www.digitalmars.com         C & C++   DMDScript  

digitalmars.D.bugs - [Issue 12150] New: Regression (2.063): char[] implicitly converts to string in .dup expression

reply d-bugmail puremagic.com writes:
https://d.puremagic.com/issues/show_bug.cgi?id=12150

           Summary: Regression (2.063): char[] implicitly converts to
                    string in .dup expression
           Product: D
           Version: D2
          Platform: All
        OS/Version: All
            Status: NEW
          Keywords: accepts-invalid
          Severity: regression
          Priority: P2
         Component: DMD
        AssignedTo: nobody puremagic.com
        ReportedBy: andrej.mitrovich gmail.com



02:10:17 PST ---
-----
int foo(string arg)
{
    return foo(arg.dup);  // calls itself, stack overflow!
}

void main()
{
    foo("foo");
}
-----

Note that storing the .dup to a variable first avoids the accepts-invalid:

-----
int foo(string arg)
{
    auto duped = arg.dup;
    return foo(duped);  // NG, caught at compile-time
}

void main()
{
    foo("foo");
}
-----

-- 
Configure issuemail: https://d.puremagic.com/issues/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
Feb 13 2014
next sibling parent d-bugmail puremagic.com writes:
https://d.puremagic.com/issues/show_bug.cgi?id=12150




02:12:32 PST ---
Here's the slightly reduced example code of where I ran into the issue:

-----
import std.file;

int parseCode(string code)
{
    return parseCode(code.dup);
}

int parseCode(ubyte[] code)
{
    return 0;
}

void main()
{
    parseCode(cast(ubyte[])std.file.read("test.d"));  // ok
    parseCode("foo");  // stack overflow
}
-----

-- 
Configure issuemail: https://d.puremagic.com/issues/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
Feb 13 2014
prev sibling next sibling parent d-bugmail puremagic.com writes:
https://d.puremagic.com/issues/show_bug.cgi?id=12150




This is an intended change. See issue 9656.

-- 
Configure issuemail: https://d.puremagic.com/issues/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
Feb 13 2014
prev sibling next sibling parent d-bugmail puremagic.com writes:
https://d.puremagic.com/issues/show_bug.cgi?id=12150




07:28:15 PST ---
But the regression is likely unintended. Did anyone actually request for the
feature in Issue 9656? Magical built-in behavior is something we should avoid
IMHO, exactly because of issues like this..

-- 
Configure issuemail: https://d.puremagic.com/issues/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
Feb 13 2014
prev sibling next sibling parent d-bugmail puremagic.com writes:
https://d.puremagic.com/issues/show_bug.cgi?id=12150


bearophile_hugs eml.cc changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |bearophile_hugs eml.cc





 Magical built-in behavior is something we should avoid
 IMHO, exactly because of issues like this..


On the other hand the change of Issue 9656 seems useful.

-- 
Configure issuemail: https://d.puremagic.com/issues/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
Feb 13 2014
prev sibling next sibling parent d-bugmail puremagic.com writes:
https://d.puremagic.com/issues/show_bug.cgi?id=12150


Jakob Ovrum <jakobovrum gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jakobovrum gmail.com



---


 But the regression is likely unintended. Did anyone actually request for the
 feature in Issue 9656? Magical built-in behavior is something we should avoid
 IMHO, exactly because of issues like this..


I might be missing something, but where is the regression? The example you
posted doesn't seem to be a regression because char[] isn't implicitly
convertible to either `string` or `ubyte[]`, so surely the code would simply
not compile.

-- 
Configure issuemail: https://d.puremagic.com/issues/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
Feb 13 2014
prev sibling next sibling parent d-bugmail puremagic.com writes:
https://d.puremagic.com/issues/show_bug.cgi?id=12150






 But the regression is likely unintended. Did anyone actually request for the
 feature in Issue 9656? Magical built-in behavior is something we should avoid
 IMHO, exactly because of issues like this..


That is not magic. It is consistent with the implicit conversion for the
returned value from pure function.

E[] dup(E)(const(E)[] src) pure
{
    E[] r;
    r.reserve(src.length);
    foreach (ref e; src)
        r ~= e;
    return r;
}
int foo(string arg)
{
    return foo(dup(arg));
    // returned char[] is implicitly convertible to string
}
void main()
{
    foo("foo");
}

-- 
Configure issuemail: https://d.puremagic.com/issues/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
Feb 13 2014
prev sibling parent d-bugmail puremagic.com writes:
https://d.puremagic.com/issues/show_bug.cgi?id=12150


Andrej Mitrovic <andrej.mitrovich gmail.com> changed:

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



07:42:50 PST ---


 I might be missing something, but where is the regression? The example you
 posted doesn't seem to be a regression because char[] isn't implicitly
 convertible to either `string` or `ubyte[]`, so surely the code would simply
 not compile.


Ah I thought it would compile, after I added an explicit cast to avoid the
recursive call it ended up compiling, but it wouldn't otherwise even though I
thought it would. So you're right.

There's no regression here. The below test-case works properly:

-----
int foo(string arg)
{
    return foo(arg.dup);  // calls second overload
}

int foo(char[] b)
{
    assert(0);
}

void main()
{
    auto x = foo("");
}
-----

-- 
Configure issuemail: https://d.puremagic.com/issues/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
Feb 13 2014