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digitalmars.D.bugs - [Issue 796] New: Error: AssertError Failure internal\invariant.d(14)

reply d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=796

           Summary: Error: AssertError Failure internal\invariant.d(14)
           Product: D
           Version: 1.00
          Platform: PC
        OS/Version: Windows
            Status: NEW
          Severity: normal
          Priority: P2
         Component: DMD
        AssignedTo: bugzilla digitalmars.com
        ReportedBy: lio lunesu.com


The following code causes a run-time assertion failure in
internal\invariant.d(14) when linked against a debug build of Phobos (-unittest
-g -w):

#class Class {}
#void main(){




It causes a run-time Access Violation when linked against the release build of
Phobos.


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Jan 05 2007
next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=796


fvbommel wxs.nl changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |spec





It seems to be according to the spec though.
I just looked it up, and assert(object) checks object's invariant; not just
that it isn't null (that's assert(object !is null) apparently).
Not what I would've expected...
This isn't exactly clearly noted: this is mentioned on
http://www.digitalmars.com/d/class.html#invariants but not
http://www.digitalmars.com/d/expression.html#AssertExpression where it would be
expected (especially since you wouldn't normally look at the section on
invariants when figuring out what an assert does).
So maybe this should be noted there too (especially since every other use of
objects in boolean context is a null check AFAIK). I've already added it to the
comments page for that page.

The invariant checking routine in the runtime does perform an assert(o !is
null), but that only gets compiled into a non-release build of Phobos.
In a release build it instead segfaults trying to look up the vtable of the
object. (to get classinfo)


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Jan 05 2007
prev sibling next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=796






Nice catch! I never would have thought of that.

In any case, the assertion failure / access violation can be easily fixed if
the compiler where to add a null-pointer check prior to checking the
invariants. Frankly, I think this makes sense too. We can expect many C/C++
people doing "assert(instance)" only to check the pointer. If it were to check
both the pointer and the invariants, that would just make it even more useful.

AFAIK, this cannot be changed by adding a check to invariant.d, since that
would add unnecessary overhead to all invariant checks. The code generation for
assert(instance) should be changed to include a pointer check: the assertion
should fail for null-pointers:

assert(classref) 
// =>
assert( (classref !is null) && _d_invariant(classref) );


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Jan 06 2007
prev sibling next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=796


fvbommel wxs.nl changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|spec                        |wrong-code





It seems I misread the spec: it says the invariant *can* be checked on
assert(classref), not that it *will* be. So the spec's fine.
The bug seems to be in the compiler.


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Jan 11 2007
prev sibling next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=796


smjg iname.com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |smjg iname.com
           Keywords|                            |diagnostic
            Summary|Error: AssertError Failure  |Asserting a null object
                   |internal\invariant.d(14)    |reference throws AssertError
                   |                            |Failure
                   |                            |internal\invariant.d(14) or
                   |                            |Access Violation





Indeed,

    assert(classref)

should be translated inline to

    assert((classref !is null) && _d_invariant(classref));

so that the error location is preserved.


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Jan 11 2007
prev sibling next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=796






I think the assert feature would be more intuitive if assert(obj) would only
check for a null reference.  That's what people expect it to do, and that's
what they use it for most of the time.  But doing both kinds of checks would be
better than the current behavior.

If you really wanted to check the invariant explicitly, the syntax could be
'obj.invariant', 'invariant(obj)' or similar.  This could be useful in the
class' own methods, where there's no need to check for a null reference anyway.


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Apr 12 2007
prev sibling next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=796


Andrei Alexandrescu <andrei metalanguage.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
                 CC|                            |andrei metalanguage.com
         AssignedTo|nobody puremagic.com        |bugzilla digitalmars.com



14:13:26 PST ---
Still present in 2.050.

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Nov 26 2010
prev sibling next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=796


Bernard Helyer <blood.of.life gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |blood.of.life gmail.com



03:12:41 PST ---
Every time I write 

  assert(object);

A dagger pierces my heart and I remember I must write

  assert(object !is null); 

Could we get this fixed this decade some time?

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Mar 07 2011
prev sibling next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=796






 Every time I write 
 
   assert(object);
 
 A dagger pierces my heart and I remember I must write
 
   assert(object !is null); 
 
 Could we get this fixed this decade some time?


Indeed.  The intended behaviour (check that object is non-null AND satisfies
its invariants) needs to be built into the compiler, not delegated to the RTL.

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Mar 07 2011
prev sibling next sibling parent d-bugmail puremagic.com writes:
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Mike Shulman <viritrilbia+d gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |viritrilbia+d gmail.com



PDT ---
FYI: As a new D programmer, I found the segfault produced by this sort of code
very confusing, and spent almost an hour trying to figure out where the issue
in my code was and why I wasn't just getting an AssertError.  Only when I found
this bug report did I have any idea what was going on.

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May 31 2011
prev sibling next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=796


yebblies <yebblies gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|diagnostic                  |patch
                 CC|                            |yebblies gmail.com
           Platform|x86                         |All
            Version|1.00                        |D1 & D2
         OS/Version|Windows                     |All



https://github.com/D-Programming-Language/dmd/pull/358

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Aug 30 2011
prev sibling next sibling parent d-bugmail puremagic.com writes:
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Alex Rønne Petersen <xtzgzorex gmail.com> changed:

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



15:04:55 PST ---


 https://github.com/D-Programming-Language/dmd/pull/358


+1 to this pull req from me.

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Nov 08 2011
prev sibling next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=796


yebblies <yebblies gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |Jesse.K.Phillips+D gmail.co
                   |                            |m



*** Issue 6913 has been marked as a duplicate of this issue. ***

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Nov 08 2011
prev sibling parent d-bugmail puremagic.com writes:
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Walter Bright <bugzilla digitalmars.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|                            |FIXED



13:30:00 PST ---
https://github.com/D-Programming-Language/dmd/commit/7d942b84fd09f0a63105f6a92cd744f8b86e6021

https://github.com/D-Programming-Language/dmd/commit/1d80ce140da28518c161c5b96111d4d4f92e6027

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Jan 11 2012