FIR: Load final static constant Java fields as non-nullable

analysis/low-level-api-fir/tests/org/jetbrains/kotlin/analysis/low/level/api/fir/diagnostic/compiler/based/DiagnosisCompilerTestFE10TestdataTestGenerated.java

@@ -18080,6 +18080,12 @@ public class DiagnosisCompilerTestFE10TestdataTestGenerated extends AbstractDiag
                     runTest("compiler/testData/diagnostics/tests/j+k/types/arrayList.kt");
                 }
 
+                @Test
+                @TestMetadata("constantStaticStringField.kt")
+                public void testConstantStaticStringField() throws Exception {
+                    runTest("compiler/testData/diagnostics/tests/j+k/types/constantStaticStringField.kt");
+                }
+
                 @Test
                 @TestMetadata("notNullTypeParameterWithKotlinNullable.kt")
                 public void testNotNullTypeParameterWithKotlinNullable() throws Exception {

compiler/fir/analysis-tests/testData/resolveWithStdlib/j+k/StaticFromBaseClass.fir.txt

@@ -1,5 +1,5 @@
 FILE: main.kt
     public final fun test(): R|kotlin/Unit| {
-        lval project: R|ft<kotlin/String, kotlin/String?>| = Q|PlatformDataKeys|.R|/CommonDataKeys.PROJECT|
+        lval project: R|kotlin/String| = Q|PlatformDataKeys|.R|/CommonDataKeys.PROJECT|
         lval member: R|ft<kotlin/String, kotlin/String?>| = R|/PlatformDataKeys.PlatformDataKeys|().R|/CommonDataKeys.MEMBER|
     }

compiler/fir/analysis-tests/tests-gen/org/jetbrains/kotlin/test/runners/FirOldFrontendDiagnosticsTestGenerated.java

@@ -18080,6 +18080,12 @@ public class FirOldFrontendDiagnosticsTestGenerated extends AbstractFirDiagnosti
                     runTest("compiler/testData/diagnostics/tests/j+k/types/arrayList.kt");
                 }
 
+                @Test
+                @TestMetadata("constantStaticStringField.kt")
+                public void testConstantStaticStringField() throws Exception {
+                    runTest("compiler/testData/diagnostics/tests/j+k/types/constantStaticStringField.kt");
+                }
+
                 @Test
                 @TestMetadata("notNullTypeParameterWithKotlinNullable.kt")
                 public void testNotNullTypeParameterWithKotlinNullable() throws Exception {

compiler/fir/analysis-tests/tests-gen/org/jetbrains/kotlin/test/runners/FirOldFrontendDiagnosticsWithLightTreeTestGenerated.java

@@ -18080,6 +18080,12 @@ public class FirOldFrontendDiagnosticsWithLightTreeTestGenerated extends Abstrac
                     runTest("compiler/testData/diagnostics/tests/j+k/types/arrayList.kt");
                 }
 
+                @Test
+                @TestMetadata("constantStaticStringField.kt")
+                public void testConstantStaticStringField() throws Exception {
+                    runTest("compiler/testData/diagnostics/tests/j+k/types/constantStaticStringField.kt");
+                }
+
                 @Test
                 @TestMetadata("notNullTypeParameterWithKotlinNullable.kt")
                 public void testNotNullTypeParameterWithKotlinNullable() throws Exception {

compiler/fir/java/src/org/jetbrains/kotlin/fir/java/enhancement/SignatureEnhancement.kt

@@ -112,7 +112,18 @@ class FirSignatureEnhancement(
             }
             is FirField -> {
                 if (firElement.returnTypeRef !is FirJavaTypeRef) return original
-                val newReturnTypeRef = enhanceReturnType(firElement, emptyList(), firElement.computeDefaultQualifiers(), null)
+                val newReturnTypeRef = enhanceReturnType(
+                    firElement, emptyList(), firElement.computeDefaultQualifiers(),
+                    predefinedEnhancementInfo = null
+                ).let {
+                    val lowerBound = it.type.lowerBoundIfFlexible()
+
+                    if (firElement.isStatic && firElement.initializer != null && (lowerBound.isString || lowerBound.isInt)) {
+                        it.withReplacedConeType(it.type.withNullability(ConeNullability.NOT_NULL, session.typeContext))
+                    } else {
+                        it
+                    }
+                }
 
                 val symbol = FirFieldSymbol(original.callableId)
                 buildJavaField {

compiler/testData/diagnostics/tests/j+k/types/constantStaticStringField.fir.kt

@@ -0,0 +1,27 @@
+// SKIP_TXT
+
+// FILE: JavaClass.java
+public class JavaClass {
+    public final static String X = "";
+    public final static String Y = "";
+}
+
+// FILE: main.kt
+
+fun nullableStr(): String? = null
+
+fun foo(w: Int): String {
+    var x: String? = nullableStr()
+
+    if (x != null) {
+        return x
+    }
+
+    // Smartcast should work because when's entries' results are non-flexible
+    x = nullableStr() ?: when (w) {
+        1 -> JavaClass.X
+        else -> JavaClass.Y
+    }
+
+    return x
+}

compiler/testData/diagnostics/tests/j+k/types/constantStaticStringField.kt

@@ -0,0 +1,27 @@
+// SKIP_TXT
+
+// FILE: JavaClass.java
+public class JavaClass {
+    public final static String X = "";
+    public final static String Y = "";
+}
+
+// FILE: main.kt
+
+fun nullableStr(): String? = null
+
+fun foo(w: Int): String {
+    var x: String? = nullableStr()
+
+    if (x != null) {
+        return <!DEBUG_INFO_SMARTCAST!>x<!>
+    }
+
+    // Smartcast should work because when's entries' results are non-flexible
+    x = nullableStr() ?: when (w) {
+        1 -> JavaClass.X
+        else -> JavaClass.Y
+    }
+
+    return <!DEBUG_INFO_SMARTCAST!>x<!>
+}

compiler/testData/ir/irText/declarations/kt29833.fir.ir.txt

@@ -6,26 +6,26 @@ FILE fqName:interop fileName:/Definitions.kt
         DELEGATING_CONSTRUCTOR_CALL 'public constructor <init> () [primary] declared in kotlin.Any'
         INSTANCE_INITIALIZER_CALL classDescriptor='CLASS OBJECT name:Definitions modality:FINAL visibility:public superTypes:[kotlin.Any]'
     PROPERTY name:KT_CONSTANT visibility:public modality:FINAL [const,val]
-      FIELD PROPERTY_BACKING_FIELD name:KT_CONSTANT type:@[FlexibleNullability] kotlin.String? visibility:public [final]
+      FIELD PROPERTY_BACKING_FIELD name:KT_CONSTANT type:kotlin.String visibility:public [final]
         EXPRESSION_BODY
-          CONST String type=@[FlexibleNullability] kotlin.String value="constant"
+          CONST String type=kotlin.String value="constant"
-      FUN DEFAULT_PROPERTY_ACCESSOR name:<get-KT_CONSTANT> visibility:public modality:FINAL <> ($this:interop.Definitions) returnType:@[FlexibleNullability] kotlin.String?
+      FUN DEFAULT_PROPERTY_ACCESSOR name:<get-KT_CONSTANT> visibility:public modality:FINAL <> ($this:interop.Definitions) returnType:kotlin.String
         correspondingProperty: PROPERTY name:KT_CONSTANT visibility:public modality:FINAL [const,val]
         $this: VALUE_PARAMETER name:<this> type:interop.Definitions
         BLOCK_BODY
-          RETURN type=kotlin.Nothing from='public final fun <get-KT_CONSTANT> (): @[FlexibleNullability] kotlin.String? declared in interop.Definitions'
+          RETURN type=kotlin.Nothing from='public final fun <get-KT_CONSTANT> (): kotlin.String declared in interop.Definitions'
-            GET_FIELD 'FIELD PROPERTY_BACKING_FIELD name:KT_CONSTANT type:@[FlexibleNullability] kotlin.String? visibility:public [final]' type=@[FlexibleNullability] kotlin.String? origin=null
+            GET_FIELD 'FIELD PROPERTY_BACKING_FIELD name:KT_CONSTANT type:kotlin.String visibility:public [final]' type=kotlin.String origin=null
               receiver: GET_VAR '<this>: interop.Definitions declared in interop.Definitions.<get-KT_CONSTANT>' type=interop.Definitions origin=null
     PROPERTY name:ktValue visibility:public modality:FINAL [val]
-      FIELD PROPERTY_BACKING_FIELD name:ktValue type:@[FlexibleNullability] kotlin.String? visibility:private [final]
+      FIELD PROPERTY_BACKING_FIELD name:ktValue type:kotlin.String visibility:private [final]
         EXPRESSION_BODY
-          GET_FIELD 'FIELD IR_EXTERNAL_JAVA_DECLARATION_STUB name:CONSTANT type:@[FlexibleNullability] kotlin.String? visibility:public [final,static]' type=@[FlexibleNullability] kotlin.String? origin=GET_PROPERTY
+          GET_FIELD 'FIELD IR_EXTERNAL_JAVA_DECLARATION_STUB name:CONSTANT type:kotlin.String visibility:public [final,static]' type=kotlin.String origin=GET_PROPERTY
-      FUN DEFAULT_PROPERTY_ACCESSOR name:<get-ktValue> visibility:public modality:FINAL <> ($this:interop.Definitions) returnType:@[FlexibleNullability] kotlin.String?
+      FUN DEFAULT_PROPERTY_ACCESSOR name:<get-ktValue> visibility:public modality:FINAL <> ($this:interop.Definitions) returnType:kotlin.String
         correspondingProperty: PROPERTY name:ktValue visibility:public modality:FINAL [val]
         $this: VALUE_PARAMETER name:<this> type:interop.Definitions
         BLOCK_BODY
-          RETURN type=kotlin.Nothing from='public final fun <get-ktValue> (): @[FlexibleNullability] kotlin.String? declared in interop.Definitions'
+          RETURN type=kotlin.Nothing from='public final fun <get-ktValue> (): kotlin.String declared in interop.Definitions'
-            GET_FIELD 'FIELD PROPERTY_BACKING_FIELD name:ktValue type:@[FlexibleNullability] kotlin.String? visibility:private [final]' type=@[FlexibleNullability] kotlin.String? origin=null
+            GET_FIELD 'FIELD PROPERTY_BACKING_FIELD name:ktValue type:kotlin.String visibility:private [final]' type=kotlin.String origin=null
               receiver: GET_VAR '<this>: interop.Definitions declared in interop.Definitions.<get-ktValue>' type=interop.Definitions origin=null
     FUN FAKE_OVERRIDE name:equals visibility:public modality:OPEN <> ($this:kotlin.Any, other:kotlin.Any?) returnType:kotlin.Boolean [fake_override,operator]
       overridden:

compiler/testData/ir/irText/declarations/kt29833.fir.kt.txt

@@ -7,11 +7,11 @@ object Definitions {
 
   }
 
-  const val KT_CONSTANT: @FlexibleNullability String?
+  const val KT_CONSTANT: String
     field = "constant"
     get
 
-  val ktValue: @FlexibleNullability String?
+  val ktValue: String
     field = #CONSTANT
     get
 

compiler/testData/ir/irText/firProblems/SameJavaFieldReferences.fir.ir.txt

@@ -1,9 +1,9 @@
 FILE fqName:<root> fileName:/SameJavaFieldReferences.kt
   FUN name:foo visibility:public modality:FINAL <> () returnType:kotlin.Unit
     BLOCK_BODY
-      VAR name:ref1 type:kotlin.reflect.KProperty0<@[FlexibleNullability] kotlin.String?> [val]
+      VAR name:ref1 type:kotlin.reflect.KProperty0<kotlin.String> [val]
-        PROPERTY_REFERENCE 'public final someJavaField: @[FlexibleNullability] kotlin.String? [val]' field='FIELD IR_EXTERNAL_JAVA_DECLARATION_STUB name:someJavaField type:@[FlexibleNullability] kotlin.String? visibility:public [final,static]' getter=null setter=null type=kotlin.reflect.KProperty0<@[FlexibleNullability] kotlin.String?> origin=null
+        PROPERTY_REFERENCE 'public final someJavaField: kotlin.String [val]' field='FIELD IR_EXTERNAL_JAVA_DECLARATION_STUB name:someJavaField type:kotlin.String visibility:public [final,static]' getter=null setter=null type=kotlin.reflect.KProperty0<kotlin.String> origin=null
           <1>: <none>
-      VAR name:ref2 type:kotlin.reflect.KProperty0<@[FlexibleNullability] kotlin.String?> [val]
+      VAR name:ref2 type:kotlin.reflect.KProperty0<kotlin.String> [val]
-        PROPERTY_REFERENCE 'public final someJavaField: @[FlexibleNullability] kotlin.String? [val]' field='FIELD IR_EXTERNAL_JAVA_DECLARATION_STUB name:someJavaField type:@[FlexibleNullability] kotlin.String? visibility:public [final,static]' getter=null setter=null type=kotlin.reflect.KProperty0<@[FlexibleNullability] kotlin.String?> origin=null
+        PROPERTY_REFERENCE 'public final someJavaField: kotlin.String [val]' field='FIELD IR_EXTERNAL_JAVA_DECLARATION_STUB name:someJavaField type:kotlin.String visibility:public [final,static]' getter=null setter=null type=kotlin.reflect.KProperty0<kotlin.String> origin=null
           <1>: <none>

compiler/testData/ir/irText/firProblems/SameJavaFieldReferences.fir.kt.txt

@@ -1,4 +1,4 @@
 fun foo() {
-  val ref1: KProperty0<@FlexibleNullability String?> = SomeJavaClass::someJavaField/*</* null */>()*/
+  val ref1: KProperty0<String> = SomeJavaClass::someJavaField/*</* null */>()*/
-  val ref2: KProperty0<@FlexibleNullability String?> = SomeJavaClass::someJavaField/*</* null */>()*/
+  val ref2: KProperty0<String> = SomeJavaClass::someJavaField/*</* null */>()*/
 }

compiler/testData/loadJava/compiledJava/annotations/StringConstantInParam.fir.txt

@@ -1,5 +1,5 @@
 public abstract interface StringConstantInParam : R|kotlin/Any| {
-    public final static field HEL: R|ft<kotlin/String, kotlin/String?>| = String(hel)
+    public final static field HEL: R|kotlin/String| = String(hel)
 
     public final annotation class Anno : R|kotlin/Annotation| {
         public constructor(value: R|kotlin/String|): R|test/StringConstantInParam.Anno|

compiler/testData/loadJava/compiledJava/static/StaticFinal.fir.txt

@@ -1,13 +1,13 @@
 public open class StaticFinal : R|kotlin/Any| {
-    public final static field publicNonNull: R|ft<kotlin/String, kotlin/String?>| = String(aaa)
+    public final static field publicNonNull: R|kotlin/String| = String(aaa)
 
     public final static field publicNull: R|ft<kotlin/String, kotlin/String?>|
 
-    public/*package*/ final static field packageNonNull: R|ft<kotlin/String, kotlin/String?>| = String(bbb)
+    public/*package*/ final static field packageNonNull: R|kotlin/String| = String(bbb)
 
     public/*package*/ final static field packageNull: R|ft<kotlin/String, kotlin/String?>|
 
-    private final static field privateNonNull: R|ft<kotlin/String, kotlin/String?>| = String(bbb)
+    private final static field privateNonNull: R|kotlin/String| = String(bbb)
 
     private final static field privateNull: R|ft<kotlin/String, kotlin/String?>|
 

compiler/tests-common-new/tests-gen/org/jetbrains/kotlin/test/runners/DiagnosticTestGenerated.java

@@ -18086,6 +18086,12 @@ public class DiagnosticTestGenerated extends AbstractDiagnosticTest {
                     runTest("compiler/testData/diagnostics/tests/j+k/types/arrayList.kt");
                 }
 
+                @Test
+                @TestMetadata("constantStaticStringField.kt")
+                public void testConstantStaticStringField() throws Exception {
+                    runTest("compiler/testData/diagnostics/tests/j+k/types/constantStaticStringField.kt");
+                }
+
                 @Test
                 @TestMetadata("notNullTypeParameterWithKotlinNullable.kt")
                 public void testNotNullTypeParameterWithKotlinNullable() throws Exception {