contextual error

Author: hamishknight

lib/Sema/CSGen.cpp

@@ -4907,9 +4907,14 @@ bool ConstraintSystem::generateConstraints(
         return convertTypeLocator;
       };
 
-      // Substitute type variables in for placeholder types.
+      if (convertType->hasError()) {
+        recordFix(
+            IgnoreInvalidASTNode::create(*this, convertTypeLocator));
+      }
+
+      // Substitute type variables in for placeholder and error types.
       convertType = convertType.transformRec([&](Type type) -> std::optional<Type> {
-        if (type->is<PlaceholderType>()) {
+        if (isa<PlaceholderType, ErrorType>(type.getPointer())) {
           return Type(createTypeVariable(getLocator(type),
                                          TVO_CanBindToNoEscape |
                                              TVO_PrefersSubtypeBinding |

lib/Sema/TypeCheckStmt.cpp

@@ -1075,7 +1075,7 @@ class StmtChecker : public StmtVisitor<StmtChecker, Stmt*> {
     assert(TheFunc && "Should have bailed from pre-check if this is None");
 
     Type ResultTy = TheFunc->getBodyResultType();
-    if (!ResultTy || ResultTy->hasError())
+    if (!ResultTy)
       return nullptr;
 
     if (!RS->hasResult()) {

test/AutoDiff/Sema/differentiable_attr_type_checking.swift

@@ -643,7 +643,7 @@ class Super: Differentiable {
   // "covariant 'Self' can only appear at the top level of method result type".
   // expected-error @+1 2 {{'TangentVector' is not a member type of type 'Self'}}
   func vjpDynamicSelfResult() -> (Self, (Self.TangentVector) -> Self.TangentVector) {
-    return (self, { $0 })
+    return (self, { $0 }) // expected-error {{cannot infer type of closure parameter '$0' without a type annotation}}
   }
 }
 

test/Parse/subscripting.swift

@@ -142,7 +142,7 @@ struct A2 {
   subscript (i : Int) -> // expected-error{{expected subscripting element type}}
      {
     get {
-      return stored
+      return stored // expected-error {{cannot find 'stored' in scope}}
     }
     set {
       stored = newValue // expected-error{{cannot find 'stored' in scope}}

test/SPI/implicit_spi_import.swift

@@ -95,7 +95,9 @@ import Lib
 public func useImplicit() -> _Klass { return _Klass() } // expected-error{{cannot use class '_Klass' here; it is an SPI imported from 'Lib'}}
 
 @_spi(core)
-public func useSPICore() -> CoreStruct { return CoreStruct() } // expected-error{{cannot find type 'CoreStruct' in scope}}
+public func useSPICore() -> CoreStruct { return CoreStruct() }
+// expected-error@-1 {{cannot find type 'CoreStruct' in scope}}
+// expected-error@-2 {{cannot find 'CoreStruct' in scope}}
 
 public func useMain() -> APIProtocol? { return nil }
 

test/Sema/placeholder_type.swift

@@ -205,7 +205,7 @@ struct Just<Output>: Publisher {
 struct SetFailureType<Output, Failure>: Publisher {}
 
 extension Publisher {
-    func setFailureType<T>(to: T.Type) -> SetFailureType<Output, T> { // expected-note 2 {{in call to function 'setFailureType(to:)'}}
+    func setFailureType<T>(to: T.Type) -> SetFailureType<Output, T> { // expected-note 3 {{in call to function 'setFailureType(to:)'}}
         return .init()
     }
 }
@@ -257,6 +257,8 @@ func mismatchedReturnTypes() -> _ { // expected-error {{type placeholder may not
 @available(iOS 13.0, OSX 10.15, tvOS 13.0, watchOS 6.0, *)
 func opaque() -> some _ { // expected-error {{type placeholder not allowed here}}
   return Just<Int>().setFailureType(to: _.self)
+  // expected-error@-1 {{type placeholder not allowed here}}
+  // expected-error@-2 {{generic parameter 'T' could not be inferred}}
 }
 
 enum EnumWithPlaceholders {

test/decl/protocol/protocols.swift

@@ -423,12 +423,14 @@ protocol P1 {
 protocol P2 {
 }
 
-struct X3<T : P1> where T.Assoc : P2 {}
+struct X3<T : P1> where T.Assoc : P2 {} // expected-note {{'T' declared as parameter to type 'X3'}}
 
 struct X4 : P1 { 
   // expected-error@-1 {{type 'X4' does not conform to protocol 'P1'}}
   // expected-note@-2 {{add stubs for conformance}}
   func getX1() -> X3<X4> { return X3() }
+  // expected-error@-1 {{generic parameter 'T' could not be inferred}}
+  // expected-note@-2 {{explicitly specify the generic arguments to fix this issue}}
 }
 
 protocol ShouldntCrash {

validation-test/compiler_crashers_2_fixed/issue-52031.swift

@@ -16,5 +16,6 @@ extension S: P where N: P {
   // expected-error@-3 {{'A' is not a member type of type 'X'}}
   // expected-error@-4 {{'A' is not a member type of type 'X'}}
     return S<X.A>()
+    // expected-error@-1 {{'A' is not a member type of type 'X'}}
   }
 }