lcov incompatible with GCC 9.x coverage data

[berrange]

Fedora 30 rawhide has pulled in the last GCC 9.0.0 version and this appears incompatible with lcov

$ echo "const int a = 5; int main(void) { return 1;}" > t.c
$ gcc -Wall -Wextra -Werror ./t.c --coverage
$ ./a.out 

Previously with GCC 8 compiled binaries this would work:

$ lcov -t "result" -o ex_test.info -c -d .
Capturing coverage data from .
Found gcov version: 8.2.1
Scanning . for .gcda files ...
Found 1 data files in .
Processing t.gcda
Finished .info-file creation
$ lcov -l ex_test.info
Reading tracefile ex_test.info
            |Lines       |Functions  |Branches    
Filename    |Rate     Num|Rate    Num|Rate     Num
==================================================
[/home/berrange/src/virt/libvirt-go/]
t.c         | 100%      1| 100%     1|    -      0
==================================================
      Total:| 100%      1| 100%     1|    -      0

With GCC 9 compiled binaries it fails

$ ./lcov/bin/lcov -t "result" -o ex_test.info -c -d .
Capturing coverage data from .
Found gcov version: 9.0.0
Scanning . for .gcda files ...
Found 1 data files in .
Processing t.gcda
geninfo: WARNING: /home/berrange/t.gcno: Overlong record at end of file!
geninfo: WARNING: gcov did not create any files for /home/berrange/t.gcda!
Finished .info-file creation

There are some GCC changes that affected coverage data format:

https://gcc.gnu.org/viewcvs/gcc?view=revision&revision=261189
https://gcc.gnu.org/viewcvs/gcc?view=revision&revision=264462

The info above is all taken from a Fedora bug report https://bugzilla.redhat.com/show_bug.cgi?id=1668843

[robinmoussu]

In case it may help, on my pet project I can use gcov to get the code coverage, but lcov fails. A really recent g++9 build is required, some stuff were fixed in gcov less than a week go and it uses C++20 feature only available on g++ at the moment.

if you have meson + conan + lcov + genhtml installed, and an extremely fresh build of g++9, it should be as easy to test as

git clone https://gitlab.com/robinmoussu/rollordie3.git && cd rollordie3
make
make coverage

I didn't tested to install it from another computer than mine however.

Feel free to ask me any additional data.

[oberpar]

I can confirm that the problem exists with LCOV and GCC 9.0 .gcno files. This will be addressed via the LCOV intermediate file format support that I'm working on.

[marxin]

I can confirm that the problem exists with LCOV and GCC 9.0 .gcno files. This will be addressed via the LCOV intermediate file format support that I'm working on.

Great, may I ignore this as the intermediate support in LCOV will appear before GCC 9.1 is released (May 2019) ?

[oberpar]

LCOV support for the intermediate file format will (hopefully) be available before May.

[oxr463]

In my tests, I can confirm this issue affects the following versions:

• 9.1, (See: https://gitlab.com/proot/proot/-/jobs/199163599).
• 8.3, (See: https://gitlab.com/proot/proot/-/jobs/209815447).

Tested on official docker images, (See: https://hub.docker.com/_/gcc), for each version, respectfully.

@oberpar are there any issues blocking this that require assistance?

[oberpar]

This should be fixed with commit 75fbae1.

[LesnyRumcajs]

I can confirm, this is working fine with gcc-9.1.1 minus the extra dependencies I had to install manually.