`compiler-artifact` message doesn't include WASM files for `--example ...` builds

[tangmi]

Problem

Hi all, when I build a binary with --target wasm32-unknown-emscripten, the compiler-artifact message includes the .js and .wasm files under the filenames property. However, when I build an example with --example ..., only the .js file appears in the compiler-artifact message.

cargo-web depends on the compiler-artifacts message to determine which files to serve for its cargo web start command, but it seems no message from cargo provides references to the generated .wasm files for example builds.

Thanks for your time!

Steps

I'm currently experiencing this with the cube example in gfx.

Example output of building cargo build --message-format json --target wasm32-unknown-emscripten --example cube (this output is missing the .wasm file):

{
    "reason": "compiler-artifact",
    "package_id": "gfx_app 0.9.0 (path+file:///E:/external/gfx)",
    "target": {
        "kind": [
            "example"
        ],
        "crate_types": [
            "bin"
        ],
        "name": "cube",
        "src_path": "E:\\external\\gfx\\examples/cube/main.rs",
        "edition": "2015"
    },
    "profile": {
        "opt_level": "0",
        "debuginfo": 2,
        "debug_assertions": true,
        "overflow_checks": true,
        "test": false
    },
    "features": [
        "default"
    ],
    "filenames": [
        "E:\\external\\gfx\\target\\wasm32-unknown-emscripten\\debug\\examples\\cube.js"
        // missing path to: `target\wasm32-unknown-emscripten\debug\examples\cube-9626de08b1305a96.wasm`!
    ],
    "executable": "E:\\external\\gfx\\target\\wasm32-unknown-emscripten\\debug\\examples\\cube.js",
    "fresh": false
}

For comparison, I have copied it to the src directory as cube_example_as_bin and added an entry to the Cargo.toml file:

[[bin]]
name = "cube"
path = "src/cube_example_as_bin/main.rs"

Example output of building cargo build --message-format json --target wasm32-unknown-emscripten (this output includes the .wasm file):

{
    "reason": "compiler-artifact",
    "package_id": "gfx_app 0.9.0 (path+file:///E:/external/gfx)",
    "target": {
        "kind": [
            "bin"
        ],
        "crate_types": [
            "bin"
        ],
        "name": "cube",
        "src_path": "E:\\external\\gfx\\src/cube_example_as_bin/main.rs",
        "edition": "2015"
    },
    "profile": {
        "opt_level": "0",
        "debuginfo": 2,
        "debug_assertions": true,
        "overflow_checks": true,
        "test": false
    },
    "features": [
        "default"
    ],
    "filenames": [
        "E:\\external\\gfx\\target\\wasm32-unknown-emscripten\\debug\\cube.js",
        "E:\\external\\gfx\\target\\wasm32-unknown-emscripten\\debug\\cube.wasm"
    ],
    "executable": "E:\\external\\gfx\\target\\wasm32-unknown-emscripten\\debug\\cube.js",
    "fresh": false
}

Possible Solution(s)

Notes

Output of cargo version: cargo 1.33.0 (f099fe94b 2019-02-12)

[ehuss]

Oops, looks like a simple fix. I'm going to review the code to see if there are other places where the same mistake was made.