Merge pull request #17550 from rudkx/rdar41306933-4.2

[4.2] [ConstraintSystem] Use the type cache to read types in constraint gen…

Author: rudkx

lib/Sema/CSGen.cpp

@@ -2756,8 +2756,8 @@ namespace {
       auto locator = CS.getConstraintLocator(expr);
       auto projectedTy = CS.createTypeVariable(locator,
                                                TVO_CanBindToLValue);
-      CS.addKeyPathApplicationConstraint(expr->getKeyPath()->getType(),
-                                         expr->getBase()->getType(),
+      CS.addKeyPathApplicationConstraint(CS.getType(expr->getKeyPath()),
+                                         CS.getType(expr->getBase()),
                                          projectedTy,
                                          locator);
       return projectedTy;