Merge pull request swiftlang#58740 from LucianoPAlmeida/hole-opt-try

[Sema] Limit optional type variable hole propagation only to OptionalEvaluationExpr binding

Author: LucianoPAlmeida

lib/Sema/CSBindings.cpp

@@ -1993,7 +1993,8 @@ bool TypeVariableBinding::attempt(ConstraintSystem &cs) const {
   // without any contextual information, so even though `x` would get
   // bound to result type of the chain, underlying type variable wouldn't
   // be resolved, so we need to propagate holes up the conversion chain.
-  if (TypeVar->getImpl().canBindToHole()) {
+  if (TypeVar->getImpl().canBindToHole() &&
+      srcLocator->directlyAt<OptionalEvaluationExpr>()) {
     if (auto objectTy = type->getOptionalObjectType()) {
       if (auto *typeVar = objectTy->getAs<TypeVariableType>())
         cs.recordPotentialHole(typeVar);

test/Constraints/optional.swift

@@ -509,3 +509,6 @@ func rdar85166519() {
     v?.addingReportingOverflow(0) // expected-error {{cannot convert value of type '(partialValue: Int, overflow: Bool)?' to expected dictionary key type 'Int'}}
   ]
 }
+
+// https://github.com/apple/swift/issues/58539
+if let x = nil {} // expected-error{{'nil' requires a contextual type}}

test/Constraints/try_swift5.swift

@@ -0,0 +1,12 @@
+// RUN: %target-typecheck-verify-swift -swift-version 5
+
+// https://github.com/apple/swift/issues/58661
+class I58661 {
+  func throwing<T>() throws -> T { // expected-note{{in call to function 'throwing()'}}
+    throw Swift.fatalError()
+  }
+
+  func reproduce() {
+    let check = try? throwing() // expected-error{{generic parameter 'T' could not be inferred}}
+  }
+}