Won't that only be supported in gnu89 or gnu90 mode?

edmccard · on March 17, 2015

No, it will be supported using -std=c89 or -std=90, unless you also specify -pedantic.

michaelmior · on March 17, 2015

Yes, I realized after posting that -pedantic is required for strict standards compliance.

mikeash · on March 17, 2015

The GNU modes just enable additional features which conflict with plain C. Any feature which can coexist with plain C will be enabled in the regular C modes too. For example, __typeof__ is enabled everywhere, because the compiler is allowed to do just about anything it wants with a __ prefix, but plain typeof is only enabled in the GNU modes, since it could cause valid C programs using "typeof" for their own purposes to fail to compile.