[Diagnostics] Don't filter overload set candidates based on labels in lookup

include/swift/AST/DiagnosticsSema.def

@@ -1051,6 +1051,9 @@ ERROR(argument_out_of_order_unnamed_named,none,
 ERROR(argument_out_of_order_unnamed_unnamed,none,
       "unnamed argument #%0 must precede unnamed argument #%1",
       (unsigned, unsigned))
+NOTE(candidate_expected_different_labels,none,
+     "incorrect labels for candidate (have: '%0', expected: '%1')",
+     (StringRef, StringRef))
 
 ERROR(member_shadows_global_function,none,
       "use of %0 refers to %1 %2 rather than %3 %4 in %5 %6",

lib/Sema/CSDiag.cpp

@@ -741,7 +741,6 @@ void FailureDiagnosis::diagnoseUnviableLookupResults(
       return;
 
     switch (firstProblem) {
-    case MemberLookupResult::UR_LabelMismatch:
     case MemberLookupResult::UR_WritableKeyPathOnReadOnlyMember:
     case MemberLookupResult::UR_ReferenceWritableKeyPathOnMutatingMember:
     case MemberLookupResult::UR_KeyPathWithAnyObjectRootType:
@@ -4192,7 +4191,7 @@ bool FailureDiagnosis::diagnoseTrailingClosureErrors(ApplyExpr *callExpr) {
   };
 
   SmallPtrSet<TypeBase *, 4> possibleTypes;
-  auto currentType = CS.getType(fnExpr);
+  auto currentType = CS.simplifyType(CS.getType(fnExpr));
 
   // If current type has type variables or unresolved types
   // let's try to re-typecheck it to see if we can get some

lib/Sema/CSDiagnostics.cpp

@@ -33,6 +33,7 @@
 #include "swift/Parse/Lexer.h"
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/SmallString.h"
+#include <string>
 
 using namespace swift;
 using namespace constraints;
@@ -691,6 +692,46 @@ bool LabelingFailure::diagnoseAsError() {
                                     isa<SubscriptExpr>(anchor));
 }
 
+bool LabelingFailure::diagnoseAsNote() {
+  auto *anchor = getRawAnchor();
+
+  auto *argExpr = getArgumentExprFor(anchor);
+  if (!argExpr)
+    return false;
+
+  SmallVector<Identifier, 4> argLabels;
+  if (auto *paren = dyn_cast<ParenExpr>(argExpr)) {
+    argLabels.push_back(Identifier());
+  } else if (auto *tuple = dyn_cast<TupleExpr>(argExpr)) {
+    argLabels.append(tuple->getElementNames().begin(),
+                     tuple->getElementNames().end());
+  } else {
+    return false;
+  }
+
+  auto stringifyLabels = [](ArrayRef<Identifier> labels) -> std::string {
+    std::string str;
+    for (auto label : labels) {
+      str += label.empty() ? "_" : label.str();
+      str += ':';
+    }
+    return "(" + str + ")";
+  };
+
+  auto selectedOverload = getChoiceFor(anchor);
+  if (!selectedOverload)
+    return false;
+
+  const auto &choice = selectedOverload->choice;
+  if (auto *decl = choice.getDeclOrNull()) {
+    emitDiagnostic(decl, diag::candidate_expected_different_labels,
+                   stringifyLabels(argLabels), stringifyLabels(CorrectLabels));
+    return true;
+  }
+
+  return false;
+}
+
 bool NoEscapeFuncToTypeConversionFailure::diagnoseAsError() {
   auto *anchor = getAnchor();
 

lib/Sema/CSDiagnostics.h

@@ -529,6 +529,7 @@ class LabelingFailure final : public FailureDiagnostic {
       : FailureDiagnostic(root, cs, locator), CorrectLabels(labels) {}
 
   bool diagnoseAsError() override;
+  bool diagnoseAsNote() override;
 };
 
 /// Diagnose errors related to converting function type which

lib/Sema/CSSimplify.cpp

@@ -110,36 +110,31 @@ bool constraints::doesMemberRefApplyCurriedSelf(Type baseTy,
   // curried self.
   if (decl->isInstanceMember()) {
     assert(baseTy);
-    if (isa<AbstractFunctionDecl>(decl) && baseTy->is<AnyMetatypeType>())
+    if (isa<AbstractFunctionDecl>(decl) &&
+        baseTy->getRValueType()->is<AnyMetatypeType>())
       return false;
   }
 
   // Otherwise the reference applies self.
   return true;
 }
 
-bool constraints::areConservativelyCompatibleArgumentLabels(
-                                               OverloadChoice choice,
-                                               ArrayRef<Identifier> labels,
-                                               bool hasTrailingClosure) {
+static bool
+areConservativelyCompatibleArgumentLabels(OverloadChoice choice,
+                                          ArrayRef<FunctionType::Param> args,
+                                          bool hasTrailingClosure) {
   ValueDecl *decl = nullptr;
-  Type baseType;
   switch (choice.getKind()) {
   case OverloadChoiceKind::Decl:
   case OverloadChoiceKind::DeclViaBridge:
   case OverloadChoiceKind::DeclViaDynamic:
   case OverloadChoiceKind::DeclViaUnwrappedOptional:
     decl = choice.getDecl();
-    baseType = choice.getBaseType();
-    if (baseType)
-      baseType = baseType->getRValueType();
     break;
 
-  case OverloadChoiceKind::KeyPathApplication:
-    // Key path applications are written as if subscript[keyPath:].
-    return !hasTrailingClosure && labels.size() == 1 && labels[0].is("keyPath");
-
   case OverloadChoiceKind::BaseType:
+  // KeyPath application is not filtered in `performMemberLookup`.
+  case OverloadChoiceKind::KeyPathApplication:
   case OverloadChoiceKind::DynamicMemberLookup:
   case OverloadChoiceKind::KeyPathDynamicMemberLookup:
   case OverloadChoiceKind::TupleIndex:
@@ -149,17 +144,13 @@ bool constraints::areConservativelyCompatibleArgumentLabels(
   if (!decl->hasParameterList())
     return true;
 
-  SmallVector<AnyFunctionType::Param, 8> argInfos;
-  for (auto argLabel : labels) {
-    argInfos.push_back(AnyFunctionType::Param(Type(), argLabel, {}));
-  }
-
   // This is a member lookup, which generally means that the call arguments
   // (if we have any) will apply to the second level of parameters, with
   // the member lookup applying the curried self at the first level. But there
   // are cases where we can get an unapplied declaration reference back.
   auto hasAppliedSelf =
-      decl->hasCurriedSelf() && doesMemberRefApplyCurriedSelf(baseType, decl);
+      decl->hasCurriedSelf() &&
+      doesMemberRefApplyCurriedSelf(choice.getBaseType(), decl);
 
   auto *fnType = decl->getInterfaceType()->castTo<AnyFunctionType>();
   if (hasAppliedSelf) {
@@ -173,10 +164,9 @@ bool constraints::areConservativelyCompatibleArgumentLabels(
   MatchCallArgumentListener listener;
   SmallVector<ParamBinding, 8> unusedParamBindings;
 
-  return !matchCallArguments(argInfos, params, paramInfo,
-                             hasTrailingClosure,
-                             /*allow fixes*/ false,
-                             listener, unusedParamBindings);
+  return !matchCallArguments(args, params, paramInfo, hasTrailingClosure,
+                             /*allow fixes*/ false, listener,
+                             unusedParamBindings);
 }
 
 Expr *constraints::getArgumentLabelTargetExpr(Expr *fn) {
@@ -873,14 +863,19 @@ getCalleeDeclAndArgs(ConstraintSystem &cs,
 
 class ArgumentFailureTracker : public MatchCallArgumentListener {
   ConstraintSystem &CS;
+  ArrayRef<AnyFunctionType::Param> Arguments;
+  ArrayRef<AnyFunctionType::Param> Parameters;
   SmallVectorImpl<ParamBinding> &Bindings;
   ConstraintLocatorBuilder Locator;
 
 public:
   ArgumentFailureTracker(ConstraintSystem &cs,
+                         ArrayRef<AnyFunctionType::Param> args,
+                         ArrayRef<AnyFunctionType::Param> params,
                          SmallVectorImpl<ParamBinding> &bindings,
                          ConstraintLocatorBuilder locator)
-      : CS(cs), Bindings(bindings), Locator(locator) {}
+      : CS(cs), Arguments(args), Parameters(params), Bindings(bindings),
+        Locator(locator) {}
 
   bool missingLabel(unsigned paramIndex) override {
     return !CS.shouldAttemptFixes();
@@ -912,9 +907,27 @@ class ArgumentFailureTracker : public MatchCallArgumentListener {
     if (!anchor)
       return true;
 
+    unsigned numExtraneous = 0;
+    for (unsigned paramIdx = 0, n = Bindings.size(); paramIdx != n;
+         ++paramIdx) {
+      if (Bindings[paramIdx].empty())
+        continue;
+
+      const auto paramLabel = Parameters[paramIdx].getLabel();
+      for (auto argIdx : Bindings[paramIdx]) {
+        auto argLabel = Arguments[argIdx].getLabel();
+        if (paramLabel.empty() && !argLabel.empty())
+          ++numExtraneous;
+      }
+    }
+
     auto *locator = CS.getConstraintLocator(anchor);
     auto *fix = RelabelArguments::create(CS, newLabels, locator);
     CS.recordFix(fix);
+    // Re-labeling fixes with extraneous labels should take
+    // lower priority vs. other fixes on same/different
+    // overload(s) where labels did line up correctly.
+    CS.increaseScore(ScoreKind::SK_Fix, numExtraneous);
     return false;
   }
 };
@@ -944,7 +957,8 @@ ConstraintSystem::TypeMatchResult constraints::matchCallArguments(
 
   // Match up the call arguments to the parameters.
   SmallVector<ParamBinding, 4> parameterBindings;
-  ArgumentFailureTracker listener(cs, parameterBindings, locator);
+  ArgumentFailureTracker listener(cs, argsWithLabels, params, parameterBindings,
+                                  locator);
   if (constraints::matchCallArguments(argsWithLabels, params,
                                       paramInfo,
                                       hasTrailingClosure,
@@ -4175,19 +4189,15 @@ performMemberLookup(ConstraintKind constraintKind, DeclName memberName,
 
   // If we have a simple name, determine whether there are argument
   // labels we can use to restrict the set of lookup results.
-  Optional<ArgumentLabelState> argumentLabels;
-  if (memberName.isSimpleName()) {
-    argumentLabels = getArgumentLabels(*this,
-                                       ConstraintLocatorBuilder(memberLocator));
-
+  if (baseObjTy->isAnyObject() && memberName.isSimpleName()) {
     // If we're referencing AnyObject and we have argument labels, put
     // the argument labels into the name: we don't want to look for
     // anything else, because the cost of the general search is so
     // high.
-    if (baseObjTy->isAnyObject() && argumentLabels) {
+    if (auto argumentLabels =
+            getArgumentLabels(*this, ConstraintLocatorBuilder(memberLocator))) {
       memberName = DeclName(TC.Context, memberName.getBaseName(),
                             argumentLabels->Labels);
-      argumentLabels.reset();
     }
   }
 
@@ -4226,7 +4236,6 @@ performMemberLookup(ConstraintKind constraintKind, DeclName memberName,
       bridgedType = classType;
     }
   }
-  bool labelMismatch = false;
 
   // Local function that adds the given declaration if it is a
   // reasonable choice.
@@ -4291,20 +4300,6 @@ performMemberLookup(ConstraintKind constraintKind, DeclName memberName,
       hasInstanceMethods = true;
     }
 
-    // If the argument labels for this result are incompatible with
-    // the call site, skip it.
-    // FIXME: The subscript check here forces the use of the
-    // function-application simplification logic to handle labels.
-    if (argumentLabels &&
-        (!candidate.isDecl() || !isa<SubscriptDecl>(candidate.getDecl())) &&
-        !areConservativelyCompatibleArgumentLabels(
-            candidate, argumentLabels->Labels,
-            argumentLabels->HasTrailingClosure)) {
-      labelMismatch = true;
-      result.addUnviable(candidate, MemberLookupResult::UR_LabelMismatch);
-      return;
-    }
-
     // If our base is an existential type, we can't make use of any
     // member whose signature involves associated types.
     if (instanceTy->isExistentialType()) {
@@ -4494,8 +4489,6 @@ performMemberLookup(ConstraintKind constraintKind, DeclName memberName,
   };
 
   // Add all results from this lookup.
-retry_after_fail:
-  labelMismatch = false;
   for (auto result : lookup)
     addChoice(getOverloadChoice(result.getValueDecl(),
                                 /*isBridged=*/false,
@@ -4603,14 +4596,6 @@ performMemberLookup(ConstraintKind constraintKind, DeclName memberName,
     }
   }
 
-  // If we rejected some possibilities due to an argument-label
-  // mismatch and ended up with nothing, try again ignoring the
-  // labels. This allows us to perform typo correction on the labels.
-  if (result.ViableCandidates.empty() && labelMismatch && shouldAttemptFixes()){
-    argumentLabels.reset();
-    goto retry_after_fail;
-  }
-
   // If we have no viable or unviable candidates, and we're generating,
   // diagnostics, rerun the query with inaccessible members included, so we can
   // include them in the unviable candidates list.
@@ -4855,7 +4840,6 @@ fixMemberRef(ConstraintSystem &cs, Type baseTy,
                  : nullptr;
     }
 
-    case MemberLookupResult::UR_LabelMismatch:
     // TODO(diagnostics): Add a new fix that is suggests to
     // add `subscript(dynamicMember: {Writable}KeyPath<T, U>)`
     // overload here, that would help if such subscript has
@@ -5882,7 +5866,6 @@ ConstraintSystem::simplifyKeyPathApplicationConstraint(
 Type ConstraintSystem::simplifyAppliedOverloads(
                                 TypeVariableType *fnTypeVar,
                                 const FunctionType *argFnType,
-                                Optional<ArgumentLabelState> argumentLabels,
                                 ConstraintLocatorBuilder locator) {
   Type fnType(fnTypeVar);
 
@@ -5923,6 +5906,8 @@ Type ConstraintSystem::simplifyAppliedOverloads(
       return markFailure();
   };
 
+  auto argumentInfo = getArgumentLabels(*this, locator);
+
   // Consider each of the constraints in the disjunction.
 retry_after_fail:
   bool hasUnhandledConstraints = false;
@@ -5936,12 +5921,18 @@ Type ConstraintSystem::simplifyAppliedOverloads(
 
         // Determine whether the argument labels we have conflict with those of
         // this overload choice.
-        if (argumentLabels &&
-            !areConservativelyCompatibleArgumentLabels(
-                choice, argumentLabels->Labels,
-                argumentLabels->HasTrailingClosure)) {
-          labelMismatch = true;
-          return false;
+        if (argumentInfo) {
+          auto args = argFnType->getParams();
+
+          SmallVector<FunctionType::Param, 8> argsWithLabels;
+          argsWithLabels.append(args.begin(), args.end());
+          FunctionType::relabelParams(argsWithLabels, argumentInfo->Labels);
+
+          if (!areConservativelyCompatibleArgumentLabels(
+                  choice, argsWithLabels, argumentInfo->HasTrailingClosure)) {
+            labelMismatch = true;
+            return false;
+          }
         }
 
         // Determine the type that this choice will have.
@@ -5968,7 +5959,7 @@ Type ConstraintSystem::simplifyAppliedOverloads(
   switch (filterResult) {
   case SolutionKind::Error:
     if (labelMismatch && shouldAttemptFixes()) {
-      argumentLabels = None;
+      argumentInfo.reset();
       goto retry_after_fail;
     }
 
@@ -6081,16 +6072,20 @@ ConstraintSystem::simplifyApplicableFnConstraint(
 
   };
 
-  // If the right-hand side is a type variable, try to simplify the overload
-  // set.
-  if (auto typeVar = desugar2->getAs<TypeVariableType>()) {
-    auto argumentLabels = getArgumentLabels(*this, locator);
-    Type newType2 =
-        simplifyAppliedOverloads(typeVar, func1, argumentLabels, locator);
-    if (!newType2)
-      return SolutionKind::Error;
+  // Don't attempt this optimization in "diagnostic mode" because
+  // in such mode we'd like to attempt all of the available
+  // overloads regardless of of problems related to missing or
+  // extraneous labels and/or arguments.
+  if (!(solverState && shouldAttemptFixes())) {
+    // If the right-hand side is a type variable,
+    // try to simplify the overload set.
+    if (auto typeVar = desugar2->getAs<TypeVariableType>()) {
+      Type newType2 = simplifyAppliedOverloads(typeVar, func1, locator);
+      if (!newType2)
+        return SolutionKind::Error;
 
-    desugar2 = newType2->getDesugaredType();
+      desugar2 = newType2->getDesugaredType();
+    }
   }
 
   // If right-hand side is a type variable, the constraint is unsolved.