Fix crash in restrict_fun2 on polymorphic THF unification#105
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Xujiangjing wants to merge 1 commit intosneeuwballen:masterfrom
Open
Fix crash in restrict_fun2 on polymorphic THF unification#105Xujiangjing wants to merge 1 commit intosneeuwballen:masterfrom
Xujiangjing wants to merge 1 commit intosneeuwballen:masterfrom
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restrict_fun2 and flex_flex_matching compute the intersection of two argument lists using T.is_bvar_i (comparing only de Bruijn index), but mk_rhs searches using T.equal (comparing index + type). In polymorphic THF problems, the same de Bruijn index can have different types across scopes, causing CCList.find_idx to return None and CCOption.get_exn to crash with Invalid_argument. Fix: use T.is_bvar_i for lookup in mk_rhs to match the intersection logic, and switch from List.map to List.filter_map to handle missing entries gracefully. Reproducer: TPTP ANA088^1.p (TH1_THM_EQU_NAR, exported from HOL Light) crashes with 'Error: invalid_argument: CCOption.get_exn' on both the Isabelle-bundled binary and GitHub HEAD. After fix, Zipperposition correctly proves the theorem in 428 iterations.
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Fixes #104
restrict_fun2 and flex_flex_matching compute the intersection of two argument lists using T.is_bvar_i (comparing only de Bruijn index), but mk_rhs searches using T.equal (comparing index + type). In polymorphic THF problems, the same de Bruijn index can have different types across scopes, causing CCList.find_idx to return None and CCOption.get_exn to crash with Invalid_argument.
Fix: use T.is_bvar_i for lookup in mk_rhs to match the intersection logic, and switch from List.map to List.filter_map to handle missing entries gracefully.
Reproducer: TPTP ANA088^1.p (TH1_THM_EQU_NAR, exported from HOL Light) crashes with 'Error: invalid_argument: CCOption.get_exn' on both the Isabelle-bundled binary and GitHub HEAD. After fix, Zipperposition correctly proves the theorem in 428 iterations.