Merge pull request #79026 from xedin/rdar-143474313

[CSBindings] Allow optional subtype inference when closure result is …

lib/Sema/CSBindings.cpp

@@ -2596,7 +2596,8 @@ bool TypeVarBindingProducer::computeNext() {
         // expression is non-optional), if we allow  both the solver would
         // find two solutions that differ only in location of optional
         // injection.
-        if (!TypeVar->getImpl().isClosureResultType() || objTy->isVoid()) {
+        if (!TypeVar->getImpl().isClosureResultType() || objTy->isVoid() ||
+            objTy->isTypeVariableOrMember()) {
           // If T is a type variable, only attempt this if both the
           // type variable we are trying bindings for, and the type
           // variable we will attempt to bind, both have the same

test/Constraints/argument_matching.swift

@@ -1488,19 +1488,15 @@ func trailingclosure4(f: () -> Int) {}
 trailingclosure4 { 5 }
 
 func trailingClosure5<T>(_ file: String = #file, line: UInt = #line, expression: () -> T?) { }
-// expected-note@-1 {{in call to function 'trailingClosure5(_:line:expression:)'}}
 func trailingClosure6<T>(value: Int, expression: () -> T?) { }
-// expected-note@-1 {{in call to function 'trailingClosure6(value:expression:)'}}
 
 trailingClosure5(file: "hello", line: 17) { // expected-error{{extraneous argument label 'file:' in call}}{{18-24=}}
-  // expected-error@-1 {{generic parameter 'T' could not be inferred}}
   return Optional.Some(5)
   // expected-error@-1 {{enum type 'Optional<Wrapped>' has no case 'Some'; did you mean 'some'?}} {{19-23=some}}
   // expected-error@-2 {{generic parameter 'Wrapped' could not be inferred}}
   // expected-note@-3 {{explicitly specify the generic arguments to fix this issue}}
 }
 trailingClosure6(5) { // expected-error{{missing argument label 'value:' in call}}{{18-18=value: }}
-  // expected-error@-1 {{generic parameter 'T' could not be inferred}}
   return Optional.Some(5)
   // expected-error@-1 {{enum type 'Optional<Wrapped>' has no case 'Some'; did you mean 'some'?}} {{19-23=some}}
   // expected-error@-2 {{generic parameter 'Wrapped' could not be inferred}}

test/Constraints/closures.swift

@@ -1305,3 +1305,24 @@ do {
         })
   }
 }
+
+// rdar://143474313 - invalid error: member 'init(item:)' in 'Test.Item?' produces result of type 'Test.Item', but context expects 'Test.Item?'
+do {
+  struct List {
+    struct Item {
+    }
+
+    var items: [Item] = []
+  }
+
+  struct Test {
+    struct Item {
+      init(item: List.Item) {
+      }
+    }
+
+    let list: List
+
+    var items: [Test.Item] { .init(list.items.compactMap { .init(item: $0) }) } // Ok
+  }
+}

validation-test/Sema/type_checker_perf/slow/rdar22079400.swift

@@ -1,7 +1,7 @@
 // RUN: %target-typecheck-verify-swift -solver-expression-time-threshold=1
 // REQUIRES: tools-release,no_asan
 
-let _ = (0...1).lazy.flatMap {
+let _ = (0...1).lazy.flatMap { // expected-error {{reasonable time}}
   a in (1...2).lazy.map { b in (a, b) }
 }.filter {
   1 < $0 && $0 < $1 && $0 + $1 < 3