From 18bfcd6af0b48b8b41ede85f28668245161500e2 Mon Sep 17 00:00:00 2001 From: Mark Wielaard Date: Mon, 11 Sep 2017 22:50:22 +0200 Subject: [PATCH] Bug 22075 - data_member_diff_comp comparison functor isn't a total ordering Make data_member_diff_comp comparison functor a total ordering. The initial value offset can be similar, in that case order based on the offset of the second instance, or if those are also equal order based on the qualified name. This makes sure that offset change reports have a stable ordering. Makes the runtestdiffpkg testcase succeeds on debian-i386. * src/abg-comparison.cc (data_member_diff_comp): Make comparison functor a total ordering. Signed-off-by: Mark Wielaard Signed-off-by: Dodji Seketeli --- src/abg-comparison.cc | 49 ++++++++++++++++++++++++++++++++++++++++++++++--- 1 file changed, 46 insertions(+), 3 deletions(-) diff --git a/src/abg-comparison.cc b/src/abg-comparison.cc index 8747e0c..86d8cb0 100644 --- a/src/abg-comparison.cc +++ b/src/abg-comparison.cc @@ -6730,8 +6730,10 @@ sort_string_base_diff_sptr_map(const string_base_diff_sptr_map& map, } /// A comparison functor to compare two instances of @ref var_diff -/// that represent changed data members based on the offset of their -/// initial value. +/// that represent changed data members based on the offset of the +/// initial data members, or if equal, based on their qualified name. +/// If equal again, then the offset and qualified name of the of the +/// new data members are considered. struct data_member_diff_comp { /// @param f the first change to data member to take into account @@ -6749,7 +6751,48 @@ struct data_member_diff_comp assert(is_data_member(first_dm)); assert(is_data_member(second_dm)); - return get_data_member_offset(first_dm) < get_data_member_offset(second_dm); + size_t off1 = get_data_member_offset(first_dm); + size_t off2 = get_data_member_offset(second_dm); + + if (off1 != off2) + return off1 < off2; + + // The two offsets of the initial data members are the same. So + // lets compare the qualified name of these initial data members. + + string name1 = first_dm->get_qualified_name(); + string name2 = second_dm->get_qualified_name(); + + assert (name1 != name2); + + if (name1 != name2) + return name1 < name2; + + // The offsets and the qualified names of the initial data members + // are the same. Let's now compare the offsets of the *new* data + // members. + + first_dm = f->second_var(); + second_dm = s->second_var(); + + assert(is_data_member(first_dm)); + assert(is_data_member(second_dm)); + + off1 = get_data_member_offset(first_dm); + off2 = get_data_member_offset(second_dm); + + if (off1 != off2) + return off1 < off2; + + // The offsets of the new data members are the same, dang! Let's + // compare the qualified names of these new data members then. + + name1 = first_dm->get_qualified_name(); + name2 = second_dm->get_qualified_name(); + + assert (name1 != name2); + + return name1 < name2; } }; // end struct var_diff_comp -- 1.8.3.1