There is a typo on this page of the gcov online documentation:

  https://gcc.gnu.org/onlinedocs/gcc/Invoking-Gcov.html

It states:

"Unexecuted lines are marked ‘#####’ or ‘====’, depending on whether..."


It should be "=====" (five consecutive equal signs instead of four).

This simple test program shows that 5 is correct:

----------------------
int main()
{
    int i=0;
    try {
        if (i==4)
            throw 7;
    }
    catch (...) {
        i=5;
    }
    return 0;
}
----------------------

g++ -Wall -Wextra -g -fprofile-arcs -ftest-coverage coverage.cpp -o coverage
gcov coverage.gcda

----------------------
        -:    0:Source:coverage.cpp
        -:    0:Graph:coverage.gcno
        -:    0:Data:coverage.gcda
        -:    0:Runs:1
        -:    0:Programs:1
        1:    1:int main()
        -:    2:{
        1:    3:    int i=0;
        -:    4:    try {
        1:    5:        if (i==4)
    #####:    6:            throw 7;
        -:    7:    }
    =====:    8:    catch (...) {
    =====:    9:        i=5;
        -:   10:    }
        1:   11:    return 0;
        -:   12:}
----------------------