Merge branch 'releases/gcc-15' into devel/omp/gcc-15

Merge up to r15-10483-gcc39aed963b5c6 (5 Nov 2025)

diff --cc gcc/cp/decl.cc
Simple merge

diff --cc gcc/cp/decl2.cc
Simple merge

diff --cc gcc/cp/parser.cc
Simple merge

diff --cc gcc/fortran/trans-expr.cc
Simple merge