Avoid running wasm-opt when compiling test programs

[philipc]

wasm-opt will strip DWARF debug info, which causes a test failure for debug::lldb::dwarf_codegen_optimized_wasm_optimized.

clang automatically runs wasm-opt if it is found in PATH and if optimization is enabled. clang-20 has a --no-wasm-opt option, but that doesn't work for wasi-sdk-25.

[alexcrichton]

Is there a compiler flag to tell wasm-opt to preserve debuginfo we could pass? I'm a bit wary to null out PATH as I think that may cause issues on Windows and otherwise thwart detection of various tools clang might otherwise do?

[philipc]

wasm-opt has a -g flag which may or may not be sufficient, but I can't see a way to pass that through clang. But even if that worked, I would still prefer to not run wasm-opt. I don't think tests should be changing behaviour based on whether wasm-opt happens to be in the path.

I could add something to wasmtime to build a binary called wasm-opt which does nothing, and place that first in the path when building the test program.

Or I could change my own system to avoid the problem, but that won't fix it for others.

[philipc]

Maybe it's best to wait for wasi-sdk to use a newer clang version so we can use --no-wasm-opt.