[GRASS-dev] C and C++ standards used by GRASS

[Glynn Clements]

Vaclav Petras wrote:

> which C and C++ standards we are using? And which we want to use? Do we
> even care? Since we can always fix it if somebody wants to build GRASS on
> some other compiler than relatively new GCC.

C code is supposed to conform to C89 and POSIX.

There are no standards for C++ code.

> For example, lib/gis build fails with gcc option -std=c89 [1] because of
> missing `hypot` buildin [2].

hypot() is specified by POSIX.

Using -std=c89 or -ansi will, by default, omit the POSIX extensions
from any headers which are specified by C89. To re-enable them, you
need something along the lines of:

	-D_POSIX_C_SOURCE=200112L -D_XOPEN_SOURCE -D_SVID_SOURCE

We already require POSIX for open() etc, so there isn't much point in
excluding POSIX functions which are declared in the C89 headers.

-- 
Glynn Clements <glynn at gclements.plus.com>