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digitalmars.D.bugs - [Issue 4413] New: typeof(this) doesn't work in method template signature

reply d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=4413

           Summary: typeof(this) doesn't work in method template signature
           Product: D
           Version: D2
          Platform: x86
        OS/Version: Windows
            Status: NEW
          Severity: normal
          Priority: P2
         Component: DMD
        AssignedTo: nobody puremagic.com
        ReportedBy: bearophile_hugs eml.cc


--- Comment #0 from bearophile_hugs eml.cc 2010-07-01 14:27:43 PDT ---
dmd v2.047 shows a compilation error on the call to bar4, but in my opinion the
compiler has to compile all four those bar methods:


struct Foo {
    alias typeof(this) typeof_this;
    void bar1(typeof_this other) {}
    void bar2()(typeof_this other) {}
    void bar3(typeof(this) other) {}
    void bar4()(typeof(this) other) {}
}
void main() {
    Foo f;
    f.bar1(f); // OK
    f.bar2(f); // OK
    f.bar3(f); // OK
    f.bar4(f); // ERR
}


The generated errors:
test.d(13): Error: template test.Foo.bar4() does not match any function
template declaration
test.d(13): Error: template test.Foo.bar4() cannot deduce template function
from argument types !()(Foo)


The problem of bar4 has shown up in D2 code similar to this one, where I have
used typeof(this) to follow the DRY strategy and avoid repeating the struct
name more than one time:

struct Vec2 {
    float x, y;
    auto opBinary(string op)(typeof(this) other) if (op == "+") {
      ...
    }
}


A workaround that can be used is:

struct Vec2 {
    float x, y;
    alias typeof(this) typeof_this;
    auto opBinary(string op)(typeof_this other) if (op == "+") {
      ...
    }
}

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next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=4413


Iain Buclaw <ibuclaw ubuntu.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |ibuclaw ubuntu.com


--- Comment #1 from Iain Buclaw <ibuclaw ubuntu.com> 2011-02-06 07:32:03 PST ---
Calling semantic on the param type in ::deduceType seems to be simplest
workaround without causing side effects.


--- a/src/template.c
+++ b/src/template.c
   -2183,6 +2183,7    MATCH TypeStruct::deduceType(Scope *sc, Type *tparam,
TemplateParameters *parame
      * to a template instance, too, and try again.
      */
     TemplateInstance *ti = sym->parent->isTemplateInstance();
+    tparam = tparam->semantic(0, sc);

     if (tparam && tparam->ty == Tinstance)
     {
   -2317,6 +2318,7    MATCH TypeClass::deduceType(Scope *sc, Type *tparam,
TemplateParameters *paramet
      * to a template instance, too, and try again.
      */
     TemplateInstance *ti = sym->parent->isTemplateInstance();
+    tparam = tparam->semantic(0, sc);

     if (tparam && tparam->ty == Tinstance)
     {


Ideally though, all typeof()'s should have been expanded beforehand.

Regards

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prev sibling next sibling parent d-bugmail puremagic.com writes:
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bearophile_hugs eml.cc changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |akb825 gmail.com


--- Comment #2 from bearophile_hugs eml.cc 2011-02-06 11:58:12 PST ---
*** Issue 5532 has been marked as a duplicate of this issue. ***

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klickverbot <code klickverbot.at> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |code klickverbot.at


--- Comment #3 from klickverbot <code klickverbot.at> 2011-03-30 17:53:08 PDT
---
The patch by Iain seems to break std.datetime:

/usr/local/include/d2/std/datetime.d(9217): Error: template instance
std.datetime.DTRebindable!(immutable(TimeZone)) error instantiating

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--- Comment #4 from Iain Buclaw <ibuclaw ubuntu.com> 2011-03-31 05:43:42 PDT ---
(In reply to comment #3)
 The patch by Iain seems to break std.datetime:
 
 /usr/local/include/d2/std/datetime.d(9217): Error: template instance
 std.datetime.DTRebindable!(immutable(TimeZone)) error instantiating
Yep, I was merely suggesting that things should ideally be worked out before this point (because they *can* be worked out). -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
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--- Comment #5 from Kenji Hara <k.hara.pg gmail.com> 2011-12-21 05:55:25 PST ---
*** Issue 5801 has been marked as a duplicate of this issue. ***

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |rejects-valid
           Platform|x86                         |All
         OS/Version|Windows                     |All


--- Comment #6 from Kenji Hara <k.hara.pg gmail.com> 2011-12-21 05:55:58 PST ---
https://github.com/D-Programming-Language/dmd/pull/572

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Walter Bright <bugzilla digitalmars.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
                 CC|                            |bugzilla digitalmars.com
         Resolution|                            |FIXED


--- Comment #7 from Walter Bright <bugzilla digitalmars.com> 2011-12-26
18:26:35 PST ---
https://github.com/D-Programming-Language/dmd/commit/8fa99fca73fea3a5130939ecaa83596f925cdbb8

https://github.com/D-Programming-Language/dmd/commit/2324c9903f99bb355ac5b2f25298a4f05ab0fba1

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |kennytm gmail.com


--- Comment #8 from Kenji Hara <k.hara.pg gmail.com> 2012-04-23 17:04:51 PDT ---
*** Issue 5903 has been marked as a duplicate of this issue. ***

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