UNNECESSARY_LATEINIT warning introduced #KT-13295 Fixed

(cherry picked from commit 88f9938)

compiler/frontend/src/org/jetbrains/kotlin/diagnostics/Errors.java

@@ -407,6 +407,7 @@ public interface Errors {
 
     DiagnosticFactory0<KtProperty> MUST_BE_INITIALIZED = DiagnosticFactory0.create(ERROR, DECLARATION_SIGNATURE);
     DiagnosticFactory0<KtProperty> MUST_BE_INITIALIZED_OR_BE_ABSTRACT = DiagnosticFactory0.create(ERROR, DECLARATION_SIGNATURE);
+    DiagnosticFactory0<KtProperty> UNNECESSARY_LATEINIT = DiagnosticFactory0.create(WARNING, LATEINIT_MODIFIER);
 
     DiagnosticFactory0<KtExpression> EXTENSION_PROPERTY_WITH_BACKING_FIELD = DiagnosticFactory0.create(ERROR);
     DiagnosticFactory0<KtExpression> PROPERTY_INITIALIZER_NO_BACKING_FIELD = DiagnosticFactory0.create(ERROR);
@@ -827,7 +828,7 @@ public interface Errors {
             INVISIBLE_MEMBER, NON_PUBLIC_CALL_FROM_PUBLIC_INLINE, INVISIBLE_REFERENCE, INVISIBLE_SETTER);
     ImmutableSet<? extends DiagnosticFactory<?>> UNUSED_ELEMENT_DIAGNOSTICS = ImmutableSet.of(
             UNUSED_VARIABLE, UNUSED_PARAMETER, ASSIGNED_BUT_NEVER_ACCESSED_VARIABLE, VARIABLE_WITH_REDUNDANT_INITIALIZER,
-            UNUSED_LAMBDA_EXPRESSION, USELESS_CAST, UNUSED_VALUE, USELESS_ELVIS);
+            UNUSED_LAMBDA_EXPRESSION, USELESS_CAST, UNUSED_VALUE, USELESS_ELVIS, UNNECESSARY_LATEINIT);
     ImmutableSet<? extends DiagnosticFactory<?>> TYPE_INFERENCE_ERRORS = ImmutableSet.of(
             TYPE_INFERENCE_NO_INFORMATION_FOR_PARAMETER, TYPE_INFERENCE_CONFLICTING_SUBSTITUTIONS,
             TYPE_INFERENCE_PARAMETER_CONSTRAINT_ERROR,

compiler/frontend/src/org/jetbrains/kotlin/diagnostics/PositioningStrategies.kt

@@ -201,6 +201,8 @@ object PositioningStrategies {
 
     @JvmField val PRIVATE_MODIFIER: PositioningStrategy<KtModifierListOwner> = modifierSetPosition(KtTokens.PRIVATE_KEYWORD)
 
+    @JvmField val LATEINIT_MODIFIER: PositioningStrategy<KtModifierListOwner> = modifierSetPosition(KtTokens.LATEINIT_KEYWORD)
+
     @JvmField val VARIANCE_MODIFIER: PositioningStrategy<KtModifierListOwner> = modifierSetPosition(KtTokens.IN_KEYWORD, KtTokens.OUT_KEYWORD)
 
     @JvmField val FOR_REDECLARATION: PositioningStrategy<PsiElement> = object : PositioningStrategy<PsiElement>() {

compiler/frontend/src/org/jetbrains/kotlin/diagnostics/rendering/DefaultErrorMessages.java

@@ -229,6 +229,7 @@ public class DefaultErrorMessages {
         MAP.put(BACKING_FIELD_IN_INTERFACE, "Property in an interface cannot have a backing field");
         MAP.put(MUST_BE_INITIALIZED, "Property must be initialized");
         MAP.put(MUST_BE_INITIALIZED_OR_BE_ABSTRACT, "Property must be initialized or be abstract");
+        MAP.put(UNNECESSARY_LATEINIT, "Lateinit is unnecessary: definitely initialized in constructors");
         MAP.put(PROPERTY_INITIALIZER_IN_INTERFACE, "Property initializers are not allowed in interfaces");
         MAP.put(PRIVATE_PROPERTY_IN_INTERFACE, "Abstract property in an interface cannot be private");
         MAP.put(EXTENSION_PROPERTY_WITH_BACKING_FIELD, "Extension property cannot be initialized because it has no backing field");

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

@@ -657,8 +657,8 @@ class DeclarationsChecker(
             }
         }
         else {
-            if (backingFieldRequired && !inTrait && !propertyDescriptor.isLateInit &&
-                trace.bindingContext.get(BindingContext.IS_UNINITIALIZED, propertyDescriptor) ?: false) {
+            val isUninitialized = trace.bindingContext.get(BindingContext.IS_UNINITIALIZED, propertyDescriptor) ?: false
+            if (backingFieldRequired && !inTrait && !propertyDescriptor.isLateInit && isUninitialized) {
                 if (containingDeclaration !is ClassDescriptor || hasAccessorImplementation) {
                     trace.report(MUST_BE_INITIALIZED.on(property))
                 }
@@ -669,6 +669,9 @@ class DeclarationsChecker(
             else if (property.typeReference == null) {
                 trace.report(PROPERTY_WITH_NO_TYPE_NO_INITIALIZER.on(property))
             }
+            if (backingFieldRequired && !inTrait && propertyDescriptor.isLateInit && !isUninitialized) {
+                trace.report(UNNECESSARY_LATEINIT.on(property))
+            }
         }
     }
 

compiler/testData/diagnostics/tests/controlFlowAnalysis/unnecessaryLateinit/lateinitWithConstructor.kt

@@ -0,0 +1,9 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class Foo {
+    <!UNNECESSARY_LATEINIT!>lateinit<!> var bar: String
+
+    constructor(baz: Int) {
+        bar = ""
+    }
+}

compiler/testData/diagnostics/tests/controlFlowAnalysis/unnecessaryLateinit/lateinitWithConstructor.txt

@@ -0,0 +1,9 @@
+package
+
+public final class Foo {
+    public constructor Foo(/*0*/ baz: kotlin.Int)
+    public final lateinit var bar: kotlin.String
+    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/controlFlowAnalysis/unnecessaryLateinit/lateinitWithErroneousDelegation.kt

@@ -0,0 +1,11 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class Foo {
+    <!UNNECESSARY_LATEINIT!>lateinit<!> var x: String
+
+    constructor() {
+        x = "Foo"
+    }
+
+    constructor(x: String, y: String): <!NONE_APPLICABLE!>this<!>(y.hashCode())
+}

compiler/testData/diagnostics/tests/controlFlowAnalysis/unnecessaryLateinit/lateinitWithErroneousDelegation.txt

@@ -0,0 +1,10 @@
+package
+
+public final class Foo {
+    public constructor Foo()
+    public constructor Foo(/*0*/ x: kotlin.String, /*1*/ y: kotlin.String)
+    public final lateinit var x: kotlin.String
+    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/controlFlowAnalysis/unnecessaryLateinit/lateinitWithInit.kt

@@ -0,0 +1,7 @@
+class Foo {
+    <!UNNECESSARY_LATEINIT!>lateinit<!> var bar: String
+
+    init {
+        bar = ""
+    }
+}

compiler/testData/diagnostics/tests/controlFlowAnalysis/unnecessaryLateinit/lateinitWithInit.txt

@@ -0,0 +1,9 @@
+package
+
+public final class Foo {
+    public constructor Foo()
+    public final lateinit var bar: kotlin.String
+    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/controlFlowAnalysis/unnecessaryLateinit/lateinitWithMultipleConstructors.kt

@@ -0,0 +1,13 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class Foo {
+    <!UNNECESSARY_LATEINIT!>lateinit<!> var bar: String
+
+    constructor() {
+        bar = ""
+    }
+
+    constructor(baz: Int) {
+        bar = ""
+    }
+}

compiler/testData/diagnostics/tests/controlFlowAnalysis/unnecessaryLateinit/lateinitWithMultipleConstructors.txt

@@ -0,0 +1,10 @@
+package
+
+public final class Foo {
+    public constructor Foo()
+    public constructor Foo(/*0*/ baz: kotlin.Int)
+    public final lateinit var bar: kotlin.String
+    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/controlFlowAnalysis/unnecessaryLateinit/lateinitWithMultipleConstructorsAndDelegation.kt

@@ -0,0 +1,15 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class Foo {
+    <!UNNECESSARY_LATEINIT!>lateinit<!> var bar: String
+
+    constructor() {
+        bar = ""
+    }
+
+    constructor(a: Int) : this() {
+    }
+
+    constructor(a: Int, b: Int) : this(a) {
+    }
+}

compiler/testData/diagnostics/tests/controlFlowAnalysis/unnecessaryLateinit/lateinitWithMultipleConstructorsAndDelegation.txt

@@ -0,0 +1,11 @@
+package
+
+public final class Foo {
+    public constructor Foo()
+    public constructor Foo(/*0*/ a: kotlin.Int)
+    public constructor Foo(/*0*/ a: kotlin.Int, /*1*/ b: kotlin.Int)
+    public final lateinit var bar: kotlin.String
+    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/controlFlowAnalysis/unnecessaryLateinit/lateinitWithPlusAssign.kt

@@ -0,0 +1,10 @@
+class Foo {
+    // Erroneous case: after lateinit removal, we'll have error at 'bar += baz', not here
+    // However, looks like we must have error at 'bar += baz' even with lateinit
+    // because nobody can initialize this 'bar' before constructor is called
+    <!UNNECESSARY_LATEINIT!>lateinit<!> var bar: String
+
+    constructor(baz: Int) {
+        bar += baz
+    }
+}

compiler/testData/diagnostics/tests/controlFlowAnalysis/unnecessaryLateinit/lateinitWithPlusAssign.txt

@@ -0,0 +1,9 @@
+package
+
+public final class Foo {
+    public constructor Foo(/*0*/ baz: kotlin.Int)
+    public final lateinit var bar: kotlin.String
+    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/controlFlowAnalysis/unnecessaryLateinit/lateinitWithPrimaryConstructorAndConstructor.kt

@@ -0,0 +1,9 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class Foo() {
+    lateinit var bar: String
+
+    constructor(baz: Int) : this() {
+        bar = ""
+    }
+}

compiler/testData/diagnostics/tests/controlFlowAnalysis/unnecessaryLateinit/lateinitWithPrimaryConstructorAndConstructor.txt

@@ -0,0 +1,10 @@
+package
+
+public final class Foo {
+    public constructor Foo()
+    public constructor Foo(/*0*/ baz: kotlin.Int)
+    public final lateinit var bar: kotlin.String
+    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/controlFlowAnalysis/unnecessaryLateinit/normalLateinit.kt

@@ -0,0 +1,7 @@
+class Foo {
+    lateinit var bar: String
+
+    fun init() {
+        bar = ""
+    }
+}

compiler/testData/diagnostics/tests/controlFlowAnalysis/unnecessaryLateinit/normalLateinit.txt

@@ -0,0 +1,10 @@
+package
+
+public final class Foo {
+    public constructor Foo()
+    public final lateinit var bar: kotlin.String
+    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 final fun init(): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}

compiler/testData/diagnostics/tests/controlFlowAnalysis/unnecessaryLateinit/normalLateinitWithTwoConstructors.kt

@@ -0,0 +1,9 @@
+class Foo {
+    lateinit var x: String
+
+    constructor(y: String) {
+        x = y
+    }
+
+    constructor()
+}

compiler/testData/diagnostics/tests/controlFlowAnalysis/unnecessaryLateinit/normalLateinitWithTwoConstructors.txt

@@ -0,0 +1,10 @@
+package
+
+public final class Foo {
+    public constructor Foo()
+    public constructor Foo(/*0*/ y: kotlin.String)
+    public final lateinit var x: kotlin.String
+    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/controlFlowAnalysis/unnecessaryLateinit/secondaryConstructorDelegateItself.kt

@@ -0,0 +1,13 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class Foo {
+    <!UNNECESSARY_LATEINIT!>lateinit<!> var bar: String
+
+    constructor() {
+        bar = ""
+    }
+
+    constructor(a: Int) : <!CYCLIC_CONSTRUCTOR_DELEGATION_CALL!>this<!>(a) {
+        bar = "a"
+    }
+}

compiler/testData/diagnostics/tests/controlFlowAnalysis/unnecessaryLateinit/secondaryConstructorDelegateItself.txt

@@ -0,0 +1,10 @@
+package
+
+public final class Foo {
+    public constructor Foo()
+    public constructor Foo(/*0*/ a: kotlin.Int)
+    public final lateinit var bar: kotlin.String
+    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/controlFlowAnalysis/unnecessaryLateinit/secondaryConstructorDelegateLoop.kt

@@ -0,0 +1,18 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class Foo {
+    <!UNNECESSARY_LATEINIT!>lateinit<!> var bar: String
+
+    constructor() {
+        bar = ""
+    }
+
+    constructor(a: Int) : <!CYCLIC_CONSTRUCTOR_DELEGATION_CALL!>this<!>(a, 0, 0) {
+    }
+
+    constructor(a: Int, b: Int) : <!CYCLIC_CONSTRUCTOR_DELEGATION_CALL!>this<!>(a) {
+    }
+
+    constructor(a: Int, b: Int, c: Int) : <!CYCLIC_CONSTRUCTOR_DELEGATION_CALL!>this<!>(a, b) {
+    }
+}

compiler/testData/diagnostics/tests/controlFlowAnalysis/unnecessaryLateinit/secondaryConstructorDelegateLoop.txt

@@ -0,0 +1,12 @@
+package
+
+public final class Foo {
+    public constructor Foo()
+    public constructor Foo(/*0*/ a: kotlin.Int)
+    public constructor Foo(/*0*/ a: kotlin.Int, /*1*/ b: kotlin.Int)
+    public constructor Foo(/*0*/ a: kotlin.Int, /*1*/ b: kotlin.Int, /*2*/ c: kotlin.Int)
+    public final lateinit var bar: kotlin.String
+    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/tests/org/jetbrains/kotlin/checkers/DiagnosticsTestGenerated.java

@@ -3881,6 +3881,81 @@ public class DiagnosticsTestGenerated extends AbstractDiagnosticsTest {
                     doTest(fileName);
                 }
             }
+
+            @TestMetadata("compiler/testData/diagnostics/tests/controlFlowAnalysis/unnecessaryLateinit")
+            @TestDataPath("$PROJECT_ROOT")
+            @RunWith(JUnit3RunnerWithInners.class)
+            public static class UnnecessaryLateinit extends AbstractDiagnosticsTest {
+                public void testAllFilesPresentInUnnecessaryLateinit() throws Exception {
+                    KotlinTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("compiler/testData/diagnostics/tests/controlFlowAnalysis/unnecessaryLateinit"), Pattern.compile("^(.+)\\.kt$"), true);
+                }
+
+                @TestMetadata("lateinitWithConstructor.kt")
+                public void testLateinitWithConstructor() throws Exception {
+                    String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/controlFlowAnalysis/unnecessaryLateinit/lateinitWithConstructor.kt");
+                    doTest(fileName);
+                }
+
+                @TestMetadata("lateinitWithErroneousDelegation.kt")
+                public void testLateinitWithErroneousDelegation() throws Exception {
+                    String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/controlFlowAnalysis/unnecessaryLateinit/lateinitWithErroneousDelegation.kt");
+                    doTest(fileName);
+                }
+
+                @TestMetadata("lateinitWithInit.kt")
+                public void testLateinitWithInit() throws Exception {
+                    String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/controlFlowAnalysis/unnecessaryLateinit/lateinitWithInit.kt");
+                    doTest(fileName);
+                }
+
+                @TestMetadata("lateinitWithMultipleConstructors.kt")
+                public void testLateinitWithMultipleConstructors() throws Exception {
+                    String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/controlFlowAnalysis/unnecessaryLateinit/lateinitWithMultipleConstructors.kt");
+                    doTest(fileName);
+                }
+
+                @TestMetadata("lateinitWithMultipleConstructorsAndDelegation.kt")
+                public void testLateinitWithMultipleConstructorsAndDelegation() throws Exception {
+                    String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/controlFlowAnalysis/unnecessaryLateinit/lateinitWithMultipleConstructorsAndDelegation.kt");
+                    doTest(fileName);
+                }
+
+                @TestMetadata("lateinitWithPlusAssign.kt")
+                public void testLateinitWithPlusAssign() throws Exception {
+                    String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/controlFlowAnalysis/unnecessaryLateinit/lateinitWithPlusAssign.kt");
+                    doTest(fileName);
+                }
+
+                @TestMetadata("lateinitWithPrimaryConstructorAndConstructor.kt")
+                public void testLateinitWithPrimaryConstructorAndConstructor() throws Exception {
+                    String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/controlFlowAnalysis/unnecessaryLateinit/lateinitWithPrimaryConstructorAndConstructor.kt");
+                    doTest(fileName);
+                }
+
+                @TestMetadata("normalLateinit.kt")
+                public void testNormalLateinit() throws Exception {
+                    String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/controlFlowAnalysis/unnecessaryLateinit/normalLateinit.kt");
+                    doTest(fileName);
+                }
+
+                @TestMetadata("normalLateinitWithTwoConstructors.kt")
+                public void testNormalLateinitWithTwoConstructors() throws Exception {
+                    String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/controlFlowAnalysis/unnecessaryLateinit/normalLateinitWithTwoConstructors.kt");
+                    doTest(fileName);
+                }
+
+                @TestMetadata("secondaryConstructorDelegateItself.kt")
+                public void testSecondaryConstructorDelegateItself() throws Exception {
+                    String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/controlFlowAnalysis/unnecessaryLateinit/secondaryConstructorDelegateItself.kt");
+                    doTest(fileName);
+                }
+
+                @TestMetadata("secondaryConstructorDelegateLoop.kt")
+                public void testSecondaryConstructorDelegateLoop() throws Exception {
+                    String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/controlFlowAnalysis/unnecessaryLateinit/secondaryConstructorDelegateLoop.kt");
+                    doTest(fileName);
+                }
+            }
         }
 
         @TestMetadata("compiler/testData/diagnostics/tests/controlStructures")