IR: add IrSimpleFunction.isInfix

compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/ir/IrUtils.kt

@@ -490,6 +490,7 @@ fun IrClass.addFakeOverridesViaIncorrectHeuristic(implementedMembers: List<IrSim
                 isTailrec = irFunction.isTailrec
                 isSuspend = irFunction.isSuspend
                 isOperator = irFunction.isOperator
+                isInfix = irFunction.isInfix
                 isExpect = irFunction.isExpect
                 isFakeOverride = true
             }.apply {
@@ -540,7 +541,8 @@ fun createStaticFunctionWithReceivers(
         isSuspend = oldFunction.isSuspend,
         isExpect = oldFunction.isExpect,
         isFakeOverride = isFakeOverride,
-        isOperator = oldFunction is IrSimpleFunction && oldFunction.isOperator
+        isOperator = oldFunction is IrSimpleFunction && oldFunction.isOperator,
+        isInfix = oldFunction is IrSimpleFunction && oldFunction.isInfix
     ).apply {
         descriptor.bind(this)
         parent = irParent

compiler/ir/backend.common/src/org/jetbrains/kotlin/ir/builders/declarations/declarationBuilders.kt

@@ -136,7 +136,7 @@ internal fun IrFunctionBuilder.buildFunction(originalDescriptor: FunctionDescrip
         startOffset, endOffset, origin,
         IrSimpleFunctionSymbolImpl(wrappedDescriptor),
         name, visibility, modality, returnType,
-        isInline, isExternal, isTailrec, isSuspend, isOperator, isExpect, isFakeOverride
+        isInline, isExternal, isTailrec, isSuspend, isOperator, isInfix, isExpect, isFakeOverride
     ).also {
         wrappedDescriptor.bind(it)
     }