[CSSimplify] Fix sub-pattern matching logic related closure and enum element (#62777)

* [CSSimplify] fix pattern matching logic which is as part of the enum element for closure

* add test

* Fixed logic to apply to N levels of nesting

* update tests that take into account N levels of nesting.

* fix indentation

* use dynamic variables and uppdate some logic

* Revert "use dynamic variables and uppdate some logic"

This reverts commit 279dc4f.

* fix logic to only see pattern matches

* clean up unnecessary logic

Co-authored-by: Luciano Almeida <[email protected]>

* Clean up unnecessary logic(2)

* remove dropping

* Fix documentation comments to match current context

* clean up unnecessary logic

* remove comments

Co-authored-by: Luciano Almeida <[email protected]>

Author: takeshi-1000

lib/Sema/CSSimplify.cpp

@@ -2055,25 +2055,10 @@ static bool isInPatternMatchingContext(ConstraintLocatorBuilder locator) {
   SmallVector<LocatorPathElt, 4> path;
   (void)locator.getLocatorParts(path);
 
-  while (!path.empty() && path.back().is<LocatorPathElt::TupleType>())
-    path.pop_back();
-
-  if (!path.empty()) {
-    // Direct pattern matching between tuple pattern and tuple type.
-    if (path.back().is<LocatorPathElt::PatternMatch>()) {
-      return true;
-    } else if (path.size() > 1) {
-      // sub-pattern matching as part of the enum element matching
-      // where sub-element is a tuple pattern e.g.
-      // `case .foo((a: 42, _)) = question`
-      auto lastIdx = path.size() - 1;
-      if (path[lastIdx - 1].is<LocatorPathElt::PatternMatch>() &&
-          path[lastIdx].is<LocatorPathElt::FunctionArgument>())
-        return true;
-    }
-  }
-
-  return false;
+  auto pathElement = llvm::find_if(path, [](LocatorPathElt &elt) {
+    return elt.is<LocatorPathElt::PatternMatch>();
+  });
+  return pathElement != path.end();
 }
 
 namespace {

test/Constraints/sub-pattern-matching-of-enum-element-for-closure.swift

@@ -0,0 +1,18 @@
+// RUN: %target-typecheck-verify-swift
+enum TestType {
+    case foo
+    case bar(Bool, (a: String, (b: String, (String, (c: String, Bool), String), String)))
+}
+
+func test(type: TestType) -> String {
+    let str: String = {
+        switch type {
+        case .foo:
+            return ""
+        case .bar(_, (_, (_, (_, (let c, _), _), _))):
+            return c
+        }
+    }()
+    
+    return str
+}