686597 - nsAutoTArray doesn't have a copy-constructor.

Status: RESOLVED FIXED

(Core :: XPCOM, defect)

Description

[Justin Lebar (not reading bugmail)]

In bug 682735 comment 52, we noticed that nsAutoTArray doesn't have a copy-constructor.  The following code:

  nsAutoTArray<E, 16> foo;
  // put some elements in foo
  nsAutoTArray<E, 16> bar(foo);

effectively makes |bar| a nsTArray; |bar| will never use its auto storage.

We can fix this simply by adding copy constructors.

Comment 1

[Justin Lebar (not reading bugmail)]

Luke pointed out that js vectors don't have copy constructors -- if you want to copy a vector, you need to do so explicitly.

I'm going to see whether we can just do that here.

Comment 2

[Justin Lebar (not reading bugmail)]

Well, nsTArray has a copy-constructor, and I'm not sure we're ready to get rid of that.  So maybe nsAutoTArray should also have one.

Comment 3

[Justin Lebar (not reading bugmail)]

Attachment: Add a copy constructor to nsAutoTArray and friends.

I need to test that this fixes the issues we saw in bug 682735 comment 52, but unfortunately my instrumentation doesn't work on mac.  I think this should work...

Comment 4

[Boris Zbarsky [:bzbarsky]]

Comment on attachment 560281 [details] [diff] [review]
Add a copy constructor to nsAutoTArray and friends.

>+++ b/xpcom/glue/nsTArray.h
>+  nsAutoArrayBase(const nsAutoArrayBase<TArrayBase, N> &aOther) {

Any reason to not make that argument |const TArrayBase &aOther|?

r=me either way.

Comment 5

[Justin Lebar (not reading bugmail)]

(In reply to Boris Zbarsky (:bz) from comment #4)
> >+++ b/xpcom/glue/nsTArray.h
> >+  nsAutoArrayBase(const nsAutoArrayBase<TArrayBase, N> &aOther) {
> 
> Any reason to not make that argument |const TArrayBase &aOther|?

I think just to emphasize that the constructor shouldn't be called except by nsAutoArrayBase's children's copy-constructors.

But in that case, maybe it should be protected...

Comment 6

[Justin Lebar (not reading bugmail)]

Attachment: Patch v2

Making the constructors protected.

Comment 7

[Boris Zbarsky [:bzbarsky]]

Comment on attachment 560504 [details] [diff] [review]
Patch v2

r=me

Comment 8

[(no longer active)]

https://hg.mozilla.org/mozilla-central/rev/304a0a282365