FindGTest: Revert "Allow either "Debug" or "Release" configurations."
Revert !4950 (merged). If both configurations are found then GTEST_LIBRARY
is populated in a way that breaks __gtest_determine_library_type
, and the imported target is not created correctly.
Fixes: #21473 (closed)
Issue: #17799
Backport: release:HEAD~1
Edited by Brad King