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digitalmars.D.bugs - [Issue 8329] New: foreach over string with dchar as element isn't nothrow

reply d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=8329

           Summary: foreach over string with dchar as element isn't
                    nothrow
           Product: D
           Version: unspecified
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: normal
          Priority: P2
         Component: druntime
        AssignedTo: nobody puremagic.com
        ReportedBy: jmdavisProg gmx.com


--- Comment #0 from Jonathan M Davis <jmdavisProg gmx.com> 2012-06-30 18:31:02
PDT ---
This code fails to compile:

import std.stdio;

void main() nothrow
{
    foreach(dchar c; "hello world")
    {}
}

giving the error

q.d(5): Error: _aApplycd1 is not nothrow
q.d(3): Error: function D main 'main' is nothrow yet may throw

if the dchar is removed, then it compiles just fine. Clearly, there's an issue
with the apply function which implements iterating over strings as characters
other than the character type of the string, since this really should be
nothrow, but it's not.

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next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=8329



--- Comment #1 from Kenji Hara <k.hara.pg gmail.com> 2012-06-30 22:22:23 PDT ---
(In reply to comment #0)

 This code fails to compile:
 
 import std.stdio;
 
 void main() nothrow
 {
     foreach(dchar c; "hello world")
     {}
 }
 
 giving the error
 
 q.d(5): Error: _aApplycd1 is not nothrow
 q.d(3): Error: function D main 'main' is nothrow yet may throw
 
 if the dchar is removed, then it compiles just fine. Clearly, there's an issue
 with the apply function which implements iterating over strings as characters
 other than the character type of the string, since this really should be
 nothrow, but it's not.


I think it should not be nothrow. Iterating string(== immutable(char)[]) as a
range of dchar runs decoding of UTF-8, and if given string has invalid UTF-8
sequence, it should throw UnicodeException (it's declared in core.exception).

On the other hand, such a transcoding iteration should be pure and  safe. It's
enough worth.

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prev sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=8329


Jonathan M Davis <jmdavisProg gmx.com> changed:

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


--- Comment #2 from Jonathan M Davis <jmdavisProg gmx.com> 2012-06-30 22:37:36
PDT ---
Valid point. I forgot about invalid unicode.

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