[ConstraintSystem] Account for missing unwrap(s) in call to optional Objective-C members

Author: xedin

lib/Sema/CSSimplify.cpp

@@ -7427,6 +7427,26 @@ ConstraintSystem::simplifyApplicableFnConstraint(
       // Track how many times we do this so that we can record a fix for each.
       ++unwrapCount;
     }
+
+    // Let's account for optional members concept from Objective-C
+    // which forms a disjunction for member type to check whether
+    // it would be possible to use optional type directly or it has
+    // to be force unwrapped (because such types are imported as IUO).
+    if (unwrapCount > 0 && desugar2->is<TypeVariableType>()) {
+      auto *typeVar = desugar2->castTo<TypeVariableType>();
+      auto *locator = typeVar->getImpl().getLocator();
+      if (locator->isLastElement<LocatorPathElt::Member>()) {
+        auto *fix = ForceOptional::create(*this, origType2, desugar2,
+                                          getConstraintLocator(locator));
+        if (recordFix(fix, /*impact=*/unwrapCount))
+          return SolutionKind::Error;
+
+        // Since the right-hand side of the constraint has been changed
+        // we have to re-generate this constraint to use new type.
+        flags |= TMF_GenerateConstraints;
+        return formUnsolved();
+      }
+    }
   }
 
   // For a function, bind the output and convert the argument to the input.

test/Constraints/iuo_objc.swift

@@ -9,23 +9,29 @@ func iuo_error(prop: IUOProperty) {
   // expected-note@-2{{coalesce}}
   // expected-note@-3{{force-unwrap}}
   let _: Coat? = prop.iuo.optional()!
-  // expected-error@-1 {{cannot invoke 'optional' with no arguments}}
+  // expected-error@-1 {{value of optional type '(() -> Coat?)?' must be unwrapped to a value of type '() -> Coat?'}}
+  // expected-note@-2{{coalesce}}
+  // expected-note@-3{{force-unwrap}}
   let _: Coat? = prop.iuo.optional!()
   let _: Coat? = prop.iuo.optional!()!
   let _: Coat? = prop.iuo!.optional()
   // expected-error@-1 {{value of optional type '(() -> Coat?)?' must be unwrapped}}
   // expected-note@-2{{coalesce}}
   // expected-note@-3{{force-unwrap}}
   let _: Coat? = prop.iuo!.optional()!
-  // expected-error@-1 {{cannot invoke 'optional' with no arguments}}
+  // expected-error@-1 {{value of optional type '(() -> Coat?)?' must be unwrapped to a value of type '() -> Coat?'}}
+  // expected-note@-2{{coalesce}}
+  // expected-note@-3{{force-unwrap}}
   let _: Coat? = prop.iuo!.optional!()
   let _: Coat? = prop.iuo!.optional!()!
   let _: Coat = prop.iuo.optional()
   // expected-error@-1 {{value of optional type '(() -> Coat)?' must be unwrapped}}
   // expected-note@-2{{coalesce}}
   // expected-note@-3{{force-unwrap}}
   let _: Coat = prop.iuo.optional()!
-  // expected-error@-1 {{cannot invoke 'optional' with no arguments}}
+  // expected-error@-1 {{value of optional type '(() -> Coat?)?' must be unwrapped to a value of type '() -> Coat?'}}
+  // expected-note@-2{{coalesce}}
+  // expected-note@-3{{force-unwrap}}
   let _: Coat = prop.iuo.optional!()
   let _: Coat = prop.iuo.optional!()!
   let _: Coat = prop.iuo!.optional()
@@ -34,7 +40,9 @@ func iuo_error(prop: IUOProperty) {
   // expected-note@-3{{force-unwrap}}
 
   let _: Coat = prop.iuo!.optional()!
-  // expected-error@-1 {{cannot invoke 'optional' with no arguments}}
+  // expected-error@-1 {{value of optional type '(() -> Coat?)?' must be unwrapped to a value of type '() -> Coat?'}}
+  // expected-note@-2{{coalesce}}
+  // expected-note@-3{{force-unwrap}}
   let _: Coat = prop.iuo!.optional!()
   let _: Coat = prop.iuo!.optional!()!