On 2025-06-25 08:20, Dan Carpenter wrote: > On Sat, Jun 14, 2025 at 12:50:37PM +0200, Miguel Ojeda wrote: >> On Fri, 13 Jun 2025 20:33:42 -0400 Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> wrote: >>> >>> Great writeup, but as Miguel says, this isn't needed at all, the kernel >>> relies on the compiler to be sane :) >> >> We may still want to clean them up, e.g. for tooling -- Kees/Dan: do we? >> e.g. I see a similar case with discussion at: >> >> https://lore.kernel.org/lkml/3f1e7aaa-501a-44f1-8122-28e9efa0a33c@xxxxxx/ >> >> Which in the end was picked up as commit 2df2c0caaecf ("fbdev: au1100fb: >> Move a variable assignment behind a null pointer check"). > > Putting the declarations at the top was always just a style preference. No, "const" and variable scopes are not just "style", please do a bit of research. For instance... > Putting declarations at the top causes issues for __cleanup magic and... https://stackoverflow.com/questions/368385/implementing-raii-in-pure-c https://en.wikipedia.org/wiki/Resource_acquisition_is_initialization#Compiler_%22cleanup%22_extensions Not just "style" either: - Automagically avoiding exploits like TUN https://lwn.net/Articles/342330/ - The unusual flag -fno-delete-null-pointer-checks and incompatibility with other analyzers and compilers - All the complex compiler discussions around those. Declaration-after-statement was an important (and obviously: optional) C99 feature that let C catch up with every other language. Forbidding it just for "style" would be a serious misunderstanding of that feature. I don't know any yet but there has to be some more important reason(s) than "style".
