Re: [PATCH] gdbsupport, gdbserver, gdb: use -Wno-vla-cxx-extension

[Luis Machado <luis.machado@arm.com>]

On 4/15/24 17:22, Tom Tromey wrote:
>>>>>> "Simon" == Simon Marchi <simon.marchi@efficios.com> writes:
> 
> Simon> When building with clang 18, I see:
> Simon>       CXX    aarch64-linux-tdep.o
> Simon>     /home/smarchi/src/binutils-gdb/gdb/aarch64-linux-tdep.c:1299:26: error: variable length arrays in C++ are a Clang extension [-Werror,-Wvla-cxx-extension]
> Simon>      1299 |       gdb_byte za_zeroed[za_bytes];
> Simon>           |                          ^~~~~~~~
> Simon>     /home/smarchi/src/binutils-gdb/gdb/aarch64-linux-tdep.c:1299:26: note: read of non-const variable 'za_bytes' is not allowed in a constant expression
> Simon>     /home/smarchi/src/binutils-gdb/gdb/aarch64-linux-tdep.c:1282:10: note: declared here
> Simon>      1282 |   size_t za_bytes = std::pow (sve_vl_from_vg (svg), 2);
> Simon>           |          ^
> 
> Simon> Since we are using VLAs right now, that warning doesn't make sense for
> Simon> us.  add `-Wno-vla-cxx-extension` to the list of warning flags we try to
> Simon> enable.  If we ever choose to disallow VLAs, we can remove that flag.
> 
> I wonder if we should instead remove the use of VLAs.
> Is it just the one spot?

If we want to go that route, we can modify that code to not use it. I think it was mostly convenience rather than a need for it.