[CSGen] Allow is pattern types to be holes

Author: xedin

lib/Sema/CSGen.cpp

@@ -2768,8 +2768,9 @@ namespace {
         // correct handling of patterns like `_ as Foo` where `_` would
         // get a type of `Foo` but `is` pattern enclosing it could still be
         // inferred from enclosing context.
-        auto isType = CS.createTypeVariable(CS.getConstraintLocator(pattern),
-                                            TVO_CanBindToNoEscape);
+        auto isType =
+            CS.createTypeVariable(CS.getConstraintLocator(pattern),
+                                  TVO_CanBindToNoEscape | TVO_CanBindToHole);
         CS.addConstraint(
             ConstraintKind::Conversion, subPatternType, isType,
             locator.withPathElement(LocatorPathElt::PatternMatch(pattern)));

validation-test/Sema/type_checker_crashers_fixed/issue-65360.swift

@@ -0,0 +1,8 @@
+// RUN: %target-typecheck-verify-swift
+
+var a: Any?
+
+let _: () -> Void = {
+  for case (is Int)? in [a] {}
+  if case (is Int, is Int) = a {} // expected-error {{cannot convert value of type 'Any?' to specified type '(_, _)'}}
+}