FIR: report VARARG_OUTSIDE_PARENTHESES

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

@@ -166,6 +166,8 @@ object DIAGNOSTICS_LIST : DiagnosticList() {
         val INAPPLICABLE_LATEINIT_MODIFIER by error<FirSourceElement, KtModifierListOwner>(PositioningStrategy.LATEINIT_MODIFIER) {
             parameter<String>("reason")
         }
+
+        val VARARG_OUTSIDE_PARENTHESES by error<FirSourceElement, KtExpression>()
     }
 
     val AMBIGUITY by object : DiagnosticGroup("Ambiguity") {

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

@@ -145,6 +145,7 @@ object FirErrors {
     val NONE_APPLICABLE by error1<FirSourceElement, PsiElement, Collection<AbstractFirBasedSymbol<*>>>(SourceElementPositioningStrategies.REFERENCE_BY_QUALIFIED)
     val INAPPLICABLE_CANDIDATE by error1<FirSourceElement, PsiElement, AbstractFirBasedSymbol<*>>(SourceElementPositioningStrategies.REFERENCE_BY_QUALIFIED)
     val INAPPLICABLE_LATEINIT_MODIFIER by error1<FirSourceElement, KtModifierListOwner, String>(SourceElementPositioningStrategies.LATEINIT_MODIFIER)
+    val VARARG_OUTSIDE_PARENTHESES by error0<FirSourceElement, KtExpression>()
 
     // Ambiguity
     val AMBIGUITY by error1<FirSourceElement, PsiElement, Collection<AbstractFirBasedSymbol<*>>>(SourceElementPositioningStrategies.REFERENCE_BY_QUALIFIED)

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

@@ -173,6 +173,7 @@ import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.UPPER_BOUND_VIOLA
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.USELESS_VARARG_ON_PARAMETER
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.VAL_REASSIGNMENT
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.VAL_WITH_SETTER
+import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.VARARG_OUTSIDE_PARENTHESES
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.VARIABLE_EXPECTED
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.VARIABLE_INITIALIZER_IS_REDUNDANT
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.VARIABLE_NEVER_READ
@@ -323,6 +324,7 @@ class FirDefaultErrorMessages : DefaultErrorMessages.Extension {
             map.put(NONE_APPLICABLE, "None of the following functions are applicable: {0}", SYMBOLS)
             map.put(INAPPLICABLE_CANDIDATE, "Inapplicable candidate(s): {0}", SYMBOL)
             map.put(INAPPLICABLE_LATEINIT_MODIFIER, "''lateinit'' modifier {0}", TO_STRING)
+            map.put(VARARG_OUTSIDE_PARENTHESES, "Passing value as a vararg is only allowed inside a parenthesized argument list")
 
             // Ambiguity
             map.put(AMBIGUITY, "Ambiguity between candidates: {0}", SYMBOLS)

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

@@ -14,6 +14,7 @@ import org.jetbrains.kotlin.fir.declarations.isInfix
 import org.jetbrains.kotlin.fir.declarations.isOperator
 import org.jetbrains.kotlin.fir.diagnostics.*
 import org.jetbrains.kotlin.fir.resolve.calls.InapplicableWrongReceiver
+import org.jetbrains.kotlin.fir.resolve.calls.VarargArgumentOutsideParentheses
 import org.jetbrains.kotlin.fir.resolve.diagnostics.*
 import org.jetbrains.kotlin.fir.types.*
 import org.jetbrains.kotlin.lexer.KtTokens
@@ -95,7 +96,11 @@ private fun mapInapplicableCandidateError(
 
         return FirErrors.UNSAFE_CALL.on(source, rootCause.actualType!!)
     }
-    return FirErrors.INAPPLICABLE_CANDIDATE.on(source, diagnostic.candidate.symbol)
+
+    return when (rootCause) {
+        is VarargArgumentOutsideParentheses -> FirErrors.VARARG_OUTSIDE_PARENTHESES.on(rootCause.argument.source ?: source)
+        else -> FirErrors.INAPPLICABLE_CANDIDATE.on(source, diagnostic.candidate.symbol)
+    }
 }
 
 private fun ConeSimpleDiagnostic.getFactory(): FirDiagnosticFactory0<FirSourceElement, *> {

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

@@ -12,6 +12,6 @@ fun test() {
     v1({}, {})
     <!INAPPLICABLE_CANDIDATE!>v1<!>({}, 1, {})
     v1({}, {}, {it})
-    <!INAPPLICABLE_CANDIDATE!>v1<!>({}) {}
+    v1({}) <!VARARG_OUTSIDE_PARENTHESES!>{}<!>
-    <!INAPPLICABLE_CANDIDATE!>v1<!> {}
+    v1 <!VARARG_OUTSIDE_PARENTHESES!>{}<!>
 }

compiler/testData/diagnostics/tests/resolve/newLineLambda.fir.kt

@@ -69,23 +69,23 @@ fun testLambdaArg() {
 
 fun testVararg() {
     varargFn(1,2,3)
-    <!INAPPLICABLE_CANDIDATE!>varargFn<!> {}
+    varargFn <!VARARG_OUTSIDE_PARENTHESES!>{}<!>
-    <!INAPPLICABLE_CANDIDATE!>varargFn<!>(1,2,3) {}
+    varargFn(1,2,3) <!VARARG_OUTSIDE_PARENTHESES!>{}<!>
     varargFn(1,2,3) // {}
-    <!INAPPLICABLE_CANDIDATE!>varargFn<!>(1,2,3) /* */ {}
+    varargFn(1,2,3) /* */ <!VARARG_OUTSIDE_PARENTHESES!>{}<!>
-    <!INAPPLICABLE_CANDIDATE!>varargFn<!>(1,2,3) /*
+    varargFn(1,2,3) /*
         block comment, no new line
-    */ {}
+    */ <!VARARG_OUTSIDE_PARENTHESES!>{}<!>
-    <!INAPPLICABLE_CANDIDATE!>varargFn<!>(1,2,3)
+    varargFn(1,2,3)
     /*
         block comment with new line
-    */ {}
+    */ <!VARARG_OUTSIDE_PARENTHESES!>{}<!>
-    <!INAPPLICABLE_CANDIDATE!>varargFn<!>(1,2,3) // comment
+    varargFn(1,2,3) // comment
     // comment
-    {}
+    <!VARARG_OUTSIDE_PARENTHESES!>{}<!>
-    <!INAPPLICABLE_CANDIDATE!>varargFn<!>(1,2,3) {} {}
+    varargFn(1,2,3) {} <!VARARG_OUTSIDE_PARENTHESES!>{}<!>
-    <!INAPPLICABLE_CANDIDATE!>varargFn<!>(1,2,3) {}
+    varargFn(1,2,3) {}
-    {}
+    <!VARARG_OUTSIDE_PARENTHESES!>{}<!>
 }
 
 fun testTwoLambdas() {

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

@@ -24,6 +24,7 @@ import org.jetbrains.kotlin.psi.KtFunction
 import org.jetbrains.kotlin.psi.KtIfExpression
 import org.jetbrains.kotlin.psi.KtModifierListOwner
 import org.jetbrains.kotlin.psi.KtNamedDeclaration
+import org.jetbrains.kotlin.psi.KtObjectDeclaration
 import org.jetbrains.kotlin.psi.KtParameter
 import org.jetbrains.kotlin.psi.KtProperty
 import org.jetbrains.kotlin.psi.KtPropertyAccessor
@@ -539,6 +540,12 @@ internal val KT_DIAGNOSTIC_CONVERTER = KtDiagnosticConverterBuilder.buildConvert
             token,
         )
     }
+    add(FirErrors.VARARG_OUTSIDE_PARENTHESES) { firDiagnostic ->
+        VarargOutsideParenthesesImpl(
+            firDiagnostic as FirPsiDiagnostic<*>,
+            token,
+        )
+    }
     add(FirErrors.AMBIGUITY) { firDiagnostic ->
         AmbiguityImpl(
             firDiagnostic.a.map { abstractFirBasedSymbol ->

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

@@ -28,6 +28,7 @@ import org.jetbrains.kotlin.psi.KtFunction
 import org.jetbrains.kotlin.psi.KtIfExpression
 import org.jetbrains.kotlin.psi.KtModifierListOwner
 import org.jetbrains.kotlin.psi.KtNamedDeclaration
+import org.jetbrains.kotlin.psi.KtObjectDeclaration
 import org.jetbrains.kotlin.psi.KtParameter
 import org.jetbrains.kotlin.psi.KtProperty
 import org.jetbrains.kotlin.psi.KtPropertyAccessor
@@ -389,6 +390,10 @@ sealed class KtFirDiagnostic<PSI: PsiElement> : KtDiagnosticWithPsi<PSI> {
         abstract val reason: String
     }
 
+    abstract class VarargOutsideParentheses : KtFirDiagnostic<KtExpression>() {
+        override val diagnosticClass get() = VarargOutsideParentheses::class
+    }
+
     abstract class Ambiguity : KtFirDiagnostic<PsiElement>() {
         override val diagnosticClass get() = Ambiguity::class
         abstract val candidates: List<KtSymbol>
@@ -535,7 +540,7 @@ sealed class KtFirDiagnostic<PSI: PsiElement> : KtDiagnosticWithPsi<PSI> {
         override val diagnosticClass get() = NonFinalMemberInObject::class
     }
 
-    abstract class ManyCompanionObjects : KtFirDiagnostic<PsiElement>() {
+    abstract class ManyCompanionObjects : KtFirDiagnostic<KtObjectDeclaration>() {
         override val diagnosticClass get() = ManyCompanionObjects::class
     }
 

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

@@ -30,6 +30,7 @@ import org.jetbrains.kotlin.psi.KtFunction
 import org.jetbrains.kotlin.psi.KtIfExpression
 import org.jetbrains.kotlin.psi.KtModifierListOwner
 import org.jetbrains.kotlin.psi.KtNamedDeclaration
+import org.jetbrains.kotlin.psi.KtObjectDeclaration
 import org.jetbrains.kotlin.psi.KtParameter
 import org.jetbrains.kotlin.psi.KtProperty
 import org.jetbrains.kotlin.psi.KtPropertyAccessor
@@ -618,6 +619,13 @@ internal class InapplicableLateinitModifierImpl(
     override val firDiagnostic: FirPsiDiagnostic<*> by weakRef(firDiagnostic)
 }
 
+internal class VarargOutsideParenthesesImpl(
+    firDiagnostic: FirPsiDiagnostic<*>,
+    override val token: ValidityToken,
+) : KtFirDiagnostic.VarargOutsideParentheses(), KtAbstractFirDiagnostic<KtExpression> {
+    override val firDiagnostic: FirPsiDiagnostic<*> by weakRef(firDiagnostic)
+}
+
 internal class AmbiguityImpl(
     override val candidates: List<KtSymbol>,
     firDiagnostic: FirPsiDiagnostic<*>,
@@ -857,7 +865,7 @@ internal class NonFinalMemberInObjectImpl(
 internal class ManyCompanionObjectsImpl(
     firDiagnostic: FirPsiDiagnostic<*>,
     override val token: ValidityToken,
-) : KtFirDiagnostic.ManyCompanionObjects(), KtAbstractFirDiagnostic<PsiElement> {
+) : KtFirDiagnostic.ManyCompanionObjects(), KtAbstractFirDiagnostic<KtObjectDeclaration> {
     override val firDiagnostic: FirPsiDiagnostic<*> by weakRef(firDiagnostic)
 }