[CS] Don't crash when default argument is magic literal and types don't match

include/swift/AST/DiagnosticsSema.def

@@ -350,6 +350,9 @@ ERROR(cannot_convert_default_arg_value,none,
       (Type,Type))
 ERROR(cannot_convert_default_arg_value_protocol,none,
       "default argument value of type %0 does not conform to %1", (Type,Type))
+ERROR(default_argument_literal_cannot_convert, none,
+      "cannot call %0 %1 because default argument of type %2 cannot be "
+      "converted to type %3", (DescriptiveDeclKind, DeclName, Type, Type))
 ERROR(cannot_convert_default_arg_value_nil,none,
       "nil default argument value cannot be converted to type %0", (Type))
 

lib/Sema/CSDiagnostics.cpp

@@ -2728,6 +2728,21 @@ bool MissingArgumentsFailure::diagnoseTrailingClosure(ClosureExpr *closure) {
   return true;
 }
 
+bool DefaultArgumentTypeMismatch::diagnoseAsError() {
+  auto choice = getChoiceFor(getRawAnchor());
+  if (!choice.hasValue())
+    return false;
+
+  auto declName = choice.getValue().choice.getName();
+  auto declKind = choice.getValue().choice.getDecl()->getDescriptiveKind();
+
+  emitDiagnostic(getAnchor()->getLoc(),
+                 diag::default_argument_literal_cannot_convert, declKind,
+                 declName, FromType, ToType);
+
+  return true;
+}
+
 bool ClosureParamDestructuringFailure::diagnoseAsError() {
   auto *closure = cast<ClosureExpr>(getAnchor());
   auto params = closure->getParameters();

lib/Sema/CSDiagnostics.h

@@ -1086,6 +1086,21 @@ class MissingArgumentsFailure final : public FailureDiagnostic {
   bool diagnoseTrailingClosure(ClosureExpr *closure);
 };
 
+class DefaultArgumentTypeMismatch final : public FailureDiagnostic {
+  using Param = AnyFunctionType::Param;
+
+  Type FromType;
+  Type ToType;
+
+public:
+  DefaultArgumentTypeMismatch(Expr *root, ConstraintSystem &cs, Type fromType,
+                              Type toType, ConstraintLocator *locator)
+      : FailureDiagnostic(root, cs, locator), FromType(fromType),
+        ToType(toType) {}
+
+  bool diagnoseAsError() override;
+};
+
 class OutOfOrderArgumentFailure final : public FailureDiagnostic {
   using ParamBinding = SmallVector<unsigned, 1>;
 

lib/Sema/CSFix.cpp

@@ -451,6 +451,21 @@ bool AddMissingArguments::diagnose(Expr *root, bool asNote) const {
   return failure.diagnose(asNote);
 }
 
+IgnoreDefaultArgumentTypeMismatch *
+IgnoreDefaultArgumentTypeMismatch::create(ConstraintSystem &cs, Type fromType,
+                                          Type toType,
+                                          ConstraintLocator *locator) {
+  return new (cs.getAllocator())
+      IgnoreDefaultArgumentTypeMismatch(cs, fromType, toType, locator);
+}
+
+bool IgnoreDefaultArgumentTypeMismatch::diagnose(Expr *root,
+                                                 bool asNote) const {
+  DefaultArgumentTypeMismatch failure(root, getConstraintSystem(), FromType,
+                                      ToType, getLocator());
+  return failure.diagnose(asNote);
+}
+
 AddMissingArguments *
 AddMissingArguments::create(ConstraintSystem &cs, FunctionType *funcType,
                             llvm::ArrayRef<Param> synthesizedArgs,

lib/Sema/CSFix.h

@@ -185,6 +185,9 @@ enum class FixKind : uint8_t {
   /// when base is an r-value type.
   AllowMutatingMemberOnRValueBase,
 
+  /// Fix the type of the default argument
+  DefaultArgumentTypeMismatch,
+
   /// Allow a single tuple parameter to be matched with N arguments
   /// by forming all of the given arguments into a single tuple.
   AllowTupleSplatForSingleParameter,
@@ -946,6 +949,27 @@ class AddMissingArguments final
   }
 };
 
+class IgnoreDefaultArgumentTypeMismatch final : public ConstraintFix {
+  Type FromType;
+  Type ToType;
+
+  IgnoreDefaultArgumentTypeMismatch(ConstraintSystem &cs, Type fromType,
+                                    Type toType, ConstraintLocator *locator)
+      : ConstraintFix(cs, FixKind::DefaultArgumentTypeMismatch, locator),
+        FromType(fromType), ToType(toType) {}
+
+public:
+  std::string getName() const override {
+    return "ignore default argument type mismatch";
+  }
+
+  bool diagnose(Expr *root, bool asNote = false) const override;
+
+  static IgnoreDefaultArgumentTypeMismatch *create(ConstraintSystem &cs,
+                                                   Type fromType, Type toType,
+                                                   ConstraintLocator *locator);
+};
+
 class MoveOutOfOrderArgument final : public ConstraintFix {
   using ParamBinding = SmallVector<unsigned, 1>;
 

lib/Sema/CSSimplify.cpp

@@ -966,9 +966,36 @@ ConstraintSystem::TypeMatchResult constraints::matchCallArguments(
 
   for (unsigned paramIdx = 0, numParams = parameterBindings.size();
        paramIdx != numParams; ++paramIdx){
-    // Skip unfulfilled parameters. There's nothing to do for them.
-    if (parameterBindings[paramIdx].empty())
+    // If a parameter is unfulfilled, validate the default argument if it is a
+    // magic literal expression.
+    if (parameterBindings[paramIdx].empty()) {
+      if (!callee)
+        continue;
+
+      if (!callee->hasParameterList())
+        continue;
+
+      auto param = getParameterAt(callee, paramIdx);
+
+      auto defaultValueExpr = param->getDefaultValue();
+
+      if (!(defaultValueExpr &&
+            isa<MagicIdentifierLiteralExpr>(defaultValueExpr)))
+        continue;
+
+      if (defaultValueExpr->getType())
+        continue;
+
+      cs.generateConstraints(defaultValueExpr, param->getDeclContext());
+
+      auto defaultTy = cs.getType(defaultValueExpr);
+      auto paramTy = param->getType();
+      cs.addConstraint(
+          ConstraintKind::ArgumentConversion, defaultTy, paramTy,
+          locator.withPathElement(ConstraintLocator::DefaultArgument));
+
       continue;
+    }
 
     // Determine the parameter type.
     const auto &param = params[paramIdx];
@@ -2335,6 +2362,12 @@ bool ConstraintSystem::repairFailures(
     break;
   }
 
+  case ConstraintLocator::DefaultArgument: {
+    conversionsOrFixes.push_back(IgnoreDefaultArgumentTypeMismatch::create(
+        *this, lhs, rhs, getConstraintLocator(anchor, path)));
+    break;
+  }
+
   case ConstraintLocator::TypeParameterRequirement:
   case ConstraintLocator::ConditionalRequirement: {
     // If dependent members are present here it's because
@@ -6965,6 +6998,7 @@ ConstraintSystem::SolutionKind ConstraintSystem::simplifyFixConstraint(
   case FixKind::SkipSuperclassRequirement:
   case FixKind::ContextualMismatch:
   case FixKind::AddMissingArguments:
+  case FixKind::DefaultArgumentTypeMismatch:
   case FixKind::SkipUnhandledConstructInFunctionBuilder:
   case FixKind::UsePropertyWrapper:
   case FixKind::UseWrappedValue: {

lib/Sema/ConstraintLocator.cpp

@@ -52,6 +52,7 @@ void ConstraintLocator::Profile(llvm::FoldingSetNodeID &id, Expr *anchor,
     case ApplyArgument:
     case ApplyFunction:
     case FunctionArgument:
+    case DefaultArgument:
     case FunctionResult:
     case OptionalPayload:
     case Member:
@@ -270,6 +271,10 @@ void ConstraintLocator::dump(SourceManager *sm, raw_ostream &out) {
       out << "function argument";
       break;
 
+    case DefaultArgument:
+      out << "default argument";
+      break;
+
     case FunctionResult:
       out << "function result";
       break;

lib/Sema/ConstraintLocator.h

@@ -65,6 +65,8 @@ class ConstraintLocator : public llvm::FoldingSetNode {
     GenericParameter,
     /// The argument type of a function.
     FunctionArgument,
+    /// The default argument type of a function.
+    DefaultArgument,
     /// The result type of a function.
     FunctionResult,
     /// A tuple element referenced by position.
@@ -147,6 +149,7 @@ class ConstraintLocator : public llvm::FoldingSetNode {
     case ApplyFunction:
     case GenericParameter:
     case FunctionArgument:
+    case DefaultArgument:
     case FunctionResult:
     case OptionalPayload:
     case Member:
@@ -244,6 +247,7 @@ class ConstraintLocator : public llvm::FoldingSetNode {
       return 0;
 
     case FunctionArgument:
+    case DefaultArgument:
     case FunctionResult:
       return IsFunctionConversion;
     }

test/decl/func/default-values.swift

@@ -168,3 +168,12 @@ let fooThing5 = Foo(a: 0, d: 1, h: nil) // expected-error {{missing argument for
 // Here b = false and g = nil, but we're checking that f doesn't get a default value
 let fooThing6 = Foo(a: 0, d: 1, e: 2, h: nil) // expected-error {{missing argument for parameter 'f' in call}}
                                               // expected-note@-29 {{'init(a:b:d:e:f:g:h:)' declared here}}
+
+// SR-11074
+
+func sr_11074(x: Int) {}
+func sr_11074(line: String = #line) {} // expected-error {{default argument value of type 'Int' cannot be converted to type 'String'}}
+sr_11074() // expected-error {{cannot call global function 'sr_11074(line:)' because default argument of type 'Int' cannot be converted to type 'String'}}
+
+class SR_11074_C { init(line: String = #line) {} } // expected-error {{default argument value of type 'Int' cannot be converted to type 'String'}}
+let _ = SR_11074_C() // expected-error {{cannot call initializer 'init(line:)' because default argument of type 'Int' cannot be converted to type 'String'}}

validation-test/compiler_crashers_2_fixed/sr11074.swift

@@ -0,0 +1,5 @@
+// RUN: not %target-swift-frontend -typecheck %s
+
+func foo(x: Int) {}
+func foo(line: String = #line) {}
+foo()