Merge pull request #19980 from xedin/rdar-45415874

[ConstraintSystem] Properly cache type for literal initialization coe…

Author: xedin

lib/Sema/CSApply.cpp

@@ -3599,6 +3599,7 @@ namespace {
 
         literalInit->setImplicit(false);
 
+        cs.setType(expr, toType);
         // Keep the coercion around, because it contains the source range
         // for the original constructor call.
         return expr;

test/Constraints/rdar45415874.swift

@@ -0,0 +1,15 @@
+// RUN: %target-typecheck-verify-swift
+
+final class A<T> {
+  init(_: T) {}
+}
+
+extension A: ExpressibleByNilLiteral where T: ExpressibleByNilLiteral {
+  convenience init(nilLiteral: ()) {
+    self.init(nil)
+  }
+}
+
+struct B {
+  var foo: A<B?> = A(nil)
+}