[clang-tidy] Check to add `void` to functions without parameters in C

[parmi93]

I would like clang tidy to add void for functions without parameters, as in the following example:

void foo();

void foo()
{
    printf("Hello World!");
}

void foo(void);

void foo(void)
{
    printf("Hello World!");
}

[llvmbot]

@llvm/issue-subscribers-clang-format

Author: Parminder Singh (parmi93)

Details

I would like clang format to add `void` for functions without parameters, as in the following example:

void foo();

void foo()
{
    printf("Hello World!");
}

void foo(void);

void foo(void)
{
    printf("Hello World!");
}

[EugeneZelenko]

This is task for tools like Clang-Tidy.

[llvmbot]

@llvm/issue-subscribers-clang-tidy

Author: Parminder Singh (parmi93)

Details

I would like clang format to add `void` for functions without parameters, as in the following example:

void foo();

void foo()
{
    printf("Hello World!");
}

void foo(void);

void foo(void)
{
    printf("Hello World!");
}

[carlosgalvezp]

I guess this is also a C-only use case.

[LegalizeAdulthood]

This seems kind of the opposite of the check I wrote: modernize-redundant-void-arg

[AaronBallman]

This seems kind of the opposite of the check I wrote: modernize-redundant-void-arg

That check should probably be updated for C23 now that it accepts () as analogous to (void). Which is a reason we might want an option for this new proposed check. Users may want to force (void) because they want to enforce compatibility with older C modes or they may want to use whatever the current language mode supports so they get code that's idiomatic for the language being used.

[LegalizeAdulthood]

Presumably you would check the C standard level?

The check I wrote explicitly does nothing on C code, only suggesting fixits on C++ code.

[parmi93]

This seems kind of the opposite of the check I wrote: modernize-redundant-void-arg

That check should probably be updated for C23 now that it accepts () as analogous to (void). Which is a reason we might want an option for this new proposed check. Users may want to force (void) because they want to enforce compatibility with older C modes or they may want to use whatever the current language mode supports so they get code that's idiomatic for the language being used.

I agree, in my specific case we are working on a new project written in c99 and having this feature would be helpful.