SILGen: Fix crash with non-scalar casts requiring re-abstraction

This might only come up in invalid code, but for example
casting a function type to String would trigger it.

Author: slavapestov

lib/SILGen/SILGenDynamicCast.cpp

@@ -357,20 +357,18 @@ adjustForConditionalCheckedCastOperand(SILLocation loc, ManagedValue src,
   }
 
   std::unique_ptr<TemporaryInitialization> init;
-  SGFContext ctx;
   if (requiresAddress) {
     init = SGF.emitTemporary(loc, srcAbstractTL);
-    
+
+    if (hasAbstraction)
+      src = SGF.emitSubstToOrigValue(loc, src, abstraction, sourceType);
+
     // Okay, if all we need to do is drop the value in an address,
     // this is easy.
-    if (!hasAbstraction) {
-      SGF.B.emitStoreValueOperation(loc, src.forward(SGF), init->getAddress(),
-                                    StoreOwnershipQualifier::Init);
-      init->finishInitialization(SGF);
-      return init->getManagedAddress();
-    }
-    
-    ctx = SGFContext(init.get());
+    SGF.B.emitStoreValueOperation(loc, src.forward(SGF), init->getAddress(),
+                                  StoreOwnershipQualifier::Init);
+    init->finishInitialization(SGF);
+    return init->getManagedAddress();
   }
 
   assert(hasAbstraction);

validation-test/compiler_crashers_2/0038-lowering-CheckedCastEmitter-emitConditional.swift

@@ -0,0 +1,4 @@
+// RUN: %target-swift-frontend %s -emit-silgen
+
+let a: () -> Int? = { return nil }
+a as? Int

validation-test/compiler_crashers_2_fixed/0038-lowering-CheckedCastEmitter-emitConditional.swift

@@ -5,7 +5,7 @@
 // See https://swift.org/LICENSE.txt for license information
 // See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
 
-// RUN: not --crash %target-swift-frontend %s -emit-ir
+// RUN: not %target-swift-frontend %s -emit-ir
 // REQUIRES: asserts
 struct A{
 func a()->String{