30 pointsby nateb20223 days ago4 comments
  • jchw2 hours ago
    I frequently use this to make clangd work well. With CMake-based projects, you can just set CMAKE_EXPORT_COMPILE_COMMANDS then create a symlink from compile_commands.json in your source directory to the CMake build directory. (If you control the CMake file, you can even set this by default and make CMake create this symlink automatically.) To keep the symlink out of Git, you can add it to .gitignore of course, or if you don't control that, the lesser-known local equivalent, .git/info/exclude.

    I use this often in combination with direnv and Nix flakes for a good developer experience. (Note that if you need to keep the Nix flake VCS-ignored, you'll need to tell direnv to explicitly not use a Git fetcher for Nix using something like `use flake path://$PWD` though this isn't needed if you can just re-use a Nixpkgs expression, e.g. `use flake nixpkgs#wineWow64Packages.wine-unstable` or so.)

    One thing that sucks is that it doesn't seem to be easy to handle cross-compilation stuff. Wine is a particularly challenging case, as many of the binaries are now cross-compiled with MinGW. It still provides better completion than nothing, but I do wish I could get it to be perfect.

    When using Nix with MinGW I struggled even harder because Nix's MinGW is even weirder... But with enough mangling, you can even convince clangd on Linux to give somewhat decent completions for a MinGW compilation.

    One obvious disadvantage is that you kind of need a full rebuild to get the compilation database to work correctly. At least in my personal experience, running bear on a partial build seems to not work in an additive fashion, though maybe I was holding it wrong.

  • AceJohnny210 hours ago
    If you have control over the build system, clang can generate that directly nowadays, by adding -MJ path to CFLAGS (or equiv). This will save JSON fragments to path (make'em separate for each compiled file), then you can concatenate all the fragments into a compilation database.

    I use this approach because on macOS, with SIP, Bear no longer works as it is forbidden from injecting its hooks into the system-protected clang shim. There may be other solutions.

    (I haven't explored the space in a few years. They've historically fared poorly with embedded targets where one file may be compiled many different ways for targeting different platforms)

    • maccard10 hours ago
      One of the major problems approach with this is that you need to run the compile before you can generate this database.
      • suprjami8 hours ago
        How do you propose to generate the compilation database without compiling? I would really like that for the Linux kernel.
        • xxpor5 hours ago
          You really need build system support. For example, Ninja can generate the file without actually doing the build because it knows everything it _would_ do.
      • 8 hours ago
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      • wakawaka284 hours ago
        Is this really a major problem? Is there any tool that supports generating the database without compiling? I think the answer to both of these is "no". In fact I can't even think of a reasonable case where it would be even a minor problem.
        • jchw2 hours ago
          Ninja and CMake do. It's especially useful if you want a compilation database for a project that takes an extremely long time to build.
          • wakawaka2838 minutes ago
            CMake does but I think you have to attempt a build to get the database. On the other hand I don't think that should be necessary, as it is capable of generating Ninja build files.

            Almost nobody is writing Ninja files by hand. If you have to write something along those lines by hand, Makefiles would make more sense than Ninja. If Ninja does support exporting commands, it's a use case that doesn't matter because almost everyone uses CMake-generated Ninja files.

            • jchw37 minutes ago
              You do not need to attempt a build with CMake.

              Also, that's kind of the point of mentioning Ninja. Inherently, anything that uses Ninja is in the same boat and doesn't need to start a build.

  • synergy2010 hours ago
    the compilation database is essential for editors these days, cmake can generate it directly but not all code use cmake, in that case I just use compiledb, which is inactive (there is a newer compiledb-go though), then use bear. somehow bear did not work well for me comparing to compiledb so compiledb(now compiledb-go) is my main tool now.
  • BoingBoomTschak8 hours ago
    Just shilling a single-file almost POSIX sh script I made to do the same: https://git.sr.ht/~q3cpma/scripts/tree/master/item/mkcdb