Make WASM3 build bindgen instead of requiring the CLI program to be installed

[Michael-F-Bryan]

This is something both @jacekpie and @kthakore ran into.

Out of the box we are unable to compile wasm3-sys because its build script requires the bindgen CLI tool to be installed. There is a build-bindgen feature flag which tells it to pull bindgen in as a crate instead that we should use.

[Michael-F-Bryan]

It looks like you can't naively apply the following patch because wasm3-sys uses an older version of bindgen (which in turn requires an old version of clang-sys, which clashes with the tflite build script).

diff --git a/crates/wasm3-runtime/Cargo.toml b/crates/wasm3-runtime/Cargo.toml
index c288bc2817..dab6f3a534 100644
--- a/crates/wasm3-runtime/Cargo.toml
+++ b/crates/wasm3-runtime/Cargo.toml
@@ -18,7 +18,7 @@ anyhow = "1.0.40"
 log = "0.4.14"
 hotg-rune-runtime = { path = "../runtime", version = "^0.5.4-dev"}
 hotg-rune-core = { path = "../rune-core", version = "^0.5.4-dev"}
-wasm3 = "0.1.3"
+wasm3 = { version = "0.1.3", features = ["build-bindgen"] }

 [dev-dependencies]
 tempfile = "3.2.0"

The build error:

$ cargo build -p hotg-rune-wasm3-runtime
error: failed to select a version for `clang-sys`.
    ... required by package `bindgen v0.54.0`
    ... which is depended on by `wasm3-sys v0.1.2`
    ... which is depended on by `wasm3 v0.1.3`
    ... which is depended on by `hotg-rune-wasm3-runtime v0.5.4-dev (/home/michael/Documents/hotg-ai/rune/crates/wasm3-runtime)`
versions that meet the requirements `^0.29` are: 0.29.3, 0.29.2, 0.29.1, 0.29.0

the package `clang-sys` links to the native library `clang`, but it conflicts with a previous package which links to `clang` as well:
package `clang-sys v1.2.0`
    ... which is depended on by `bindgen v0.55.1`
    ... which is depended on by `tflite v0.9.6`
    ... which is depended on by `hotg-rune-cli v0.5.4-dev (/home/michael/Documents/hotg-ai/rune/crates/rune-cli)`
Only one package in the dependency graph may specify the same links value. This helps ensure that only one copy of a native library is linked in the final binary. Try to adjust your dependencies so that only one package uses the links ='clang-sys' value. For more information, see https://doc.rust-lang.org/cargo/reference/resolver.html#links.

failed to select a version for `clang-sys` which could resolve this conflict

[Michael-F-Bryan]

Updating to wasm3 v0.2.0 now results in the opposite problem... tflite pulls in bindgen v0.55.1 (clang-sys v0.29.0) while wasm3-sys pulls in bindgen v0.58.1 (clang-sys 1.20), and linking to multiple versions of the same *-sys crate isn't allowed because you'd get duplicate symbol errors when linking in the native library they bind to.

[jonas-schievink]

I've opened https://github.com/boncheolgu/tflite-rs/pull/53 to update tflite's bindgen dependency to a version that shouldn't cause this conflict.

[Michael-F-Bryan]

I just tried making the switch locally and ran into the same linking conflict because the wasm3-sys on crates.io uses bindgen v0.54.0 while hotg-runecoral uses bindgen v0.59.1.

I've created https://github.com/wasm3/wasm3-rs/issues/32 upstream.