[Diagnostics] Properly diagnose missing optional unwrap(s) related to closure result

Author: xedin

lib/Sema/CSSimplify.cpp

@@ -3287,6 +3287,10 @@ bool ConstraintSystem::repairFailures(
   }
 
   case ConstraintLocator::ClosureResult: {
+    if (repairViaOptionalUnwrap(*this, lhs, rhs, matchKind, conversionsOrFixes,
+                                locator))
+      return true;
+
     // If we could record a generic arguments mismatch instead of this fix,
     // don't record a ContextualMismatch here.
     if (hasConversionOrRestriction(ConversionRestrictionKind::DeepEquality))
@@ -3391,9 +3395,15 @@ bool ConstraintSystem::repairFailures(
         loc->isLastElement<LocatorPathElt::ApplyArgToParam>()) {
       auto *argExpr = simplifyLocatorToAnchor(loc);
       if (argExpr && isa<ClosureExpr>(argExpr)) {
-        conversionsOrFixes.push_back(ContextualMismatch::create(
-            *this, lhs, rhs,
-            getConstraintLocator(argExpr, ConstraintLocator::ClosureResult)));
+        auto *locator =
+            getConstraintLocator(argExpr, ConstraintLocator::ClosureResult);
+
+        if (repairViaOptionalUnwrap(*this, lhs, rhs, matchKind,
+                                    conversionsOrFixes, locator))
+          break;
+
+        conversionsOrFixes.push_back(
+            IgnoreContextualType::create(*this, lhs, rhs, locator));
         break;
       }
     }

test/Constraints/fixes.swift

@@ -167,8 +167,9 @@ struct S1116 {
 }
 
 let a1116: [S1116] = []
-var s1116 = Set(1...10).subtracting(a1116.map({ $0.s })) // expected-error {{cannot convert value of type '[Int?]' to expected argument type 'Set<Int>'}}
-
+var s1116 = Set(1...10).subtracting(a1116.map({ $0.s })) // expected-error {{value of optional type 'Int?' must be unwrapped to a value of type 'Int'}}
+// expected-note@-1{{coalesce using '??' to provide a default when the optional value contains 'nil'}} {{49-49=(}} {{53-53= ?? <#default value#>)}}
+// expected-note@-2{{force-unwrap using '!' to abort execution if the optional value contains 'nil'}} {{53-53=!}}
 
 func moreComplexUnwrapFixes() {
   struct S {