• d-bugmail puremagic.com Nov 29 2009
• d-bugmail puremagic.com Jan 10 2010
• d-bugmail puremagic.com Jan 11 2010
• d-bugmail puremagic.com Jan 11 2010
• d-bugmail puremagic.com Jan 12 2010

d-bugmail puremagic.com writes:

http://d.puremagic.com/issues/show_bug.cgi?id=3557

           Summary: Pure function cannot call struct constructor
           Product: D
           Version: 2.036
          Platform: x86
        OS/Version: Windows
            Status: NEW
          Severity: normal
          Priority: P2
         Component: DMD
        AssignedTo: nobody puremagic.com
        ReportedBy: tomeksowi gmail.com


--- Comment #0 from Tomasz Sowiński <tomeksowi gmail.com> 2009-11-29 03:19:44
PST ---
struct A {
    float f;
    this (float f) {
        this.f = f;
    }
    static pure A stworz(float f) {
        return A(f);
    }
}

The above doesn't compile:
Error: pure function 'stworz' cannot call impure function 'this'

What's interesting, if stworz signature is one of the below:

static pure stworz(float f);
static pure auto stworz(float f);

then it merrily compiles. So it's sth about the explicit return type.

If I remove the constructor, it also compiles.
If A is a class, it also compiles.

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d-bugmail puremagic.com writes:

http://d.puremagic.com/issues/show_bug.cgi?id=3557


Don <clugdbug yahoo.com.au> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |rejects-valid
                 CC|                            |clugdbug yahoo.com.au


--- Comment #1 from Don <clugdbug yahoo.com.au> 2010-01-10 11:54:44 PST ---
It shouldn't compile, since the constructor isn't marked as pure. But if you
mark the constructor as pure:

 pure {
     this (float f) {
        this.f = f;
    }
 }

you get:
bug.d(14): Error: cannot modify const/immutable/inout expression this.f

So we definitely have a problem.

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d-bugmail puremagic.com writes:

http://d.puremagic.com/issues/show_bug.cgi?id=3557



--- Comment #2 from Tomasz Sowiński <tomeksowi gmail.com> 2010-01-11 13:33:40
PST ---
(In reply to comment #1)
 It shouldn't compile, since the constructor isn't marked as pure. But if you
 mark the constructor as pure:
 
  pure {
      this (float f) {
         this.f = f;
     }
  }
 
 you get:
 bug.d(14): Error: cannot modify const/immutable/inout expression this.f
 
 So we definitely have a problem.


Yes, I had a feeling compiler should let me have pure ctors..

What about the problem I mentioned at the bottom (if A is a class):

class A {
    float f;
    this (float f) {    // NOT pure
        this.f = f;
    }
    static pure A stworz(float f) {
        return new A(f);
    }
}

This compiles. Should it?

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d-bugmail puremagic.com writes:

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--- Comment #3 from Tomasz Sowiński <tomeksowi gmail.com> 2010-01-11 13:40:33
PST ---
(In reply to comment #2)
 This compiles. Should it?


I'm now confident it shouldn't:

string global;
class A {
    float f;
    this (float f) {    // NOT pure
        this.f = f;
        global = "BUGABUGA!";
    }
    static pure A stworz(float f) {
        return new A(f);
    }
}

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d-bugmail puremagic.com writes:

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Don <clugdbug yahoo.com.au> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|Pure function cannot call   |Struct constructors cannot
                   |struct constructor          |be declared as pure


--- Comment #4 from Don <clugdbug yahoo.com.au> 2010-01-12 02:20:30 PST ---
(In reply to comment #3)
 (In reply to comment #2)
 This compiles. Should it?


 I'm now confident it shouldn't:
 
 string global;
 class A {
     float f;
     this (float f) {    // NOT pure
         this.f = f;
         global = "BUGABUGA!";
     }
     static pure A stworz(float f) {
         return new A(f);
     }
 }


That's bug 3573.

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