http://d.puremagic.com/issues/show_bug.cgi?id=8099
Summary: Inner class's outer pointer matches constancy of
inner, but can be set to object of arbitrary constancy
Product: D
Version: D2
Platform: x86
OS/Version: Windows
Status: NEW
Keywords: accepts-invalid
Severity: normal
Priority: P2
Component: DMD
AssignedTo: [email protected]
ReportedBy: [email protected]
Blocks: 2573
--- Comment #0 from Stewart Gordon <[email protected]> 2012-05-15 08:16:32 PDT ---
An inner class considers the pointer to the outer object to have the same
constancy as itself. (This doesn't seem to be stated in the spec, but by
const-transitivity rules it would have to be the same or stronger. See issue
8098 comment 1.)
Nonetheless, when instantiating the inner class it totally disregards the
constancy of the outer with which it is instantiated. This means that the
inner class can be viewing a mutable outer object as immutable, or vice versa.
----------
import std.stdio;
class Outer {
class Inner {}
}
void test(X, Y)(X x, Y y) {
writefln("%-20s %-20s %s", X.stringof, Y.stringof,
typeof(y.outer).stringof);
}
void main() {
auto m = new Outer;
auto c = new const(Outer);
auto i = new immutable(Outer);
auto mm = m.new Inner; test(m, mm); // m -> m OK
auto mc = m.new const(Inner); test(m, mc); // m -> c OK
auto mi = m.new immutable(Inner); test(m, mi); // m -> i bad
auto cm = c.new Inner; test(c, cm); // c -> m bad
auto cc = c.new const(Inner); test(c, cc); // c -> c OK
auto ci = c.new immutable(Inner); test(c, ci); // c -> i bad
auto im = i.new Inner; test(i, im); // i -> m bad
auto ic = i.new const(Inner); test(i, ic); // i -> c OK
auto ii = i.new immutable(Inner); test(i, ii); // i -> i OK
}
----------
C:\Users\Stewart\Documents\Programming\D\Tests>inner_const_2
Outer Inner Outer
Outer const(Inner) const(Outer)
Outer immutable(Inner) immutable(Outer)
const(Outer) Inner Outer
const(Outer) const(Inner) const(Outer)
const(Outer) immutable(Inner) immutable(Outer)
immutable(Outer) Inner Outer
immutable(Outer) const(Inner) const(Outer)
immutable(Outer) immutable(Inner) immutable(Outer)
----------
(DMD 2.059 Win32)
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