[CSGen] Allow expression pattern types to be holes

(cherry picked from commit 20d7642)

Author: xedin

lib/Sema/CSGen.cpp

@@ -2920,8 +2920,8 @@ namespace {
         // TODO: we could try harder here, e.g. for enum elements to provide the
         // enum type.
         return setType(
-            CS.createTypeVariable(
-              CS.getConstraintLocator(locator), TVO_CanBindToNoEscape));
+            CS.createTypeVariable(CS.getConstraintLocator(locator),
+                                  TVO_CanBindToNoEscape | TVO_CanBindToHole));
       }
 
       llvm_unreachable("Unhandled pattern kind");

test/expr/closure/multi_statement.swift

@@ -336,9 +336,10 @@ func test_unknown_refs_in_tilde_operator() {
   enum E {
   }
 
-  let _: (E) -> Void = { // expected-error {{unable to infer closure type in the current context}}
+  let _: (E) -> Void = {
     if case .test(unknown) = $0 {
       // expected-error@-1 2 {{cannot find 'unknown' in scope}}
+      // expected-error@-2 {{type 'E' has no member 'test'}}
     }
   }
 }

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

@@ -6,3 +6,17 @@ 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 '(_, _)'}}
 }
+
+let _: () -> Void = {
+  for case (0)? in [a] {}
+  if case (0, 0) = a {}
+  // expected-error@-1 {{cannot convert value of type 'Any?' to specified type '(_, _)}}
+}
+
+let _: () -> Void = {
+  for case (0)? in [a] {}
+  for case (0, 0) in [a] {}
+  // expected-error@-1 {{conflicting arguments to generic parameter 'Elements' ('[Any]' vs. '[Any?]')}}
+  // expected-error@-2 {{conflicting arguments to generic parameter 'Element' ('Any' vs. 'Any?')}}
+  // expected-error@-3 {{conflicting arguments to generic parameter 'Self' ('[Any]' vs. '[Any?]')}}
+}

validation-test/Sema/type_checker_crashers_fixed/rdar92327807.swift

@@ -10,7 +10,7 @@ func test(result: MyEnum, optResult: MyEnum?) {
   }
 
   if let .co(42) = result { // expected-error {{pattern matching in a condition requires the 'case' keyword}}
-    // expected-error@-1 {{type of expression is ambiguous without more context}}
+    // expected-error@-1 {{type 'MyEnum' has no member 'co'}}
   }
 
   if let .co = optResult { // expected-error {{pattern matching in a condition requires the 'case' keyword}}