No autocomplete from generated bindings even with Evaluate Build Scripts enabled

[druerridge]

Environment

• IntelliJ Rust plugin version: 0.3.138.3572-203
• Rust toolchain version: rustup 1.23.1 (3df2264a9 2020-11-30) + rustc 1.48.0 (7eac88abb 2020-11-16) (stable-x86_64-pc-windows-msvc)
• IDE name and version: IntelliJ IDEA 2020.3 (Ultimate Edition) Build #IU-203.5981.155, built on November 30, 2020
• Operating system: Windows 10

Problem description

Not receiving auto-complete (or related features, go-to defintion, etc.) for generated bindings even with (Experimental) org.rust.cargo.evaluate.build.scripts = true OR org.rust.cargo.fetch.out.dir = true In my example, I'm writing rust code to be used by the Godot game engine via Godot-Rust and the gdnative crate, which generates bindings to Godot's gdnative interface.

VS Code will give auto-completion on this sort of thing, when enabling fetchOutDir in the rust analyzer plugin.

Reading through related issues like (#1908 and #6135), most of which seem closed/working, it seems relevant that the bindings in use are being generated inside of the dependency gdnative (https://github.com/godot-rust/godot-rust) and that gdnative uses a couple lines like this to include the bindings it generates from include!(concat!(env!("OUT_DIR"), "/generated.rs"));

This is my first bug report so I hope I didn't miss something obvious, but none of the answers I found worked for me. I'd really prefer to use IntelliJ / CLion on Godot projects, especially given it seems evaluate.build.scripts will be more performant than fetching OUT_DIR.

Steps to reproduce

Using the very bare-bones Godot-Rust hello_world example project:

1. In IntelliJ: ctrl-shift-a > Experimental Features... > org.rust.cargo.evaluate.build.scripts = true OR org.rust.cargo.fetch.out.dir = true
2. git clone https://github.com/godot-rust/godot-rust/ (latest is probably fine, but I did it at this commit: 57973d71f0ef32fcf0e6e616ff37537d4b6a93b4)
3. cd to examples/hello_world
4. cargo check
5. Open IntelliJ to /examples/hello_world/src/lib.rs
6. Attempt to add a new line below line 15 and begin typing this: _owner.set_script(script)
7. Expect set_script to autocomplete, as it will with VS Code + rust analyzer (when fetchOutDir is enabled)

Note that the project compiles and runs exactly as expected. All of the example projects in there suffer from the same problem with autocomplete though.

[Undin]

@druerridge Thanks for the report!
As I can see, the problem is in the size of generated file by gdnative-bindings package. Try to open generated.rs produced by gdnative-bindings and you should see something like

It's because all IntelliJ-based IDEs have a limit of file size where code insight is available. By default, the limit is 2.56 MB and since generated.rs takes more space, it is not properly processed by your IDE.
You can increase this limit. To do it:

• open custom VM options dialog (Help | Find Action and type Edit Custom VM Options)
• add -Didea.max.intellisense.filesize=limitValue line where limitValue is desired limit in KB, for example, 10240. Note, it cannot be more than 20 MB.
• restart IDE

It should solve your issue

[druerridge]

This fixed my issue, thank you so much! I'll submit a PR to godot-rust tutorial to make sure others can find it.

[Undin]

@druerridge Great!

I'll submit a PR to godot-rust tutorial to make sure others can find it.

Note, org.rust.cargo.fetch.out.dir experimental feature breaks incremental compilation and most likely it will be removed in the future so it's better to mention only org.rust.cargo.evaluate.build.scripts in the tutorial

[Cightline]

For anybody that comes across this do ctrl+shift+A then search for "experimental features".