Bug 167282 – JavaScriptCore has a weak external symbol in it

• Component: JavaScriptCore
• Status: RESOLVED FIXED

[Shuan Zhao]

ERROR: JavaScriptCore has a weak external symbol in it (/Users/hoolai/Library/Developer/Xcode/DerivedData/WebKit-ehpvmnqmihxdvndqudiokzoxdfuu/Build/Products/Debug/JavaScriptCore.framework/Versions/A/JavaScriptCore)
ERROR: A weak external symbol is generated when a symbol is defined in multiple compilation units and is also marked as being exported from the library.
ERROR: A common cause of weak external symbols is when an inline function is listed in the linker export file.
ERROR: symbol automatically hidden __ZTVN3JSC8Debugger15ProfilingClientE

[Alexey Proskuryakov]

I don't think that we've seen this particular error. What version of Xcode are you building with?

[Shuan Zhao]

I'm using Xcode Version 8.2.1 (8C1002)

[Alexey Proskuryakov]

Our bots have version 8.2, which is unlikely to be different in this regard. What command do you build with?

[Shuan Zhao]

I just open the workspace file with Xcode, and select the JavaScriptCore target. I have changed the Mach-O Type to static library to run on iOS with my own app. Error was reported for debug build. I can make the release build successfully.

[Joseph Pecoraro]

This seems like an issue that I used to see in the past that was solved by newer compilers. In any case, it sounds like we can just make the destructor:

    virtual ~ProfilingClient() { }

Not be inlined to solve this. I'll try to reproduce myself tonight, but I'll just throw up a patch anyways.

[Joseph Pecoraro]

With:

  $ xcrun clang++ -v
  Apple LLVM version 8.1.0 (clang-802.0.21.2)

I only see these weak externals:

  $ nm -m $build/Release/JavaScriptCore.framework/JavaScriptCore | grep 'weak external'
    (undefined) weak external __ZdaPv (from libc++)
    (undefined) weak external __ZdlPv (from libc++)
    (undefined) weak external __Znam (from libc++)
    (undefined) weak external __Znwm (from libc++)

So I guess I can go ahead speculatively here, seems harmless.

[Joseph Pecoraro]

Created attachment 299500 [details]
[PATCH] Proposed Fix

[Joseph Pecoraro]

Shuan, since I can't reproduce but you can, would you be willing to try the attached patch (very basic) and see if it solves the problem for you?

[Shuan Zhao]

Ok, I'll try it and report my result later.

[Shuan Zhao]

The patch solved my problem. Thanks for you work.

[Yusuke Suzuki]

Comment on attachment 299500 [details]
[PATCH] Proposed Fix

ok, r=me

[WebKit Commit Bot]

Comment on attachment 299500 [details]
[PATCH] Proposed Fix

Clearing flags on attachment: 299500

Committed r211037: <http://trac.webkit.org/changeset/211037>

[WebKit Commit Bot]

All reviewed patches have been landed.  Closing bug.