feat: on-demand compile_commands.json generation

[413x1nkp]

The goal was to add compile_commands.json generator into nob.
Application: LSP

Windows testing is still required, works well on linux though

Example 1

// nob.c

#define NOB_IMPLEMENTATION
#include "nob.h"

int main(int argc, char** argv) {
    NOB_GO_REBUILD_URSELF(argc, argv);

    Nob_Cmd cmd = {0};
    nob_cmd_append(&cmd, "gcc", "-o", "main", "main.c");
    nob_add_to_compile_database(cmd);

    nob_cmd_run_sync(cmd);

    return 0;
}

// main.c

int main() {
    return 0;
}

produces:

[
{
	"directory": "/kirby/Coding/nobtest",
	"commands": "gcc -o main main.c",
	"file": "main.c"
}
]

Example 2

// nob.c

#define NOB_IMPLEMENTATION
#include "nob.h"

int main(int argc, char** argv) {
    NOB_GO_REBUILD_URSELF(argc, argv);

    Nob_Cmd cmd = {0};
    nob_cmd_append(&cmd, "gcc", "-o", "main", "main.c", "main1.c");
    nob_add_to_compile_database(cmd);

    nob_cmd_run_sync(cmd);

    return 0;
}

// main.c

int main() {
    return 0;
}

// main1.c

int test() {

    return 1;
}

int lulz() {

    return 2;
}

produces:

[
{
	"directory": "/kirby/Coding/nobtest",
	"commands": "gcc -o main main.c main1.c",
	"file": "main.c"
},
{
	"directory": "/kirby/Coding/nobtest",
	"commands": "gcc -o main main.c main1.c",
	"file": "main1.c"
}
]

Example 3

// nob.c

#define NOB_IMPLEMENTATION
#define NOB_COMPILE_COMMANDS_PATH "build/compile_commands.json"
#include "nob.h"

int main(int argc, char** argv) {
    NOB_GO_REBUILD_URSELF(argc, argv);

    Nob_Cmd cmd = {0};
    nob_cmd_append(&cmd, "gcc", "-DSOME_VALUE=\"SOMEVALUE\"", "-o", "main", "main.c", "main1.c");
    nob_cmd_run_sync(cmd);
    nob_add_to_compile_database(cmd);

    return 0;
}

// main.c

int main() {
    return 0;
}

// main1.c

int test() {

    return 1;
}

int lulz() {

    return 2;
}

produces build/compile_commands.json:

[
{
	"directory": "/kirby/Coding/nobtest",
	"command": "gcc -DSOME_VALUE=\"LOLO\" -o main main.c main1.c",
	"file": "main.c"
},
{
	"directory": "/kirby/Coding/nobtest",
	"command": "gcc -DSOME_VALUE=\"LOLO\" -o main main.c main1.c",
	"file": "main1.c"
}
]

[413x1nkp]

Clang is stingy about including POSIX extensions implicitly, so -std=c99 to it means "NO POSIX ALLOWED"
GCC is more lenient about this on the other hand, it'll use POSIX if available and if required.
Functions ftruncate and readlink are therefore invisible, but only to Clang.
Solution is to either change workflow file to have -std=gnu99 instead of -std=c99, to define test macros required, to not rely on either (pretty hard), or to declare ftruncate and readlink explicitly.

I couldn't figure out what the best option is, so i settled for declaring both explicitly. Let me know if this causes issues!

[rhmoller]

Alternatively, you can use Bear together with nob for generating compile_commands.json

[finnkauski]

+1 for Bear. No issues here with LSP and using what it generates.

bear -- ./nob

lol

[413x1nkp]

Alternatively, you can use Bear together with nob for generating compile_commands.json

Yeah, bear works, but having explicit control on what ends up in compile_commands.json sounds like a good idea.
My approach is self-contained and doesn't rely on other tools, which might be a good or a bad thing depending on how you look at it. In my opinion, less dependencies to worry about - the better.