.gcda files don't merge on multiple runs - c++

Question

I have two main functions that use a common C++ class.
File1: main.cpp
#include <iostream>
#include "HelloAnother.h"
int main() {
HelloAnother::sayHello1();
return 0;
}
File2: main2.cpp
#include <iostream>
#include "HelloAnother.h"
int main() {
HelloAnother::sayHello2();
return 0;
}
File3: HelloAnother.h
#pragma once
class HelloAnother {
public:
static void sayHello1();
static void sayHello2();
};
File4: HelloAnother.cpp
#include <iostream>
#include "HelloAnother.h"
void HelloAnother::sayHello1() {
std::cout << "Hello 1!!!" << std::endl;
}
void HelloAnother::sayHello2() {
std::cout << "Hello 2 !!!" << std::endl;
}
Now I compile two executables:
clang-3.8 -o main -fprofile-arcs -ftest-coverage --coverage -g -fPIC -lstdc++ main.cpp HelloAnother.cpp
clang-3.8 -o main2 -fprofile-arcs -ftest-coverage --coverage -g -fPIC -lstdc++ main2.cpp HelloAnother.cpp
Now, I run ./main
Hello 1!!!
When I rerun ./main
Hello 1!!!
profiling: /media/sf_ubuntu-shared/test-profiling/main.gcda: cannot map: Invalid argument
profiling: /media/sf_ubuntu-shared/test-profiling/HelloAnother.gcda: cannot map: Invalid argument
One second run, I get this error (above) in trying to create/merge .gcda files.
Now, If I try to run ./main2
Hello 2 !!!
profiling: /media/sf_ubuntu-shared/test-profiling/HelloAnother.gcda: cannot map: Invalid argument
When I generate the code coverage report, the call to second function doesn't show up as if the call wasn't made.
Can anyone help me debug this issue pls? The issue seems to be related to merging of .gcda files on multiple runs, but not sure how to solve it.
I also tried clang-3.5 but with same results.

Answer 1

After a lot of searching and trial/error this is what works for me:
Compile first executable, run it. This generates HelloAnother.gcda and main.gcda files.
Execute lcov --gcov-tool=gcov-4.4 --directory . --capture --output-file coverage.main.info
rm -rf *.gcda; rm -rf *.gcno
Compile second executable (main2.cpp), run it. This generates another HelloAnother.gcda and a main2.gcda file.
Execute lcov --gcov-tool=gcov-4.4 --directory . --capture --output-file coverage.main2.info
Now to generate nice looking html report do: genhtml -o coverage coverage.main.info coverage.main2.info

Answer 2

Your problem is that you compile the shared file (HelloAnother.cc) twice and gcov fails to understand that two copies of HelloAnother.o inside main1 and main2 need to be shared.
Instead, compile the shared code once and link it into each executable:
$ g++ --coverage -c HelloAnother.cc
$ g++ --coverage main1.cc HelloAnother.o -o main1
$ g++ --coverage main2.cc HelloAnother.o -o main2
$ ./main1
Hello 1!!!
$ ./main2
Hello 2 !!!
$ gcov --stdout HelloAnother.gcno
...
1: 4:void HelloAnother::sayHello1() {
1: 5: std::cout << "Hello 1!!!" << std::endl;
1: 6:}
-: 7:
1: 8:void HelloAnother::sayHello2() {
1: 9: std::cout << "Hello 2 !!!" << std::endl;
1: 10:}
-: 11: