Re: Elaboration in GNAT

[Mark Johnson <Mark_H_Johnson@Raytheon.com>]

Frode Tenneboe wrote:

> Using -gnatwa I get some elaboration issues with some legacy code in GNAT.
> One of these are:
>
> foo.adb:69:04: warning: instantiation of "Client" may raise Program_Error
> foo.adb:69:04: warning: missing pragma Elaborate_All for "bar"
>
> The problem is that this crops up everywhere which I asume is because
> the elboration of package bar is not very healthy.
>
> The package in question uses Ada.Calendar, however there must be some
> code in one (or more) of the dependencies in the body of bar which
> causes this. A manual inspection of this code is not done over night.
>
> Is there a way of getting the information above a bit more verbose?

Not that I am aware of.

I had some lengthy discussions with Robert Dewar about this particular issue.
The warning basically says that elaboration code in the current package
depends upon another package. To be safe - elaborate the other package (and
all packages it depends upon) prior to elaboration of the current package. I
agree with the reasoning behind this so I have this warning turned on all
compiles we do as well.

Since I also demand warning free software in our facility, my "solution" is to
add pragma Elaborate_All(bar); in every place the warning is issued. That way
if we have any mutual dependencies [we haven't] they become compiler errors.
This is a quick solution and doesn't require any extensive analysis to put
into place.

Robert of course may give you slightly different suggestions. One that I tend
to ignore is to not use "gnatwa", but to specify exactly which warnings you
want and don't want. I have found over the last several months that added
warnings from gnatwa are beneficial and I'm sticking with it.

  --Mark