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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Multiple inheritance in interfaces leads to segmentation faults with GMock","articleBody":"When mocking an interface that inherits from multiple other interfaces, segmentation fault happens on `EXPECT_CALL` or call itself.\r\nExample:\r\n```\r\nstruct a\r\n{\r\n\tvirtual ~a() = default;\r\n\tvirtual void func_a() = 0;\r\n};\r\nstruct b\r\n{\r\n\tvirtual ~b() = default;\r\n\tvirtual void func_b() = 0;\r\n};\r\nstruct ab : public a, public b\r\n{\r\n\t~ab() override = default;\r\n};\r\n\r\nauto mock = std::make_shared\u003ctesting::StrictGMock\u003cab\u003e\u003e();\r\nstd::shared_ptr\u003cab\u003e obj = object(mock);\r\nEXPECT_CALL(*mock, (func_a)()); // works as expected\r\nobj-\u003efunc_a(); // works as expected\r\nEXPECT_CALL(*mock, (func_b)()); // may already crash\r\nobj-\u003efunc_b(); // latest here crash happens\r\n```\r\n\r\nWhen mocking or calling a function on the second interface a crash happens. I played around a little bit and observed crashes on `EXPECT_CALL` as well as on function call itself.\r\nTo me it seems that offset calculation for vtable doesn't work reliable for such cases. However unfortunately I couldn't find the exact reason for the issue. It may also depend on the used compiler. I observed the issue with clang-13.\r\n\r\nThis may be a duplicate of issue #12, however I'm unsure as the description is not very detailed there.","author":{"url":"https://github.com/mstaz","@type":"Person","name":"mstaz"},"datePublished":"2022-04-06T13:49:38.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":3},"url":"https://github.com/74/GUnit/issues/74"}