stat-without-message (C183)

What does it do?

This rule detects whether stat is used without also setting errmsg when allocating or deallocating. Similarly checks for the use of iostat without iomsg with IO routines, and cmdstat without cmdmsg when using execute_command_line.

Why is this bad?

The error codes returned when using stat, iostat, or cmdstat are not very informative on their own, and are not portable across compilers. It is recommended to always capture the associated error message alongside the error code:

real, allocatable :: x(:)
integer :: status
character(256) :: message ! N.B. Can be allocatable in F2023+

allocate (x(100), stat=status, errmsg=message)
open (unit=10, file="data.txt", iostat=status, iomsg=message)
call execute_command_line("ls", cmdstat=status, cmdmsg=message)