FIR checker: fix positioning of CONFLICTING_IMPORT

FE1.0 puts it on the alias when applicable.

compiler/fir/checkers/checkers-component-generator/src/org/jetbrains/kotlin/fir/checkers/generator/diagnostics/FirDiagnosticsList.kt

@@ -1322,7 +1322,7 @@ object DIAGNOSTICS_LIST : DiagnosticList("FirErrors") {
             parameter<Name>("name")
         }
 
-        val CONFLICTING_IMPORT by error<KtImportDirective>(PositioningStrategy.IMPORT_LAST_NAME) {
+        val CONFLICTING_IMPORT by error<KtImportDirective>(PositioningStrategy.IMPORT_ALIAS) {
             parameter<Name>("name")
         }
 

compiler/fir/checkers/checkers-component-generator/src/org/jetbrains/kotlin/fir/checkers/generator/diagnostics/model/RegularDiagnosticData.kt

@@ -108,6 +108,7 @@ enum class PositioningStrategy(private val strategy: String? = null) {
     ENUM_MODIFIER,
     FIELD_KEYWORD,
     TAILREC_MODIFIER,
+    IMPORT_ALIAS,
     PROPERTY_DELEGATE,
 
     ;

compiler/fir/checkers/gen/org/jetbrains/kotlin/fir/analysis/diagnostics/FirErrors.kt

@@ -684,7 +684,7 @@ object FirErrors {
     val CANNOT_ALL_UNDER_IMPORT_FROM_SINGLETON by error1<KtImportDirective, Name>(SourceElementPositioningStrategies.IMPORT_LAST_NAME)
     val PACKAGE_CANNOT_BE_IMPORTED by error0<KtImportDirective>(SourceElementPositioningStrategies.IMPORT_LAST_NAME)
     val CANNOT_BE_IMPORTED by error1<KtImportDirective, Name>(SourceElementPositioningStrategies.IMPORT_LAST_NAME)
-    val CONFLICTING_IMPORT by error1<KtImportDirective, Name>(SourceElementPositioningStrategies.IMPORT_LAST_NAME)
+    val CONFLICTING_IMPORT by error1<KtImportDirective, Name>(SourceElementPositioningStrategies.IMPORT_ALIAS)
     val OPERATOR_RENAMED_ON_IMPORT by error0<KtImportDirective>(SourceElementPositioningStrategies.IMPORT_LAST_NAME)
 
     // Suspend errors

compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/diagnostics/LightTreePositioningStrategies.kt

@@ -879,6 +879,23 @@ object LightTreePositioningStrategies {
         }
     }
 
+    val IMPORT_ALIAS: LightTreePositioningStrategy = object : LightTreePositioningStrategy() {
+        override fun mark(
+            node: LighterASTNode,
+            startOffset: Int,
+            endOffset: Int,
+            tree: FlyweightCapableTreeStructure<LighterASTNode>
+        ): List<TextRange> {
+            tree.findChildByType(node, KtNodeTypes.IMPORT_ALIAS)?.let {
+                tree.findChildByType(it, KtTokens.IDENTIFIER)?.let {
+                    return markElement(it, startOffset, endOffset, tree, node)
+                }
+            }
+            return IMPORT_LAST_NAME.mark(node, startOffset, endOffset, tree)
+        }
+    }
+
+
     val SPREAD_OPERATOR: LightTreePositioningStrategy = object : LightTreePositioningStrategy() {
         override fun mark(
             node: LighterASTNode,

compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/diagnostics/SourceElementPositioningStrategies.kt

@@ -330,6 +330,11 @@ object SourceElementPositioningStrategies {
         PositioningStrategies.TAILREC_MODIFIER
     )
 
+    val IMPORT_ALIAS = SourceElementPositioningStrategy(
+        LightTreePositioningStrategies.IMPORT_ALIAS,
+        PositioningStrategies.IMPORT_ALIAS
+    )
+
     val PROPERTY_DELEGATE = SourceElementPositioningStrategy(
         LightTreePositioningStrategies.PROPERTY_DELEGATE,
         PositioningStrategies.PROPERTY_DELEGATE

compiler/testData/diagnostics/tests/imports/ImportClassClash.kt

@@ -46,4 +46,8 @@ import a.B
 
 // FILE: 6.kt
 import a.<!CONFLICTING_IMPORT!>B<!>
-import b.<!CONFLICTING_IMPORT!>B<!>
+import b.<!CONFLICTING_IMPORT!>B<!>
+
+// FILE: 7.kt
+import a.B as <!CONFLICTING_IMPORT!>Foo<!>
+import b.B as <!CONFLICTING_IMPORT!>Foo<!>