Disable AST type caching for SILFunctionTypes since the mapping isn't

[adrian-prantl]

bijective, and relax check in TypeSystemSwiftTypeRef to take this fact
into account.

rdar://70552614

[adrian-prantl]

@swift-ci test

[vedantk]

Note that we might be able to un-XFAIL the stepper integration test once this lands.

[slavapestov]

Can we just get rid of this mapping? IIRC, the old type reconstruction code didn't handle SILFunctionType at all, always returning () -> (). When I implemented full type reconstruction, there were a few places in lldb that weren't set up to handle a SILFunctionType so I added this hack to get the old behavior back. We should just remove it.

[adrian-prantl]

If I remove it completely I get the following SIL verification error for the expression and it's not clear to me what :

SIL verification failed: init_existential_addr payload must be a lowering of the formal concrete type: isLoweringOf(AEI->getLoweredConcreteType(), AEI->getFormalConcreteType())
Verifying instruction:
     %132 = alloc_stack $Any                      // users: %139, %138, %137, %134
->   %134 = init_existential_addr %132 : $*Any, $Optional<@callee_guaranteed (@guaranteed String) -> ()> // user: %135
     store %133 to [init] %134 : $*Optional<@callee_guaranteed (@guaranteed String) -> ()> // id: %135

...

(lldb) p AEI->getLoweredConcreteType().dump()
error: Couldn't lookup symbols:
  __ZNK5swift23InitExistentialAddrInst22getLoweredConcreteTypeEv
(lldb) p AEI->dump()
  %134 = init_existential_addr %132 : $*Any, $Optional<@callee_guaranteed (@guaranteed String) -> ()> // user: %135

[adrian-prantl]

frame #4: 0x0000000101988805 LLDB`swift::SILInstructionVisitor<(anonymous namespace)::SILVerifier, void>::visit(swift::SILInstruction*) [inlined] (anonymous namespace)::SILVerifier::checkInitExistentialAddrInst(this=0x00007ffeefbfa1f0, AEI=0x00000002ed33d050) at SILVerifier.cpp:3510:5 [opt]
   3502	    auto loweredTy = F.getLoweredType(Lowering::AbstractionPattern(archetype),
   3503	                                      AEI->getFormalConcreteType())
   3504	                      .getAddressType();
   3505	    
   3506	    requireSameType(loweredTy, AEI->getLoweredConcreteType(),
   3507	                    "init_existential_addr result type must be the lowered "
   3508	                    "concrete type at the right abstraction level");
   3509	
-> 3510	    require(isLoweringOf(AEI->getLoweredConcreteType(),
   3511	                         AEI->getFormalConcreteType()),
   3512	            "init_existential_addr payload must be a lowering of the formal "
   3513	            "concrete type");