• d-bugmail puremagic.com (73/73) Sep 22 2009 http://d.puremagic.com/issues/show_bug.cgi?id=3339
• d-bugmail puremagic.com (15/15) Nov 09 2010 http://d.puremagic.com/issues/show_bug.cgi?id=3339

d-bugmail puremagic.com writes:

http://d.puremagic.com/issues/show_bug.cgi?id=3339

           Summary: template "is not evaluatable at compile time" error
                    inconsistencies
           Product: D
           Version: 2.032
          Platform: x86_64
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: P2
         Component: DMD
        AssignedTo: nobody puremagic.com
        ReportedBy: chadjoan gmail.com



Version 1 of the program:
---------------------------------------
pure string wham(string str)
{
    return str;
}

template ouch(string val)
{
    mixin(`const bool ouch = `~wham(val)~`;`);
}

static assert( ouch!("true") );
static assert( !ouch!("false") );

void main(){}
---------------------------------------
This will compile just fine.  

I'm actually not sure if it should or not.

By moving the wham function into the ouch template, the code will no longer
compile; complaining about not being able to evaluate ouch at compile time. 
The changes make it look like so:
---------------------------------------
template ouch(string val)
{
    pure string wham(string str)
    {
        return str;
    }

    mixin(`const bool ouch = `~wham(val)~`;`);
}

static assert( ouch!("true") );
static assert( !ouch!("false") );

void main(){}
---------------------------------------
main2.d(11): Error: static assert  (ouch!("true")) is not evaluatable at
compile time


Another way to get the error is to store the result of wham into a constant and
try to use it:
---------------------------------------
pure string wham(string str)
{
    return str;
}

template ouch(string val)
{
    const string str = wham(val);
    mixin(`const bool ouch = `~str~`;`);
    // Same goes for `enum str = wham(val);`
}

static assert( ouch!("true") );
static assert( !ouch!("false") );

void main(){}
---------------------------------------
main3.d(13): Error: static assert  (ouch!("true")) is not evaluatable at
compile time

Again, I'm not actually sure whether these examples should compile or not. 
However, they should all be equivalent, yet one case will compile and the other
ones will not.

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d-bugmail puremagic.com writes:

http://d.puremagic.com/issues/show_bug.cgi?id=3339


Don <clugdbug yahoo.com.au> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
                 CC|                            |clugdbug yahoo.com.au
         Resolution|                            |INVALID



The syntax in cases 2 and 3 is wrong. It should be 
ouch!(true).ouch
because there is more than one member in the template.

When this is done, everything works correctly.

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