Wasi + Emscripten: configure behavior with --enable-optimizations seems incorrect?

[hoodmane]

configure.ac sets DEF_MAKE_ALL_RULE to:

• if --enable-optimizations is passed, then profile-opt
• if ac_sys_system is Emscripten or WASI then build_wasm
• if neither of these, then build_all.

build_wasm is a modified version of the build_all target that drops some targets that don't build correctly in webassembly targets or are unneeded. This logic hasn't been added for the case when --enable-optimizations is passed. I think the best solution for now would be to check for these targets with --enable-optimizations and error out. I don't think PGO will work on the wasm targets without tinkering either way.

Linked PRs

• GH-126748: amend configure.rst description for the 'build_wasm' make target #126687

[brettcannon]

I agree that erroring out if WASI or Emscripten is selected is best.