add comments

Author: Vercantez

lib/Sema/TypeCheckDecl.cpp

@@ -483,49 +483,60 @@ static void checkInheritanceClause(
 }
 
 // Check for static properties that produce empty option sets
+// using a rawValue initializer with a value of '0'
 static void checkForEmptyOptionSet(const VarDecl *VD, TypeChecker &tc) {
+  // Check if property is a 'static let'
   if (!VD->isStatic() || !VD->isLet())
     return;
 
   auto DC = VD->getDeclContext();
 
+  // Make sure property is of same type as the type it is declared in
   if (!VD->getType()->isEqual(DC->getSelfTypeInContext()))
     return;
 
+  // Make sure this type conforms to OptionSet
   auto *optionSetProto = tc.Context.getProtocol(KnownProtocolKind::OptionSet);
-  auto protocolConformance = !tc.containsProtocol(
+  bool conformsToOptionSet = tc.containsProtocol(
                                                   DC->getSelfTypeInContext(),
                                                   optionSetProto,
                                                   DC,
-                                                  /*Flags*/None);
+                                                  /*Flags*/None).hasValue();
 
-  if (!protocolConformance)
+  if (!conformsToOptionSet)
     return;
 
   auto PBD = VD->getParentPatternBinding();
   if (!PBD)
     return;
 
-  for (auto entry : PBD->getPatternList()) {
-    if (entry.getPattern()->getSingleVar() != VD) continue;
-    
-    auto ctor = dyn_cast<CallExpr>(entry.getInit());
-    if (!ctor) continue;
-    if (!isa<ConstructorDecl>(ctor->getCalledValue())) continue;
-    
-    if (ctor->getNumArguments() != 1) continue;
-    if (ctor->getArgumentLabels().front() != tc.Context.Id_rawValue) continue;
-    
-    auto *args = cast<TupleExpr>(ctor->getArg());
-    auto intArg = dyn_cast<IntegerLiteralExpr>(args->getElement(0));
-    if (!intArg) continue;
-    if (intArg->getValue() != 0) continue;
-    
-    auto loc = VD->getLoc();
-    tc.diagnose(loc, diag::option_set_zero_constant, VD->getName());
-    tc.diagnose(loc, diag::option_set_empty_set_init)
-      .fixItReplace(args->getSourceRange(), "([])");
-  }
+  auto entry = PBD->getPatternEntryForVarDecl(VD);
+  
+  // Make sure property is being set with a constructor
+  auto ctor = dyn_cast<CallExpr>(entry.getInit());
+  if (!ctor)
+    return;
+  if (!isa<ConstructorDecl>(ctor->getCalledValue()))
+    return;
+  
+  // Make sure it is calling the rawValue constructor
+  if (ctor->getNumArguments() != 1)
+    return;
+  if (ctor->getArgumentLabels().front() != tc.Context.Id_rawValue)
+    return;
+  
+  // Make sure the rawValue parameter is a '0' integer literal
+  auto *args = cast<TupleExpr>(ctor->getArg());
+  auto intArg = dyn_cast<IntegerLiteralExpr>(args->getElement(0));
+  if (!intArg)
+    return;
+  if (intArg->getValue() != 0)
+    return;
+  
+  auto loc = VD->getLoc();
+  tc.diagnose(loc, diag::option_set_zero_constant, VD->getName());
+  tc.diagnose(loc, diag::option_set_empty_set_init)
+  .fixItReplace(args->getSourceRange(), "([])");
 }