'make' step fails: libtool: error: specify a tag with '--tag'

[patrickdepinguin]

crosstool-NG version: current git 1b18fd6
host OS: Gentoo Linux, x86_64
host gcc version 6.4.0 (Gentoo 6.4.0-r1 p1.3)
host libtool (GNU libtool) 2.4.6

I'm doing steps:

./bootstrap
./configure --enable-local
make

This works fine in crosstool-ng 1.23.0, but no longer in current git.
It fails at the make step, with:

/usr/bin/libtool    --mode=link gcc  -g -O2   -o conf conf.o zconf.o  
libtool: link: unable to infer tagged configuration
libtool:   error: specify a tag with '--tag'
gmake[3]: *** [Makefile:496: conf] Error 1
gmake[3]: Leaving directory '/home/tdescham/repo/contrib/crosstool-ng/kconfig'

The full log is in attachment.
crosstool-ng-problem.log

I did a bisect, and following candidates pop up (there was some issue with strip-program that caused me to skip some revisions):

There are only 'skip'ped commits left to test.
The first bad commit could be any of:
d401afbddaae56093cce388e62f7ba4d9d68a327
1ce2eab963a004ba352a5cea800e2765a7c6affd
576dcc3fee5b949cbf439fd95ab642dfcfe51a74
0bcb67fa52b1318b098366fa44955f528999f4db
9238b587210c53ba51dd665ffb9ff3e13456880f
7655fc2a3c64fce46517d4a2af047d4c6e663f50
896bc2d17313f32a968efb09917cc3eb2b4e3ed8
66821508f4064904995189f4b46652eb6257b1ea
We cannot bisect more!

Most likely candidate seems 9238b58 to me, but I could be wrong.

[stilor]

From libtool's code, it looks like it could happen if the CC is set in the environment variable to something different than the compiler found by configure. Can you check if it is set in your environment? I can reproduce the problem, for example, if I configure without CC being set (which detects gcc as the compiler) and then run make all CC=/usr/bin/clang.

That said, I'll try to set the tag explicitly.

[patrickdepinguin]

I have no CC or similar variable set in my environment. Not sure why I see this problem and you don't.

Thanks for the fix, I confirm it solves the problem.