[Issue 18484] New: [dip1000] Subtype allows reference to escape with implicit casting

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=18484

          Issue ID: 18484
           Summary: [dip1000] Subtype allows reference to escape with
                    implicit casting
           Product: D
           Version: D2
          Hardware: x86_64
                OS: Windows
            Status: NEW
          Severity: major
          Priority: P1
         Component: dmd
          Assignee: nobody at puremagic.com
          Reporter: radu.racariu at gmail.com

Compile the following with dmd 2.079-beta1 (older compilers behave the same)
and -dip1000:

================================
struct S
{
    @property char[] c() return
    {
        return i.c;
    }

    alias c this;

    static struct I
    {
        char[] c;
    }

    I* i;
}

char[] c()
{
    auto x = S();
    return x;
}
===========================

Produces a nice error:

Error: returning x.c() escapes a reference to local variable x

Now change 'c' function to this

===========================
char[] c()
{
    return S();
}
===========================

No error is reported.

Expected to see the same error.

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