On 2021-11-16 at 12:19:43, Jeff King wrote: > On Tue, Nov 16, 2021 at 02:12:41AM +0000, brian m. carlson wrote: > > > The C99 standard was released in January 1999, now 22 years ago. It > > provides a variety of useful features, including variadic arguments for > > macros, declarations after statements, variable length arrays, and a > > wide variety of other useful features, many of which we already use. > > I like the idea of being able to assume C99. And I know this list is > just "here are some things we could do". But I'd like to express caution > over variable length arrays. We've already had problems with alloca() > causing stack exhaustion, and VLAs are basically the same thing. And the > worst part is there's no way to recover; you just get a segfault. Since it looks like I'll be doing a v3, I'll reroll without that. > > diff --git a/Makefile b/Makefile > > index 12be39ac49..893d533d22 100644 > > --- a/Makefile > > +++ b/Makefile > > @@ -1204,7 +1204,7 @@ endif > > # Set CFLAGS, LDFLAGS and other *FLAGS variables. These might be > > # tweaked by config.* below as well as the command-line, both of > > # which'll override these defaults. > > -CFLAGS = -g -O2 -Wall > > +CFLAGS = -g -O2 -Wall -std=gnu99 > > LDFLAGS = > > CC_LD_DYNPATH = -Wl,-rpath, > > BASIC_CFLAGS = -I. > > Do most compilers understand -std=gnu99? It seems like we're breaking > the out-of-the-box build for everything that isn't gcc or clang. I'm pretty sure -Wall is GCC- and clang-specific, as is -Wl,-rpath, so I think we've already crossed that bridge. There are places in config.mak.uname where they're specifically overridden for that reason. -std=gnu99 (or -std=c99) is absolutely required for sparse, though, since it defaults to C89 (at least in CI). > I understand that older versions of gcc (prior to 5.1.0, from my > digging) default to gnu89, and so they would be broken _without_ this. > So it is a tradeoff one way or the other. But somehow this seems > backwards to me. We should assume that modern compilers support C99 out > of the box, and put the burden on older ones to trigger C99 support in > whatever non-portable way they need. We'll have to adjust the CI job that builds with GCC 4.8, but I can do that. I just am not eager to hear complaints from people that it doesn't work out of the box, especially since CentOS 7 is going to hit this case. -- brian m. carlson (he/him or they/them) Toronto, Ontario, CA
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