It seems that the "--as-needed" option introduced recently caused net-misc/dahdi-tools-2.1.0.2 emerge to fail. When I tried to rebuild net-misc/dahdi-tools-2.1.0.2, it failed with error: i686-pc-linux-gnu-gcc -Wl,-O1 -Wl,--as-needed -lm -o fxotune fxotune.o version.o make[2]: Entering directory `/var/tmp/portage/net-misc/dahdi-tools-2.1.0.2/work/dahdi-tools-2.1.0.2/xpp' for i in dahdi_registration xpp_sync lsdahdi xpp_blink dahdi_genconf dahdi_hardware; do perl -I./perl_modules -c $i || exit 1; done fxotune.o: In function `power_of': /var/tmp/portage/net-misc/dahdi-tools-2.1.0.2/work/dahdi-tools-2.1.0.2/fxotune.c:285: undefined reference to `sqrtf' fxotune.o: In function `one_point_dft': /var/tmp/portage/net-misc/dahdi-tools-2.1.0.2/work/dahdi-tools-2.1.0.2/fxotune.c:318: undefined reference to `sincos' fxotune.o: In function `gentone': /var/tmp/portage/net-misc/dahdi-tools-2.1.0.2/work/dahdi-tools-2.1.0.2/fxotune.c:206: undefined reference to `sin' fxotune.o: In function `genwaveform': /var/tmp/portage/net-misc/dahdi-tools-2.1.0.2/work/dahdi-tools-2.1.0.2/fxotune.c:228: undefined reference to `sin' fxotune.o: In function `gentone': /var/tmp/portage/net-misc/dahdi-tools-2.1.0.2/work/dahdi-tools-2.1.0.2/fxotune.c:206: undefined reference to `sin' /var/tmp/portage/net-misc/dahdi-tools-2.1.0.2/work/dahdi-tools-2.1.0.2/fxotune.c:206: undefined reference to `sin' fxotune.o: In function `genwaveform': /var/tmp/portage/net-misc/dahdi-tools-2.1.0.2/work/dahdi-tools-2.1.0.2/fxotune.c:228: undefined reference to `sin' fxotune.o: In function `db_loss': /var/tmp/portage/net-misc/dahdi-tools-2.1.0.2/work/dahdi-tools-2.1.0.2/fxotune.c:309: undefined reference to `logf' collect2: ld returned 1 exit status make[1]: *** [fxotune] Error 1 When I tried to compile the file: # cd /var/tmp/portage/net-misc/dahdi-tools-2.1.0.2/work/dahdi-tools-2.1.0.2/ # gcc -Wl,-O1 -Wl,--as-needed -lm -o fxotune fxotune.o version.o The above error. # gcc -Wl,-O1 -lm -o fxotune fxotune.o version.o No error. # gcc -Wl,-O1 -Wl,--as-needed -o fxotune fxotune.o version.o -lm No error.
Yep, the build system needs to be patched so that -lm is passed to the linker last (after objects)
It was fixed in tree and reported upstream around March 2009. Please sync.
For the record, the only way in which you could run into this is by building dahdi-tools from the VoIP overlay. Please do not, ever, report bugs for overlay ebuilds on the main Gentoo tracker. As you have now found out, overlay ebuilds are not subject to the same QA that tree ebuilds are.