IF Generator expression evaluates both branches eagerly

When writing an IF generator expression, both branches of the IF are evaluated eagerly, which leads to problems if the non-selected branch evaluates another generator expression that is invalid in that context. For example, consider:

set(link_command "$<IF:$<TARGET_EXISTS:${target}>,-l$<TARGET_PROPERTY:${target},OUTPUT_NAME>,-l${target}>")

The goal here is to evaluate the $<TARGET_PROPERTY:${target},OUTPUT_NAME> only when the $<TARGET_EXISTS:${target}> condition is true, because trying to do otherwise is obviously wrong. However, CMake appears to evaluate both branches regardless of which one is selected, and this yields an error when ${target} does not exist.