[qt/qt/qtimageformats]: Summary of bulk changes made

Git repository change summary for qt/qt/qtimageformats
Pushed by mirror-service into branch '6.11'.
Changed from 607945496bd71aed26b7b69b682773a02d96dd67 to f9342fa4954d270beb5aae0abae33e6713c533cf
Acknowledgement was received that this change introduces only existing code that has been pushed to another public open source repository.

This change contains the following new commits:

Git commit f9342fa4954d270beb5aae0abae33e6713c533cf by Qt Cherry-pick Bot (on behalf of Marc Mutz) on 21/07/2026 at 00:45..
QTiffHandler: fix UB (integer size mismatch in varargs) in write()

The old code stored a qsizetype through variadic arguments (...) while
the variadic function read it back as a uint32_t.

This is UB at the C/C++ level¹, but apparently ABIs handle this
gracefully, even BE ones, even on the stack (as opposed to in
registers) because (TIL) va_arg arguments always occupy at least a
machine-word-sized slot (think Q5List) and, regardless of endianness,
the 32-bit extraction always reads the LSB32 of such a slot².

Be that as it may, though: I think we should fix the C++ UB, even if
concrete ABIs allow this: Just because the ABI allows it doesn't mean
the compiler's optimizer doesn't find the UB and exploit it.

So explicitly narrow the QByteArray::size() to uint32_t and use
q20::cmp_equal to check whether they differ. If they do, we overflowed
and don't continue. This is not very likely, considering ICC profiles
shouldn't be > 2GiB, but API misuse could cause this, presumably, and
it doesn't cost much.

As a drive-by, remove the unnecessary reinterpret_cast (char* is
allowed to alias void* in va_arg¹) and use data() instead of
constData() (the QByteArray is already const). This helps keep line
lengths in check. Finally, place the opening { following the
multi-line if condition on a line of its own, because the Qt Style
Guide is wrong on this: if it's placed at the end of the last line of
the condition, this whole thing becomes totally unreadable.

References:

¹ C11 7.16.1.1p2 (inherited by C++ via <cstdarg>):
  https://port70.net/~nsz/c/c11/n1570.html#7.16.1.1

² Here are some example ABIs:
- System V AMD64 psABI, Section "The va_arg Macro", Steps 9 and 10.
  https://github.com/hjl-tools/x86-psABI/wiki/x86-64-psABI-1.0.pdf
  (LE only)
- AAPCS64 Appendix 14.4.
  https://github.com/ARM-software/abi-aa/blob/main/aapcs64/aapcs64.rst
  (cf. #ifdef BIG_ENDIAN)
- Power: Section "Parameter Save Area" → "each parameter occupies one
  or more doublewords"
  https://openpowerfoundation.org/specifications/64bitelfabi/
  ("Sign or zero extend values shorter than a doubleword...")

Amends d63c1d05e455921b1ea4e351e770316c3494ee63 (5.14), but really the
port of QByteArray::size_type to qsizetype (6.0).

Pick-to: 6.8 6.5
Change-Id: Id971d73c1e7b3138139fc83bf5406312319fb5cf
Reviewed-by: Thiago Macieira <[email protected]>
(cherry picked from commit a5925c5053893ddfa9df2affc65048c60850eb24)
Reviewed-by: Qt Cherry-pick Bot <[email protected]>
(cherry picked from commit aa3f6b61e7be2fe449b2eab57948c7b1fc77b082)
https://invent.kde.org/qt/qt/qtimageformats/-/commit/f9342fa4954d270beb5aae0abae33e6713c533cf