Disable an assert in LinearLifetimeChecker pending design changes.

This assert does not make sense because consumingUses in some cases
only contains the destroying uses. Owned values may not be destroyed
because they may be converted to ValueOwnershipKind::None on all paths
reaching a return. Instead, this utility needs to find liveness first
considering all uses (or at least all uses that may be on a lifetime
boundary). We probably then won't need this assert, but I'm leaving
the FIXME as a placeholder for that work.

Fixes rdar://71240363.

Author: atrick

lib/SIL/Verifier/LinearLifetimeChecker.cpp

@@ -551,9 +551,17 @@ LinearLifetimeChecker::Error LinearLifetimeChecker::checkValueImpl(
     Optional<function_ref<void(SILBasicBlock *)>> leakingBlockCallback,
     Optional<function_ref<void(Operand *)>>
         nonConsumingUseOutsideLifetimeCallback) {
-  assert((!consumingUses.empty()
-          || deadEndBlocks.isDeadEnd(value->getParentBlock())) &&
-         "Must have at least one consuming user?!");
+  // FIXME: rdar://71240363. This assert does not make sense because
+  // consumingUses in some cases only contains the destroying uses. Owned values
+  // may not be destroyed because they may be converted to
+  // ValueOwnershipKind::None on all paths reaching a return. Instead, this
+  // utility needs to find liveness first considering all uses (or at least all
+  // uses that may be on a lifetime boundary). We probably then won't need this
+  // assert, but I'm leaving the FIXME as a placeholder for that work.
+  //
+  // assert((!consumingUses.empty()
+  //        || deadEndBlocks.isDeadEnd(value->getParentBlock())) &&
+  //       "Must have at least one consuming user?!");
 
   State state(value, visitedBlocks, errorBuilder, leakingBlockCallback,
               nonConsumingUseOutsideLifetimeCallback, consumingUses,