FreeBSD build problem

Brad King brad.king at
Mon Jul 7 17:15:16 CEST 2008

David Faure wrote:
> The -L parameters are definitely generated, by cmake.
> The question is how. And the answer is complex AFAIK, and depends on the cmake version.

In CMake 2.4 the set of -L paths come from arguments to the
link_directories() command and the locations of libraries given to
target_link_libraries() by full path.  In CMake 2.6 the latter case is
usually handled just by passing the full path to the library file
directly to the linker with no searching, but there are still some cases
where it behaves similarly to 2.4.

The input to the ordering algorithm is the original list of
user-specified library search paths (given to link_directories) plus
some set of library file full paths.  The output is an ordered linker
search path.  We try to preserve the original order of user-specified
directories, but the main rule is that the order is such that the
libraries whose full paths are known will be found first if the linker
searches for them with a -lfoo option.  This guarantees that when a
library is specified by full path that the copy of the library is
favored over any other copy of the library at another place in the
linker search path.

CMake actually inspects all the linker search path locations to look for
possibly conflicting files and builds a constraint graph.  A topological
sort on the resulting constraint graph produces the order.  The order
among an unconstrained group of paths is that in the original
user-specified order.  This is done much more formally in CMake 2.6 than
in 2.4.


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