https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105238
--- Comment #4 from Esger Abbink <esgergn at hotmail dot com> --- We use Ubuntu 20.04 currently for our jenkins images. With gcc built from master with patch using -fprofile-prefix-map works as expected: with a main.cpp in /home/esger/src/application/coverage_test/dir1/source compiling with: cd /home/esger/src/application/coverage_test/dir1/source/ && g++-11 --coverage -fprofile-prefix-map=/home/esger/src/application/coverage_test/dir1=dir2 -c /home/esger/src/application/coverage_test/dir1/source/main.cpp cd /home/esger/src/application/coverage_test/dir1/source/ && g++-11 --coverage -fprofile-prefix-map=/home/esger/src/application/coverage_test/dir1=dir2 main.o -o ../bin/a.out results in a main.gcno in the source directory, and after running ./dir1/bin/a.out from /home/esger/src/application/coverage_test there is a main.gcda (non-mangled) in dir2/source. Note that I was not able to produce a meaningful coverage report even for the simplest/first case of the four above with gcc 11. I think gcovr might not yet support newer formats used? So I can't currently verify if with -fprofile-prefix-map the coverage report is ok, but I would assume so. (Still, I don't quite understand why behavior that was working is now broken/changed and needs a new option? ie. why is -fprofile-dir mangling the name, and -fprofile-prefix-map not? and 9.4 behavior with -fprofile-dir still seems broken when explicitly specifying the default?) If I perform a small experiment more closely resembling what cmake + ccache do: cd /home/esger/src/application/coverage_test/dir1/source/ && CCACHE_BASEDIR=/home/esger/src/application/coverage_test/dir1 ccache /usr/bin/g++-11 --coverage -fprofile-prefix-map=/home/esger/src/application/coverage_test/dir1=. -fdebug-prefix-map=/home/esger/src/application/coverage_test/dir1=. -c /home/esger/src/application/coverage_test/dir1/source/main.cpp cd /home/esger/src/application/coverage_test/dir1/source/ && CCACHE_BASEDIR=/home/esger/src/application/coverage_test/dir1 ccache /usr/bin/g++-11 --coverage -fprofile-prefix-map=/home/esger/src/application/coverage_test/dir1=. -fdebug-prefix-map=/home/esger/src/application/coverage_test/dir1=. main.o -o ../bin/a.out and then from /home/esger/src/application/coverage_test/dir2 run ../dir1/bin/a.out (to simulate a run with a binary built from cached .o and .gcno run from a different directory) again the gcda is created in the dir2/source directory with a non-mangled name. yey :) I can also see the source file paths in the gcno are relative: main.gcno:note:magic `gcno':version `B20 ' main.gcno:stamp 625107654 main.gcno:checksum 0 main.gcno:cwd: /home/esger/src/application/coverage_test/dir1/source main.gcno: 01000000: 83:FUNCTION ident=1482908279, lineno_checksum=0x2c72f060, cfg_checksum=0xc0bbb23e, `_GLOBAL__sub_I__Z5funcAi' ./source/main.cpp:21:1-21:1, artificial main.gcno: 01410000: 4:BLOCKS 4 blocks main.gcno: 01430000: 12:ARCS 1 arcs main.gcno: 01430000: 20:ARCS 2 arcs main.gcno: 01430000: 12:ARCS 1 arcs main.gcno: 01450000: 42:LINES main.gcno: 01450000: 42:LINES ... So with a patched gcc11, dropping -fprofile-dir and using -fprofile-prefix-map instead, gcda creation seems ok. The gcno files seem to contain relative paths to the source file too. However, the gcno file also still contains the compilation CWD which interferes with caching it and re-using it for different build dirs. Is there any way to get rid of that? And of course I still need to verify such created gcda files will actually result in a proper coverage report. Applying the patch to 9.4 or 10.3 as vit9696 did should allow me to test that. Will try that tomorrow if I have time.
