I've tried to start building my project with xfbuild today (running everything through DMD was finally starting to get slow), and every so often, Optlink dies with something like this:<div><div>OPTLINK (R) for Win32  Release 8.00.8</div>

<div>Copyright (C) Digital Mars 1989-2010  All rights reserved.</div><div><a href="http://www.digitalmars.com/ctg/optlink.html">http://www.digitalmars.com/ctg/optlink.html</a></div><div>.objs\dinecraft-world-backend-backend.obj(dinecraft-world-backend-backend) </div>

<div> Error 42: Symbol Undefined _D3std11concurreéy83__T6_spawnTOC9dinecraft5world7backenÿd12W€„—B€†ŽTS€‘Ð3TidZ€‡ÐFbPF€°Ó€—Òv€ÇÈ€–—</div><div>.objs\dinecraft-world-backend-backend.obj(dinecraft-world-backend-backend) </div>

<div> Error 42: Symbol Undefined _D3std11concurreéy59__T5_sendTOC9dinecraft5world7back€ƒ›6bridge13ChunkResponseZ€†¸FS€‘Ö3Tid€±Îv</div><div>.objs\dinecraft-world-backend-backend.obj(dinecraft-world-backend-backend) </div>
<div>
 Error 42: Symbol Undefined _D3std11concurreéy60__T5_sendTOC9dinecraft5world7back€ƒ›6bridge14PlayerResponseZ€†¹FS€‘×3Tid€²Ïv</div><div>.objs\dinecraft-world-backend-backend.obj(dinecraft-world-backend-backend) </div><div>

 Error 42: Symbol Undefined _D3std11concurrency262__T8checkopsTDFOC9dinecraft6global11StopMessageZvTDFOC9dinecraft5world7bac16BA63AB4F5238EB56B8A073CCF850BC</div><div>.objs\dinecraft-world-backend-backend.obj(dinecraft-world-backend-backend) </div>

<div> Error 42: Symbol Undefined _D3std11concurrency10MessageBox257__T3getTDFOC9dinecraft6global11StopMessageZvTDFOC9dinecraft5wo153D92039F751A809C20E14F769954BC</div><div>.objs\dinecraft-world-gen-worldgen.obj(dinecraft-world-gen-worldgen) </div>

<div> Error 42: Symbol Undefined _D3std11concurreéy75__T6_spawnTOC9dinecraft5world3gen8€…Š€„‰W€„‰GenTS€‘È3TidZ€‡ÈFbPF€¨Ë€—Êv€¿À€–—</div><div>.objs\dinecraft-world-gen-worldgen.obj(dinecraft-world-gen-worldgen) </div><div>

 Error 42: Symbol Undefined _D3std4conv62__T6toImplTAyaTC9dinecraft5world7backend6bridge12ChunkRequestZ€‡»F€®·x€ƒêZÚ</div><div>.objs\dinecraft-world-gen-worldgen.obj(dinecraft-world-gen-worldgen) </div><div> Error 42: Symbol Undefined _D3std11concurreéy102__T8checkopsTDFOC9dinecraft5world7backend6bridge12ChunkRequestZv€�´6global11StopMessageZvZ€‰ãF€³ã€¥âv</div>

<div>.objs\dinecraft-world-gen-worldgen.obj(dinecraft-world-gen-worldgen) </div><div> Error 42: Symbol Undefined _D3std11concurreéy10MessageBox97__T3getTDFOC9dinecraft5world7backend6bridge12ChunkRequestZv€�´6global11Stop€‡ãZvZ€„ÞMF€³ß€¥Þb</div>

</div><div><br></div><div>To me, this looks like I'm somehow missing template implementations. When I delete all the object files and build again, everything generally works. Is there any reason this happens and/or a way to fix it?</div>