TypeError: wasm.__wbindgen_global_argument_ptr is not a function

[markandrus]

Hi,

I'm trying to write some Rust "Hello, World!" code that can be shared between C and JavaScript. My project lives here. The C part is working, but I'm having some trouble getting the JavaScript part working. I'm following the "Basic Usage" example in this repo, the console.log example in this repo, and this example for calling Rust from C.

My first attempt used cfg to conditionally compile the necessary code, but it failed with

TypeError: wasm.__wbindgen_global_argument_ptr is not a function

src/lib.rs

#![feature(proc_macro, wasm_custom_section, wasm_import_module)]

#[cfg(target_arch = "wasm32")]
extern crate wasm_bindgen;
#[cfg(target_arch = "wasm32")]
use wasm_bindgen::prelude::*;

#[cfg(target_arch = "wasm32")]
#[wasm_bindgen]
extern {
    #[wasm_bindgen(js_namespace = console)]
    fn log(s: &str);
}

#[cfg(target_arch = "wasm32")]
#[wasm_bindgen]
pub fn greet(name: &str) {
    do_greet(name);
}

#[cfg(not(target_arch = "wasm32"))]
extern crate libc;
#[cfg(not(target_arch = "wasm32"))]
use std::ffi::CStr;
#[cfg(not(target_arch = "wasm32"))]
use libc::c_char;

#[cfg(not(target_arch = "wasm32"))]
fn log(str: &str) {
    println!("{}", str);
}

#[cfg(not(target_arch = "wasm32"))]
#[no_mangle]
pub extern "C" fn greet(name: *const c_char) {
    let c_name = unsafe { CStr::from_ptr(name) };
    do_greet(c_name.to_str().unwrap());
}

fn do_greet(name: &str) {
    log(&format!("Hello, {}!", name));
}

$ make

cargo build
   Compiling unicode-xid v0.1.0
   Compiling wasm-bindgen-shared v0.2.0
   Compiling serde v1.0.37
   Compiling fnv v1.0.6
   Compiling dtoa v0.4.2
   Compiling num-traits v0.2.2
   Compiling itoa v0.4.1
   Compiling libc v0.2.40
   Compiling cfg-if v0.1.2
   Compiling proc-macro2 v0.3.6
   Compiling quote v0.5.1
   Compiling syn v0.13.1
   Compiling serde_json v1.0.13
   Compiling serde_derive_internals v0.23.0
   Compiling serde_derive v1.0.37
   Compiling wasm-bindgen-backend v0.2.0
   Compiling wasm-bindgen-macro v0.2.0
   Compiling wasm-bindgen v0.2.0
   Compiling rust-c-js v0.1.0 (file:///Users/mroberts/src/personal/rust-c-js)
    Finished dev [unoptimized + debuginfo] target(s) in 30.1 secs
gcc src/main.c -L target/debug -lrust_c_js -o main
LD_LIBRARY_PATH=target/debug ./main
Hello, World!
cargo build --target wasm32-unknown-unknown
   Compiling libc v0.2.40
   Compiling cfg-if v0.1.2
   Compiling wasm-bindgen v0.2.0
   Compiling rust-c-js v0.1.0 (file:///Users/mroberts/src/personal/rust-c-js)
    Finished dev [unoptimized + debuginfo] target(s) in 0.94 secs
wasm-bindgen target/wasm32-unknown-unknown/debug/rust_c_js.wasm --nodejs --out-dir .
node src/main.js
/Users/mroberts/src/personal/rust-c-js/rust_c_js.js:40
                    cachedGlobalArgumentPtr = wasm.__wbindgen_global_argument_ptr();
                                                   ^

TypeError: wasm.__wbindgen_global_argument_ptr is not a function
    at globalArgumentPtr (/Users/mroberts/src/personal/rust-c-js/rust_c_js.js:40:52)
    at getGlobalArgument (/Users/mroberts/src/personal/rust-c-js/rust_c_js.js:45:29)
    at module.exports.__wbg_f_log_log_n (/Users/mroberts/src/personal/rust-c-js/rust_c_js.js:52:44)
    at _ZN9rust_c_js3log17h1f115e1b4ecdf46cE (wasm-function[19]:116)
    at _ZN9rust_c_js8do_greet17he15c7e5d2547b85bE (wasm-function[18]:285)
    at _ZN9rust_c_js5greet17h7ed355f005238f2eE (wasm-function[20]:54)
    at greet (wasm-function[21]:178)
    at Object.<anonymous> (/Users/mroberts/src/personal/rust-c-js/src/main.js:2:1)
    at Module._compile (module.js:649:30)
    at Object.Module._extensions..js (module.js:660:10)
make: *** [test-js] Error 1

Next, I tried to consolidate my cfg statements using cfg_if. That failed with

error[E0428]: the name `__wasm_bindgen_generated_greet` is defined multiple times

src/lib.rs

#![feature(proc_macro, wasm_custom_section, wasm_import_module)]

#[macro_use]
extern crate cfg_if;

cfg_if! {
    if #[cfg(target_arch = "wasm32")] {

        extern crate wasm_bindgen;
        use wasm_bindgen::prelude::*;

        #[wasm_bindgen]
        extern {
            #[wasm_bindgen(js_namespace = console)]
            fn log(s: &str);
        }

        #[wasm_bindgen]
        pub fn greet(name: &str) {
            do_greet(name);
        }
    } else {
        extern crate libc;
        use std::ffi::CStr;
        use libc::c_char;

        fn log(str: &str) {
            println!("{}", str);
        }

        #[no_mangle]
        pub extern "C" fn greet(name: *const c_char) {
            let c_name = unsafe { CStr::from_ptr(name) };
            do_greet(c_name.to_str().unwrap());
        }
    }
}

fn do_greet(name: &str) {
    log(&format!("Hello, {}!", name));
}

$ make

cargo build
   Compiling unicode-xid v0.1.0
   Compiling wasm-bindgen-shared v0.2.0
   Compiling fnv v1.0.6
   Compiling serde v1.0.37
   Compiling dtoa v0.4.2
   Compiling itoa v0.4.1
   Compiling num-traits v0.2.2
   Compiling libc v0.2.40
   Compiling cfg-if v0.1.2
   Compiling proc-macro2 v0.3.6
   Compiling quote v0.5.1
   Compiling syn v0.13.1
   Compiling serde_json v1.0.13
   Compiling serde_derive_internals v0.23.0
   Compiling serde_derive v1.0.37
   Compiling wasm-bindgen-backend v0.2.0
   Compiling wasm-bindgen-macro v0.2.0
   Compiling wasm-bindgen v0.2.0
   Compiling rust-c-js v0.1.0 (file:///Users/mroberts/src/personal/rust-c-js)
    Finished dev [unoptimized + debuginfo] target(s) in 27.70 secs
gcc src/main.c -L target/debug -lrust_c_js -o main
LD_LIBRARY_PATH=target/debug ./main
Hello, World!
cargo build --target wasm32-unknown-unknown
   Compiling libc v0.2.40
   Compiling cfg-if v0.1.2
   Compiling wasm-bindgen v0.2.0
   Compiling rust-c-js v0.1.0 (file:///Users/mroberts/src/personal/rust-c-js)
error[E0428]: the name `__wasm_bindgen_generated_greet` is defined multiple times
  --> src/lib.rs:6:1
   |
6  | / cfg_if! {
7  | |     if #[cfg(target_arch = "wasm32")] {
8  | |
9  | |         extern crate wasm_bindgen;
...  |
18 | |         #[wasm_bindgen]
   | |         --------------- previous definition of the value `__wasm_bindgen_generated_greet` here
...  |
36 | |     }
37 | | }
   | |_^ `__wasm_bindgen_generated_greet` redefined here
   |
   = note: `__wasm_bindgen_generated_greet` must be defined only once in the value namespace of this module
   = note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)

error[E0428]: the name `__wasm_bindgen_generated_greet` is defined multiple times
  --> <macro expansion>:1:1
   |
1  | #[wasm_bindgen]
   | ^ `__wasm_bindgen_generated_greet` redefined here
   | 
  ::: src/lib.rs:18:9
   |
18 |         #[wasm_bindgen]
   |         --------------- previous definition of the value `__wasm_bindgen_generated_greet` here
   |
   = note: `__wasm_bindgen_generated_greet` must be defined only once in the value namespace of this module

error[E0428]: the name `__wasm_bindgen_generated_greet` is defined multiple times
  --> <macro expansion>:1:1
   |
1  | #[wasm_bindgen]
   | ^ `__wasm_bindgen_generated_greet` redefined here
   | 
  ::: src/lib.rs:18:9
   |
18 |         #[wasm_bindgen]
   |         --------------- previous definition of the value `__wasm_bindgen_generated_greet` here
   |
   = note: `__wasm_bindgen_generated_greet` must be defined only once in the value namespace of this module

error: aborting due to 3 previous errors

For more information about this error, try `rustc --explain E0428`.
error: Could not compile `rust-c-js`.

To learn more, run the command again with --verbose.
make: *** [target/wasm32-unknown-unknown/debug/rust_c_js.wasm] Error 101

[alexcrichton]

Thanks for the report! For the first issue can you try updating the wasm-bindgen tool and the dependency? I'm curious if that was a version mismatch going on perhaps.

For the latter issue I'm digging in to see what's what!

[markandrus]

Thanks, @alexcrichton. I checked the CLI and the version used by Cargo. Both appeared to be 0.2.0. I've since updated to 0.2.1 (on both) and I'm still getting the TypeError issue.

$ wasm-bindgen --version
wasm-bindgen 0.2.0
$ cargo install wasm-bindgen-cli --force
$ wasm-bindgen --version
wasm-bindgen 0.2.1

$ make

cargo build
    Updating registry `https://github.com/rust-lang/crates.io-index`
 Downloading wasm-bindgen v0.2.1
 Downloading wasm-bindgen-macro v0.2.1
 Downloading wasm-bindgen-backend v0.2.1
   Compiling unicode-xid v0.1.0
   Compiling wasm-bindgen-shared v0.2.1
   Compiling fnv v1.0.6
   Compiling serde v1.0.37
   Compiling dtoa v0.4.2
   Compiling num-traits v0.2.2
   Compiling itoa v0.4.1
   Compiling cfg-if v0.1.2
   Compiling libc v0.2.40
   Compiling proc-macro2 v0.3.6
   Compiling quote v0.5.1
   Compiling syn v0.13.1
   Compiling serde_json v1.0.13
   Compiling serde_derive_internals v0.23.0
   Compiling serde_derive v1.0.37
   Compiling wasm-bindgen-backend v0.2.1
   Compiling wasm-bindgen-macro v0.2.1
   Compiling wasm-bindgen v0.2.1
   Compiling rust-c-js v0.1.0 (file:///Users/mroberts/src/personal/rust-c-js)
    Finished dev [unoptimized + debuginfo] target(s) in 26.32 secs
gcc src/main.c -L target/debug -lrust_c_js -o main
LD_LIBRARY_PATH=target/debug ./main
Hello, World!
cargo build --target wasm32-unknown-unknown
   Compiling cfg-if v0.1.2
   Compiling libc v0.2.40
   Compiling wasm-bindgen v0.2.1
   Compiling rust-c-js v0.1.0 (file:///Users/mroberts/src/personal/rust-c-js)
    Finished dev [unoptimized + debuginfo] target(s) in 1.27 secs
wasm-bindgen target/wasm32-unknown-unknown/debug/rust_c_js.wasm --nodejs --out-dir .
node src/main.js
/Users/mroberts/src/personal/rust-c-js/rust_c_js.js:34
                    cachedGlobalArgumentPtr = wasm.__wbindgen_global_argument_ptr();
                                                   ^
TypeError: wasm.__wbindgen_global_argument_ptr is not a function
    at globalArgumentPtr (/Users/mroberts/src/personal/rust-c-js/rust_c_js.js:34:52)
    at getGlobalArgument (/Users/mroberts/src/personal/rust-c-js/rust_c_js.js:39:29)
    at module.exports.__wbg_f_log_log_n (/Users/mroberts/src/personal/rust-c-js/rust_c_js.js:46:44)
    at _ZN9rust_c_js3log17h1f115e1b4ecdf46cE (wasm-function[19]:116)
    at _ZN9rust_c_js8do_greet17he15c7e5d2547b85bE (wasm-function[18]:285)
    at _ZN9rust_c_js5greet17h7ed355f005238f2eE (wasm-function[20]:54)
    at greet (wasm-function[21]:178)
    at Object.<anonymous> (/Users/mroberts/src/personal/rust-c-js/src/main.js:2:1)
    at Module._compile (module.js:649:30)
    at Object.Module._extensions..js (module.js:660:10)
make: *** [test-js] Error 1

[alexcrichton]

Aha! This took me too long to find... The type error can be fixed by updating this line, you'll want to import ../rust_c_js, not ../rust_c_js_bg which is an internal helper (and one that I'll go remove now!)

[markandrus]

Ah, crud. Thanks!!!

[alexcrichton]

Er actually, hm...

So I can't actually remove rustc_c_js_bg as that's supposed to be the "wasm es module" which is useful for poking at the memory. I've opened #116 to dedicate to the experience there.

I've diagnosed the cfg_if! bug and it's unfortunately a rustc bug but I'll open an issue there soon and cc this.

[alexcrichton]

Ok for the weird issue with cfg_if! I've diagnosed that as rust-lang/rust#49846 which is in general tracked by rust-lang/rust#43081, so I'm going to close this