I've pushed the following backports to the releases/gcc-15 branch,
after a successfully bootstrap & regrtest on x86_64-pc-linux-gnu:
* git_commit.py: add "diagnostics" to bug components
* Trunk: r16-2587-g95f517dc7796ba
* gcc 15: r15-10669-ge8238de6161614
* testsuite: fix typo in name of plugin test file
* Trunk: r16-3826-g85a97e1a8ee934
* gcc 15: r15-10670-g5bb0345ab3b6d0
* diagnostics: handle fatal_error in SARIF output [PR120063]
* Trunk: r16-3828-g259347de43e965
* gcc 15: r15-10671-g2fdebdd5690c01
* c++: fix count of z candidates for non-viable candidates, nesting [PR121966]
* Trunk: r16-3940-gc0b21d1f45ac6a
* gcc 15: r15-10672-ge2b6c1ca1c0b9f
* analyzer: fold X + (-X) to zero [PR122975]
* Trunk: r16-6136-gc48970fc4a4d17
* gcc 15: r15-10673-ge869244a134c84
* analyzer: fix strlen(STRING_CST + OFFSET) [PR123085]
Trunk: r16-6137-g8f84c84e571ae6
gcc 15: r15-10674-g004e2f3cc5a6c8
Dave