These are the packages that would be merged, in order:

Calculating dependencies ... done!
Dependency resolution took 1.75 s (backtrack: 0/20).



[ebuild  N     ] net-misc/onedrive-2.5.10::gentoo  USE="-libnotify" 10059 KiB
[ebuild     U  ]  sys-devel/gcc-15.3.1_p20261009:15::gentoo [15.2.1_p20260214:15::gentoo] USE="cet (cxx) d* (default-stack-clash-protection) (default-znow) fortran graphite lto nls openmp pgo (pie) sanitize ssp zstd -ada -cobol (-custom-cflags) -debug -doc (-fixed-point) -go -hardened (-ieee-long-double) -jit -libgdiagnostics (-libssp) -modula2 (-multilib) -objc -objc++ -objc-gc (-pch) -rust -systemtap -test (-time64) -valgrind -vanilla -vtv" 90378 KiB

Total: 2 packages (1 upgrade, 1 new), Size of downloads: 100436 KiB

 * Error: circular dependencies:

(sys-devel/gcc-15.3.1_p20261009:15/15::gentoo, ebuild scheduled for merge) depends on
 (sys-devel/gcc-15.3.1_p20261009:15/15::gentoo, ebuild scheduled for merge) (buildtime, USE=d)

 * Note that circular dependencies can often be avoided by temporarily
 * disabling USE flags that trigger optional dependencies.

The following USE changes are necessary to proceed:
 (see "package.use" in the portage(5) man page for more details)
# required by net-misc/onedrive-2.5.10::gentoo
# required by =net-misc/onedrive-2.5.10 (argument)
>=sys-devel/gcc-15.3.1_p20261009:15 d

 * In order to avoid wasting time, backtracking has terminated early
 * due to the above autounmask change(s). The --autounmask-backtrack=y
 * option can be used to force further backtracking, but there is no
 * guarantee that it will produce a solution.