CMAKE_CXX_FLAGS are flags for the C++ compiler. -l is a linker flag. To link to a library, use this:

target_link_libraries(alfa_1 m)

You might also want to replace -std=c11 with use of CMAKE_C_STANDARD and related variables (CMAKE_C_STANDARD_REQUIRED, CMAKE_C_EXTENSIONS), and possibly replace use of CMAKE_CXX_FLAGS with a call to target_compile_options().

You need to link with the math library:

gcc -o sphere sphere.c -lm

The error you are seeing: error: ld returned 1 exit status is from the linker ld (part of gcc that combines the object files) because it is unable to find where the function pow is defined.

Including math.h brings in the declaration of the various functions and not their definition. The def is present in the math library libm.a. You need to link your program with this library so that the calls to functions like pow() are resolved.

-lm should go into LDLIBS, not CFLAGS in the Makefile.

LDLIBS = -lm

See https://www.gnu.org/software/make/manual/html_node/Implicit-Variables.html

Although, CFLAGS is also passed to the compiler, ``-lmneeds to be at the *end* of the commandline. That's why specifying it inCFLAGSdoesn't work because it needs to be passed at the *linking* stage (specifying-lm` at the end provides equivalent functionality).

Instead of

cc -g -lm -DBLITZ_HOST_IS_LITTLE_ENDIAN foo.c

Try:

cc -g -DBLITZ_HOST_IS_LITTLE_ENDIAN foo.c -lm

When the linker searches a library, it links in modules that contain definitions for previously-undefined symbols.

If the linker searches -lm before foo.o, then pow() is not yet undefined. Conversely, if foo.o comes first, it undefines pow(), which -lm can then resolve.

EDIT: To accomplish this advice in your makefile, make these changes:

CFLAGS=-g -DBLITZ_HOST_IS_LITTLE_ENDIAN
LDLIBS=-lm

...

asm: asm.c
        $(CC) $(CFLAGS) asm.c $(LDLIBS) -o asm