Thread overview
[Issue 9162] New: [tdpl] Non-static structs should have access to outer lexical scope
Dec 15, 2012
Walter Bright
Dec 16, 2012
js.mdnq@gmail.com
Dec 16, 2012
Walter Bright
Dec 16, 2012
Kenji Hara
Dec 17, 2012
Walter Bright
December 15, 2012
http://d.puremagic.com/issues/show_bug.cgi?id=9162

           Summary: [tdpl] Non-static structs should have access to outer
                    lexical scope
           Product: D
           Version: D2
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: normal
          Priority: P2
         Component: DMD
        AssignedTo: nobody@puremagic.com
        ReportedBy: hsteoh@quickfur.ath.cx


--- Comment #0 from hsteoh@quickfur.ath.cx 2012-12-15 11:40:31 PST ---
The following is adapted from Walter's "Voldemort Types" article:

import std.stdio;

auto makeVoldemort(int x) {
        struct Voldemort {
                @property int value() { return x; }
                // Compile error:
        }
        return Voldemort();
}

void main() {
        auto v = makeVoldemort(123);
        writeln(v.value);
}

Compiler output:
test.d(5): Error: function test.makeVoldemort.Voldemort.value cannot access
frame of function test.makeVoldemort

According to TDPL, ยง7.1.9 (p.263): <quote>Nested structs embed the magic "frame pointer" that allows them to access outer values such as a and b in the example above."</quote>

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--- Comment #1 from hsteoh@quickfur.ath.cx 2012-12-15 11:48:42 PST ---
Also from that paragraph in TDPL:

"If you want to define a nested struct without that baggage, just prefix struct with static in the definition of Local, which makes Local a regular struct and consequently prevents it from accessing a and b."

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Walter Bright <bugzilla@digitalmars.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |bugzilla@digitalmars.com


--- Comment #2 from Walter Bright <bugzilla@digitalmars.com> 2012-12-15 14:51:29 PST ---
This fails:

    auto makeVoldemort(int x) {
        struct Voldemort {
                @property int value() { return x; }
        }
        return Voldemort();
    }

This works:

    auto makeVoldemort(int x) {
        struct Voldemort {
                int value() { return x; }
        }
        return Voldemort();
    }

So it's a problem with @property.

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--- Comment #3 from js.mdnq@gmail.com 2012-12-15 23:43:35 PST ---
When using a normal method instead of a property I then get the error: "Internal Error: ..\ztc\cod2.c 4727" on release build. Debug build does not return this error. 2.060.

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--- Comment #4 from Walter Bright <bugzilla@digitalmars.com> 2012-12-16 01:07:31 PST ---
(In reply to comment #3)
> When using a normal method instead of a property I then get the error: "Internal Error: ..\ztc\cod2.c 4727" on release build. Debug build does not return this error. 2.060.

Current head does not return errors on normal method.

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Kenji Hara <k.hara.pg@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |pull


--- Comment #5 from Kenji Hara <k.hara.pg@gmail.com> 2012-12-16 04:42:50 PST ---
https://github.com/D-Programming-Language/dmd/pull/1379

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Walter Bright <bugzilla@digitalmars.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED


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