# Clang failing compiling itself when make buildworld



## Snurg (Nov 8, 2016)

Finally I am trying to update from 11-RC1 to releng according to the guide here.
First problem occurred after I deleted the /usr/src.
`svn` failed because there was no IPv6 enabled in the kernel config.
So to make a kernel with IPv6 enabled I downloaded src.txz from 11 stable, unpacked it into /usr/src and uttered `make buildworld KERNCONF=GENERIC`.
Now this aborted while building llvm complaining about an ambiguous abs() call.

```
/usr/src/lib/clang/libllvmanalysis/../../../contrib/llvm/lib/Analysis/BasicAliasAnalysis.cpp:1564:52: error: call to 'abs' is ambiguous
  uint64_t MinDiffBytes = MinDiff.getZExtValue() * std::abs(Var0.Scale);
                                                   ^~~~~~~~
```
I guess I did some horribly wrong again.
Any idea how to fix that situation?

Edit: I am leaving the PC doing a `make buildkernel` only overnight. Maybe I am just confusing something. I better have a nap now...


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## Paul Floyd (Nov 14, 2016)

Hi

Can you see which are the two or more candidate overloads and which headers they come from?

A+
Paul


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## kpa (Nov 14, 2016)

Snurg said:


> Finally I am trying to update from 11-RC1 to releng
> ...
> So to make a kernel with IPv6 enabled I downloaded src.txz from 11 stable, unpacked it into /usr/src and uttered `make buildworld KERNCONF=GENERIC`.



You have the wrong sources, get these instead:

https://download.freebsd.org/ftp/releases/amd64/11.0-RELEASE/src.txz


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