gcov with CMake using a separate build directory

Question

I'm struggling to get coverage information for gcov. No errors during compilation and linking, but when I run the executable, no coverage data is produced.

I'm using CMake with a separate build directory, passing flags to the compiler and linker in this way:

add_definitions(--coverage)
set(CMAKE_EXE_LINKER_FLAGS ${CMAKE_EXE_LINKER_FLAGS} " --coverage")

Does the executable expect the source code to be in a specific location? What do I have to add to my CMakeLists.txt to get things going?

Kind regards, Bjoern

delcypher · Accepted Answer · 2012-02-23 00:34:51Z

17

CMake seems to put the code coverage (*.gcda, *.gcdo) files with the object files of your project. If your executable was named "tester" then they would appear in the following path

${CMAKE_BINARY_DIR}/CMakeFiles/tester.dir/

CMake seems to name the source files in a way that isn't very compatible with gcov though. For example if I had a source file called "mytestprog.cpp" it would be build

mytestprog.cpp.o
mytestprog.cpp.gcda
mytestprog.cpp.gcdno

where as gcov seems to expect

mytestprog.gcda
mytestprog.gcdno

I'm not really sure how to fix it. I've tried using LCov instead and that "appeared" to work but I'm not really sure if it did.

answered Feb 23, 2012 at 0:34

delcypher

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2 Comments

bcmpinc Over a year ago

for some reason you can get profile information by specifying only the object files and passing a bogus value as sourcefile. For example: gcov -o mytestprog.cpp.o x will produce mytestprog.cpp.gcov.

jackyalcine Over a year ago

@bcmpinc It won't be able to check the headers you used in that file, though.

robert · Accepted Answer · 2016-10-19 08:35:13Z

12

Delcypher pointed out the problem.

Solution 1: you can ask cmake to name object files as main.o instead of main.cpp.o etc. using the undocumented CMAKE_CXX_OUTPUT_EXTENSION_REPLACE switch:

cmake -DCMAKE_CXX_OUTPUT_EXTENSION_REPLACE=ON ...

Solution 2: if you do not need the .gcov files you can call lcov from the build directory:

lcov --capture --directory . --output-file coverage.info
genhtml coverage.info --output-directory out

You will find the coverage information in the out directory in html form.

edited Oct 19, 2016 at 8:35

answered Oct 18, 2016 at 14:19

robert

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Community · Accepted Answer · 2020-06-20 09:12:55Z

3

Not sure where you got --coverage from, but these are the arguments I use on Linux to get coverage information using gcc and gcov:

set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -fprofile-arcs -ftest-coverage")
set(CMAKE_EXE_LINKER_FLAGS
    "${CMAKE_EXE_LINKER_FLAGS} -fprofile-arcs -ftest-coverage")

Here's what gcc --help --verbose has to say about those options:

-ftest-coverage Create data files needed by "gcov"

-fprofile-arcs Insert arc-based program profiling code

edited Jun 20, 2020 at 9:12

CommunityBot

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answered May 22, 2011 at 19:14

richq

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2 Comments

jackyalcine Over a year ago

When using Clang, --coverage does what those two arguments do in a shorter format.

mloskot Over a year ago

GCC supports --coverage gcc.gnu.org/onlinedocs/gcc/Instrumentation-Options.html

able · Accepted Answer · 2011-05-23 15:08:33Z

You don't need to pass --coverage to the linker. --coverage will pass -fprofile-arcs -ftest-coverage to the compiler and -lgcov to the linker.

Are you sure that it isn't creating any gcdo or gcda files? Where are you looking for these files? It should put the gcov file for each object file into the same directory as the object file. Do a find for .gcda files at the top of your build directory. If nothing shows up, gcov might not be getting linked in. Run the following command to see if it is:

nm name_of_binary | grep "gcov"

If it is getting linked in, then gcov might not have permission to write files to where you are running the executable. If it has permission, then I am stumped.

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