Regressions on native/releases/gcc-15 at commit r15-10227 vs commit r15-10223 on Linux/x86_64

[Haochen Jiang via Gcc-regression]

Regressions on releases/gcc-15 at commit r15-10227 vs commit r15-10223 on 
Linux/x86_64
New failures:
FAIL: 27_io/basic_istream/ignore/wchar_t/94749.cc  -std=gnu++17 execution test

New passes:
FAIL: 30_threads/future/members/poll.cc  -std=gnu++17 execution test