# Bindgen basic help **URL:** \ **Category:** help\ **Created:** [June 22, 2017, 9:54am UTC](https://users.rust-lang.org/t/bindgen-basic-help/11478 "2017-06-22T09:54:25Z")\ **Posts on this page:** 13\ **Page:** 1
**Author:** ![0xSpock](https://sea1.discourse-cdn.com/flex019/user_avatar/users.rust-lang.org/0xspock/32/2926_2.png) [@0xSpock](https://users.rust-lang.org/u/0xSpock)\ **Post date:** [June 22, 2017, 9:54am UTC](https://users.rust-lang.org/t/bindgen-basic-help/11478/1 "2017-06-22T09:54:26Z")
Hi, I'm trying to use bindgen to create bindings to C++ code (kea dhcp server). I'm following guides but I've stumbled on first step.. 🙂 My Cargo.toml contains required declarations: ``` [package] build = "build.rs" [dependencies] bindgen = "0.26.1" ``` build.rs in my crate root folder have content according to example from bindgen: ``` extern crate bindgen; use std::env; use std::path::PathBuf; fn main() { // code here ``` And I'm getting error when running cargo build: ``` error[E0463]: can't find crate for `bindgen` --> build.rs:1:1 | 1 | extern crate bindgen; | ^^^^^^^^^^^^^^^^^^^^^ can't find crate error: aborting due to previous error ``` What I'm doing wrong ? ---
**Author:** ![Keats](https://sea1.discourse-cdn.com/flex019/user_avatar/users.rust-lang.org/keats/32/1922_2.png) [@Keats](https://users.rust-lang.org/u/Keats)\ **Post date:** [June 22, 2017, 9:58am UTC](https://users.rust-lang.org/t/bindgen-basic-help/11478/2 "2017-06-22T09:58:33Z")
Put it in `[build-dependencies]` like [https://github.com/compass-rs/sass-rs/pull/11/files#diff-3f5590e43a4a71147163b6b694dc7c66R16](https://github.com/compass-rs/sass-rs/pull/11/files#diff-3f5590e43a4a71147163b6b694dc7c66R16) ---
**Author:** ![0xSpock](https://sea1.discourse-cdn.com/flex019/user_avatar/users.rust-lang.org/0xspock/32/2926_2.png) [@0xSpock](https://users.rust-lang.org/u/0xSpock)\ **Post date:** [June 22, 2017, 10:15am UTC](https://users.rust-lang.org/t/bindgen-basic-help/11478/3 "2017-06-22T10:15:18Z")
Ha, This helped. Thanks ! Why such information is not present in any bindgen doc/example ? ---
**Author:** ![Michael-F-Bryan](https://sea1.discourse-cdn.com/flex019/user_avatar/users.rust-lang.org/michael-f-bryan/32/28749_2.png) [@Michael-F-Bryan](https://users.rust-lang.org/u/Michael-F-Bryan)\ **Post date:** [June 23, 2017, 9:20am UTC](https://users.rust-lang.org/t/bindgen-basic-help/11478/4 "2017-06-23T09:20:23Z")
> [@0xSpock](#): > > Why such information is not present in any bindgen doc/example I just had a skim through their guide and found [this](https://servo.github.io/rust-bindgen/tutorial-1.html). ---
**Author:** ![megha1906](https://sea1.discourse-cdn.com/flex019/user_avatar/users.rust-lang.org/megha1906/32/19189_2.png) [@megha1906](https://users.rust-lang.org/u/megha1906)\ **Post date:** [January 22, 2021, 7:18am UTC](https://users.rust-lang.org/t/bindgen-basic-help/11478/5 "2021-01-22T07:18:10Z")
Still now working. already kept it in [build-dependencies] ---
**Author:** ![Michael-F-Bryan](https://sea1.discourse-cdn.com/flex019/user_avatar/users.rust-lang.org/michael-f-bryan/32/28749_2.png) [@Michael-F-Bryan](https://users.rust-lang.org/u/Michael-F-Bryan)\ **Post date:** [January 22, 2021, 8:24am UTC](https://users.rust-lang.org/t/bindgen-basic-help/11478/6 "2021-01-22T08:24:59Z")
It works fine on my machine. Can you share the code or error messages? ---
**Author:** ![megha1906](https://sea1.discourse-cdn.com/flex019/user_avatar/users.rust-lang.org/megha1906/32/19189_2.png) [@megha1906](https://users.rust-lang.org/u/megha1906)\ **Post date:** [January 22, 2021, 9:39am UTC](https://users.rust-lang.org/t/bindgen-basic-help/11478/7 "2021-01-22T09:39:53Z")
error[E0463]: can't find crate for `bindgen` --\> build.rs:1:1 | 1 | extern crate bindgen; | ^^^^^^^^^^^^^^^^^^^^^ can't find crate error: aborting due to previous error in Cargo.toml: [build-dependencies] bindgen = "0.53.1" ---
**Author:** ![Michael-F-Bryan](https://sea1.discourse-cdn.com/flex019/user_avatar/users.rust-lang.org/michael-f-bryan/32/28749_2.png) [@Michael-F-Bryan](https://users.rust-lang.org/u/Michael-F-Bryan)\ **Post date:** [January 22, 2021, 9:54am UTC](https://users.rust-lang.org/t/bindgen-basic-help/11478/8 "2021-01-22T09:54:55Z")
That's odd, it works for me. ```rust $ cargo --version cargo 1.51.0-nightly (a73e5b7d5 2021-01-12) $ rustc --version --verbose rustc 1.51.0-nightly (c5a96fb79 2021-01-19) binary: rustc commit-hash: c5a96fb7973649807a7943e7395456db158dcab6 commit-date: 2021-01-19 host: x86_64-unknown-linux-gnu release: 1.51.0-nightly LLVM version: 11.0.1 $ cargo new --lib repro $ cd repro $ cat Cargo.toml [package] name = "repro" version = "0.1.0" authors = ["Michael-F-Bryan "] edition = "2018" build = "build.rs" # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html [dependencies] [build-dependencies] bindgen = "0.56.0" $ cat build.rs extern crate bindgen; fn main() { } $ cat src/lib.rs #[cfg(test)] mod tests { #[test] fn it_works() { assert_eq!(2 + 2, 4); } } $ cargo build Compiling repro v0.1.0 (/tmp/repro) Finished dev [unoptimized + debuginfo] target(s) in 0.10s ``` ---
**Author:** ![megha1906](https://sea1.discourse-cdn.com/flex019/user_avatar/users.rust-lang.org/megha1906/32/19189_2.png) [@megha1906](https://users.rust-lang.org/u/megha1906)\ **Post date:** [January 22, 2021, 10:16am UTC](https://users.rust-lang.org/t/bindgen-basic-help/11478/9 "2021-01-22T10:16:08Z")
Do i need to "cargo build" or rustc build.rs. cargo build gives different errors cannot find macro `llvm_asm` in this scope /mod.rs:16:5 | 16 | llvm\_asm!("syscall" | ^^^^^^^^ **strong text** ---
**Author:** ![megha1906](https://sea1.discourse-cdn.com/flex019/user_avatar/users.rust-lang.org/megha1906/32/19189_2.png) [@megha1906](https://users.rust-lang.org/u/megha1906)\ **Post date:** [January 22, 2021, 10:20am UTC](https://users.rust-lang.org/t/bindgen-basic-help/11478/10 "2021-01-22T10:20:04Z")
cargo --version cargo 1.43.0 $ rustc --version --verbose rustc 1.43.0 binary: rustc commit-hash: unknown commit-date: unknown host: x86\_64-unknown-linux-gnu release: 1.43.0 LLVM version: 9.0 ---
**Author:** ![Michael-F-Bryan](https://sea1.discourse-cdn.com/flex019/user_avatar/users.rust-lang.org/michael-f-bryan/32/28749_2.png) [@Michael-F-Bryan](https://users.rust-lang.org/u/Michael-F-Bryan)\ **Post date:** [January 22, 2021, 10:47am UTC](https://users.rust-lang.org/t/bindgen-basic-help/11478/11 "2021-01-22T10:47:06Z")
You should be building with `cargo build`. Cargo is the Rust package manager and looks after downloading dependencies and making sure they get compiled into your program. For more on how to compile things I'd recommend reading the corresponding chapter from the book: [https://doc.rust-lang.org/book/ch01-03-hello-cargo.html](https://doc.rust-lang.org/book/ch01-03-hello-cargo.html) > [@megha1906](#): > > cannot find macro `llvm_asm` in this scope [The `llvm_asm!()` macro](https://doc.rust-lang.org/stable/unstable-book/library-features/llvm-asm.html) was an unstable feature for telling LLVM (the thing inside Rust which generates machine code) to insert some assembly instructions. You'll need to opt into this unstable/incomplete feature it by adding `#![feature(llvm_asm)]` to the top of your `lib.rs` or `main.rs`. I believe it's since been superseded by [the `asm!()` macro](https://doc.rust-lang.org/stable/unstable-book/library-features/asm.html). ---
**Author:** ![megha1906](https://sea1.discourse-cdn.com/flex019/user_avatar/users.rust-lang.org/megha1906/32/19189_2.png) [@megha1906](https://users.rust-lang.org/u/megha1906)\ **Post date:** [January 22, 2021, 11:05am UTC](https://users.rust-lang.org/t/bindgen-basic-help/11478/12 "2021-01-22T11:05:04Z")
should i just add `#![feature(llvm_asm)]` in the first line of lib.rs? ---
**Author:** ![steffahn](https://sea1.discourse-cdn.com/flex019/user_avatar/users.rust-lang.org/steffahn/32/47569_2.png) [@steffahn](https://users.rust-lang.org/u/steffahn)\ **Post date:** [January 12, 2023, 9:02am UTC](https://users.rust-lang.org/t/bindgen-basic-help/11478/13 "2023-01-12T09:02:11Z")