inlining function defs

[JaapAap]

I am compiling the serialization library Cereal, which relies on doctest for its unit testing, using VS2017. I get loads of linking errors due to multiple inclusions of the doctest functions, for example, for the function definition of doctest::Approx::Approx(double) (and many others). Defining these as inline would resolve these. Is there a reason why this currently not the case?

[onqtam]

Hi there - So glad I hear about another big project using doctest!

About your linker errors... doctest is a single header library with 2 parts - the top one is the interface, and the bottom one is the test runner implementation.

The definition of doctest::Approx::Approx(double) is in the implementation, which is conditionally compiled only if DOCTEST_CONFIG_IMPLEMENT is defined before including the framework header. That should be done in only one source file in the target binary (executable/shared object). You can think of the doctest header as 2 files - a .h and a .cpp which are concatenated in one file for easier distribution. That is also how all the dependencies are contained in only one translation unit of your project - all the #includes go into the implementation part. That is also the reason for the incredible compile times of doctest.

So if there are tons of linker errors - I would assume that there are multiple .cpp files which include the header and define that identifier within the same project (exe/dll/so) - and that is a broken setup - I'm not sure if it's because of the cmake files of Cereal, but this is not a problem in doctest per-se.

I cannot currently look into the doctest/cmake integration of cereal because I'm currently at work. If you manage to figure it out - let me know! Otherwise I'll check it out in a few hours/days...

[JaapAap]

Thanks for your reply and clear explanation - I used the VS2013 project file included by Cereal (not cmake), and indeed this is likely to be a broken setup (related to the way the unit tests within Cereal are organized), which I should be able to fix easily given the above.

[onqtam]

I'm closing this since (I assume) it's not a problem with doctest.