[ConstraintSystem] Teach init ref validation about implicit conversions

Implicit conversion used to erase path for contextual type conversions
but it does so no longer, this means that invalid initializer reference
check needs to know about existence of implicit conversions that are
not reflected in the AST until solution is applied.

Resolves: rdar://99352676

Author: xedin

lib/Sema/CSSimplify.cpp

@@ -8861,6 +8861,10 @@ static ConstraintFix *validateInitializerRef(ConstraintSystem &cs,
   if (!anchor)
     return nullptr;
 
+  // Avoid checking implicit conversions injected by the compiler.
+  if (locator->findFirst<LocatorPathElt::ImplicitConversion>())
+    return nullptr;
+
   auto getType = [&cs](Expr *expr) -> Type {
     return cs.simplifyType(cs.getType(expr))->getRValueType();
   };

test/Constraints/implicit_double_cgfloat_conversion.swift

@@ -330,3 +330,15 @@ func test_implicit_conversion_clash_with_partial_application_check() {
     }
   }
 }
+
+// rdar://99352676
+func test_init_validation() {
+  class Foo {
+    static let bar = 100.0
+
+    func getBar() -> CGFloat? {
+      return Self.bar
+      // CHECK: function_ref @$s12CoreGraphics7CGFloatVyACSdcfC : $@convention(method) (Double, @thin CGFloat.Type) -> CGFloat
+    }
+  }
+}