805555 - nsXBLProtoImpl fields "cx" and "versionBefore" are unused in opt builds

Status: RESOLVED FIXED

(Core :: XBL, defect)

Description

[Daniel Holbert [:dholbert]]

content/xbl/src/ is warning-free on Linux g++-4.7, so I tried marking it as FAIL_ON_WARNINGS -- but I got failures under clang on mac, due to these warnings:
../../../../../content/xbl/src/nsXBLProtoImpl.cpp:22:21: error: private field 'cx' is not used [-Werror,-Wunused-private-field]
  JSContext * const cx;
                    ^
content/xbl/src/nsXBLProtoImpl.cpp:23:13: error: private field 'versionBefore' is not used [-Werror,-Wunused-private-field]
  JSVersion versionBefore;
            ^
https://tbpl.mozilla.org/php/getParsedLog.php?id=16463653&tree=Try

Comment 1

[Boris Zbarsky [:bzbarsky]]

BurnThemWithFire!

Comment 2

[Daniel Holbert [:dholbert]]

Actually, they're used, but only in debug builds. Code snippet:

20 class AutoVersionChecker
21 {
22   JSContext * const cx;
23   JSVersion versionBefore;
24 
25 public:
26   explicit AutoVersionChecker(JSContext *cx) : cx(cx) {
27 #ifdef DEBUG
28     versionBefore = JS_GetVersion(cx);
29 #endif
30   }

So they probably want to be labeled DebugOnly<>.

Comment 3

[Daniel Holbert [:dholbert]]

Attachment: fix

This marks them as DebugOnly, and also renames the constructor argument to "aCx" instead of "cx" to avoid confusion about the "cx(cx)" initialization.
                                 member-var---^   ^---arg

Comment 4

[Daniel Holbert [:dholbert]]

(In reply to Daniel Holbert [:dholbert] from comment #3)
> "aCx" instead of "cx" to avoid confusion about the "cx(cx)" initialization.
>                                        member-var---^   ^---arg

(er, my ASCII art was misaligned in comment 3; hopefully fixed in this quoted chunk)

Comment 5

[Boris Zbarsky [:bzbarsky]]

Comment on attachment 675284 [details] [diff] [review]
fix

r=me

Comment 6

[Daniel Holbert [:dholbert]]

https://hg.mozilla.org/integration/mozilla-inbound/rev/59c09d991d7b

Comment 7

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/mozilla-central/rev/59c09d991d7b