http://d.puremagic.com/issues/show_bug.cgi?id=1924

           Summary: fail to pragma compile time constant
           Product: D
           Version: 1.026
          Platform: PC
        OS/Version: Windows
            Status: NEW
          Severity: normal
          Priority: P2
         Component: DMD
        AssignedTo: bugzilla@digitalmars.com
        ReportedBy: davidl@126.com


char[] wrongfunc()
{
    char[] result;
    pragma(msg, result);       // fail at this line
    return result;
}
mixin(wrongfunc);


-- 

http://d.puremagic.com/issues/show_bug.cgi?id=1924


fvbommel@wxs.nl changed:

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




------- Comment #1 from fvbommel@wxs.nl  2008-03-14 09:44 -------
Your 'result' is a variable that happens not to get assigned at runtime, but the fact that it happens not to change doesn't mean it's a constant.


P.S. According to the spec it even needs to be a string literal (which I don't think is what the compiler implements, since I'm pretty sure it allows string constants constructed by templates and ctfe). But either way your code is clearly illegal.


-- 

http://d.puremagic.com/issues/show_bug.cgi?id=1924


davidl@126.com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |REOPENED
         Resolution|INVALID                     |




------- Comment #2 from davidl@126.com  2008-03-15 00:23 -------
char[] wrongfunc()
{
    char[] result="void main()";
    result ~= "{}";
    const char[] myresult= result;
    pragma(msg, myresult);       // fail at this line
    return result;
}
mixin(wrongfunc);

abc.d(6): Error: string expected for message, not 'result'

pragma here is clearly for debugging CTFE. I don't want to make it as the following

char[] getresult()
{
    char[] result="void main()";
    result ~= "{}";
    return result;
}
char[] myfunc()
{
    const char[] result = getresult();
    pragma(msg,result);
    return result;
}
mixin(myfunc);

it's way dummier for debugging CTFE, especially if i want to do only some simple inspect on some particular vars.


-- 

http://d.puremagic.com/issues/show_bug.cgi?id=1924


clugdbug@yahoo.com.au changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Severity|normal                      |enhancement
           Keywords|spec                        |
            Summary|fail to pragma compile time |Allow pragma(msg) in CTFE
                   |constant                    |




------- Comment #3 from clugdbug@yahoo.com.au  2008-11-26 08:35 -------
Although a way of debugging CTFE functions would be very nice to have, this is definitely not a bug.

I'm changing this to an enhancement, changed title from: fail to pragma compile time constant


-- 

http://d.puremagic.com/issues/show_bug.cgi?id=1924





------- Comment #4 from smjg@iname.com  2008-11-26 08:52 -------
I think we need separate notation for this.  Generating a compiler message while compiling a function is conceptually different from generating a compiler message while evaluating it.


-- 

http://d.puremagic.com/issues/show_bug.cgi?id=1924


shro8822@vandals.uidaho.edu changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |shro8822@vandals.uidaho.edu




------- Comment #5 from shro8822@vandals.uidaho.edu  2008-11-26 10:32 -------

pragma(writefln,"hello #%d", 1);
vote++;


-- 

http://d.puremagic.com/issues/show_bug.cgi?id=1924





------- Comment #6 from smjg@iname.com  2008-11-26 11:13 -------
From the names pragma(msg) and pragma(writefln), it isn't clear at all that
one's while compiling and one's while evaluating.

Better would be to name it something like "ctfeMsg" or "msgCTFE".  And perhaps writefln notation could be supported in both this and regular msg.  This won't break existing code as long as pragma(msg, string) with no further arguments is still defined to write that exact string.


-- 

http://d.puremagic.com/issues/show_bug.cgi?id=1924





------- Comment #7 from shro8822@vandals.uidaho.edu  2008-11-26 11:17 -------
To date, every use of writefln I've seen has been run time. So it doesn't seem particularly ambiguous at least to me,


-- 

http://d.puremagic.com/issues/show_bug.cgi?id=1924





------- Comment #8 from smjg@iname.com  2008-11-26 12:05 -------
(In reply to comment #7)
> To date, every use of writefln I've seen has been run time. So it doesn't seem particularly ambiguous at least to me,

That's because at the moment writefln can only be executed at run time.  If it (or something resembling it) becomes executable at compile time, it could just as well be either as and when compiled or during CTFE.

Having a difference between pragma(msg) and pragma(writefln) beyond what they
say on the tin would be arbitrary and confusing.


-- 

http://d.puremagic.com/issues/show_bug.cgi?id=1924





------- Comment #9 from shro8822@vandals.uidaho.edu  2008-11-26 12:43 -------

Sorry, I was far less than clear.

writefln in all cases we use it in now executes with the code path, e.g. when the code is executed rather than generated. pragma is compile time in all cases. Seems like a good fit to me.

OTOH as long as it's not something like pragma(D9B01F73-E64A-4FA9-A2DE-C20CD24560BA) I'm not going to object to getting it!


--