This is triggered on start up with an UBSan build. To enable this check add the following to your mozconfig:

ac_add_options --enable-address-sanitizer
ac_add_options --enable-undefined-sanitizer="function"
ac_add_options --disable-jemalloc

This issue can be triggered by running gtests or attempting to launch the browser.

src/xpcom/glue/standalone/nsXPCOMGlue.cpp:389:3: runtime error: call to function XRE_GetBootstrap through pointer to incorrect function type 'void (*)(mozilla::UniquePtr<mozilla::Bootstrap, mozilla::Bootstrap::BootstrapDelete> &)'
src/toolkit/xre/Bootstrap.cpp:108: note: XRE_GetBootstrap defined here
    #0 0x55d344dfb394 in mozilla::GetBootstrap(char const*, mozilla::LibLoadingStrategy) src/xpcom/glue/standalone/nsXPCOMGlue.cpp:389:3
    #1 0x55d344df88b2 in InitXPCOMGlue(mozilla::LibLoadingStrategy) src/browser/app/nsBrowserApp.cpp:228:16
    #2 0x55d344df832a in main src/browser/app/nsBrowserApp.cpp:289:17
    #3 0x7f5e614eeb96 in __libc_start_main /build/glibc-OTsEL5/glibc-2.27/csu/../csu/libc-start.c:310
    #4 0x55d344d1a029 in _start (src/objdir-ff-ubsan/dist/bin/firefox+0x141029)

The params look ok to me. Did we miss the calling convention or other attributes?