bearophile wrote:
Don:
Pure functions are allowed to read immutable global variables.
Currently, this even includes globals which are initialized from inside
'static this()'.
Here's an example of how this can be a problem:
immutable int unstable;
pure int buggy() { return unstable; }
static this() {
// fails even though buggy is pure
assert( buggy() == ( ++unstable , buggy() ) );
}
I suspect that such functions should be forbidden from being 'pure'.
Note that they cannot be used in CTFE (conceptually, all other @safe
pure functions could be used in CTFE, even though the current
implementation doesn't always allow it).
I don't understand what exactly you propose to ban.
Do you want to ban any function to be pure if such function reads any global
immutable/const variable? Or do you want to just ban pure functions that read
global immutables if an only if such global immutables are initialized inside
static this()?
The second. Consider:
immutable int x;
immutable int y = 2;
static this() { x = 3; }
y should be usable from inside pure, x should not.
