gh-154786: Fix crashes on a screen without a terminal - #154787
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serhiy-storchaka merged 1 commit intoJul 28, 2026
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screen.use() makes its screen current for the callback, so a new_prescr() screen, which has no terminal, can be current without set_term(). Operations that need a terminal then crashed inside curses. Raise curses.error instead, checking that stdscr exists.
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screen.use()makes its screen current for the callback, by callinguse_screen(), so a screen made bynew_prescr()can be current without going throughset_term(). It has no terminal, and operations that need one crashed inside curses.Eleven window methods crashed --
refresh(),noutrefresh(),getch(),getkey(),get_wch(),getstr(),get_wstr(),echochar(),keypad(),idlok(),idcok()-- andnewwin()andnewpad()returned a window whosedelwin()failed. They were found by calling every window method and every module-level function inside such a callback; some crash only for some arguments,idlok(0)is harmless whileidlok(True)is not.The check is that
stdscrexists, which is true whichever way the screen became current. It is added toPyCursesStatefulInitialised(), so every module-level function that already requiredinitscr()requires a terminal too, and to the window methods that need one. Window methods that only touch the window's own memory, such asaddstr()orclearok(), are unchanged.pre.use(lambda s: curses.use_env(False))keeps working: affecting the state beforeinitscr()is what such a screen is for, and those functions are not gated.