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digitalmars.D - 6 problems with DMD

reply Piotr Fusik <Piotr_member pathlink.com> writes:
Hello,

I have encountered the following problems with DMD 0.122:

1. DMD crashes after the error message
"function foo.bar (int) does not match argument types ()".

2. DMD crashes on "int x = 1 % 0;".

3. "debug:" does not work.
"debug {}" does.

4. Should I use "is" or "===" for comparing against null? Are they equivalent?

5. I think that the comparisons "== null" and "!= null" should be compile-time
errors.
Now they are run-time errors.

6. Why "array.length--" does not work?
"array.length = array.length - 1;" does.
May 17 2005
next sibling parent reply "Unknown W. Brackets" <unknown simplemachines.org> writes:
1. Already fixed in next release, regression in this release.

2. I think I read a bug report on that or similar... but, that should be 
in D.bugs.

3. Should it?  I don't see anything here that indicates it should:

http://www.digitalmars.com/d/version.html

And then how do you end the debug block?  Seems to me braces are better.

4. They are equivalent.  Some prefer is because it doesn't look like 
"==" to blind people or with bad fonts.

5. This has been discussed often, although it's theoretically possible 
for an initiated class to be equal to null (e.g. a string, if "", might be.)

6. Not sure on that one, although I know it was mentioned at least once.

-[Unknown]


 Hello,
 
 I have encountered the following problems with DMD 0.122:
 
 1. DMD crashes after the error message
 "function foo.bar (int) does not match argument types ()".
 
 2. DMD crashes on "int x = 1 % 0;".
 
 3. "debug:" does not work.
 "debug {}" does.
 
 4. Should I use "is" or "===" for comparing against null? Are they equivalent?
 
 5. I think that the comparisons "== null" and "!= null" should be compile-time
 errors.
 Now they are run-time errors.
 
 6. Why "array.length--" does not work?
 "array.length = array.length - 1;" does.
 
 

May 17 2005
parent reply Piotr Fusik <Piotr_member pathlink.com> writes:
 3. "debug:" does not work.
 "debug {}" does.
 

http://www.digitalmars.com/d/version.html

There's the following example: class Foo { int a, b; debug: int flag; }
May 17 2005
parent "TechnoZeus" <TechnoZeus PeoplePC.com> writes:
"Piotr Fusik" <Piotr_member pathlink.com> wrote in message
news:d6cfq1$12fe$1 digitaldaemon.com...
 3. "debug:" does not work.
 "debug {}" does.

http://www.digitalmars.com/d/version.html

There's the following example: class Foo { int a, b; debug: int flag; }

/* Not sure why you used the colon character after the "debug" keyword. Try removing it. The following code compiles... */ void main() { int a, b; debug int flag; } // TZ
May 18 2005
prev sibling parent reply Derek Parnell <derek psych.ward> writes:
On Tue, 17 May 2005 07:49:35 +0000 (UTC), Piotr Fusik wrote:

 Hello,
 
 I have encountered the following problems with DMD 0.122:
 
 1. DMD crashes after the error message
 "function foo.bar (int) does not match argument types ()".

This has been fixed in v0.123
 2. DMD crashes on "int x = 1 % 0;".

Don't know about this one.
 3. "debug:" does not work.
 "debug {}" does.

This is a mistake in the documentation. The example should read ... class Foo { int a, b; debug int flag; }
 4. Should I use "is" or "===" for comparing against null? Are they equivalent?

They are the same thing. The preferred usage is "is". Don't use "===" as it is sometimes harder to read.
 5. I think that the comparisons "== null" and "!= null" should be compile-time
 errors.
 Now they are run-time errors.

How can they be compile-time errors? void Func( Foo a) { if (a == null) . . . } This can only be determined at run time, because sometimes it is not an error. There could be an opEqual member defined for the Foo class.
 6. Why "array.length--" does not work?
 "array.length = array.length - 1;" does.

Because 'length' is not a member variable of an array. It is more like a property function. It is as if you had a class called array and it has a property function called length... class array { uint length() { return ... } void length(uint newvalue) { . . . } } so that when you type array.length++; its is like you typed ... array.length()++; and that is not possible as a function call is not an lvalue. array.length = array.length + 1; is like typing ... array.length( array.length() + 1); -- Derek Parnell Melbourne, Australia 17/05/2005 9:17:39 PM
May 17 2005
next sibling parent reply "Ben Hinkle" <ben.hinkle gmail.com> writes:
 5. I think that the comparisons "== null" and "!= null" should be 
 compile-time
 errors.
 Now they are run-time errors.

How can they be compile-time errors? void Func( Foo a) { if (a == null) . . . } This can only be determined at run time, because sometimes it is not an error. There could be an opEqual member defined for the Foo class.

The problem with "a == null" comes when "a is null" since calling opEquals causes a null-pointer dereference (it never even makes it to the opEquals body). A compile-time error is pretty harsh though I sympathize because it is pretty obviously a coder error. I want to add a check for this to dlint but I haven't gotten around to it.
May 17 2005
parent "TechnoZeus" <TechnoZeus PeoplePC.com> writes:
"Ben Hinkle" <ben.hinkle gmail.com> wrote in message
news:d6cnp1$195o$1 digitaldaemon.com...
 5. I think that the comparisons "== null" and "!= null" should be
 compile-time
 errors.
 Now they are run-time errors.

How can they be compile-time errors? void Func( Foo a) { if (a == null) . . . } This can only be determined at run time, because sometimes it is not an error. There could be an opEqual member defined for the Foo class.

The problem with "a == null" comes when "a is null" since calling opEquals causes a null-pointer dereference (it never even makes it to the opEquals body). A compile-time error is pretty harsh though I sympathize because it is pretty obviously a coder error. I want to add a check for this to dlint but I haven't gotten around to it.

In other words, the compiler could be made to compensate for the problem by attaching a default behavior to the requested action at compile-time. TZ
May 18 2005
prev sibling parent "TechnoZeus" <TechnoZeus PeoplePC.com> writes:
"Derek Parnell" <derek psych.ward> wrote in message
news:nfamciwrwl02.1vztstuf0ghzv$.dlg 40tude.net...
 On Tue, 17 May 2005 07:49:35 +0000 (UTC), Piotr Fusik wrote:

 3. "debug:" does not work.
 "debug {}" does.

This is a mistake in the documentation. The example should read ... class Foo { int a, b; debug int flag; }

 -- 
 Derek Parnell
 Melbourne, Australia
 17/05/2005 9:17:39 PM

Oops... I should have read ahead before saying basically the same thing you had already said. Hehe. TZ
May 18 2005