Comment 5 for bug 1601810

The problem would only occur when using dpkg-buildpackage. (slightly different link order was generated).

The symbols that were missing were templates from gmock that were generated and in the mock_egl.cpp.o file. Given the right link order (namely, mirserver.so before libmir-test-assist.a), things would resolve correctly. If mirserver.so came after libmir-test-assist.a, then the egl functions would get resolved, but for whatever reason, the weak symbols generated as part of the gmock stuff wouldn't get pulled in again before getting to the end of the linkage list.

The proper solution seems to be to use -Wl,--whole-archive to make sure that the symbols generated from the gmock templates are still available despite linkage order