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 | Posted by andy@aligature.com |  Permalink Reply |
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andy@aligature.com 
| http://d.puremagic.com/issues/show_bug.cgi?id=4613
Summary: temporary generated inside foreach is not correctly
destructed
Product: D
Version: D2
Platform: Other
OS/Version: Mac OS X
Status: NEW
Severity: major
Priority: P2
Component: DMD
AssignedTo: nobody@puremagic.com
ReportedBy: andy@aligature.com
--- Comment #0 from andy@aligature.com 2010-08-10 08:54:33 PDT ---
Using dmd v2.047 it seems like there is a bug when generating a temporary inside a foreach statement. Here's an example.
<code>
#!/usr/bin/env rdmd
import std.stdio;
import std.conv;
struct MyFile
{
private struct Impl
{
uint refs = 0;
string name;
this(uint r, string n)
{
refs = r;
name = n;
}
}
private Impl* p;
this(string s)
{
writeln("MyFile ctor ", s);
p = new Impl(1, s);
}
this(this)
{
writeln("Adding ref ", p.name);
++p.refs;
}
~this()
{
writeln("MyFile dtor ", p.name);
if(p.refs == 1) close;
else{ writeln("Removing ref ", p.name); --p.refs;}
}
void close()
{
writeln("close ", p.name);
scope(exit) p = null;
}
int opApply(int delegate(ref char) dg)
{
foreach(char c; p.name)
{
dg(c);
}
return 0;
}
}
void doOne()
{
writeln("begin one");
auto f = MyFile("one");
foreach(c; f)
{
writeln(c);
}
writeln("end one");
}
void doTwo()
{
writeln("begin two");
foreach(c; MyFile("two"))
{
writeln(c);
}
writeln("end two");
}
void main()
{
writeln("before one");
doOne();
writeln("after one");
writeln("before two");
doTwo();
writeln("after two");
}
</code>
The first case is handled correctly. When the scope of doOne() ends, the f instance is correctly destroyed. However, in doTwo(), the temporary MyFile created in the foreach statement is not destroyed. In this case, "MyFile dtor two" and "close two" should be printed before "after two". I hit this bug specifically when using something like foreach(ubyte[] buf; chunks(file, 4096)). This keeps file handles open past their lifetime and is causing a file handle leak in my app.
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