http://d.puremagic.com/issues/show_bug.cgi?id=10215

           Summary: const causes false float calculation
           Product: D
           Version: D2
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: major
          Priority: P2
         Component: DMD
        AssignedTo: nobody@puremagic.com
        ReportedBy: rswhite4@googlemail.com


--- Comment #0 from rswhite4@googlemail.com 2013-05-30 12:38:47 PDT ---
Example #1:
----
import std.stdio;

class Foo {
public:
    float a = 3.14 / 2 / 0.5;
    const float b = 3.14 / 2 / 0.5;
}

void main()
{
    float a = 3.14 / 2 / 0.5;
    const float b = 3.14 / 2 / 0.5;

    writefln("a = %f, b = %f", a, b);

    Foo f = new Foo();
    writefln("a = %f, b = %f", f.a, f.b);
}
----
Expected:
a = 3.140000, b = 3.140000
a = 3.140000, b = 3.140000

I get:
a = 3.140000, b = 3.140000
a = 3.140000, b = 0.000000

Example #2:
----
import std.math;
import std.stdio;

class Foo {
public:
    const float airTime = 0.5;

    //Speed to progress the jump
    const float jumpSinWaveSpeed = PI_2 / airTime;
    float jumpSinWaveSpeed2 = PI_2 / airTime;
}

void main() {
    Foo f = new Foo();
    writeln(f.jumpSinWaveSpeed);
    writeln(f.jumpSinWaveSpeed2);
}
----

Expected:
3.14159
3.14159

I get:
6.39384e-39
3.14159

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Andrej Mitrovic <andrej.mitrovich@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |andrej.mitrovich@gmail.com


--- Comment #1 from Andrej Mitrovic <andrej.mitrovich@gmail.com> 2013-05-30 14:18:08 PDT ---
Compiler options, OS, 32/64bit, and compiler version please. I can't reproduce this locally.

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--- Comment #2 from rswhite4@googlemail.com 2013-05-30 14:25:36 PDT ---
No compiler options and on Linux / Windows with dmd 2.063.
"Works" also on Dpaste:
http://dpaste.1azy.net/e6e3bb7b
and
http://dpaste.1azy.net/e1975814

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--- Comment #3 from Andrej Mitrovic <andrej.mitrovich@gmail.com> 2013-05-30 14:28:04 PDT ---
(In reply to comment #2)
> No compiler options and on Linux / Windows with dmd 2.063.
> "Works" also on Dpaste:
> http://dpaste.1azy.net/e6e3bb7b
> and
> http://dpaste.1azy.net/e1975814

Ok I can recreate it in 2.063, but not in git-head. This seems like a pretty huge bug to have in a release version.

Whatever it was it seems to be fixed now. Anyone know what happened?

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--- Comment #4 from rswhite4@googlemail.com 2013-05-30 14:32:50 PDT ---
Maybe we should offer a patch for this bug? It's a bit annoying. ;)

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Andrej Mitrovic <andrej.mitrovich@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|const causes false float    |Regression (2.063 release):
                   |calculation                 |const causes wrong float
                   |                            |calculation
           Severity|major                       |regression


--- Comment #5 from Andrej Mitrovic <andrej.mitrovich@gmail.com> 2013-05-30 15:00:22 PDT ---
I can't seem to bisect this. Does anyone know which specific commit the 2.063 release is based on?

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Tiberiu Gal <galtiberiu@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |galtiberiu@gmail.com


--- Comment #6 from Tiberiu Gal <galtiberiu@gmail.com> 2013-05-31 01:04:56 PDT ---
import std.stdio, std.math;


class Foo {
public:

    const int i = 3;
    auto getI(){ return i ; }
    int j = 3;
    auto getJ(){ return j;}
    const float x = 0.4;
    auto getX(){ return x; }
    float y = 0.4;
    auto getY(){ return y; }


}


struct Soo {

    const int i = 3;
    auto getI(){ return i ; }
    int j = 3;
    auto getJ(){ return j;}
    const float x = 0.4;
    auto getX(){ return x; }
    float y = 0.4;
    auto getY(){ return y; }
}

void main() {



    writeln("with local vars");
    const float x = 3.12;
    const int y = 3;
    writeln(x , " / " , x == 3.12);
    writeln(y, " / ", y == 3);

    writeln("with classes");
    Foo f = new Foo();
    writeln(f.x, " ", f.getX(), " / ", f.x == f.getX() );
    writeln(f.y, " ", f.getY(), " / ", f.y == f.getY() );
    writeln(f.i, " ", f.getI(), " / ", f.i == f.getI() );
    writeln(f.j, " ", f.getJ(), " / ", f.j == f.getJ() );


    writeln("now with structs");
    Soo s;
    writeln(s.x, " ", s.getX(), " / ", s.x == s.getX() );
    writeln(s.y, " ", s.getY(), " / ", s.y == s.getY() );
    writeln(s.i, " ", s.getI(), " / ", s.i == s.getI() );
    writeln(s.j, " ", s.getJ(), " / ", s.j == s.getJ() );


}
// outputs
/**

with local vars
3.12 / true
3 / true
with classes
6.09598e-39 0.4 / false
0.4 0.4 / true
4350240 3 / false
3 3 / true
now with structs
4.2039e-45 0.4 / false
0.4 0.4 / true
3 3 / true
3 3 / true

*/

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--- Comment #7 from Tiberiu Gal <galtiberiu@gmail.com> 2013-05-31 01:17:04 PDT ---
it's not about calculations, it's about accessing const fields in classes and
structs.
it works perfectly with local variables, it works when accessing the them from
within the class itself.

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--- Comment #8 from rswhite4@googlemail.com 2013-05-31 03:27:14 PDT ---
Does anyone knows in the meanwhile, which commit solved the problem?
The workaround is to use enum but it would be nice if const would work in dmd
2.063...

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |wrong-code


--- Comment #9 from Kenji Hara <k.hara.pg@gmail.com> 2013-06-01 08:10:52 PDT ---
(In reply to comment #8)
> Does anyone knows in the meanwhile, which commit solved the problem?
> The workaround is to use enum but it would be nice if const would work in dmd
> 2.063...

This bug reproduces just only with dmd2.063 "release".

Current 2.063 branch in github

  http://github.com/D-Programming-Language/dmd/branches/2.063

and released zip does not contain exactly same source code.

I found a difference between them, in expression.c DotVarExp::semantic.


https://github.com/D-Programming-Language/dmd/blob/2.063/src/expression.c#L7501

The line "#if PULL93" and "#endif" does not exist in released src/expression.c, and the bug reproduces 2.063 branch + removing the #if and #endif lines.

Therefore, I can say that the root cause was exists in the mis-operation for building and packaging release files.

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