1487398 - Remove useless use of SetCapacity()

Status: RESOLVED FIXED

(Core :: XPCOM, enhancement)

Description

[Henri Sivonen (:hsivonen)]

Remove various calls to SetCapacity() that fall into various misuse categories:

 1) Mistakenly believing that the caller should advice the string about zero terminator.
 2) Cases where appending does the right computation on its own.
 3) Calling SetCapacity() with a constant when the string is self-allocated and could be an nsAuto[C]StringN.
 4) Calling SetCapacity() before assigning a shared buffer to the string.
 5) Calling SetCapacity() before calling a function that will either call SetLength() anyway or call Adopt().

Comment 1

[Henri Sivonen (:hsivonen)]

(In reply to Henri Sivonen (:hsivonen) from comment #0)
>  3) Calling SetCapacity() with a constant when the string is self-allocated
> and could be an nsAuto[C]StringN.

...and used in such a way that the buffer isn't going to be shared with some future Assign target anyway.

Comment 2

[Henri Sivonen (:hsivonen)]

Attachment: Bug 1487398 - Remove useless use of SetCapacity().

Remove various calls to SetCapacity() that fall into various misuse categories:

 1) Mistakenly believing that the caller should advice the string about zero
    terminator.
 2) Cases where a single append does the right computation on its own.
 3) Calling SetCapacity() with a constant when the string is self-allocated
    and could be an nsAuto[C]StringN and the string doesn't get passed on
    in a way that could benefit from a heap-allocated buffer.
 4) Calling SetCapacity() before assigning a shared buffer to the string.
 5) Calling SetCapacity() before calling a function that will either calls
    SetLength() anyway or calls Adopt().

MozReview-Commit-ID: IKjfl5gLmcD

Comment 3

[Henri Sivonen (:hsivonen)]

Try run:
https://treeherder.mozilla.org/#/jobs?repo=try&revision=6c9b7d8ef9ad0110b1739b3e359cf4a034808ec6

Comment 4

[Nathan Froyd [:froydnj]]

Comment on attachment 9005197 [details]
Bug 1487398 - Remove useless use of SetCapacity().

Nathan Froyd [:froydnj] has approved the revision.

Comment 5

[u408661]

Comment on attachment 9005197 [details]
Bug 1487398 - Remove useless use of SetCapacity().

Nicholas Hurley [:nwgh][:hurley] (he/him) has approved the revision.

Comment 6

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/c67411f144d6
Remove useless use of SetCapacity(). r=froydnj,nwgh

Comment 7

[Arthur Iakab [arthur_iakab]]

https://hg.mozilla.org/mozilla-central/rev/c67411f144d6