Should warnings be issued for unrecognised pragmas ?

[Nick Clifton <nickc at cygnus dot com>]

I am currently writting a patch for gcc2 that implements a new command
line option '-wunrecognised-pragmas' which will cause warning messages
to be generated when GCC encounters pragmas which is does not handle.
At the moment this patch also enables these warnings if -Wall is
enabled, expect for the case where the pragmas are in system header
files.   Is this the right thing to do ?

The '89 ANSI C standard says:
"Any pragma that is not recognized by the implementation is ignored."

It is my opinion that "ignoring" is not the same as "not issuing a
warning", if such warnings have been requested, and that it is
important to know if a compiler is ignoring pragmas as they may have
been intended to affect code generation.

Any comments ?

Nick Clifton