feat(c-api) Implement cross-compilation API in C

[Hywan]

Description

Depends on #2071 (merged).

This patch implements wasm_target_t, wasm_triple_t, wasm_cpu_features_t.

This patch also implements wasm_config_set_target to set… a wasm_target_t. The wasm_config_new_with_engine function has been updated to handle the new wasm_target_t.

Example

int main() {
    // Create the configuration.
    wasm_config_t* config = wasm_config_new();

    // Set the target.
    {
      // Declare the target triple.
      wasm_triple_t* triple;
  
      {
          wasm_name_t triple_name;
          wasm_name_new_from_string(&triple_name, "x86_64-apple-darwin");
  
          triple = wasm_triple_new(&triple_name);
  
          wasm_name_delete(&triple_name);
      }
  
      assert(triple);
  
      // Declare the target CPU features.
      wasm_cpu_features_t* cpu_features = wasm_cpu_features_new();
  
      {
          wasm_name_t cpu_feature_name;
          wasm_name_new_from_string(&cpu_feature_name, "sse2");
  
          wasm_cpu_features_add(cpu_features, &cpu_feature_name);
  
          wasm_name_delete(&cpu_feature_name);
      }
  
      assert(cpu_features);
  
      // Create the target!
      wasm_target_t* target = wasm_target_new(triple, cpu_features);
      assert(target);
  
      // Set the target onto the configuration!
      wasm_config_set_target(config, target);
    }

    // Create the engine.
    wasm_engine_t* engine = wasm_engine_new_with_config(config);

    // Check we have an engine!
    assert(engine);

    // Free everything.
    wasm_engine_delete(engine);

    return 0;
}

Review

• Add a short description of the the change to the CHANGELOG.md file

[MarkMcCaskey]

Looks pretty good overall

[MarkMcCaskey]

Does it make sense to set the target for a headless-only engine?

It's fine for symmetry I suppose but I don't think this can ever do anything

[Hywan]

Yeah I was wondering if that was making sense. Using the target makes sense only when compiling, but we never know, maybe one day, someone, somewhere… :-p. Let's keep it for “the symmetry” as you said, how does it sound?

[MarkMcCaskey]

These ones too

[MarkMcCaskey]

I don't think we need Option around all user-supplied pointers, the standard wasm-c-api doesn't bother with that in a lot of cases, if the pointer is invalid it'll crash or do what C does

[Hywan]

Yeah but I prefer to prevent bad usage of our API. That's what we already do everywhere almost.

[Hywan]

bors r+

[Hywan]

bors r-

waiting on #2083 to finish

[bors]

Canceled.

[Hywan]

bors r+

[bors]

Build succeeded:

• Audit
• Code lint
• Test cross-compile on linux
• Test cross-compile on macos
• Test on linux-aarch64
• Test on linux-x64
• Test on macos-x64
• Test on windows-x64