set the maximum depth to explore during type inference

Author: vladima

src/compiler/checker.ts

@@ -6585,6 +6585,7 @@ namespace ts {
  function inferTypes(context: InferenceContext, source: Type, target: Type) {
  let sourceStack: Type[];
  let targetStack: Type[];
+ const maxDepth = 5;
  let depth = 0;
  let inferiority = 0;
  const visited: Map<boolean> = {};
@@ -6713,6 +6714,11 @@ namespace ts {
  if (isInProcess(source, target)) {
  return;
  }
+ // we delibirately limit the depth we examine to infer types: this speeds up the overall inference process
+ // and user rarely expects inferences to be made from the deeply nested constituents.
+ if (depth > maxDepth) {
+ return;
+ }
  if (isDeeplyNestedGeneric(source, sourceStack, depth) && isDeeplyNestedGeneric(target, targetStack, depth)) {
  return;
  }