CODEWITHSUNDEEP
cgccmakefilecflagsldflags
Marcos Taranta
Marcos Taranta

Reputation: 33

CFLAGS CPPFLAGS and LDFLAGS invoke cc but don't pass the values to gcc

I wrote a simple printf C code and made a simple makefile. When I run make with CFLAGS, CPPFLAGS and LDFLAGS, the values of the variables goes into a cc execution, followed by a gcc execution without those values, like this:

$ CFLAGS="-I." CPPFLAGS="-D TESTEDEFINE" CXXFLAGS="TESTECXXFLAGS" LDFLAGS="-L." LFLAGS="TESTELFLAGS" make
cc -I. -D TESTEDEFINE -L.  teste.c   -o teste
gcc -o teste teste.c

When I run the built program, the define isn't defined since it gives me the printf of the not defined #else.

teste.c

#include <stdio.h>

int main()
{
#if defined(TESTEDEFINE)
  printf("TESTEDEFINE!!!");
#else
  printf("!!!");
#endif
  return 0;
}

Makefile

all: teste
  gcc -o teste teste.c

Upvotes: 2

Views: 1937

Answers (1)

John T Cox
John T Cox

Reputation: 101

The variables are for consistency, readability, and ease of use. Neither your compile nor your makefile reference them. The compiler does not automatically reference those variables.

Try this instead:

$ export CFLAGS="-I." CPPFLAGS="-D TESTEDEFINE" CXXFLAGS="TESTECXXFLAGS" LDFLAGS="-L." LFLAGS="TESTELFLAGS"
$ gcc $CFLAGS $CPPFLAGS $CXXFLAGS $LDFLAGS $LFLAGS -o teste teste.c

You would also need to define them in your makefile and reference them in the compiler line.

Upvotes: 4

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