How to find C functions without a prototype?

Question

Company policy dictates that every function in C source code has a prototype. I inherited a project with its own make system (so I cannot test it on gcc or Visual Studio) and found that one of the files has some static functions declared without prototypes. Is there a way (not necessarily with a compiler) to list all functions without prototypes in all .c files?

Accepted Answer

gcc has an option to warn you about this:

```
gcc -Wmissing-prototypes
```

You can turn this warning into an error to stop compilation and force people to fix it:

```
gcc -Werror=missing-prototypes
```

If you just want to list it you can compile with the `gcc` option `-Wmissing-prototypes` and grep for no previous prototype for in the log.

Update based on edit:

Since you now mention that you can't use gcc, you'll have to find a similar option for your current compiler. Most compilers have such an option. Start with the man page or the built in help output.

How to find C functions without a prototype?

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