Merge pull request #58776 from LucianoPAlmeida/hole-try-5-7

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

Author: LucianoPAlmeida

lib/Sema/CSBindings.cpp

@@ -1993,10 +1993,16 @@ 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.
+  // Also propagate in code completion mode because in some cases code
+  // completion relies on type variable being a potential hole.
   if (TypeVar->getImpl().canBindToHole()) {
-    if (auto objectTy = type->getOptionalObjectType()) {
-      if (auto *typeVar = objectTy->getAs<TypeVariableType>())
-        cs.recordPotentialHole(typeVar);
+    if (srcLocator->directlyAt<OptionalEvaluationExpr>() ||
+        cs.isForCodeCompletion()) {
+      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}}
+  }
+}

validation-test/IDE/stress_tester_issues_fixed/rdar93127707.swift

@@ -0,0 +1,9 @@
+// RUN: %swift-ide-test -code-completion -source-filename %s -code-completion-token COMPLETE | %FileCheck %s
+
+struct Foo {
+  var x: Int = {
+    guard let foo = #^COMPLETE^#
+  }()
+}
+
+// CHECK: Decl[Struct]/CurrModule:            Foo[#Foo#];