Miss Dada  🏳️‍⚧️

C99 says (6.7.5.3p10): "The special case of an unnamed parameter of type void as the only item in the list specifies that the function has no parameters"

(so there definitely *is* such a thing as a no-arg function. But you do have to explicitly put "void" rather than an empty parameter list).

If I recall, the distinction only exists in declarations. In a function definition, an empty list is equivalent to 'void'.

No; the form used in the definition acts as an equivalent declaration, so no parameter list acts allows calls which supply parameters ( = UB at run time, which is broken, yes).

That's not how I read it: C99.7.5.3-p14: "An empty list in a function declarator that is part of a definition of that function specifies that the function has no parameters."

C99.7.5.3-p14: "The empty list in a function declarator that is not part of a definition of that function specifies that no information about the number or types of the parameters is supplied."

Hmm. 6.9.1p7: "If the declarator includes a parameter type list [...]; such a declarator also serves as a function prototype for later calls to the same function in the same translation unit" - so - 1/

- that implies if it doesn't include a parameter type list, then it doesn't serve as a function prototype, i.e. it's the same as a declaration with no parameter list. So while it "specifies that ... function has no parameters", it doesn't serve as a prototype - 2/2