CODEWITHSUNDEEP
cmakeclang
Necto
Necto

Reputation: 2654

Why -DCMAKE_EXPORT_COMPILE_COMMANDS does not create compile_commands.json file

My cmake --version is 2.8.12.2.

I configure my project build with these commands:

cmake ../klein/ -DBUILD_KLEIN_DEPS=1 -DCMAKE_EXPORT_COMPILE_COMMANDS=1
cmake ../klein/ -DBUILD_KLEIN_DEPS=1 -DCMAKE_EXPORT_COMPILE_COMMANDS=ON
cmake ../klein/ -DBUILD_KLEIN_DEPS=1 -DCMAKE_EXPORT_COMPILE_COMMANDS=on
CMAKE_EXPORT_COMPILE_COMMANDS=1 cmake ../klein/ -DBUILD_KLEIN_DEPS=1

From a clean build, and from a directory with an existing successful build. And want to see the compiler_commands.json file, but it does not appear.

At which moment should it be created: after cmake, or after make command? Where should it be in ./, or in ../klein directory? My cmake does not say anything about this option while it always complains about unused build variables.

Should it work from in a "dirty" directory, where I've performed one successful build, or does it work only on a fresh run in an empty folder?

Edit: I use a default generator "Unix Makefiles" on my ubuntu linux machine

Edit2: I'm not an author of the project under the question (I just want to explore it with rtags which requires compile_commands.json file), and I'm not very familiar with CMake mechanics. However, the CMakeLists.txt is probably configured as a super-build (it indeed downloads and builds dependencies - like llvm, z3, ...), and it includes ExternalProject, however it also builds the project itself (klein) from sources. So it's a mix, as I would say.

Upvotes: 3

Views: 7352

Answers (1)

StAlphonzo
StAlphonzo

Reputation: 766

Can you specify what generator your using? A quick scan of the cmake source from version 3.1.0 suggests that this command is still only available in the following 2 cases. 

if(CMAKE_GENERATOR MATCHES "Unix Makefiles")

and 

if(CMAKE_GENERATOR MATCHES "Ninja")

if you're using Visual Studio directly you're out of luck unless you want to add a patch to CMake. Otherwise, I know many Windows developers who've gone to Ninja. One advantage is that it's vastly faster than Visual Studio for building. If you are, in fact using Ninja or Unix Makefiles, then it's worth digging deeper.

Upvotes: 2

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