Merge pull request #20402 from rudkx/fix-default-literal-type-bug

[ConstraintSystem] Fix crash due to not all literal protocols having …

Author: rudkx

lib/Sema/CSSolver.cpp

@@ -1750,6 +1750,9 @@ void ConstraintSystem::sortDesignatedTypes(
 
   for (auto *protocol : argInfo.getLiteralProtocols()) {
     auto defaultType = TC.getDefaultType(protocol, DC);
+    // ExpressibleByNilLiteral does not have a default type.
+    if (!defaultType)
+      continue;
     auto *nominal = defaultType->getAnyNominal();
     for (size_t i = nextType + 1; i < nominalTypes.size(); ++i) {
       if (nominal == nominalTypes[i]) {

test/Constraints/add_with_nil.swift

@@ -0,0 +1,6 @@
+// RUN: %target-typecheck-verify-swift -swift-version 5 -solver-enable-operator-designated-types -solver-disable-shrink -disable-constraint-solver-performance-hacks
+
+func test(_ x: Int) -> Int {
+  return x + nil
+  // expected-error@-1 {{cannot convert value of type 'Int' to expected argument type '_.Stride'}}
+}