Undefined reference to everything, when using libm

Question

I have a program using the standard maths function in C++. On my Mac, it links just fine using clang, and without even using -lm. However, on Ubuntu, also using clang, after adding -lm to my command line, I get undefined reference to EVERYTHING. I mean literally everything.

My Makefile looks like this:

CC = clang
CFLAGS = -fmessage-length=0 -std=c++11 -pipe
LDFLAGS = -pipe
LDLIBS = -lpng -lpthread -lm
OBJS = Colour.o GraphicsLibrary/SimpleVector.o Camera.o Ray.o \
Material.o SceneObject.o Sphere.o Plane.o Polygon.o PolygonPatch.o Cone.o \
Cylinder.o Light.o Scene.o SimpleScene.o BoxedScene.o RTreeScene.o AABB.o Main.o \
AFF/parse.o AFF/texture.o AFF/animation.o AFF/quat.o AFF/kbsplpos.o \
AFF/kbsplrot.o
TARGET = straylight


######################
# ------------------ #
# Top level targets. #
# ------------------ #
######################

all: ${TARGET}

clean:
    rm -v ${OBJS} ${TARGET}

debug:
    ${MAKE} EXTRA_C_FLAGS="-g3 -pg" EXTRA_LD_FLAGS="-g3 -pg"

optimized:
    ${MAKE} EXTRA_C_FLAGS="-O3" EXTRA_LD_FLAGS="-O3"

######################
# ------------------ #
# Low level targets. #
# ------------------ #
######################

${TARGET}: ${OBJS}
    ${CC} ${LDFLAGS} ${EXTRA_LD_FLAGS} -o ${TARGET} $^ ${LDLIBS} 

%.o: %.C %.h Makefile
    ${CC} ${CFLAGS} ${EXTRA_C_FLAGS} -c -o $@ $<

Answer 1

As per the comments, when compiling C++, you need to use the correct compiler. clang++ for C++.

Often the C and C++ compilers are the same basic program, but invoking them as eg. clang or clang++ invokes them with the correct options for the target language.

Most likely the errors you saw were the result of the program not being linked against the correct runtime libraries.