digitalmars.D.bugs - [Issue 16987] New: ABI error wrt. COM interfaces returning structs
- via Digitalmars-d-bugs (25/26) Dec 19 2016 https://issues.dlang.org/show_bug.cgi?id=16987
https://issues.dlang.org/show_bug.cgi?id=16987 Issue ID: 16987 Summary: ABI error wrt. COM interfaces returning structs Product: D Version: D2 Hardware: All OS: Windows Status: NEW Severity: major Priority: P1 Component: dmd Assignee: nobody puremagic.com Reporter: kinke gmx.netFrom http://forum.dlang.org/post/tiyttpodenppvlfxixcw forum.dlang.org, relevantwrt. interfacing with DirectX libraries: COM classes/interfaces are apparently subject to a separate ABI. Unfortunately, googling it hasn't turned up any official (and not even some inofficial) documentation so far. Based on the first few tests on Win64, integers are returned in RAX, floats (and I guess doubles too) in XMM0, and structs (incl. 2x int32 and 2x float) via hidden sret pointer, with `this` pointer in RCX (1st arg) and `sret` in RDX (2nd arg). Compared to the normal Win64 C++ ABI it just seems more conservative by always returning structs via hidden pointer. While at it, please also fix https://issues.dlang.org/show_bug.cgi?id=16527 by simply swapping the order of `this` and `sret` pointer arguments on Windows (32-bit: extern(C++) methods only, 64-bit: always; LDC already does so). --
Dec 19 2016