Adding a library - c++

Question

I'm doing some modifications to an existing project which is pretty big, so it's built with the autotools. The modifications involve the Ibex library, so I've added an #include "ibex.h" in one of the source files. The library is properly installed on my system, I have the following files:
/usr/local/lib/libibex.a
/usr/local/include/ibex/ibex.h
/usr/local/share/pkgconfig/ibex.pc
Results of the pkg-config commands:
$ pkg-config --libs ibex
-L/usr/local/lib -libex -lprim -lClp -lCoinUtils -lm
$ pkg-config --cflags ibex
-frounding-math -ffloat-store -I/usr/local/include -I/usr/local/include/ibex
The original Makefile.am corresponding to the compil unit I want to get to use ibex, is as follows:
noinst_LTLIBRARIES = liblrasolver.la
AM_CPPFLAGS=$(config_includedirs)
liblrasolver_la_SOURCES = LAVar.h LAVar.C Delta.h Delta.C LRASolver.h LRASolver.C LAArray.h LAArray.C LARow.h LARow.C LAColumn.h LAColumn.C
if WANT_LIBRARY
include_HEADERS = Delta.h LAArray.h LAColumn.h LARow.h LAVar.h LRASolver.h
endif
I modified it this way:
noinst_LTLIBRARIES = liblrasolver.la
AM_CPPFLAGS=$(config_includedirs) `pkg-config --cflags ibex`
AM_LDFLAGS=`pkg-config --libs ibex` -lblas -llapack
liblrasolver_la_SOURCES = LAVar.h LAVar.C Delta.h Delta.C LRASolver.h LRASolver.C LAArray.h LAArray.C LARow.h LARow.C LAColumn.h LAColumn.C
if WANT_LIBRARY
include_HEADERS = Delta.h LAArray.h LAColumn.h LARow.h LAVar.h LRASolver.h
endif
Came to this modification by looking into the generic Makefile provided along with ibex sources to compile ibex projects:
SRCS=$(wildcard *.cpp)
BINS=$(SRCS:.cpp=)
CXXFLAGS := $(shell pkg-config --cflags ibex)
LIBS := $(shell pkg-config --libs ibex) -lblas -llapack
ifeq ($(DEBUG), yes)
CXXFLAGS := $(CXXFLAGS) -O0 -g -pg -Wall -frounding-math
else
CXXFLAGS := $(CXXFLAGS) -O3 -DNDEBUG -Wno-deprecated -frounding-math
endif
all: $(BINS)
% : %.cpp
$(CXX) $(CPPFLAGS) $(CXXFLAGS) -o $# $< $(LIBS)
clean:
rm -f $(BINS)
Ok, autoreconf works, as well as ./configure (though its output never talks about "ibex" which I find suspicious already). But make fails. Doesn't find the header:
../../../src/tsolvers/lrasolver/LRASolver.h:38:18: fatal error: ibex.h: No such file or directory
#include "ibex.h"

Answer 1

You're not using pkg-config correctly. You should use the PKG_CHECK_MODULES macro, see for reference https://autotools.io/pkgconfig/pkg_check_modules.html (full disclosure: I wrote that.)
You're also using AM_LDFLAGS incorrectly since libraries are not ldflags. You should use _LIBADD.