[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: deprecated symbol warnings
Re: deprecated symbol warnings
Sat, 14 May 2005 14:48:23 -0400
On May 14, 2005, at 08:40, Neil Jerram wrote:
This looks very useful. I'm not an expert in this kind of thing, but
here are some comments.
#elif defined _WIN32
Does the __declspec syntax work for all Windows compilers? If it's
actually specific to MSVC (which is the only compiler I'm familiar
with), you should use _MSC_VER. If it's for all Windows compilers,
I'm surprised by the underscore - i.e. I'd normally use WIN32; are
WIN32 and _WIN32 equivalent?
I have no idea. I do a small amount of work with MSVC, and the other
compiler I'd be concerned about would be GCC, which is checked for
first (though, actually, only for gcc 3 and later, should fix that); I
have no idea what other Windows compilers would do, though I would
expect for maximum interoperability they would implement or at least
ignore the __declspec annotations. In the code I deal with at work, we
generally check _WIN32.
I'm hoping some Windows developer can help out here... we've got some
at work, maybe I can ping them about it.
/* N.B.: Application code will sometimes test whether one of these
macros is defined, to figure out if the version of Guile in use
predates the creation of the macro. So at deprecation time, we
still want the macro to be visible. ANSI C says "#define foo foo"
is okay, but if we get complaints about it, try switching the
non-macro name to "foo_" or "foo_deprecated" or something; make it
a simple concatenation so that we can make the other macros
continue to be simple. */
I think we should assume in advance that we'll hit trouble with this
on some platforms. Otherwise it's just another hiccup to push people
away from trying Guile out.
*sigh* I was afraid of that. So when do we start requiring "real"
ANSI C support? :-(
Doing this means the compile-time messages will give the wrong symbol
names. They'll be close to the names used by the application, but not
the same. Still, getting messages that are close is probably better
than explaining to people why this strange use of the preprocessor is
actually valid and it's their compiler that's broken. I wonder if it's
really a problem these days, though, a decade and a half after the spec
Nice. Slight extra overhead, but well worth it IMO for the extra
Yeah, consuming a bit more space in the library is slightly annoying,
but the run-time performance for deprecated functions probably isn't
anything to worry about.
The link-time warnings are a bit messier.
What is the extra benefit of link-time warnings over compile-time?
Are there any cases where the user will see a link-time warning
without a corresponding compile-time one?
If the application refers to Guile functions without including
Or if an older version of gcc is used that can generate ELF sections
but doesn't support the "deprecated" attribute. (I *think* "section"
Or if we add support for another compiler that lets us use 'asm' to
emit warning sections or symbols or whatever the tool chain supports,
but doesn't have a compile-time equivalent to the "deprecated"
attribute, but we could treat that case separately.
Would link-time warnings show up when linking against a 3rd party
library that chose to use deprecated symbols?
Yes. Hmm, at least for a static library. I'm not sure about a shared
library, if it would happen when the library was built, or used, or
both. I would assume they would be printed when the library is built,
at least. I'm guessing that this would probably be the most
interesting of the cases.
Or, in the real world, if all the non-fatal compile-time warnings have
all scrolled off the screen and the trailing bits of the "make" output
still visible, and the only bits likely to get looked at unless
something breaks, include only the final link step.
If it's not that interesting after all, I could drop it (as I
indicated, it's the more complicated approach, though not terribly so)
and just go with the compile-time warnings based on the predefined
macros. Turning macros into variables and/or functions is needed even
without link-time warnings, as GCC can't attach attributes to the
macros, only to the variable and function symbols, so it doesn't
simplify things all that much.
scm_c_issue_deprecation_warning (though I don't know if I need to
worry about i18n interactions there).
I don't believe it's yet been suggested that we would translate the
Scheme names of primitives, so I doubt there would be a problem here.
(Out of interest, do any other scripting languages do this?)
I was thinking of the "is deprecated, please use" part. The symbol
names we should display as they are, but possibly the recommendation to
change the application code should be given in Swahili or Klingon or
whatever. That we could do at run time, and gcc could do it at compile
time, but I don't think we can do anything about it at link time.
Re: deprecated symbol warnings and Windows, Ken Raeburn, 2005/05/18
- deprecated symbol warnings, Ken Raeburn, 2005/05/13
- Re: deprecated symbol warnings, Neil Jerram, 2005/05/14
- Re: deprecated symbol warnings,
Ken Raeburn <=
- Re: deprecated symbol warnings, John W. Eaton, 2005/05/15
- Re: deprecated symbol warnings, Neil Jerram, 2005/05/16
- Re: deprecated symbol warnings, Ken Raeburn, 2005/05/16
- Re: deprecated symbol warnings, tomas, 2005/05/18
- Re: deprecated symbol warnings, Ludovic Courtès, 2005/05/18
- automated testing (was Re: deprecated symbol warnings), Ken Raeburn, 2005/05/18
- Re: deprecated symbol warnings, Neil Jerram, 2005/05/26
- Re: deprecated symbol warnings, Ken Raeburn, 2005/05/28