Fix false positive "Cannot capture" error reporting

There is no need to report an error in case of non-top-level
capture conversion, just don't add relevant capture type in the system instead

If system can be solved successfully without captured type, then it's just fine
(see KT-13950)
In case of contradiction TYPE_INFERENCE_PARAMETER_CONSTRAINT_ERROR is reported

 #KT-13950 Fixed

compiler/frontend/src/org/jetbrains/kotlin/diagnostics/rendering/Renderers.kt

@@ -341,16 +341,16 @@ object Renderers {
         }
 
         val typeParameter = typeVariableWithCapturedConstraint.originalTypeParameter
-
-        val explanation: String
         val upperBound = TypeIntersector.getUpperBoundsAsType(typeParameter)
-        if (!KotlinBuiltIns.isNullableAny(upperBound) && capturedTypeConstructor.typeProjection.projectionKind == Variance.IN_VARIANCE) {
-            explanation = "Type parameter has an upper bound '" + result.typeRenderer.render(upperBound, RenderingContext.of(upperBound)) + "'" +
-                          " that cannot be satisfied capturing 'in' projection"
-        }
-        else {
-            explanation = "Only top-level type projections can be captured"
+
+        assert(!KotlinBuiltIns.isNullableAny(upperBound) && capturedTypeConstructor.typeProjection.projectionKind == Variance.IN_VARIANCE) {
+            "There is the only reason to report TYPE_INFERENCE_CANNOT_CAPTURE_TYPES"
         }
+
+        val explanation =
+                "Type parameter has an upper bound '" + result.typeRenderer.render(upperBound, RenderingContext.of(upperBound)) + "'" +
+                " that cannot be satisfied capturing 'in' projection"
+
         result.text(newText().normal(
                 "'" + typeParameter.name + "'" +
                 " cannot capture " +
@@ -454,4 +454,4 @@ object Renderers {
     }.asRenderer()
 }
 
-fun DescriptorRenderer.asRenderer() = SmartDescriptorRenderer(this)
+fun DescriptorRenderer.asRenderer() = SmartDescriptorRenderer(this)

compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/inference/ConstraintSystemBuilderImpl.kt

@@ -152,13 +152,10 @@ open class ConstraintSystemBuilderImpl(private val mode: Mode = ConstraintSystem
             }
 
             override fun capture(type: KotlinType, typeProjection: TypeProjection): Boolean {
-                if (isMyTypeVariable(typeProjection.type)) return false
+                if (isMyTypeVariable(typeProjection.type) || depth > 0) return false
                 val myTypeVariable = getMyTypeVariable(type)
 
                 if (myTypeVariable != null && constraintPosition.isParameter()) {
-                    if (depth > 0) {
-                        errors.add(CannotCapture(constraintPosition, myTypeVariable))
-                    }
                     generateTypeParameterCaptureConstraint(myTypeVariable, typeProjection, newConstraintContext, type.isMarkedNullable)
                     return true
                 }

compiler/testData/diagnostics/tests/inference/capturedTypes/captureTypeOnlyOnTopLevel.kt

@@ -3,7 +3,7 @@
 fun <T> foo(array: Array<Array<T>>): Array<Array<T>> = array
 
 fun test(array: Array<Array<out Int>>) {
-    <!TYPE_INFERENCE_CANNOT_CAPTURE_TYPES!>foo<!>(array)
+    <!TYPE_INFERENCE_PARAMETER_CONSTRAINT_ERROR!>foo<!>(array)
 
-    val f: Array<out Array<out Int>> = <!TYPE_INFERENCE_CANNOT_CAPTURE_TYPES!>foo<!>(array)
-}
+    val f: Array<out Array<out Int>> = <!TYPE_INFERENCE_PARAMETER_CONSTRAINT_ERROR!>foo<!>(<!TYPE_MISMATCH!>array<!>)
+}

compiler/testData/diagnostics/tests/inference/capturedTypes/noCaptureTypeErrorForNonTopLevel.kt

@@ -0,0 +1,18 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+class A<T>
+class B<T>
+
+fun <E> foo(b: B<in A<E>>) {}
+fun <E> baz(b: B<out A<E>>) {}
+
+// See KT-13950
+fun bar(b: B<in A<out Number>>, bOut: B<out A<out Number>>, bOut2: B<out A<Number>>) {
+    foo(b)
+    foo<Number>(b)
+
+    <!TYPE_INFERENCE_CONFLICTING_SUBSTITUTIONS!>baz<!>(bOut)
+    baz<Number>(<!TYPE_MISMATCH!>bOut<!>)
+
+    baz(bOut2)
+    baz<Number>(bOut2)
+}

compiler/testData/diagnostics/tests/inference/capturedTypes/noCaptureTypeErrorForNonTopLevel.txt

@@ -0,0 +1,19 @@
+package
+
+public fun bar(/*0*/ b: B<in A<out kotlin.Number>>, /*1*/ bOut: B<out A<out kotlin.Number>>, /*2*/ bOut2: B<out A<kotlin.Number>>): kotlin.Unit
+public fun </*0*/ E> baz(/*0*/ b: B<out A<E>>): kotlin.Unit
+public fun </*0*/ E> foo(/*0*/ b: B<in A<E>>): kotlin.Unit
+
+public final class A</*0*/ T> {
+    public constructor A</*0*/ T>()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public final class B</*0*/ T> {
+    public constructor B</*0*/ T>()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}

compiler/testData/diagnostics/tests/resolve/capturedTypesInLambdaParameter.kt

@@ -4,6 +4,7 @@ class B<E>
 
 fun <T> B<T>.foo(f: (T) -> Unit) {}
 fun <T> B<T>.bar(f: (T, T) -> Unit, g: (T, T) -> Unit) {}
+fun <T> B<T>.baz(f: (B<T>) -> Unit) {}
 
 fun number(x: Number) {}
 fun Number.foobar() {}
@@ -34,4 +35,8 @@ fun test(b: B<out Number>) {
 
     b.foo(::number)
     b.foo(Number::foobar)
+
+    b.baz {
+        b -> b checkType { _<B<out Number>>() }
+    }
 }

compiler/testData/diagnostics/tests/resolve/capturedTypesInLambdaParameter.txt

@@ -3,6 +3,7 @@ package
 public fun number(/*0*/ x: kotlin.Number): kotlin.Unit
 public fun test(/*0*/ b: B<out kotlin.Number>): kotlin.Unit
 public fun </*0*/ T> B<T>.bar(/*0*/ f: (T, T) -> kotlin.Unit, /*1*/ g: (T, T) -> kotlin.Unit): kotlin.Unit
+public fun </*0*/ T> B<T>.baz(/*0*/ f: (B<T>) -> kotlin.Unit): kotlin.Unit
 public fun </*0*/ T> B<T>.foo(/*0*/ f: (T) -> kotlin.Unit): kotlin.Unit
 public fun kotlin.Number.foobar(): kotlin.Unit
 

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

@@ -9389,6 +9389,12 @@ public class DiagnosticsTestGenerated extends AbstractDiagnosticsTest {
                     doTest(fileName);
                 }
 
+                @TestMetadata("noCaptureTypeErrorForNonTopLevel.kt")
+                public void testNoCaptureTypeErrorForNonTopLevel() throws Exception {
+                    String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/inference/capturedTypes/noCaptureTypeErrorForNonTopLevel.kt");
+                    doTest(fileName);
+                }
+
                 @TestMetadata("notApproximateWhenCopyDescriptors.kt")
                 public void testNotApproximateWhenCopyDescriptors() throws Exception {
                     String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/inference/capturedTypes/notApproximateWhenCopyDescriptors.kt");

idea/testData/diagnosticMessage/typeInferenceCannotCaptureTypes.kt

@@ -1,10 +1,8 @@
 // !DIAGNOSTICS_NUMBER: 1
 // !DIAGNOSTICS: TYPE_INFERENCE_CANNOT_CAPTURE_TYPES
 
-class My<R, T>
+fun <R : Any> bar(a: Array<R>): Array<R?> =  null!!
 
-fun <R, T> foo(my: My<Array<R>, T>): My<Array<R>, T> = my
-
-fun test11(my: My<Array<out Int>, out Int>) {
-    foo(my)
-}
+fun test1(a: Array<in Int>) {
+    val r: Array<in Int?> = bar(a)
+}

idea/testData/diagnosticMessage/typeInferenceCannotCaptureTypes1.txt

@@ -1,2 +1,2 @@
 <!-- typeInferenceCannotCaptureTypes1 -->
-Type inference failed: 'R' cannot capture 'out Int'. Only top-level type projections can be captured
+Type inference failed: 'R' cannot capture 'in Int'. Type parameter has an upper bound 'Any' that cannot be satisfied capturing 'in' projection