Recent commit 911e2b0fea ("By default use <prefix> relative paths when
installing") introduced relative install paths in CMake. But this
interacts badly with commit e6f1cffdd3 from a year ago: now, the paths in
`pkgconfig/jsoncpp.pc` are relative, which is incorrect.
Before 911e2b0fea (1.7.2 on Archlinux), this was correct:
$ head -4 /usr/lib/pkgconfig/jsoncpp.pc
prefix=/usr
exec_prefix=${prefix}
libdir=/usr/lib
includedir=/usr/include
After 911e2b0fea (1.7.3 on Archlinux), this is now incorrect:
$ head -4 /usr/lib/pkgconfig/jsoncpp.pc
prefix=/usr
exec_prefix=${prefix}
libdir=lib
includedir=include
This change causes hard-to-debug compilation errors for projects that
depend on jsoncpp, for instance:
CXXLD libring.la
/tmp/ring-daemon/src/ring-daemon/src/../libtool: line 7486: cd: lib: No such file or directory
libtool: error: cannot determine absolute directory name of 'lib'
make[3]: *** [Makefile:679: libring.la] Error 1
This is because jsoncpp contributes `-Llib -ljsoncpp` to the LDFLAGS, via
the pkg-config machinery. Notice the relative path in `-Llib`.
To fix this, simply revert commit e6f1cffdd3 ("Fix custom includedir &
libdir substitution in pkg-config"). The change in 911e2b0fea should have
the same effect.
See #279, #470 for references.
101fcf0806