On Monday, 15 May 2017 at 17:03:20 UTC, ag0aep6g wrote:
On 05/15/2017 02:27 PM, kinke wrote:
Some additional context: https://github.com/dlang/dmd/pull/5232
What I take from that is that changing the way arguments are
passed (particularly if they're reversed or not) is going to
break a ton of stuff.
Well, when I experimentally didn't reverse the args for extern(D)
back then for LDC (after patching druntime/Phobos inline asm
accordingly...), that single issue prevented a fully green
testsuite.
The problem is that druntime there goes the other way and invokes
a method via a function pointer, so in essence the inverse of
what you're after.
The problem there is that this/context may be passed differently
on Win64; I checked, and LDC only does it for `extern(C++)` for
Visual C++ compatibility, not for extern(D), so OTOH the
(absolutely unintuitive) resulting arguments order for Win64
should currently be:
extern(C++) BigStruct freeFunC(Object this, int b, int c)
=> __sret, this, b, c
extern(D) BigStruct freeFunD(Object this, int b, int c)
=> __sret, c, b, this
extern(C++) BigStruct Object.funC(int b, int c)
=> __this, __sret, b, c
extern(D) BigStruct Object.funD(int b, int c)
=> __sret, __this, c, b
And yes, for Win32 there's the __thiscall convention, but also
only for extern(C++).
`extern(C++)` functions/delegates have to follow it, obviously.
But then we can just say that implicit conversion doesn't work
with those.
Doesn't sound that bad as long as the front-end enforces it.
