[FIR] Resolve operator calls to operator functions only

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

@@ -143,6 +143,8 @@ private fun mapInapplicableCandidateError(
             is UnsafeCall -> mapUnsafeCallError(diagnostic.candidate, rootCause, source, qualifiedAccessSource)
             is ManyLambdaExpressionArguments -> FirErrors.MANY_LAMBDA_EXPRESSION_ARGUMENTS.on(rootCause.argument.source ?: source)
             is InfixCallOfNonInfixFunction -> FirErrors.INFIX_MODIFIER_REQUIRED.on(source, rootCause.function)
+            is OperatorCallOfNonOperatorFunction ->
+                FirErrors.OPERATOR_MODIFIER_REQUIRED.on(source, rootCause.function, rootCause.function.fir.name.asString())
             else -> null
         }
     }.ifEmpty { listOf(FirErrors.INAPPLICABLE_CANDIDATE.on(source, diagnostic.candidate.symbol)) }

compiler/fir/raw-fir/psi2fir/src/org/jetbrains/kotlin/fir/builder/RawFirBuilder.kt

@@ -1889,7 +1889,7 @@ open class RawFirBuilder(
                     }
                     explicitReceiver = leftArgument
                     argumentList = buildUnaryArgumentList(rightArgument)
-                    origin = if (conventionCallName != null) FirFunctionCallOrigin.REGULAR else FirFunctionCallOrigin.INFIX
+                    origin = if (conventionCallName != null) FirFunctionCallOrigin.OPERATOR else FirFunctionCallOrigin.INFIX
                 }
             } else {
                 val firOperation = operationToken.toFirOperation()

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/calls/CallKind.kt

@@ -39,7 +39,7 @@ sealed class CallKind(vararg resolutionSequence: ResolutionStage) {
         CheckDispatchReceiver,
         CheckExtensionReceiver,
         CheckArguments,
-        CheckInfixCall,
+        CheckCallModifiers,
         EagerResolveOfCallableReferences,
         CheckLowPriorityInOverloadResolution,
         PostponedVariablesInitializerResolutionStage

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/calls/ResolutionDiagnostic.kt

@@ -104,4 +104,5 @@ class ManyLambdaExpressionArguments(
     val argument: FirExpression
 ) : ResolutionDiagnostic(INAPPLICABLE_ARGUMENTS_MAPPING_ERROR)
 
-class InfixCallOfNonInfixFunction(val function: FirNamedFunctionSymbol) : ResolutionDiagnostic(INAPPLICABLE_MODIFIER)
+class InfixCallOfNonInfixFunction(val function: FirNamedFunctionSymbol) : ResolutionDiagnostic(INAPPLICABLE_MODIFIER)
+class OperatorCallOfNonOperatorFunction(val function: FirNamedFunctionSymbol) : ResolutionDiagnostic(INAPPLICABLE_MODIFIER)

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/calls/ResolutionStages.kt

@@ -267,14 +267,15 @@ internal object PostponedVariablesInitializerResolutionStage : ResolutionStage()
     }
 }
 
-internal object CheckInfixCall : CheckerStage() {
+internal object CheckCallModifiers : CheckerStage() {
     override suspend fun check(candidate: Candidate, callInfo: CallInfo, sink: CheckerSink, context: ResolutionContext) {
         if (callInfo.callSite is FirFunctionCall) {
-            if (callInfo.callSite.origin == FirFunctionCallOrigin.INFIX) {
+            val functionSymbol = candidate.symbol as? FirNamedFunctionSymbol ?: return
-                val functionSymbol = candidate.symbol as? FirNamedFunctionSymbol ?: return
+            when {
-                if (!functionSymbol.fir.isInfix) {
+                callInfo.callSite.origin == FirFunctionCallOrigin.INFIX && !functionSymbol.fir.isInfix ->
                     sink.reportDiagnostic(InfixCallOfNonInfixFunction(functionSymbol))
-                }
+                callInfo.callSite.origin == FirFunctionCallOrigin.OPERATOR && !functionSymbol.fir.isOperator ->
+                    sink.reportDiagnostic(OperatorCallOfNonOperatorFunction(functionSymbol))
             }
         }
     }

compiler/testData/diagnostics/tests/Operators.fir.kt

@@ -49,9 +49,9 @@ fun test() {
     a == b
     c != d
 
-    Example() + Example()
+    Example() <!OPERATOR_MODIFIER_REQUIRED!>+<!> Example()
 
-    a + b
+    a <!OPERATOR_MODIFIER_REQUIRED!>+<!> b
     a - b
     a[1]
     a["str"]
@@ -67,10 +67,10 @@ fun test() {
     c += d
     c -= d
 
-    a..b
+    a<!OPERATOR_MODIFIER_REQUIRED!>..<!>b
     c..d
 
-    Example()..Example()
+    Example()<!OPERATOR_MODIFIER_REQUIRED!>..<!>Example()
     Example2()..Example2()
 
     a < b
@@ -109,7 +109,7 @@ class Anc2 : Anc()
 
 fun test2() {
     Anc() + Anc()
-    Anc() - Anc()
+    Anc() <!OPERATOR_MODIFIER_REQUIRED!>-<!> Anc()
     Anc2() + Anc2()
 }
 

compiler/testData/diagnostics/tests/modifiers/operatorInfix/LocalFunctions.fir.kt

@@ -1,39 +0,0 @@
-// !DIAGNOSTICS: -UNUSED_PARAMETER
-
-class Example
-
-fun Example.plus(other: Example) = 0
-operator infix fun Example.minus(other: Example) = 0
-
-operator infix fun Example.times(other: Example) = 0
-fun Example.div(other: Example) = 0
-
-fun a() {
-    with (Example()) {
-        operator infix fun Example.plus(other: Example) = ""
-        fun Example.minus(other: Example) = ""
-
-        operator infix fun Example.times(other: Example) = ""
-        fun Example.div(other: Example) = ""
-
-        with (Example()) {
-            val a = Example()
-            val b = Example()
-
-            consumeString(a + b)
-            consumeInt(<!ARGUMENT_TYPE_MISMATCH!>a - b<!>)
-
-            consumeString(a plus b)
-            consumeInt(a minus b)
-
-            a * b
-            a / b
-
-            a times b
-            a <!INFIX_MODIFIER_REQUIRED!>div<!> b
-        }
-    }
-}
-
-fun consumeInt(i: Int) {}
-fun consumeString(s: String) {}

compiler/testData/diagnostics/tests/modifiers/operatorInfix/LocalFunctions.kt

@@ -1,3 +1,4 @@
+// FIR_IDENTICAL
 // !DIAGNOSTICS: -UNUSED_PARAMETER
 
 class Example

compiler/testData/diagnostics/tests/modifiers/operatorInfix/MemberFunctions.fir.kt

@@ -1,45 +0,0 @@
-// !DIAGNOSTICS: -UNUSED_PARAMETER, -EXTENSION_SHADOWED_BY_MEMBER
-
-class Example {
-    operator infix fun plus(other: Example) = 0
-    fun minus(other: Example) = 0
-
-    operator infix fun times(other: Example) = 0
-    fun div(other: Example) = 0
-}
-
-fun Example.plus(other: Example) = ""
-operator infix fun Example.minus(other: Example) = ""
-
-operator infix fun Example.times(other: Example) = ""
-fun Example.div(other: Example) = ""
-
-fun a() {
-    val a = Example()
-    val b = Example()
-
-    a + b
-    a - b
-    a * b
-    a / b
-
-    a plus b
-    a minus b
-    a times b
-    a <!INFIX_MODIFIER_REQUIRED!>div<!> b
-
-    with (Example()) {
-        consumeInt(this + a)
-        consumeString(<!ARGUMENT_TYPE_MISMATCH!>this - b<!>)
-        consumeInt(this * a)
-        consumeInt(this / b)
-
-        consumeInt(this plus a)
-        consumeString(this minus b)
-        consumeInt(this times a)
-        consumeInt(this <!INFIX_MODIFIER_REQUIRED!>div<!> b)
-    }
-}
-
-fun consumeInt(i: Int) {}
-fun consumeString(s: String) {}

compiler/testData/diagnostics/tests/modifiers/operatorInfix/MemberFunctions.kt

@@ -1,3 +1,4 @@
+// FIR_IDENTICAL
 // !DIAGNOSTICS: -UNUSED_PARAMETER, -EXTENSION_SHADOWED_BY_MEMBER
 
 class Example {