www.digitalmars.com         C & C++   DMDScript  

digitalmars.D.bugs - [Issue 3024] New: array slicing bypass the stack var escape check

reply d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=3024

           Summary: array slicing bypass the stack var escape check
           Product: D
           Version: 2.028
          Platform: PC
        OS/Version: Windows
            Status: NEW
          Severity: normal
          Priority: P2
         Component: DMD
        AssignedTo: bugzilla digitalmars.com
        ReportedBy: davidl 126.com


import std.stdio;

string func()
{
    string s="abc";
    return s;
}

void func1()
{
    writefln("func1");
    string v = func();
    writefln("call func");
    writefln(func2());
}

byte[] func2()
{
    writefln("hello!");
    byte[16] v= [65,65,65,65,
             65,65,65,65,
             65,65,65,65,
             65,65,65,65];
    writefln(v[0..16]);
    return v[0..16];
}

void main(string[] args)
{
    func1();
}

-- 
Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
May 25 2009
next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=3024


Koroskin Denis <2korden gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |2korden gmail.com
           Severity|normal                      |enhancement




--- Comment #1 from Koroskin Denis <2korden gmail.com>  2009-05-25 06:45:13 PDT
---
It is exactly the same as

byte[] tmp = v[0..16];
return tmp;

Compiler can't detect operations like this ATM, and is not supposed to
(according to specs).

Marking it as an enhancement request, I wouldn't hold my breath for this being
fixed.

-- 
Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
May 25 2009
prev sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=3024


Matti Niemenmaa <matti.niemenmaa+dbugzilla iki.fi> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Platform|x86                         |All
            Version|2.028                       |1.045
            Summary|array slicing bypass the    |Array slicing allows
                   |stack var escape check      |returning an escaping
                   |                            |reference to a local stack
                   |                            |variable
         OS/Version|Windows                     |All




--- Comment #2 from Matti Niemenmaa <matti.niemenmaa+dbugzilla iki.fi> 
2009-07-12 08:53:14 PDT ---
Also affects 1.0.

It's true that the specs don't mention it but it's a bit inconsistent that both
the pointer and scope object cases are detected while the case of array slicing
isn't. Of the following, currently only the first three result in a compile
error:

int*   pointer() { int x;          return &x;   }
Object object()  { scope Object x; return  x;   }
int[]  array()   { int[1] x;       return  x;   }
int[]  slice()   { int[1] x;       return  x[]; }

-- 
Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
Jul 12 2009