fix 058-swift-constraints-constraintsystem-diagnosefailureforexpr.swift

CSDiag's wasn't considering the case when an operator was invalid and had ErrorType.

Author: lattner

lib/Sema/CSDiag.cpp

@@ -1071,8 +1071,11 @@ namespace {
       // If this is an operator func decl in a type context, the 'self' isn't
       // actually going to be applied.
       if (auto *fd = dyn_cast<FuncDecl>(decl))
-        if (fd->isOperator() && fd->getDeclContext()->isTypeContext())
+        if (fd->isOperator() && fd->getDeclContext()->isTypeContext()) {
+          if (type->is<ErrorType>())
+            return nullptr;
           type = type->castTo<AnyFunctionType>()->getResult();
+        }
 
       for (unsigned i = 0, e = level; i != e; ++i) {
         auto funcTy = type->getAs<AnyFunctionType>();

validation-test/IDE/crashers/058-swift-constraints-constraintsystem-diagnosefailureforexpr.swift

@@ -0,0 +1,4 @@
+// RUN: %target-swift-ide-test -code-completion -code-completion-token=A -source-filename=%s
+class T{var f=Dictionary<T
+protocol A{func<:u
+#^A^#