GFortran 15 bug

grow_type_array.f90

program grow_type_array
    type :: string_t
        character(:), allocatable :: s
    end type string_t
    
    type(string_t) :: str
    type(string_t), allocatable :: list(:)

    ! This works
    allocate(list(0))
    str = new_string("Hello!")
    list = [list, str]

    deallocate(list)

    ! This segfaults on gfortran 15.1 but works on gfortran 14
    ! when using -fcoarray=single compile flag
    allocate(list(0))
    list = [list, new_string("Hello!")]

contains

    type(string_t) function new_string(s) result(out)
        character(*), intent(in) :: s
        out%s = s
    end function new_string
      
end program grow_type_array

Fails with

$ gfortran -fcoarray=single grow_type_array.f90 && ./a.out

Program received signal SIGSEGV: Segmentation fault - invalid memory reference.

Backtrace for this error:
#0  0x7fd8ba355eef in ???
#1  0x7fd8ba3bed84 in ???
#2  0x402905 in ???
#3  0x402979 in ???
#4  0x7fd8ba33f6b4 in ???
#5  0x7fd8ba33f768 in ???
#6  0x401104 in ???
#7  0xffffffffffffffff in ???
Segmentation fault (core dumped)

Leaving out -fcoarray=single or using gfortran 14 causes no error.