Scan-Build for clang-13 not showing errors

I am using clang 13 to analyze this code:

int f1(){
int a=5;
short b=4;
bool a1=a;//maybe warn
bool b1=b;//maybe warn
if(a1&&b1)return 1;
return 0;
}
class M{
public:
    virtual int GetAge(){return 0;}
};
class P:public M{
public:
    virtual int GetAge(){return 1;}
    P(){GetAge();}//maybe warn
    ~P(){GetAge();}//maybe warn
};

int main(){
    return 0;
}

but when I run scan-build -enable-checker alpha.core.BoolAssignment clang++ a5.cpp it gives:

scan-build: Using '/usr/lib/llvm-13/bin/clang' for static analysis
scan-build: Analysis run complete.
scan-build: Removing directory '/tmp/scan-build-2021-10-15-191934-7950-1' because it contains no reports.
scan-build: No bugs found.

However I had expected errors from scan-build. What am I doing wrong?