[PATCH util-macros 1/1] Turn on the selective -Werror=... CFLAGS for development builds only

[Gaetan Nadon]

On Sun, 2011-12-18 at 16:19 -0800, Jeremy Huddleston wrote:

> For the more dangerous compiler warnings that we made into errors,
> use -Werror=... if .git exists and -W... if not.  This way we still
> force developers to trip on them but end users will just see
> warnings.
> 
> Signed-off-by: Jeremy Huddleston <jeremyhu at apple.com>
> ---
>  xorg-macros.m4.in |   17 +++++++++++++++++
>  1 files changed, 17 insertions(+), 0 deletions(-)
> 
> 

I am concerned about creating a precedent here regarding the detection
of git and the assumption of a "use model".

We have been confronted with this on numerous occasions where we wanted
to do something different depending if the build is from git or from a
tarball. I, for one, have been reminded many times by reviewers not to
make assumptions about the role of the person who is building and the
reason why the build is performed, let alone matching roles with "git vs
tarball" builds.

The proposed behavior will appear to be erratic and unpredictable when
alternating between git/tarball builds until one realizes what is going
on. Some may report bugs or post patches to fix warnings just to be told
by others that they cannot reproduce the warning. Invariably we will
begin to see questions like "are you building from git or from tarball"?

The concept of a "development build" vs a "production build" where
compiler options are different is very common. This should not occur
without the builder's knowledge or consent. We can provide some
mechanism to help builder select the type of build desired, but we
cannot enforce it. The most obvious autotools features are configure
options (we have --enable-strict-compilation) and environment variables
that would be picked up by makefiles. 

There are no centralized builds and therefore no way to enforce a more
stringent build. The tinderbox can play a role and the documented
development process too.

Some of the readers may recall this (git vs tarball) issue being
discussed at length in other areas:

        ChangeLog: git is required to generate it.
        Special tools: like lex and yacc which may not be available when
        building from tarball which contains the special tool generated
        code

I know these cases are not quite the same, but they always raised the
question "if git do this, else do that" but it never worked out and we
had to find a different way without explicitly testing for git.

Would it not be possible to modify the content and semantic of
--enable-strict-compilation to mean "development build"? Make this
option a requirement in the server build process and on tinderbox. It
will take time for working habits to adapt, as for any change.





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