[Bug 58191] New: dwrite tests fail to compile with mingw-gcc 15 due to attempt to link to truncf

[WineHQ Bugzilla]

http://bugs.winehq.org/show_bug.cgi?id=58191

Bug ID: 58191
           Summary: dwrite tests fail to compile with mingw-gcc 15 due to
                    attempt to link to truncf
           Product: Wine
           Version: 10.6
          Hardware: x86-64
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P2
         Component: dwrite
          Assignee: [e-mail]
          Reporter: [e-mail]
      Distribution: ---

Since my system updated mingw to gcc 15.1, Wine fails to build:

/usr/libexec/gcc/x86_64-w64-mingw32/ld:
dlls/dwrite/tests/x86_64-windows/layout.o: in function `test_pixelsnapping':
/home/stefan/build/_wine64/../../src/wine/dlls/dwrite/tests/layout.c:4782:(.text$test_pixelsnapping+0x312):
undefined reference to `truncf'

$ x86_64-w64-mingw32-gcc --version
x86_64-w64-mingw32-gcc (Gentoo 15.1.0 p55) 15.1.0

Windows 11's msvcrt.dll indeed does not export trunc(), truncf() or truncl(),
although ucrtbase.dll does. So adding the exports to our msvcrt would fix the
build but break running the tests on Windows.

The line in question doesn't call truncf. It calls floor(), which newer gcc
apparently lowers to truncf. Building the file in question with -O0 of
-fno-builtin-floor fixes the problem.