Running Debian Wheezy, pkg-config 0.26, autoconf 2.69.
The PKG_CHECK_MODULES autoconf macro currently does not issue an error and halt compilation when a dependency .pc file is not available.
For example, on my machine, for a particular project:
results in no error. However in the outputted Makefile, I see:
" PYCAIRO_CFLAGS =
PYCAIRO_LIBS = -L/usr/lib/x86_64-linux-gnu -lcairo "
Curiously the CFLAGS was blank, resulting in a broken build. I finally debugged the issue from this:
"$ pkg-config --cflags pycairo
Package xproto was not found in the pkg-config search path.
Perhaps you should add the directory containing `xproto.pc'
to the PKG_CONFIG_PATH environment variable
Package 'xproto', required by 'Xau', not found "
"$ pkg-config --libs pycairo
-L/usr/lib/x86_64-linux-gnu -lcairo "
The solution was an incorrectly configured PKG_CONFIG_PATH variable.
I would expect that I would have gotten an error about missing xproto when I ran autoreconf, rather than having it produce a Makefile which would not compile.
This got fixed for pkg-config-0.27 in bug43149. I think if you try the latest release this should work correctly.
*** This bug has been marked as a duplicate of bug 43149 ***