On 4/5/2012 12:23 AM, Gabriel Dos Reis wrote:
-Wall is roughtly equivalent to -gnatwa in the GNAT front end,
and this is definitely NOT on by default. If you run GNAT in
default mode, there are virtually no false positives, since
the only warnings on by default are the kind of warnings that
say "if you execute this statement, your program will go wrong"
like calling a function with non-void return type whose definition
ails to return value.
Right, BTW in Ada a failure to provide a return value is detected at
run time and raises Program_Error. This is a clear case where a
warning is always desirable (basically this would be an error in
the language, except that to make it an error would require going
into the whole issue of defining possible threads of control, and
that's too much formal effort for too little gain at the level of
the language standard. So in GNAT, this is a warning that is on
by default. Like all warnings it can be suppressed, either by
suppressing all warnings (-gnatws) or by providing a Warnings
Off pragma that suppresses this particular warning.
Note that the ONE and only case where this warning is a false
positive is the ACATS test that makes sure you raise an
exception (in practice we suppress all warnings for ACATS
tests anyway, since they are deliberately full of dubious
coding practices!)
I wonder if there is a better forum for discussing whether
-Wall should be the default than this one. After all we always
emphasize that this list is for gcc developers, and this
particular issue is one better discussed by gcc users. Yes
I know there are gcc users on this list too (I am one!) but
still we don't exactly get representative user input on this
list!
