Expected function type used for parameter types inference in function expression

compiler/frontend/src/org/jetbrains/kotlin/resolve/FunctionDescriptorResolver.kt

@@ -70,7 +70,7 @@ class FunctionDescriptorResolver(
                 CallableMemberDescriptor.Kind.DECLARATION,
                 function.toSourceElement()
         )
-        initializeFunctionDescriptorAndExplicitReturnType(containingDescriptor, scope, function, functionDescriptor, trace, null)
+        initializeFunctionDescriptorAndExplicitReturnType(containingDescriptor, scope, function, functionDescriptor, trace, TypeUtils.NO_EXPECTED_TYPE)
         initializeFunctionReturnTypeBasedOnFunctionBody(scope, function, functionDescriptor, trace, dataFlowInfo)
         BindingContextUtils.recordFunctionDeclarationToDescriptor(trace, function, functionDescriptor)
         return functionDescriptor
@@ -81,7 +81,8 @@ class FunctionDescriptorResolver(
             scope: JetScope,
             function: JetNamedFunction,
             trace: BindingTrace,
-            dataFlowInfo: DataFlowInfo
+            dataFlowInfo: DataFlowInfo,
+            expectedFunctionType: JetType
     ): SimpleFunctionDescriptor {
         val functionDescriptor = FunctionExpressionDescriptor(
                 containingDescriptor,
@@ -90,7 +91,7 @@ class FunctionDescriptorResolver(
                 CallableMemberDescriptor.Kind.DECLARATION,
                 function.toSourceElement()
         )
-        initializeFunctionDescriptorAndExplicitReturnType(containingDescriptor, scope, function, functionDescriptor, trace, null)
+        initializeFunctionDescriptorAndExplicitReturnType(containingDescriptor, scope, function, functionDescriptor, trace, expectedFunctionType)
         initializeFunctionReturnTypeBasedOnFunctionBody(scope, function, functionDescriptor, trace, dataFlowInfo)
         BindingContextUtils.recordFunctionDeclarationToDescriptor(trace, function, functionDescriptor)
         return functionDescriptor
@@ -128,7 +129,7 @@ class FunctionDescriptorResolver(
             function: JetFunction,
             functionDescriptor: SimpleFunctionDescriptorImpl,
             trace: BindingTrace,
-            expectedFunctionType: JetType?
+            expectedFunctionType: JetType
     ) {
         val innerScope = WritableScopeImpl(scope, functionDescriptor, TraceBasedRedeclarationHandler(trace), "Function descriptor header scope")
         innerScope.addLabeledDeclaration(functionDescriptor)
@@ -170,7 +171,7 @@ class FunctionDescriptorResolver(
             functionDescriptor: SimpleFunctionDescriptorImpl,
             innerScope: WritableScopeImpl,
             trace: BindingTrace,
-            expectedFunctionType: JetType?
+            expectedFunctionType: JetType
     ): List<ValueParameterDescriptor> {
         val expectedValueParameters = expectedFunctionType.getValueParameters(functionDescriptor)
         if (expectedValueParameters != null) {
@@ -198,11 +199,11 @@ class FunctionDescriptorResolver(
     }
 
     private fun JetType.functionTypeExpected() = !TypeUtils.noExpectedType(this) && KotlinBuiltIns.isFunctionOrExtensionFunctionType(this)
-    private fun JetType?.getReceiverType(): JetType? =
-            if (this != null && functionTypeExpected()) getReceiverType(this) else null
+    private fun JetType.getReceiverType(): JetType? =
+            if (functionTypeExpected()) KotlinBuiltIns.getReceiverType(this) else null
 
-    private fun JetType?.getValueParameters(owner: FunctionDescriptor): List<ValueParameterDescriptor>? =
-            if (this != null && functionTypeExpected()) getValueParameters(owner, this) else null
+    private fun JetType.getValueParameters(owner: FunctionDescriptor): List<ValueParameterDescriptor>? =
+            if (functionTypeExpected()) KotlinBuiltIns.getValueParameters(owner, this) else null
 
     public fun resolvePrimaryConstructorDescriptor(
             scope: JetScope,
@@ -316,7 +317,8 @@ class FunctionDescriptorResolver(
                     else {
                         type = TypeUtils.CANT_INFER_FUNCTION_PARAM_TYPE
                     }
-                } else {
+                }
+                else {
                     trace.report(VALUE_PARAMETER_WITH_NO_TYPE_ANNOTATION.on(valueParameter))
                     type = ErrorUtils.createErrorType("Type annotation was missing for parameter ${valueParameter.getNameAsSafeName()}")
                 }

compiler/frontend/src/org/jetbrains/kotlin/types/expressions/FunctionsTypingVisitor.kt

@@ -83,7 +83,7 @@ public class FunctionsTypingVisitor(facade: ExpressionTypingInternals) : Express
         }
         else {
             functionDescriptor = services.getFunctionDescriptorResolver().resolveFunctionExpressionDescriptor(
-                    context.scope.getContainingDeclaration(), context.scope, function, context.trace, context.dataFlowInfo)
+                    context.scope.getContainingDeclaration(), context.scope, function, context.trace, context.dataFlowInfo, context.expectedType)
         }
 
         val functionInnerScope = FunctionDescriptorUtil.getFunctionInnerScope(context.scope, functionDescriptor, context.trace)

compiler/testData/diagnostics/tests/functionAsExpression/FunctionType.kt

@@ -17,7 +17,7 @@ fun testParamType() {
     bar.checkType { it : _<(String) -> Unit> }
 
     val bas: (String) -> Unit = fun (param: String) {}
-    val bag: (Int) -> Unit = <!TYPE_MISMATCH!>fun (param: String) {}<!>
+    val bag: (Int) -> Unit = <!TYPE_MISMATCH!>fun (<!EXPECTED_PARAMETER_TYPE_MISMATCH!>param: String<!>) {}<!>
 }
 
 fun testReceiverType() {

compiler/testData/diagnostics/tests/functionAsExpression/MissingParameterTypes.kt

@@ -0,0 +1,25 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_VARIABLE
+
+val a = fun (<!CANNOT_INFER_PARAMETER_TYPE!>x<!>) = <!DEBUG_INFO_ELEMENT_WITH_ERROR_TYPE!>x<!>
+
+val b: (Int) -> Int = fun (x) = x + 3
+
+val c: (Int, String) -> Int = <!TYPE_MISMATCH!>fun <!EXPECTED_PARAMETERS_NUMBER_MISMATCH!>(x)<!> = 3<!>
+
+val d: (Int, String) -> Int = <!TYPE_MISMATCH!>fun <!EXPECTED_PARAMETERS_NUMBER_MISMATCH!>(x)<!> = 3<!>
+
+val e: (Int, String) -> Int = <!TYPE_MISMATCH!>fun <!EXPECTED_PARAMETERS_NUMBER_MISMATCH!>(<!EXPECTED_PARAMETER_TYPE_MISMATCH!>x: String<!>)<!> = 3<!>
+
+val f: (Int) -> Int = <!TYPE_MISMATCH!>fun (<!EXPECTED_PARAMETER_TYPE_MISMATCH!>x: String<!>) = 3<!>
+
+fun test1(a: (Int) -> Unit) {
+    test1(fun (<!CANNOT_INFER_PARAMETER_TYPE!>x<!>) { <!DEBUG_INFO_ELEMENT_WITH_ERROR_TYPE!>x<!> : Int})
+}
+
+fun test2(a: (Int) -> Unit) {
+    test2(<!TYPE_MISMATCH!>fun (x: String) {}<!>)
+}
+
+fun test3(a: (Int, String) -> Unit) {
+    test3(<!TYPE_MISMATCH!>fun (x: String) {}<!>)
+}

compiler/testData/diagnostics/tests/functionAsExpression/MissingParameterTypes.txt

@@ -0,0 +1,11 @@
+package
+
+internal val a: (???) -> [ERROR : Cannot be inferred]
+internal val b: (kotlin.Int) -> kotlin.Int
+internal val c: (kotlin.Int, kotlin.String) -> kotlin.Int
+internal val d: (kotlin.Int, kotlin.String) -> kotlin.Int
+internal val e: (kotlin.Int, kotlin.String) -> kotlin.Int
+internal val f: (kotlin.Int) -> kotlin.Int
+internal fun test1(/*0*/ a: (kotlin.Int) -> kotlin.Unit): kotlin.Unit
+internal fun test2(/*0*/ a: (kotlin.Int) -> kotlin.Unit): kotlin.Unit
+internal fun test3(/*0*/ a: (kotlin.Int, kotlin.String) -> kotlin.Unit): kotlin.Unit

compiler/tests/org/jetbrains/kotlin/checkers/JetDiagnosticsTestGenerated.java

@@ -4646,6 +4646,12 @@ public class JetDiagnosticsTestGenerated extends AbstractJetDiagnosticsTest {
                 doTest(fileName);
             }
 
+            @TestMetadata("MissingParameterTypes.kt")
+            public void testMissingParameterTypes() throws Exception {
+                String fileName = JetTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/functionAsExpression/MissingParameterTypes.kt");
+                doTest(fileName);
+            }
+
             @TestMetadata("NoOverloadError.kt")
             public void testNoOverloadError() throws Exception {
                 String fileName = JetTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/functionAsExpression/NoOverloadError.kt");