Re: [dpdk-dev] [PATCH] eal: remove variable length array

[Thomas Monjalon <thomas@monjalon.net>]

14/12/2018 21:28, Mattias Rönnblom:
> On 2018-12-14 20:07, Jeff Shaw wrote:
> >>> The code prior to this commit produced the following warning when
> >>> compiled with "-Wvla -std=c90".
> >>>
> >>>     warning: ISO C90 forbids variable length array ‘array’ [-Wvla]
> >>>
> >>> This commit removes the variable length array from the PMD debug
> >>> trace function by allocating memory dynamically on the stack using
> >>> alloca().
> >>
> >> Is alloca() even included in *any* C standard? As far as I see, it just
> >> achieves the same thing in an uglier, less portable way than VLAs.
> > 
> > I agree that it is much less elegant than a VLA. This is in preparation
> > for DPDK on Windows, which using the Microsoft Visual C++ (MSVC) compiler.
> > MSVC does not support variable length arrays. It does, however, support
> > alloca(), as does GCC/ICC.
> > 
> > For this particular instance, the point is moot, since the function is
> > not used anywhere and can just as easily be removed. Though it does not
> > address the issue for the ~100 other instances where VLAs are used. We
> > will be submitting patches for those as more common files are ported to
> > Windows.
> 
> If Microsoft's C compiler doesn't support C99, some 20 years after its 
> release, maybe it's time to find a new compiler, instead of messing up 
> the DPDK code in a ~100 instances.

If think there is no reasonnable compiler for Windows.
Yes I know, it's crazy.

Microsoft, should we wait 10 more years to have C99 supported in MSVC?