scan-build make does not detect any bugs

Question

I have a very simple .c file, with some obvious bugs inside it.

#include <stdio.h>

struct S {
  int x;
};

void f(struct S s){
}

void test() {
  struct S s;
  f(s); // warn
}

int test2(int x){
  return 5/(x-x); // warn
}

int main(){
  test();
  test2(532);
  printf("Hej\r\r");
}

I am trying to use the clang's static code analyzer tool (scan-build) to detect errors. When I run the tool directly on the files, as for example using the following command:

scan-build g++ -o 1 1.c

I do get the intended output, including a warning from the compiler that mentions the division by 0.

scan-build: Using '/usr/lib/llvm-3.8/bin/clang' for static analysis

1.c: In function ‘int test2(int)’: 1.c:16:11: warning: division by zero [-Wdiv-by-zero] return 5/(x-x); ^

1.c:16:11: warning: Division by zero return 5/(x-x);

~^~~~~~ 1 warning generated. scan-build: 1 bug found. scan-build: Run 'scan-view /tmp/scan-build-2016-07-11-152043-3028-1' to examine bug reports.

Now, I am trying to put that command into a very simple Makefile. The contents of my Makefile are:

all: 1.c
    g++ -o 1 1.c
clean:
    rm -f *.o 1

However, whenever I run scan-build with make, using the following command:

scan-build make

I still get the warning from the compiler, but not the scan-build tool!!!

scan-build: Using '/usr/lib/llvm-3.8/bin/clang' for static analysis

g++ -o 1 1.c

1.c: In function ‘int test2(int)’:

1.c:16:11: warning: division by zero [-Wdiv-by-zero] return 5/(x-x);

^ scan-build: Removing directory '/tmp/scan-build-2016-07-11-152326-3055-1' because it contains no reports. scan-build: No bugs found.

I have observed the same behavior in both C and C++ files. I see that someone had come across a similar error in the past (2012), however the proposed answer does not seem to work and seems to refer to C++ files only anyway. Any clues?

Answer 1

scan-build works by substituting the CC variable. Use it in your your makefile

CC=g++
all: 1.c
        $(CC) -o 1 1.c
clean:
        rm -f *.o 1

and it works

scan-build: Using '/usr/bin/clang' for static analysis
/usr/share/clang/scan-build/ccc-analyzer -o 1 1.c
1.c:16:17: warning: Division by zero
        return 5/(x-x); // warn
           ~^~~~~~
1 warning generated.
scan-build: 1 bugs found.
scan-build: Run 'scan-view /tmp/scan-build-2016-07-11-160529-5951-1' to  examine bug reports.