[Issue 18738] New: [scope] scope delegates can be escaped via closure

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=18738

          Issue ID: 18738
           Summary: [scope] scope delegates can be escaped via closure
           Product: D
           Version: D2
          Hardware: x86_64
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P1
         Component: dmd
          Assignee: nobody at puremagic.com
          Reporter: default_357-line at yahoo.de

Consider the following code:

int delegate() @safe foo(scope int delegate() @safe dg) @safe
{
    return { return dg(); };
}

int delegate() @safe bar() @safe
{
    int k = 5;
    return foo({ return k; });
}

void main() @safe
{
    writefln("%s", bar()());
}

The writefln outputs random noise because k is out of scope.

Doesn't seem very safe...

Probably foo should not have been allowed to allocate a closure that captured a
scope delegate parameter.

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