# loguru link error on macOS 10.12

**URL:** https://discourse.vtk.org/t/loguru-link-error-on-macos-10-12/6859
**Category:** Development
**Created:** [October 13, 2021, 2:51pm UTC](https://discourse.vtk.org/t/loguru-link-error-on-macos-10-12/6859 "2021-10-13T14:51:08Z")
**Posts on this page:** 3
**Page:** 1

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### Author: ![seanm](https://discourse.vtk.org/letter_avatar_proxy/v4/letter/s/a88e4f/32.png) [@seanm](https://discourse.vtk.org/u/seanm)
#### Post date: [October 13, 2021, 2:51pm UTC](https://discourse.vtk.org/t/loguru-link-error-on-macos-10-12/6859/1 "2021-10-13T14:51:08Z")

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Hi all,

One, and only one, of my bots has this build error:

```auto
Undefined symbols for architecture x86_64:
  "vtkloguru::vstrprintf(char const*, __va_list_tag*)", referenced from:
      vtkLogger::LogScopeRAII::LogScopeRAII(vtkLogger::Verbosity, char const*, unsigned int, char const*, ...) in vtkLogger.cxx.o
      vtkLogger::LogScopeRAII::LogScopeRAII(vtkLogger::Verbosity, char const*, unsigned int, char const*, ...) in vtkLogger.cxx.o
      vtkLogger::LogF(vtkLogger::Verbosity, char const*, unsigned int, char const*, ...) in vtkLogger.cxx.o
      vtkLogger::StartScopeF(vtkLogger::Verbosity, char const*, char const*, unsigned int, char const*, ...) in vtkLogger.cxx.o

```

Not sure why it’s happening only on this bot… I investigated but could not figure it out… anyone have any thoughts?

Thanks,

Sean

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### Author: ![ben.boeckel](https://discourse.vtk.org/letter_avatar_proxy/v4/letter/b/ea5d25/32.png) [@ben.boeckel](https://discourse.vtk.org/u/ben.boeckel)
#### Post date: [October 13, 2021, 4:20pm UTC](https://discourse.vtk.org/t/loguru-link-error-on-macos-10-12/6859/2 "2021-10-13T16:20:14Z")

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The `va_list` impl is only implemented if `!LOGURU_USE_FMTLIB`, so I suspect the header needs to reflect this fact. I would guess that something is generating tooling (sanitizers?) on the method and when it doesn’t exist, things go poorly.

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### Author: ![seanm](https://discourse.vtk.org/letter_avatar_proxy/v4/letter/s/a88e4f/32.png) [@seanm](https://discourse.vtk.org/u/seanm)
#### Post date: [October 14, 2021, 2:53pm UTC](https://discourse.vtk.org/t/loguru-link-error-on-macos-10-12/6859/3 "2021-10-14T14:53:30Z")

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OK, it’s fixed. Amazingly, it was caused by some unsupported warning flags, specifically:

-Wno-unused-template -Wno-shadow-field -Wno-return-std-move-in-c++11

that were leftover from a compiler version change. Really surprising to me that it could have this effect.

Sean