In order to debug your programs, you have to compile them in debug mode as described next

Create a .solution.toml file in your working directory. Then pass the -g argument to the compiler like this

[HelloWorld]
entry_point = "/path/to/my/entry_point_file/main.c"
output = "/path/where/the/program/will/be/written/hello_world"
arguments = "-g"

That will tell the compiler to compile in debug mode.

Please note that this section has nothing to do with compiler.nvim. I'm documenting this to make your life easier. To debug C with DAP you have to:

• Install the codelldb adapter using mason-dap.
• Setup DAP for C

Here you have an example of how to configure DAP for C

local dap = require("dap")

-- C
dap.adapters.codelldb = {
  type = 'server',
  port = "${port}",
  executable = {
    command = vim.fn.stdpath('data')..'/mason/bin/codelldb',
    args = {"--port", "${port}"},
    detached = function() if vim.fn.has('win32') == 1 then return false else return true end end,
  }
}
dap.configurations.c = {
  {
    name = 'Launch',
    type = 'lldb',
    request = 'launch',
    program = function() -- Ask the user what executable wants to debug
      return vim.fn.input('Path to executable: ', vim.fn.getcwd() .. '/bin/program', 'file')
    end,
    cwd = '${workspaceFolder}',
    stopOnEntry = false,
    args = {},
  },
}

Compile your program with Build solution, add a break point to your code, and then run DAP. You will see something like this.

• If you find any issue while configuring DAP, run :DapSetLogLevel trace and :DapShowLog to find the reason.
• Update 11/08/2023: Passing arguments in a .solution.toml file is not required anymore, as by default Compiler.nvim now passes the -g argument to the C compiler (gcc) to enable debug mode. But if you create a .solution.toml file in your project you will still have to set the argument manually, as that will overwrite the default compiler arguments with your own.