Release process and backwards compatibility

[bearophile]

Marco Leise:

> I don't know much about the development process, but as you
> said some bugs may be features or vice versa. Sometimes real
> bugs are fixed and peoples' code breaks. But keeping the bug
> around isn't an option.

Fixing issues like this is right, despite they will cause some 
breakage in user code.

In DMD 2.063alpha this code gives a warning 
(http://d.puremagic.com/issues/show_bug.cgi?id=7444 ):

void main() {
     int[10] a;
     a = 1;
}


temp.d(3): Warning: explicit element-wise assignment (a)[] = 1 is 
better than a = 1


My suggestion for D users is to update their DMD compiler often, 
to avoid cumulating many breakages at the same time, that is 
quite bad. It's better to fix one thing at a time.

All bug fixes are potential code breakages, but not all breakages 
have the same magnitude an importance. My suggestion for D 
developers is to focus their efforts first on the D/DMD changes 
that will cause most breaking because the more time passes, the 
more D2 code is around, and the more breakage will happen.

This also means implementing things like in/scope sooner than 
later, that probably are sometimes used wrongly, and that will 
cause some breakage once implemented. Another similar case is 
"final switch" on ints that is currently broken 
(http://d.puremagic.com/issues/show_bug.cgi?id=5713) and likely 
misused in some D program. So once it's fixed it will break some 
user code.


Time ago I have suggested to statically disallow code like this 
(starting first with a deprecation, a warning, and then an 
error), that currently compiles without errors or warnings:


string[4] colors = ["red",
                     "blue"
                     "green",
                     "yellow"];
void main() {}


If similar code will be statically disallowed, it will break some 
user code (Walter agreed to forbid half of that combo-pitfall).


I have a bit of statistical proof that code like this is a common 
source of bugs, and I'd like this to be statically disallowed 
(http://d.puremagic.com/issues/show_bug.cgi?id=5409 ):

(!x & y)

But disallowing this will break some user code (not much, because 
it's likely a bug in the first place).

Bye,
bearophile