[FIR] Implement OPERATOR_RENAMED_ON_IMPORT diagnostic

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

@@ -955,6 +955,8 @@ object DIAGNOSTICS_LIST : DiagnosticList("FirErrors") {
         val CONFLICTING_IMPORT by error<KtImportDirective>(PositioningStrategy.IMPORT_LAST_NAME) {
             parameter<Name>("name")
         }
+
+        val OPERATOR_RENAMED_ON_IMPORT by error<KtSimpleNameExpression>(PositioningStrategy.IMPORT_LAST_NAME)
     }
 }
 

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

@@ -524,5 +524,6 @@ object FirErrors {
     val PACKAGE_CANNOT_BE_IMPORTED by error0<KtSimpleNameExpression>(SourceElementPositioningStrategies.IMPORT_LAST_NAME)
     val CANNOT_BE_IMPORTED by error1<KtSimpleNameExpression, Name>(SourceElementPositioningStrategies.IMPORT_LAST_NAME)
     val CONFLICTING_IMPORT by error1<KtImportDirective, Name>(SourceElementPositioningStrategies.IMPORT_LAST_NAME)
+    val OPERATOR_RENAMED_ON_IMPORT by error0<KtSimpleNameExpression>(SourceElementPositioningStrategies.IMPORT_LAST_NAME)
 
 }

compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/declaration/FirImportsChecker.kt

@@ -15,6 +15,7 @@ import org.jetbrains.kotlin.fir.resolve.symbolProvider
 import org.jetbrains.kotlin.fir.symbols.impl.FirRegularClassSymbol
 import org.jetbrains.kotlin.fir.symbols.impl.FirTypeAliasSymbol
 import org.jetbrains.kotlin.name.ClassId
+import org.jetbrains.kotlin.types.expressions.OperatorConventions
 
 object FirImportsChecker : FirFileChecker() {
     override fun check(declaration: FirFile, context: CheckerContext, reporter: DiagnosticReporter) {
@@ -25,6 +26,9 @@ object FirImportsChecker : FirFileChecker() {
             }
             if (!import.isAllUnder) {
                 checkCanBeImported(import, context, reporter)
+                if (import is FirResolvedImport) {
+                    checkOperatorRename(import, context, reporter)
+                }
             }
         }
         checkConflictingImports(declaration.imports, context, reporter)
@@ -88,6 +92,24 @@ object FirImportsChecker : FirFileChecker() {
             }
     }
 
+    private fun checkOperatorRename(import: FirResolvedImport, context: CheckerContext, reporter: DiagnosticReporter) {
+        val alias = import.aliasName ?: return
+        val importedName = import.importedName ?: return
+        if (!OperatorConventions.isConventionName(alias)) return
+        val classId = import.resolvedClassId
+        val illegalRename = if (classId != null) {
+            val classFir = classId.resolveToClass(context) ?: return
+            classFir.classKind.isSingleton && classFir.declarations.any { it is FirSimpleFunction && it.isOperator}
+        } else {
+            context.session.symbolProvider.getTopLevelFunctionSymbols(import.packageFqName, importedName).any {
+                it.fir.isOperator
+            }
+        }
+        if (illegalRename) {
+            reporter.reportOn(import.source, FirErrors.OPERATOR_RENAMED_ON_IMPORT, context)
+        }
+    }
+
     private fun FirResolvedImport.resolvesToClass(context: CheckerContext): Boolean {
         if (resolvedClassId != null) {
             if (isAllUnder) return true

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

@@ -228,6 +228,7 @@ import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.NULLABLE_SUPERTYP
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.NULLABLE_TYPE_IN_CLASS_LITERAL_LHS
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.NULLABLE_TYPE_OF_ANNOTATION_MEMBER
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.ONLY_ONE_CLASS_BOUND_ALLOWED
+import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.OPERATOR_RENAMED_ON_IMPORT
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.OTHER_ERROR
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.OVERLOAD_RESOLUTION_AMBIGUITY
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.OVERRIDING_FINAL_MEMBER
@@ -1180,6 +1181,7 @@ class FirDefaultErrorMessages : DefaultErrorMessages.Extension {
                 "Conflicting import, imported name ''{0}'' is ambiguous",
                 TO_STRING
             )
+            map.put(OPERATOR_RENAMED_ON_IMPORT, "Operator renamed to a different operator on import")
 
             // Extended checkers group
             map.put(REDUNDANT_VISIBILITY_MODIFIER, "Redundant visibility modifier")

compiler/testData/diagnostics/tests/imports/OperatorRenameOnImport.fir.kt

@@ -1,16 +0,0 @@
-// !DIAGNOSTICS: -UNUSED_PARAMETER
-// FILE: a.kt
-package a
-
-interface A
-
-operator fun A.plus(other: A): A = this
-
-// FILE: b.kt
-package b
-
-import a.A
-import a.plus as minus
-
-fun test(a1: A, a2: A) =
-        a1 - a2

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

@@ -1,3 +1,4 @@
+// FIR_IDENTICAL
 // !DIAGNOSTICS: -UNUSED_PARAMETER
 // FILE: a.kt
 package a

idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/frontend/api/fir/diagnostics/KtFirDataClassConverters.kt

@@ -2601,6 +2601,12 @@ internal val KT_DIAGNOSTIC_CONVERTER = KtDiagnosticConverterBuilder.buildConvert
             token,
         )
     }
+    add(FirErrors.OPERATOR_RENAMED_ON_IMPORT) { firDiagnostic ->
+        OperatorRenamedOnImportImpl(
+            firDiagnostic as FirPsiDiagnostic<*>,
+            token,
+        )
+    }
     add(FirJvmErrors.CONFLICTING_JVM_DECLARATIONS) { firDiagnostic ->
         ConflictingJvmDeclarationsImpl(
             firDiagnostic as FirPsiDiagnostic<*>,

idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/frontend/api/fir/diagnostics/KtFirDiagnostics.kt

@@ -1825,6 +1825,10 @@ sealed class KtFirDiagnostic<PSI: PsiElement> : KtDiagnosticWithPsi<PSI> {
         abstract val name: Name
     }
 
+    abstract class OperatorRenamedOnImport : KtFirDiagnostic<KtSimpleNameExpression>() {
+        override val diagnosticClass get() = OperatorRenamedOnImport::class
+    }
+
     abstract class ConflictingJvmDeclarations : KtFirDiagnostic<PsiElement>() {
         override val diagnosticClass get() = ConflictingJvmDeclarations::class
     }

idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/frontend/api/fir/diagnostics/KtFirDiagnosticsImpl.kt

@@ -2960,6 +2960,13 @@ internal class ConflictingImportImpl(
     override val firDiagnostic: FirPsiDiagnostic<*> by weakRef(firDiagnostic)
 }
 
+internal class OperatorRenamedOnImportImpl(
+    firDiagnostic: FirPsiDiagnostic<*>,
+    override val token: ValidityToken,
+) : KtFirDiagnostic.OperatorRenamedOnImport(), KtAbstractFirDiagnostic<KtSimpleNameExpression> {
+    override val firDiagnostic: FirPsiDiagnostic<*> by weakRef(firDiagnostic)
+}
+
 internal class ConflictingJvmDeclarationsImpl(
     firDiagnostic: FirPsiDiagnostic<*>,
     override val token: ValidityToken,