[PATCH 0/1] MR6949: gdiplus: Cast enums to unsigned type when validating its value.

[Jacek Caban (＠jacek)]

According to the spec, the compiler is free to use a signed, unsigned, or even char type for enums, provided all values fit within the type. For example, constructs like `*_FORCE_DWORD` can force an unsigned type using a value like `0xffffffff`. While some headers use this approach, it’s inconsistent and 0x7fffffff is often used instead.

Unfortunately, MSVC and GCC differ in their behavior: GCC always uses an unsigned type, while MSVC uses a signed type when possible. Consequently, Clang’s behavior depends on the mode being used.

Additionally, Clang emits a warning for "useless" checks when building Wine in MinGW mode. For instance:
```
dlls/gdiplus/graphics.c:7337:18: warning: result of comparison of unsigned enum expression < 0 is always false [-WTautological-unsigned-enum-zero-compare]
 7337 |        src_space < 0 || src_space > CoordinateSpaceDevice)
```

This warning is impractical for code that aims to be portable. The check is not tautological when building in MSVC mode (e.g., in our CI). I considered disabling the warning, but since this is the only place in the codebase where it’s problematic, I believe we can simply adjust the check.

This resolves the last warning in LLVM builds, allowing -Werror to be used in MinGW mode as well.

-- 
https://gitlab.winehq.org/wine/wine/-/merge_requests/6949

[PATCH 1/1] gdiplus: Cast enums to unsigned type when validating its value.

[Jacek Caban]

From: Jacek Caban <jacek(a)codeweavers.com>

Fixes -Wtautological-unsigned-enum-zero-compare warning on llvm-mingw.
---
 dlls/gdiplus/graphics.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/dlls/gdiplus/graphics.c b/dlls/gdiplus/graphics.c
index 0574f6e8aba..4699f8c21d3 100644
--- a/dlls/gdiplus/graphics.c
+++ b/dlls/gdiplus/graphics.c
@@ -7332,9 +7332,8 @@ GpStatus gdip_transform_points(GpGraphics *graphics, GpCoordinateSpace dst_space
 GpStatus WINGDIPAPI GdipTransformPoints(GpGraphics *graphics, GpCoordinateSpace dst_space,
                                         GpCoordinateSpace src_space, GpPointF *points, INT count)
 {
-    if(!graphics || !points || count <= 0 ||
-       dst_space < 0 || dst_space > CoordinateSpaceDevice ||
-       src_space < 0 || src_space > CoordinateSpaceDevice)
+    if(!graphics || !points || count <= 0 || (UINT)dst_space > CoordinateSpaceDevice ||
+       (UINT)src_space > CoordinateSpaceDevice)
         return InvalidParameter;
 
     if(graphics->busy)
-- 
GitLab

https://gitlab.winehq.org/wine/wine/-/merge_requests/6949

[PATCH 0/1] MR6949: gdiplus: Cast enums to unsigned type when validating its value. - approved

[Esme Povirk (＠madewokherd)]

This merge request was approved by Esme Povirk.
-- 
https://gitlab.winehq.org/wine/wine/-/merge_requests/6949