[csdiag] missing function call failure here as a backup

Author: theblixguy

lib/Sema/CSDiag.cpp

@@ -2316,6 +2316,25 @@ bool FailureDiagnosis::diagnoseContextualConversionError(
     return false;
   }
 
+  // If we're trying to convert something of type "() -> T" to T, then we
+  // probably meant to call the value.
+  if (auto srcFT = exprType->getAs<AnyFunctionType>()) {
+    if (srcFT->getParams().empty() &&
+        !isUnresolvedOrTypeVarType(srcFT->getResult()) &&
+        CS.TC.isConvertibleTo(srcFT->getResult(), contextualType, CS.DC)) {
+
+      auto locator = CS.getConstraintLocator(expr);
+      auto extendedLocator =
+          CS.getConstraintLocator(locator, ConstraintLocator::ContextualType);
+      ContextualFailure failure = ContextualFailure(
+          nullptr, CS, srcFT, contextualType, extendedLocator);
+      auto diagnosed = failure.diagnoseAsError();
+      assert(diagnosed && "Failed to produce contextual failure diagnostic");
+      (void)diagnosed;
+      return true;
+    }
+  }
+
   // If this is a conversion from T to () in a call argument context, it is
   // almost certainly an extra argument being passed in.
   if (CTP == CTP_CallArgument && contextualType->isVoid()) {

lib/Sema/CSDiagnostics.cpp

@@ -1357,7 +1357,11 @@ bool ContextualFailure::diagnoseMissingFunctionCall() const {
   //
   // Let's offer another fix-it to remove the '=' to turn the stored
   // property into a computed property. If the variable is immutable, then
-  // replace the 'let' with a 'var'
+  // replace the 'let' with a 'var'.
+
+  if (getAnchor() && !isa<ClosureExpr>(getAnchor())) {
+    return true;
+  }
 
   // First, check if the variable is declared top level or not. If it is
   // not, then it means we're inside a decl like a class or an extension.

lib/Sema/CSSimplify.cpp

@@ -1994,10 +1994,9 @@ repairFailures(ConstraintSystem &cs, Type lhs, Type rhs,
       auto *fix = ContextualMismatch::create(cs, lhs, rhs,
                                              cs.getConstraintLocator(locator));
       conversionsOrFixes.push_back(fix);
-      break;
     }
 
-    return;
+    break;
   }
 
   default: