emcc error: member reference base type 'void' is not a structure or union

[sonygod]

build a simple code and got these error?

emcc src/Wasm_Clipper2.cpp -Iinclude -Llib -lClipper2emcc -o bin/clipper2tools.js -s EXPORTED_FUNCTIONS='["_malloc","_free","_create_offset_line"]' -s EXPORTED_RUNTIME_METHODS='["ccall", "cwrap"]' -s MALLOC=emmalloc -w -sALLOW_MEMORY_GROWTH -g3

platform:emscripten

include\clipper2/clipper.engine.h:307:53: error: member reference base type 'void' is not a structure or union
                        auto* result = childs_.emplace_back(std::move(p)).get();
                                       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~
include\clipper2/clipper.engine.h:386:58: error: member reference base type 'void' is not a structure or union
                        PolyPathD* result = childs_.emplace_back(std::move(p)).get();

[reunanen]

You need to have C++17 supported for emplace_back to return a value (reference).

You may find this helpful: emscripten-core/emscripten#5513

Alternatively, you should be able to relatively easily do something like this instead:

    childs_.emplace_back(std::move(p));
    auto* result = childs_.back().get();