[CMake] Does find_library check that a found library does in fact link?

[Micha Renner]

Am Donnerstag, den 29.09.2011, 09:22 +0200 schrieb Hendrik Sattler:
> Zitat von Michael Wild <themiwi at gmail.com>:
> > Just a few of my thoughts on this:
> 
> Same for me.
> 
> > - There are several ways to handle dead symlinks:
> >   1. Don't check, let the linker complain (status quo)
> >   2. Check whether the found library is a symlink, and if not valid,
> >      remove it silently from the list of candidates. Can be very
> >      surprising and will likely result in quite a few bug reports
> >      about CMake not finding a certain library that is "clearly" there.
> >   3. Like 2, but warn about the issue. Possibly very annoying.
> > I don't know which option to prefer (perhaps somebody finds another one
> > that is better?). IMHO bogus symlinks to shared libraries constitute a
> > real problem of the library installation, so CMake shouldn't just paper
> > over it by silently skipping the dead link, proceeding to the next
> > candidate which rules out option 2 for me. Also, option 3 can be
> > troublesome in automated setups where no user actually reads the CMake
> > output.
> 
> People tend to misunderstand the purpose of build systems like CMake  
> and autotools. They try to make the detection bullet-proof and most  
> likely fail. You can see that this is wrong by looking at those auto*  
> setups that take ages to detect all possible header files and use an  
> ifdef hell to handle that in the code, run lots of link and  
> symbol-finding tests, and still fail on conditions that the author  
> simple didn't consider or know.
> 
> I prefer option 1. It's not CMake's duty to detect or paper over  
> messed-up systems. That's the administrator's job!
> BTW: running "ldconfig -v" on Linux likely tells you about the  
> dangling symlink.
> 
> What's next? Asking for a syntax check of found header files so that  
> the compiler doesn't complain on broken header files?

This is exactly what CHECK_INCLUDE_FILES does (via TRY_COMPLIE).
It works good as long as the header file has no predecessor. In that
case CHECK_INCLUDE_FILES reports FILE-NOT-FOUND. It would save a lot of
time, if there would be notice that CHECK_INCLUDE_FILES tests the header
file.
"Check if the files can be included" is not enough.

Greetings

Micha



> 
> HS
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