[java debugger] SourcePosition#getElementAt is nullable

it indeed can return null, and clients should be ready for that

GitOrigin-RevId: c1a0c0b01951cf3035a4633bae0906f38a07060a

java/debugger/impl/src/com/intellij/debugger/engine/JavaSourcePositionHighlighter.java

@@ -1,18 +1,4 @@
-/*
- * Copyright 2000-2015 JetBrains s.r.o.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
+// Copyright 2000-2023 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
 package com.intellij.debugger.engine;
 
 import com.intellij.debugger.SourcePosition;
@@ -31,7 +17,8 @@ public class JavaSourcePositionHighlighter extends SourcePositionHighlighter imp
   public TextRange getHighlightRange(SourcePosition sourcePosition) {
     // Highlight only return keyword in case of conditional return breakpoint.
     PsiElement element = sourcePosition.getElementAt();
-    if (JavaLineBreakpointType.isReturnKeyword(element) &&
+    if (element != null &&
+        JavaLineBreakpointType.isReturnKeyword(element) &&
         element == JavaLineBreakpointType.findSingleConditionalReturn(sourcePosition)) {
       return element.getTextRange();
     }

java/debugger/impl/src/com/intellij/debugger/engine/RemappedSourcePosition.java

@@ -1,4 +1,4 @@
-// Copyright 2000-2020 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
+// Copyright 2000-2023 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
 package com.intellij.debugger.engine;
 
 import com.intellij.debugger.SourcePosition;
@@ -6,6 +6,7 @@ import com.intellij.openapi.editor.Editor;
 import com.intellij.psi.PsiElement;
 import com.intellij.psi.PsiFile;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
 
 abstract class RemappedSourcePosition extends SourcePosition {
   private SourcePosition myDelegate;
@@ -22,7 +23,7 @@ abstract class RemappedSourcePosition extends SourcePosition {
   }
 
   @Override
-  public PsiElement getElementAt() {
+  public @Nullable PsiElement getElementAt() {
     checkRemap();
     return myDelegate.getElementAt();
   }

java/debugger/openapi/src/com/intellij/debugger/SourcePosition.java

@@ -29,7 +29,7 @@ public abstract class SourcePosition implements Navigatable {
   @NotNull
   public abstract PsiFile getFile();
 
-  public abstract PsiElement getElementAt();
+  public abstract @Nullable PsiElement getElementAt();
 
   /**
    * @return a zero-based line number
@@ -137,7 +137,7 @@ public abstract class SourcePosition implements Navigatable {
     }
 
     @Override
-    public PsiElement getElementAt() {
+    public @Nullable PsiElement getElementAt() {
       updateData();
       PsiElement element = SoftReference.dereference(myPsiElementRef);
       if (element == null) {

plugins/kotlin/jvm-debugger/core-fe10/src/org/jetbrains/kotlin/idea/debugger/stepping/smartStepInto/KotlinLambdaMethodFilter.kt

@@ -63,7 +63,7 @@ class KotlinLambdaMethodFilter(
                 return@runReadAction true
             }
 
-            val blockAt = elementAt.parentOfType<KtBlockExpression>(withSelf = true)
+            val blockAt = elementAt?.parentOfType<KtBlockExpression>(withSelf = true)
             blockAt == bodyExpression
         }
     }

plugins/kotlin/jvm-debugger/core/src/org/jetbrains/kotlin/idea/debugger/core/breakpoints/KotlinFunctionBreakpoint.kt

@@ -1,4 +1,4 @@
-// Copyright 2000-2022 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
+// Copyright 2000-2023 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
 package org.jetbrains.kotlin.idea.debugger.core.breakpoints
 
 import com.intellij.debugger.SourcePosition
@@ -62,7 +62,7 @@ open class KotlinFunctionBreakpoint(
     }
 
     override fun refineSourcePosition(sourcePosition: SourcePosition): SourcePosition {
-        val declaration = sourcePosition.elementAt.parentOfType<KtDeclaration>(withSelf = true) ?: return sourcePosition
+        val declaration = sourcePosition.elementAt?.parentOfType<KtDeclaration>(withSelf = true) ?: return sourcePosition
         if (declaration.isExpectDeclaration()) {
             val actualDeclaration = declaration.getActualJvmDeclaration() ?: return sourcePosition
             return SourcePosition.createFromElement(actualDeclaration) ?: sourcePosition

plugins/kotlin/jvm-debugger/core/src/org/jetbrains/kotlin/idea/debugger/core/breakpoints/KotlinLineBreakpointType.kt

@@ -1,4 +1,4 @@
-// Copyright 2000-2022 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
+// Copyright 2000-2023 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
 
 // The package directive doesn't match the file location to prevent API breakage
 package org.jetbrains.kotlin.idea.debugger.breakpoints
@@ -112,7 +112,7 @@ class KotlinLineBreakpointType :
         if (lambdas.isEmpty() && condRet == null) return emptyList()
 
         val result = LinkedList<JavaLineBreakpointType.JavaBreakpointVariant>()
-        val elementAt = pos.elementAt.parentsWithSelf.firstIsInstance<KtElement>()
+        val elementAt = pos.elementAt?.parentsWithSelf?.firstIsInstance<KtElement>() ?: return emptyList()
         val mainMethod = PsiTreeUtil.getParentOfType(elementAt, KtFunction::class.java, false)
         var mainMethodAdded = false
         if (mainMethod != null) {
@@ -157,7 +157,7 @@ class KotlinLineBreakpointType :
         val lambdaOrdinal = properties.lambdaOrdinal ?: return null
         // Since lambda breakpoints are placed on the first lambda statement,
         // we should find the function parent to highlight lambda breakpoints properly
-        val function = position.elementAt.parentOfType<KtFunction>() ?: return null
+        val function = position.elementAt?.parentOfType<KtFunction>() ?: return null
         val updatedPosition = SourcePosition.createFromElement(function) ?: return null
         return getLambdaByOrdinal(updatedPosition, lambdaOrdinal)?.textRange
     }

plugins/kotlin/jvm-debugger/coroutines/src/org/jetbrains/kotlin/idea/debugger/coroutine/KotlinVariableNameFinder.kt

@@ -1,4 +1,4 @@
-// Copyright 2000-2022 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
+// Copyright 2000-2023 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
 package org.jetbrains.kotlin.idea.debugger.coroutine
 
 import com.intellij.debugger.engine.DebugProcessImpl
@@ -26,7 +26,8 @@ internal class KotlinVariableNameFinder(val debugProcess: DebugProcessImpl) {
     fun findVisibleVariableNames(location: Location): List<String> {
         val sourcePosition = KotlinPositionManager(debugProcess).safeGetSourcePosition(location) ?: return emptyList()
         ProgressManager.checkCanceled()
-        return findVisibleVariableNamesFrom(sourcePosition.elementAt)
+        val elementAt = sourcePosition.elementAt ?: return emptyList()
+        return findVisibleVariableNamesFrom(elementAt)
     }
 
     private fun findVisibleVariableNamesFrom(element: PsiElement): List<String> {

plugins/kotlin/jvm-debugger/test/test/org/jetbrains/kotlin/idea/debugger/test/KotlinDescriptorTestCaseWithStepping.kt

@@ -250,7 +250,10 @@ abstract class KotlinDescriptorTestCaseWithStepping : KotlinDescriptorTestCase()
             try {
                 doStepInto(ignoreFilters, filters[chooseFromList - 1])
             } catch (e: IndexOutOfBoundsException) {
-                val elementText = runReadAction { debuggerContext.sourcePosition.elementAt.getElementTextWithContext() }
+                val elementText = runReadAction {
+                    val elementAt = debuggerContext.sourcePosition.elementAt ?: return@runReadAction "<no-element>"
+                    elementAt.getElementTextWithContext()
+                }
                 throw AssertionError("Couldn't find smart step into command at: \n$elementText", e)
             }
         }
@@ -285,7 +288,7 @@ abstract class KotlinDescriptorTestCaseWithStepping : KotlinDescriptorTestCase()
     private fun List<SmartStepTarget>.getIndicesInTree(): List<Int> {
         val targetsIndicesInTree = MutableList(size) { 0 }
         runReadAction {
-            val elementAt = debuggerContext.sourcePosition.elementAt
+            val elementAt = debuggerContext.sourcePosition.elementAt ?: return@runReadAction
             val topmostElement = getTopmostElementAtOffset(elementAt, elementAt.textRange.startOffset)
             topmostElement.accept(object : KtTreeVisitorVoid() {
                 private var elementIndex = 0