wasm_c_api.c: improve unimplemented cases

[yamt]

ASSERT_NOT_IMPLEMENTED is bh_assert, which might be no-op.
in that case, it's better to fall back to the "default" case,
which reports an error properly.

[wenyongh]

This leads to compilation warning in debug mode: warning: this statement may fall through
How about changing to:

            case IMPORT_KIND_MEMORY:
            case IMPORT_KIND_TABLE:
                ASSERT_NOT_IMPLEMENTED();
                goto handle_default;
            handle_default:
            default:

[yamt]

it's unfortunate that clang doesn't recognize the traditional /* FALLTHROUGH */.
how do you think about introducing something like #defile BH_FALLTHROUGH __attribute__((fallthrough))?

[wenyongh]

Had better not, it might be not friendly to some compilers.
We have the similar case in:
https://github.com/bytecodealliance/wasm-micro-runtime/blob/main/core/iwasm/compilation/aot_emit_numberic.c#L455-L458
The modification such as that should be OK.

Or how about handling default together with case IMPORT_KIND_MEMORY/IMPORT_KIND_TABLE:

            case IMPORT_KIND_MEMORY:
            case IMPORT_KIND_TABLE:
            default:
                  ASSERT_NOT_IMPLEMENTED();
                  LOG_WARNING("%s meets unsupported kind: %d", __FUNCTION__,
                              import_rt->kind);
                  goto failed;

[yamt]

Had better not, it might be not friendly to some compilers. We have the similar case in: https://github.com/bytecodealliance/wasm-micro-runtime/blob/main/core/iwasm/compilation/aot_emit_numberic.c#L455-L458 The modification such as that should be OK.

ok

Or how about handling default together with case IMPORT_KIND_MEMORY/IMPORT_KIND_TABLE:

            case IMPORT_KIND_MEMORY:
            case IMPORT_KIND_TABLE:
            default:
                  ASSERT_NOT_IMPLEMENTED();
                  LOG_WARNING("%s meets unsupported kind: %d", __FUNCTION__,
                              import_rt->kind);
                  goto failed;

i think it makes the most sense this particular case. done.

[wenyongh]

Same as above