# 2023-10-15

I've been hacking on klib (renamed to scsl), getting packaging working,
and getting my desktop switched over to Ubuntu.

## Debugging a build failure

I went through a whole adventure where I thought my C++ setup on the
desktop was broken.  I was trying to build kutils from the Makefile,
and linking kept failing due to not being able to find symbols.  It
worked when I built it under CLion / cmake, so it was kind of strange. 
The Makefile specifically builds using clang, so I went through a bunch
of trying to track down library depdencies, tooling, etc.  I probably
spent a few hours trying to figure it out.

Finally, I cloned it on the macbook, and ran into the same errors. The
difference this time was noticing the following:

    kyle@midgard:~/src/kutil$ make

    clang++ -c -o KeyValueConfig.o -std=c++17 -g -Werror -Wall -Wextra
    -pedantic KeyValueConfig.cc
    clang++ -c -o khmgr.o -std=c++17 -g -Werror -Wall -Wextra -pedantic
    khmgr.cc
    clang++ -c -o StringUtil.o -std=c++17 -g -Werror -Wall -Wextra
    -pedantic StringUtil.cc
    cc   khmgr.o   -o khmgr
    /usr/bin/ld: /usr/bin/ld: DWARF error: invalid or unhandled FORM
    value: 0x23 khmgr.o: in
    function`KeyValueConfig::Load(std::__cxx11::basic_string<char,
    std::char_traits<char>, std::allocator<char> >)':
    khmgr.cc:(.text+0x27): undefined reference to
    >`std::basic_ifstream<char, std::char_traits<char>
    >::basic_ifstream(std::__cxx11::basic_string<char,std::char_traits<char>,
    std::allocator<char> > const&, std::_Ios_Openmode)'
    /usr/bin/ld: khmgr.cc:(.text+0x3f): undefined reference to
    / `std::basic_ios<char, std::char_traits<char> >::good() const'
    /usr/bin/ld: khmgr.cc:(.text+0x8e): undefined reference to
    / `std::basic_ifstream<char, std::char_traits<char>
    / >::~basic_ifstream()'

The output followed for many pages.

The Makefile looks like this:

	CXX :=		clang++
	
	SOURCES :=	$(wildcard *.cc)
	HEADERS :=	$(wildcard *.h)
	OBJS :=		$(patsubst %.cc,%.o,$(SOURCES))
	TARGETS :=	khmgr
	
	CXXFLAGS :=	-std=c++17 -g
	CXXFLAGS +=	-Werror -Wall -Wextra -pedantic
	
	
	all: $(OBJS) $(TARGETS)
	
	.PHONY:
	clean:
		rm -f *.o $(TARGET)
	
	tags: $(SOURCES)
		ctags -o $@ $(SOURCES)
	
	$(TARGET): khmgr.o KeyValue.o StringUtil.o
		$(CXX) -o $@ $(CXXFLAGS) $(LDFLAGS) $(OBJS) $(LIBS)
	
	print-%: ; @echo '$(subst ','\'',$*=$($*))'
	
	%.o:%.cc
		$(CXX) -c -o $@ $(CXXFLAGS) $<

Do you spot the error?

It took me an embarassingly long time to notice the transition from
clang++ to cc, even though the TARGET spec specifically uses clang.
I'd defined TARGETS and then made a build rule for TARGET. Once I
renamed TARGETS to TARGET, it built just fine.