), "/ConcreteInheritTypes.rs"));
     }
     pub(crate) use script_bindings::codegen::{PrototypeList, RegisterBindings};
     #[allow(dead_code)]
     pub(crate) mod UnionTypes {
-        include!(concat!(env!("BINDINGS_OUT_DIR"), "/UnionTypes.rs"));
+        include!(concat!(env!("OUT_DIR"), "/UnionTypes.rs"));
     }
 }

components/script/dom/mod.rs

@@ -207,7 +207,7 @@ pub(crate) mod macros;
 
 #[allow(unused_imports)]
 pub(crate) mod types {
-    include!(concat!(env!("BINDINGS_OUT_DIR"), "/InterfaceTypes.rs"));
+    include!(concat!(env!("OUT_DIR"), "/InterfaceTypes.rs"));
 }
 
 pub(crate) mod abortcontroller;

components/script_bindings/codegen/CodegenRust.py

@@ -8522,7 +8522,7 @@ class GlobalGenRoots():
         ]
         imports = CGList([CGGeneric(f"use {mod};") for mod in mods], "\n")
 
-        phf = CGGeneric("include!(concat!(env!(\"BINDINGS_OUT_DIR\"), \"/InterfaceObjectMapPhf.rs\"));")
+        phf = CGGeneric("include!(concat!(env!(\"OUT_DIR\"), \"/InterfaceObjectMapPhf.rs\"));")
 
         return CGList([
             CGGeneric(AUTOGENERATED_WARNING_COMMENT),