https://issues.dlang.org/show_bug.cgi?id=17730
Issue ID: 17730 Summary: [scope][dip1000] Can escape references to scope classes via moving Product: D Version: D2 Hardware: x86_64 OS: Linux Status: NEW Severity: normal Priority: P1 Component: dmd Assignee: nob...@puremagic.com Reporter: mor...@ucworks.org The following compiles with `dmd -dip1000 escape_scope_class.d` - escape_scope_class.d - import core.stdc.stdio : printf; import std.algorithm : move; class A { int i; this() @safe { i = 0; } } void inc(scope A a) @safe { a.i += 1; } void print(scope A a) @trusted { printf("A@%x: %d\n", cast(void*) a, a.i); } auto makeA() @safe { scope a = new A(); a.print(); return move(a); } void main() @safe { auto a = makeA(); foreach (i; 0..3) { a.print(); a.inc(); } } --- and outputs something like --- A@198d1568: 0 A@198d1568: 0 A@198d1568: 1 A@198d1568: 2 --- , i.e. a reference to the `makeA.a` object is escaped and assigned to `main.a` within @safe code. What needs fixing is that the above code should error out with an appropriate message about escaping the reference to the scope class. Additionally, it would be nice if the following code where to compile with `-dip1000`, but work like moving a std.typecons.scoped: --- void main() @safe { scope a = makeA(); foreach (i; 0..3) { a.print(); a.inc(); } } --- would then output something like --- A@198d1568: 0 // scope class object makeA.a (on makeA's stack frame) A@198d1578: 0 // scope class object main.a (on main's stack frame) A@198d1578: 1 A@198d1578: 2 --- so essentially the scope class object is blitted from makeA to main the same way it would if it were a scoped!A (and has the same dangers w.r.t. self-references, of course). --