[PATCH 0/1] MR3841: wineps: Fix EMRPOLYDRAW16 printing.

[Piotr Caban (＠piotr)]

It fixes EMRPOLYDRAW16 printing when -O2 option is used (in GCC 12.3.1). The
compiler assumes that apts table has 0 or 1 elements and optimizes the loop
out.

Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=55486

[PATCH 1/1] wineps: Fix EMRPOLYDRAW16 printing.

[Piotr Caban]

From: Piotr Caban

It fixes EMRPOLYDRAW16 printing when -O2 option is used (in GCC 12.3.1). The
compiler assumes that apts table has 0 or 1 elements and optimizes the loop
out.

Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=55486
---
 dlls/wineps.drv/printproc.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/dlls/wineps.drv/printproc.c b/dlls/wineps.drv/printproc.c
index b899814f8c1..74f43b6d27c 100644
--- a/dlls/wineps.drv/printproc.c
+++ b/dlls/wineps.drv/printproc.c
@@ -2738,8 +2738,8 @@ static int WINAPI hmf_proc(HDC hdc, HANDLETABLE *htable,
         if (!pts) return 0;
         for (i = 0; i < p->cpts; i++)
         {
-            pts[i].x = p->apts[i].x;
-            pts[i].y = p->apts[i].y;
+            pts[i].x = ((const POINTS *)p->apts)[i].x;
+            pts[i].y = ((const POINTS *)p->apts)[i].y;
         }
         i = poly_draw(data->ctx, pts, (BYTE *)(p->apts + p->cpts), p->cpts) &&
             MoveToEx(data->ctx->hdc, pts[p->cpts - 1].x, pts[p->cpts - 1].y, NULL);

[Huw Davies (＠huw)]

Isn't this compiler bug going to affect a lot of places in Wine?

[Piotr Caban (＠piotr)]

On Fri Sep 15 09:02:53 2023 +0000, Huw Davies wrote:
> Isn't this compiler bug going to affect a lot of places in Wine?

I don't think it's a compiler bug. In this case the apts table is not the last field of the struct.

I've looked on all the structures in wingdi.h. There are more structures that use variable sized array that is not last in the structure. All the other places already needed casts and were not affected. Similar code in gdi32 already has an implicit cast.

I don't know if any other part of wine is affected but such structures are uncommon - fields after variable sized array can't be accessed in normal way.

[Huw Davies (＠huw)]

On Fri Sep 15 09:02:53 2023 +0000, Piotr Caban wrote:
> I don't think it's a compiler bug. In this case the apts table is not
> the last field of the struct.
> I've looked on all the structures in wingdi.h. There are more structures
> that use variable sized array that is not last in the structure. All the
> other places already needed casts and were not affected. Similar code in
> gdi32 already has an implicit cast.
> I don't know if any other part of wine is affected but such structures
> are uncommon - fields after variable sized array can't be accessed in
> normal way.

Ah right sorry, got it.

[PATCH 0/1] MR3841: wineps: Fix EMRPOLYDRAW16 printing. - approved

[Huw Davies (＠huw)]

This merge request was approved by Huw Davies.