running " valgrind ./mir_unit_tests --gtest_filter="OutputBuilder.*" gives:
[ RUN ] OutputBuilder.hwc_version_11_success
==16634== Conditional jump or move depends on uninitialised value(s)
==16634== at 0x51835C2: (anonymous namespace)::determine_hwc11_size_and_rate(std::shared_ptr<hwc_composer_device_1> const&) (framebuffers.cpp:102)
==16634== by 0x5183719: mir::graphics::android::Framebuffers::Framebuffers(std::shared_ptr<mir::graphics::android::GraphicBufferAllocator> const&, std::shared_ptr<hwc_composer_device_1> const&) (framebuffers.cpp:112)
==16634== by 0x516D99D: _ZN9__gnu_cxx13new_allocatorIN3mir8graphics7android12FramebuffersEE9constructIS4_IRKSt10shared_ptrINS3_22GraphicBufferAllocatorEERS7_I21hwc_composer_device_1EEEEvPT_DpOT0_ (in /usr/lib/arm-linux-gnueabihf/mir/platformgraphics/android/libmirplatformgraphics.so)
==16634== by 0x516D907: _ZNSt16allocator_traitsISaIN3mir8graphics7android12FramebuffersEEE12_S_constructIS3_IRKSt10shared_ptrINS2_22GraphicBufferAllocatorEERS7_I21hwc_composer_device_1EEEENSt9enable_ifIXsrNS5_18__construct_helperIT_IDpT0_EEE5valueEvE4typeERS4_PSH_DpOSI_ (alloc_traits.h:254)
==16634== by 0x516D8A7: _ZNSt16allocator_traitsISaIN3mir8graphics7android12FramebuffersEEE9constructIS3_IRKSt10shared_ptrINS2_22GraphicBufferAllocatorEERS7_I21hwc_composer_device_1EEEEDTcl12_S_constructfp_fp0_spcl7forwardIT0_Efp1_EEERS4_PT_DpOSF_ (alloc_traits.h:393)
==16634== by 0x516D7DB: std::_Sp_counted_ptr_inplace<mir::graphics::android::Framebuffers, std::allocator<mir::graphics::android::Framebuffers>, (__gnu_cxx::_Lock_policy)2>::_Sp_counted_ptr_inplace<std::shared_ptr<mir::graphics::android::GraphicBufferAllocator> const&, std::shared_ptr<hwc_composer_device_1>&>(std::allocator<mir::graphics::android::Framebuffers>, std::shared_ptr<mir::graphics::android::GraphicBufferAllocator> const&, std::shared_ptr<hwc_composer_device_1>&) (shared_ptr_base.h:399)
==16634== by 0x516D65B: _ZN9__gnu_cxx13new_allocatorISt23_Sp_counted_ptr_inplaceIN3mir8graphics7android12FramebuffersESaIS5_ELNS_12_Lock_policyE2EEE9constructIS8_IKS6_RKSt10shared_ptrINS4_22GraphicBufferAllocatorEERSC_I21hwc_composer_device_1EEEEvPT_DpOT0_ (in /usr/lib/arm-linux-gnueabihf/mir/platformgraphics/android/libmirplatformgraphics.so)
==16634== by 0x516D563: _ZNSt16allocator_traitsISaISt23_Sp_counted_ptr_inplaceIN3mir8graphics7android12FramebuffersESaIS4_ELN9__gnu_cxx12_Lock_policyE2EEEE12_S_constructIS8_IKS5_RKSt10shared_ptrINS3_22GraphicBufferAllocatorEERSD_I21hwc_composer_device_1EEEENSt9enable_ifIXsrNSA_18__construct_helperIT_IDpT0_EEE5valueEvE4typeERS9_PSN_DpOSO_ (alloc_traits.h:254)
==16634== by 0x516D45F: _ZNSt16allocator_traitsISaISt23_Sp_counted_ptr_inplaceIN3mir8graphics7android12FramebuffersESaIS4_ELN9__gnu_cxx12_Lock_policyE2EEEE9constructIS8_IKS5_RKSt10shared_ptrINS3_22GraphicBufferAllocatorEERSD_I21hwc_composer_device_1EEEEDTcl12_S_constructfp_fp0_spcl7forwardIT0_Efp1_EEERS9_PT_DpOSL_ (alloc_traits.h:393)
==16634== by 0x516D335: std::__shared_count<(__gnu_cxx::_Lock_policy)2>::__shared_count<mir::graphics::android::Framebuffers, std::allocator<mir::graphics::android::Framebuffers>, std::shared_ptr<mir::graphics::android::GraphicBufferAllocator> const&, std::shared_ptr<hwc_composer_device_1>&>(std::_Sp_make_shared_tag, mir::graphics::android::Framebuffers*, std::allocator<mir::graphics::android::Framebuffers> const&, std::shared_ptr<mir::graphics::android::GraphicBufferAllocator> const&, std::shared_ptr<hwc_composer_device_1>&) (shared_ptr_base.h:502)
==16634== by 0x516D171: std::__shared_ptr<mir::graphics::android::Framebuffers, (__gnu_cxx::_Lock_policy)2>::__shared_ptr<std::allocator<mir::graphics::android::Framebuffers>, std::shared_ptr<mir::graphics::android::GraphicBufferAllocator> const&, std::shared_ptr<hwc_composer_device_1>&>(std::_Sp_make_shared_tag, std::allocator<mir::graphics::android::Framebuffers> const&, std::shared_ptr<mir::graphics::android::GraphicBufferAllocator> const&, std::shared_ptr<hwc_composer_device_1>&) (shared_ptr_base.h:957)
==16634== by 0x516CEC1: std::shared_ptr<mir::graphics::android::Framebuffers>::shared_ptr<std::allocator<mir::graphics::android::Framebuffers>, std::shared_ptr<mir::graphics::android::GraphicBufferAllocator> const&, std::shared_ptr<hwc_composer_device_1>&>(std::_Sp_make_shared_tag, std::allocator<mir::graphics::android::Framebuffers> const&, std::shared_ptr<mir::graphics::android::GraphicBufferAllocator> const&, std::shared_ptr<hwc_composer_device_1>&) (shared_ptr.h:316)
==16634==
[ OK ] OutputBuilder.hwc_version_11_success (345 ms)
Fix committed into lp:mir/devel at revision None, scheduled for release in mir, milestone Unknown