const int return type

[Cocon Cocon]

I see what 'const' does to global variables and pointer arguments. But
how about return types?

Consider:

const int f() {
...
}

What does the 'const' change?

Specifically, what would one have to put in for the '...' in order to
get a compile-time error?

 

[Ben Bacarisse]

I see what 'const' does to global variables and pointer arguments. But
how about return types?

Consider:

const int f() {
...
}

What does the 'const' change?

Nothing. const is a property of objects not values and in C functions
return values not objects. That's a simplification -- a more technical
description is that function calls are not lvalue expressions.

Specifically, what would one have to put in for the '...' in order to
get a compile-time error?

I'd have thought you would be likely to get a diagnostic just for having
the const there though I don't think the C standard requires one.

 

[Keith Thompson]

Nothing. const is a property of objects not values and in C functions
return values not objects. That's a simplification -- a more technical
description is that function calls are not lvalue expressions.


I'd have thought you would be likely to get a diagnostic just for having
the const there though I don't think the C standard requires one.

It doesn't, but gcc (with the right options) warns:

warning: type qualifiers ignored on function return type