ok. i think i finally solved this riddle. the cause for the problem seems to have been my CPUTYPE in /etc/make.conf. it is set to 'native'. actually i've been using the 'native' keyword for years now and never had any problems with it, but it seems a recent commit broke 'native' as CPUTYPE. for me this is 100% reproducable:

1. put 'CPUTYPE = native' in /etc/make.conf 2. build and install gnu/usr.bin/cc 3. do 'buildkernel' or 'buildworld' and observe the segfault. for some reason this always occurs in lib/libc/string/strlen.c (r205108). i've tested this with older version of libc.so (built 22. Feb) and got the same result. so i assume this is not a libc problem, but a problem with gcc tripping over some code in libc. i have no clue however why this happend just now and not earlier. i don't think there has been a recent commit to gcc.

to solve this there are two ways:

1. set CPUTYPE to 'nocona' (i'm running amd64). this will let you compile everything just fine even with a gcc that has itself been built with 'CPUTYPE = native'. 2. build and install gnu/usr.bin/cc with 'CPUTYPE = nocona'. the gcc version that has been built this way will compile everything just fine even with 'CPUTYPE = native'. the only way to break this is to go and compile gcc again with the CPUTYPE set to 'native'.

so to summarize: compiling gnu/usr.bin/cc with CPUTYPE set to 'native' will give you a broken gcc!