http://d.puremagic.com/issues/show_bug.cgi?id=3050

           Summary: Allow exception in CTFE (patch)
           Product: D
           Version: 2.030
          Platform: x86
        OS/Version: All
            Status: NEW
          Keywords: patch
          Severity: enhancement
          Priority: P2
         Component: DMD
        AssignedTo: bugzilla@digitalmars.com
        ReportedBy: rsinfu@gmail.com


Created an attachment (id=389)
 --> (http://d.puremagic.com/issues/attachment.cgi?id=389)
Patch (DMD 2.030)

The proposed patch implements support for throw/try/catch/finally in CTFE. Throw statement is, however, somewhat limited; new expression is not allowed, except for new Exception("msg").

Example and output:
--------------------
int thrower(string s)
{
    // The interpretor emulates throw new Exception("msg")
    throw new Exception("exception " ~ s);
    return 0;
}

int catcher()
{
    try
    {
        return thrower("abc");
    }
    catch (Exception e)
    {
        throw e;
    }
    return 0;
}

enum a = catcher("abc");
--------------------
test.d(21): Error: uncaught exception from catcher(): "exception abc"
test.d(21): Error: cannot evaluate catcher() at compile time
--------------------

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--- Comment #1 from Shin Fujishiro <rsinfu@gmail.com>  2009-06-04 15:37:11 PDT ---
Created an attachment (id=391)
 --> (http://d.puremagic.com/issues/attachment.cgi?id=391)
Additional patch

Please apply this patch in addition to the first one. The first one allowed this problematic code:
--------------------
Exception foo()
{
    Exception r;
    try
    {
        throw new Exception("error");
    }
    catch (Exception e)
    {
        r = e;
    }
    return r;
}
enum Exception e = foo();
--------------------

This patch fix the first patch so that a CTFE exception object cannot be used as a usual object. The only allowed use of a CTFE exception object is this: catch (Exception e) { throw e; }

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d-bugmail@puremagic.com wrote:
> http://d.puremagic.com/issues/show_bug.cgi?id=3050
> 
>            Summary: Allow exception in CTFE (patch)
>            Product: D
>            Version: 2.030
>           Platform: x86
>         OS/Version: All
>             Status: NEW
>           Keywords: patch
>           Severity: enhancement
>           Priority: P2
>          Component: DMD
>         AssignedTo: bugzilla@digitalmars.com
>         ReportedBy: rsinfu@gmail.com
> 
> 
> Created an attachment (id=389)
>  --> (http://d.puremagic.com/issues/attachment.cgi?id=389)
> Patch (DMD 2.030)
> 
> The proposed patch implements support for throw/try/catch/finally in CTFE.
> Throw statement is, however, somewhat limited; new expression is not allowed,
> except for new Exception("msg").
> 
> Example and output:
> --------------------
> int thrower(string s)
> {
>     // The interpretor emulates throw new Exception("msg")
>     throw new Exception("exception " ~ s);
>     return 0;
> }
> 
> int catcher()
> {
>     try
>     {
>         return thrower("abc");
>     }
>     catch (Exception e)
>     {
>         throw e;
>     }
>     return 0;
> }
> 
> enum a = catcher("abc");
> --------------------
> test.d(21): Error: uncaught exception from catcher(): "exception abc"
> test.d(21): Error: cannot evaluate catcher() at compile time
> --------------------
> 

Since scope() is defined in terms of try/finally, would it be much harder to get scope(success/failure/exit) working in CTFE?

http://d.puremagic.com/issues/show_bug.cgi?id=3050





--- Comment #2 from Shin Fujishiro <rsinfu@gmail.com>  2009-06-04 20:42:46 PDT ---
Created an attachment (id=392)
 --> (http://d.puremagic.com/issues/attachment.cgi?id=392)
Patch: scope(success/failure/exit)

Supplemental patch to get scope guard statement working in CTFE.

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Robert Fraser <fraserofthenight@gmail.com> wrote:
> Since scope() is defined in terms of try/finally, would it be much harder to get scope(success/failure/exit) working in CTFE?

Nope. I forgot about those. :) Thanks!

Just wow! I wonder what else can D community do since DMD has full source code available now.

http://d.puremagic.com/issues/show_bug.cgi?id=3050





--- Comment #3 from Walter Bright <bugzilla@digitalmars.com>  2009-07-14 03:02:14 PDT ---
Wow!

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--- Comment #4 from Kenji Hara <k.hara.pg@gmail.com> 2011-09-17 14:49:45 PDT ---
I have modified his patch based on git master.

https://github.com/9rnsr/dmd/commits/ctfeException

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Don <clugdbug@yahoo.com.au> changed:

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


--- Comment #5 from Don <clugdbug@yahoo.com.au> 2011-11-05 01:35:26 PDT ---
More than two years later, CTFE exceptions are fully implemented. I did use some ideas from the patch.

https://github.com/D-Programming-Language/dmd/commit/c0b26683e4e668581424e611105599ce8ab52592

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