[CSFix] Ajusting contextual type purpose for subscript destination for assign expr in getStructuralTypeContext

Author: LucianoPAlmeida

lib/Sema/CSDiagnostics.cpp

@@ -2989,14 +2989,7 @@ bool TupleContextualFailure::diagnoseAsError() {
     diagnostic = diag::tuple_types_not_convertible_nelts;
   else if ((purpose == CTP_Initialization) && !getContextualType(getAnchor()))
     diagnostic = diag::tuple_types_not_convertible;
-  else if (purpose == CTP_AssignSource) {
-    auto assignExpr = castToExpr<AssignExpr>(getAnchor());
-    if (isa<SubscriptExpr>(assignExpr->getDest())) {
-      diagnostic = *getDiagnosticFor(CTP_SubscriptAssignSource, getToType());
-    } else {
-      diagnostic = *getDiagnosticFor(purpose, getToType());
-    }
-  } else if (auto diag = getDiagnosticFor(purpose, getToType()))
+  else if (auto diag = getDiagnosticFor(purpose, getToType()))
     diagnostic = *diag;
   else
     return false;

lib/Sema/CSFix.cpp

@@ -287,7 +287,9 @@ getStructuralTypeContext(const Solution &solution, ConstraintLocator *locator) {
                            solution.getType(coerceExpr->getSubExpr()),
                            solution.getType(coerceExpr));
   } else if (auto *assignExpr = getAsExpr<AssignExpr>(locator->getAnchor())) {
-    return std::make_tuple(CTP_AssignSource,
+    auto CTP = isa<SubscriptExpr>(assignExpr->getDest()) ? CTP_SubscriptAssignSource
+                                                         : CTP_AssignSource;
+    return std::make_tuple(CTP,
                            solution.getType(assignExpr->getSrc()),
                            solution.getType(assignExpr->getDest())->getRValueType());
   } else if (auto *call = getAsExpr<CallExpr>(locator->getAnchor())) {