kconfig/menu.c: fix multiple references to expressions in menu_add_prop()
menu_add_prop() applies upper menus' visibilities to actual prompts by AND-ing the prompts visibilities with the upper menus ones. This creates a further reference to the menu's visibilities and when the expression reduction functions do their work, they may remove or modify expressions that have multiple references, thus causing unpredictable side-effects. The following example Kconfig constructs a case where this causes problems: a menu and a prompt which's visibilities depend on the same symbol. When invoking mconf with this Kconfig and pressing "Z" we see a problem caused by a free'd expression still referenced by the menu's visibility: ------------------------------------------------------------------------ mainmenu "Kconfig Testing Configuration" config VISIBLE def_bool n config Placeholder bool "Place holder" menu "Invisible" visible if VISIBLE config TEST_VAR bool "Test option" if VISIBLE endmenu ------------------------------------------------------------------------ This patch fixes this problem by creating copies of the menu's visibility expressions before AND-ing them with the prompt's one. Signed-off-by: NDirk Gouders <dirk@gouders.net> [yann.morin.1998@free.fr: move variable into its block-scope, keep lines <80 chars, typo] Tested-by: N"Yann E. MORIN" <yann.morin.1998@free.fr> Reviewed-by: N"Yann E. MORIN" <yann.morin.1998@free.fr> Signed-off-by: N"Yann E. MORIN" <yann.morin.1998@free.fr>
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