Add a Semicolon Automatically in C With a Vim Plugin

Question

I am a C programmer and I am looking for a plugin that automatically adds semicolons when necessary before writing changes to a file. For example, look at the following example.

printf("%s\n", string)

This should be turned into:

printf("%s\n", string);

It would be nice if the same plugin also did this for other languages that require semicolons, like CSS.

Answer 1

Languages with automatic semicolon insertion such as JavaScript and Go have as bunch of edge-cases where they do unexpected things, and any C solution will probably be no different. In C macros in particular make it extra hard:

#define IF    if(
#define THEN  ){
#define ELSE  } else {
#define ELIF  } else if (
#define FI    ;}

IF foo THEN
   stmt();
FI

This is a bit of a silly thing to do, but people do use macros like that. I've seen "macro abuse" like this in more modern/current codebases too.

Merely inserting a semi-colon after a )\n won't really work either:

int value = (cond == 5)
    ? (this_value)
    : (other_value);

if (foo)
{
}

if (foo) bar();  // Do need it here!

So you really need deep knowledge of the C code, and as mentioned, even with that it's pretty tricky to get right. There's an open feature request for clangd language server.

For CSS it might be a little bit more doable as the syntax is simpler, but I wouldn't be surprised if there are edge cases there too.

My advice: just type the semicolons.