make mrproper && make efi-x86_app_defconfig && make
results in
CC common/image.o {standard input}: Assembler messages: {standard input}:21662: Error: junk at end of line, first unrecognized character is `@' {standard input}:21707: Error: junk at end of line, first unrecognized character is `@' {standard input}:21662: Error: can't resolve `end.6878' {.u_boot_list_2_fit_loadable_3 section} - `start.6875' {.u_boot_list_2_fit_loadable_1 section} {standard input}:21707: Error: can't resolve `end.6878' {.u_boot_list_2_fit_loadable_3 section} - `start.6875' {.u_boot_list_2_fit_loadable_1 section}
I am using Debian Buster with gcc-8.2.0.
Building with gcc-7.3.0 works fine.
We had a similar issue for qemu-x86_defconfig in https://lists.denx.de/pipermail/u-boot/2018-July/336393.html which has been resolved.
Best regards
Heinrich Schuchardt