compilation_database.json is empty

[SoloAs]

Describe the bug Compilation database JSON has no content, just "[]"

To Reproduce Steps to reproduce the behavior: running bear to build sources via Makefile right after cleaning up previous build artifacts.

Expected behavior compile_database.json contains all the necessary data. Environment:

• OS name: Linux
• OS version: CentOS Linux release 7.7.1908
• OS architecture: x86_64
• Bear version: bear 3.0.20
• Bear install method: from the *nix package: https://search.nixos.org/packages?channel=22.05&show=bear&from=0&size=50&sort=relevance&type=packages&query=bear

Additional context

• Can you give us a reference to the project that you are running against this tool? Main project is closed, test application is very simple and contains two .c files with one header being built using Makefile. Basically, this: https://www.cs.colby.edu/maxwell/courses/tutorials/maketutor/
• What build tools this project is using? Autotools for the main project, GNU Make 4.3 for simple test application, both have the same problem.
• What architecture you are trying to compile for? x86_64, not cross-compiling.
• Could you attach build logs? If you can re-run the command which failed (e.g. bear -- make) with extra verbose log switches (e.g. bear --verbose -- make) and send the output of it, that would help a lot. - attaching logs to this message: bear.log

Also I'm using *nix shell to setup all the necessary environment and packages. SELinux is disabled:

[nix-shell:~/projects/pro-av-clean/modules/mint/test]$ sestatus | grep 'SELinux status'
SELinux status:                 disabled

Compilers seem to be set up correctly:

[nix-shell:~/projects/pro-av-clean/modules/mint/test]$ which cc
/nix/store/74kv08wjf06ifgk4dxrnra4qhzr5s1w4-gcc-wrapper-10.3.0/bin/cc
[nix-shell:~/projects/pro-av-clean/modules/mint/test]$ which g++
/nix/store/74kv08wjf06ifgk4dxrnra4qhzr5s1w4-gcc-wrapper-10.3.0/bin/g++

Please tell me if you need any additional info.

Before you send...

• Have you read the README.md file or man bear? Yes
• Have you looked what other open issues Bear has? Yes, as well as the most of the closed ones
• Are you sure that the build works without Bear? Yes

[SoloAs]

Bump!

[BeeBreeze]

i have the same problem. the only difference is that, if compiling via cmake, bear produces empty JSON, while if compiling via makefile without cmake, bear works well.

[rizsotto]

Hey @SoloAs , sorry for the delay... You've been running the bear --verbose --force-wrapper -- make command, which is using compiler wrappers to intercept the compiler calls. This needs the build system to respect the CC and CXX environment variables.

From the log I see it was calling the /nix/store/74kv08wjf06ifgk4dxrnra4qhzr5s1w4-gcc-wrapper-10.3.0/bin/gcc directly and not using the CC variable (which was set to cc).

My suggestion would be to try to change the build system (make file) to use CC for compiling the sources. (But remove this line CC=gcc at the top of the Makefile.)

You can also try to run without the --force-wrapper flag. (That works better on linux. Not sure about NIX. :))