[gdal-dev] clang-tidy 23 bugprone-signed-bitwise and CPL_LSBINT32PTR macros

[Even Rouault]

Andrew,

does https://github.com/OSGeo/gdal/pull/14524 fix the warning?

Even

Le 10/05/2026 à 16:02, Andrew C Aitchison via gdal-dev a écrit :
>
> clang-tidy 23 (I'm using Ubuntu 26.04 with build
> ++20260508083129+d791e3a6f4c8-1~exp1~20260508083148.481
> from llvm-toolchain-snapshot at https://www.llvm.org/)
> has a new? check bugprone-signed-bitwise.
>
> This check objects to macros like CPL_LSBINT32PTR:
>
> clang-tidy --config="{Checks: 'bugprone-signed-bitwise', CheckOptions: 
> {bugprone-signed-bitwise.IgnorePositiveIntegerLiterals: true}}" 
> frmts/raw/lcpdataset.cpp
>
> reports 63 warnings of [bugprone-signed-bitwise], starting with:
>
> /home/werdna/gdal/git/frmts/raw/lcpdataset.cpp:171:10: warning: use of 
> a signed integer operand with a binary bitwise operator 
> [bugprone-signed-bitwise]
>   171 |     if ((CPL_LSBSINT32PTR(poOpenInfo->pabyHeader) != 20 &&
>       |          ^
> /usr/local/gdal/git.llvm/include/cpl_port.h:799:53: note: expanded 
> from macro 'CPL_LSBSINT32PTR'
>   799 | #define CPL_LSBSINT32PTR(x) CPL_STATIC_CAST(GInt32, 
> CPL_LSBINT32PTR(x))
>       | ~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~
> /usr/local/gdal/git.llvm/include/cpl_port.h:786:6: note: expanded from 
> macro 'CPL_LSBINT32PTR'
>   786 |     ((*CPL_REINTERPRET_CAST(const GByte *, x)) 
> |                  \
>       |      ^
>   787 |      (*((CPL_REINTERPRET_CAST(const GByte *, x)) + 1) << 8U) 
> |    \
>   788 |      (*((CPL_REINTERPRET_CAST(const GByte *, x)) + 2) << 16U) 
> |   \
> |                                                               ~
> /usr/local/gdal/git.llvm/include/cpl_port.h:181:55: note: expanded 
> from macro 'CPL_STATIC_CAST'
>   181 | #define CPL_STATIC_CAST(type, expr) static_cast<type>(expr)
>       |                                                       ^~~~
>
> I suspect that default type-promotion from an unsigned GByte
> to a *signed* int does not help here.
>
> Not exactly a bug, but annoying.
>
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