FIR: Make 'suspend fun', where 'suspend' is not builtin error in 1.8

#KT-49264

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

@@ -3872,6 +3872,18 @@ internal val KT_DIAGNOSTIC_CONVERTER = KtDiagnosticConverterBuilder.buildConvert
             token,
         )
     }
+    add(FirErrors.MODIFIER_FORM_FOR_NON_BUILT_IN_SUSPEND_FUN.errorFactory) { firDiagnostic ->
+        ModifierFormForNonBuiltInSuspendFunErrorImpl(
+            firDiagnostic as KtPsiDiagnostic,
+            token,
+        )
+    }
+    add(FirErrors.MODIFIER_FORM_FOR_NON_BUILT_IN_SUSPEND_FUN.warningFactory) { firDiagnostic ->
+        ModifierFormForNonBuiltInSuspendFunWarningImpl(
+            firDiagnostic as KtPsiDiagnostic,
+            token,
+        )
+    }
     add(FirErrors.RETURN_FOR_BUILT_IN_SUSPEND) { firDiagnostic ->
         ReturnForBuiltInSuspendImpl(
             firDiagnostic as KtPsiDiagnostic,

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

@@ -2699,6 +2699,14 @@ sealed class KtFirDiagnostic<PSI : PsiElement> : KtDiagnosticWithPsi<PSI> {
         override val diagnosticClass get() = ModifierFormForNonBuiltInSuspend::class
     }
 
+    abstract class ModifierFormForNonBuiltInSuspendFunError : KtFirDiagnostic<PsiElement>() {
+        override val diagnosticClass get() = ModifierFormForNonBuiltInSuspendFunError::class
+    }
+
+    abstract class ModifierFormForNonBuiltInSuspendFunWarning : KtFirDiagnostic<PsiElement>() {
+        override val diagnosticClass get() = ModifierFormForNonBuiltInSuspendFunWarning::class
+    }
+
     abstract class ReturnForBuiltInSuspend : KtFirDiagnostic<KtReturnExpression>() {
         override val diagnosticClass get() = ReturnForBuiltInSuspend::class
     }

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

@@ -3256,6 +3256,16 @@ internal class ModifierFormForNonBuiltInSuspendImpl(
     override val token: ValidityToken,
 ) : KtFirDiagnostic.ModifierFormForNonBuiltInSuspend(), KtAbstractFirDiagnostic<PsiElement>
 
+internal class ModifierFormForNonBuiltInSuspendFunErrorImpl(
+    override val firDiagnostic: KtPsiDiagnostic,
+    override val token: ValidityToken,
+) : KtFirDiagnostic.ModifierFormForNonBuiltInSuspendFunError(), KtAbstractFirDiagnostic<PsiElement>
+
+internal class ModifierFormForNonBuiltInSuspendFunWarningImpl(
+    override val firDiagnostic: KtPsiDiagnostic,
+    override val token: ValidityToken,
+) : KtFirDiagnostic.ModifierFormForNonBuiltInSuspendFunWarning(), KtAbstractFirDiagnostic<PsiElement>
+
 internal class ReturnForBuiltInSuspendImpl(
     override val firDiagnostic: KtPsiDiagnostic,
     override val token: ValidityToken,

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

@@ -1399,6 +1399,9 @@ object DIAGNOSTICS_LIST : DiagnosticList("FirErrors") {
         val ILLEGAL_RESTRICTED_SUSPENDING_FUNCTION_CALL by error<PsiElement>(PositioningStrategy.REFERENCED_NAME_BY_QUALIFIED)
         val NON_MODIFIER_FORM_FOR_BUILT_IN_SUSPEND by error<PsiElement>(PositioningStrategy.REFERENCED_NAME_BY_QUALIFIED)
         val MODIFIER_FORM_FOR_NON_BUILT_IN_SUSPEND by error<PsiElement>(PositioningStrategy.REFERENCED_NAME_BY_QUALIFIED)
+        val MODIFIER_FORM_FOR_NON_BUILT_IN_SUSPEND_FUN by deprecationError<PsiElement>(
+            LanguageFeature.ModifierNonBuiltinSuspendFunError, PositioningStrategy.REFERENCED_NAME_BY_QUALIFIED
+        )
         val RETURN_FOR_BUILT_IN_SUSPEND by error<KtReturnExpression>()
     }
 

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

@@ -11,6 +11,7 @@ import org.jetbrains.kotlin.KtSourceElement
 import org.jetbrains.kotlin.config.LanguageFeature
 import org.jetbrains.kotlin.config.LanguageFeature.ForbidExposingTypesInPrimaryConstructorProperties
 import org.jetbrains.kotlin.config.LanguageFeature.ForbidUsingExtensionPropertyTypeParameterInDelegate
+import org.jetbrains.kotlin.config.LanguageFeature.ModifierNonBuiltinSuspendFunError
 import org.jetbrains.kotlin.config.LanguageFeature.ProhibitAssigningSingleElementsToVarargsInNamedForm
 import org.jetbrains.kotlin.config.LanguageFeature.ProhibitConfusingSyntaxInWhenBranches
 import org.jetbrains.kotlin.config.LanguageFeature.ProhibitCyclesInAnnotations
@@ -726,6 +727,7 @@ object FirErrors {
     val ILLEGAL_RESTRICTED_SUSPENDING_FUNCTION_CALL by error0<PsiElement>(SourceElementPositioningStrategies.REFERENCED_NAME_BY_QUALIFIED)
     val NON_MODIFIER_FORM_FOR_BUILT_IN_SUSPEND by error0<PsiElement>(SourceElementPositioningStrategies.REFERENCED_NAME_BY_QUALIFIED)
     val MODIFIER_FORM_FOR_NON_BUILT_IN_SUSPEND by error0<PsiElement>(SourceElementPositioningStrategies.REFERENCED_NAME_BY_QUALIFIED)
+    val MODIFIER_FORM_FOR_NON_BUILT_IN_SUSPEND_FUN by deprecationError0<PsiElement>(ModifierNonBuiltinSuspendFunError, SourceElementPositioningStrategies.REFERENCED_NAME_BY_QUALIFIED)
     val RETURN_FOR_BUILT_IN_SUSPEND by error0<KtReturnExpression>()
 
     // label

compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/expression/FirSuspendCallChecker.kt

@@ -6,6 +6,7 @@
 package org.jetbrains.kotlin.fir.analysis.checkers.expression
 
 import org.jetbrains.kotlin.KtNodeTypes
+import org.jetbrains.kotlin.config.LanguageFeature
 import org.jetbrains.kotlin.fir.FirSession
 import org.jetbrains.kotlin.fir.analysis.checkers.context.CheckerContext
 import org.jetbrains.kotlin.diagnostics.DiagnosticReporter
@@ -30,8 +31,12 @@ import org.jetbrains.kotlin.fir.symbols.impl.FirCallableSymbol
 import org.jetbrains.kotlin.fir.symbols.impl.FirNamedFunctionSymbol
 import org.jetbrains.kotlin.fir.symbols.impl.FirPropertySymbol
 import org.jetbrains.kotlin.fir.types.*
+import org.jetbrains.kotlin.lexer.KtTokens
 import org.jetbrains.kotlin.name.CallableId
 import org.jetbrains.kotlin.name.StandardClassIds
+import org.jetbrains.kotlin.psi
+import org.jetbrains.kotlin.psi.KtNamedFunction
+import org.jetbrains.kotlin.psi.stubs.elements.KtStubElementTypes
 import org.jetbrains.kotlin.utils.addToStdlib.lastIsInstanceOrNull
 
 object FirSuspendCallChecker : FirQualifiedAccessExpressionChecker() {
@@ -81,38 +86,50 @@ object FirSuspendCallChecker : FirQualifiedAccessExpressionChecker() {
         if (symbol.callableId == KOTLIN_SUSPEND_BUILT_IN_FUNCTION_CALLABLE_ID) {
             if (reference.name != BUILTIN_SUSPEND_NAME ||
                 expression.explicitReceiver != null ||
-                !expression.hasFormOfSuspendModifierForLambda()
+                expression.formOfSuspendModifierForLambdaOrFun() == null
             ) {
                 reporter.reportOn(expression.source, FirErrors.NON_MODIFIER_FORM_FOR_BUILT_IN_SUSPEND, context)
             }
-        } else {
+        } else if (reference.name == BUILTIN_SUSPEND_NAME) {
-            if (reference.name == BUILTIN_SUSPEND_NAME && expression.hasFormOfSuspendModifierForLambda()) {
+            when (expression.formOfSuspendModifierForLambdaOrFun()) {
-                reporter.reportOn(expression.source, FirErrors.MODIFIER_FORM_FOR_NON_BUILT_IN_SUSPEND, context)
+                SuspendCallArgumentKind.FUN -> {
+                    reporter.reportOn(expression.source, FirErrors.MODIFIER_FORM_FOR_NON_BUILT_IN_SUSPEND_FUN, context)
+                }
+                SuspendCallArgumentKind.LAMBDA -> {
+                    reporter.reportOn(expression.source, FirErrors.MODIFIER_FORM_FOR_NON_BUILT_IN_SUSPEND, context)
+                }
+                null -> {
+                    // Nothing to do
+                }
             }
         }
     }
 
-    private fun FirQualifiedAccessExpression.hasFormOfSuspendModifierForLambda(): Boolean {
+    private fun FirQualifiedAccessExpression.formOfSuspendModifierForLambdaOrFun(): SuspendCallArgumentKind? {
-        if (this !is FirFunctionCall) return false
+        if (this !is FirFunctionCall) return null
         val reference = this.calleeReference
-        if (reference is FirResolvedCallableReference) return false
+        if (reference is FirResolvedCallableReference) return null
-        if (typeArguments.any { it.source != null }) return false
+        if (typeArguments.any { it.source != null }) return null
         if (arguments.singleOrNull() is FirLambdaArgumentExpression) {
             // No brackets should be in a selector call
             val callExpressionSource =
                 if (explicitReceiver == null) source
                 else source?.getChild(KtNodeTypes.CALL_EXPRESSION, index = 1, depth = 1)
             if (callExpressionSource?.getChild(KtNodeTypes.VALUE_ARGUMENT_LIST, depth = 1) == null) {
-                return true
+                return SuspendCallArgumentKind.LAMBDA
             }
         }
         if (origin == FirFunctionCallOrigin.Infix) {
             val lastArgument = arguments.lastOrNull()
             if (lastArgument is FirAnonymousFunctionExpression && source?.getChild(KtNodeTypes.PARENTHESIZED, depth = 1) == null) {
-                return true
+                return if (lastArgument.source?.lighterASTNode?.tokenType == KtStubElementTypes.FUNCTION) {
+                    SuspendCallArgumentKind.FUN
+                } else {
+                    SuspendCallArgumentKind.LAMBDA
+                }
             }
         }
-        return false
+        return null
     }
 
     private fun findEnclosingSuspendFunction(context: CheckerContext): FirFunction? {
@@ -228,3 +245,7 @@ object FirSuspendCallChecker : FirQualifiedAccessExpressionChecker() {
         )
     }
 }
+
+private enum class SuspendCallArgumentKind {
+    FUN, LAMBDA
+}

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

@@ -296,6 +296,7 @@ import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.MISSING_STDLIB_CL
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.MISSING_VAL_ON_ANNOTATION_PARAMETER
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.MODIFIER_FORM_FOR_NON_BUILT_IN_SUSPEND
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.MULTIPLE_ARGUMENTS_APPLICABLE_FOR_CONTEXT_RECEIVER
+import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.MODIFIER_FORM_FOR_NON_BUILT_IN_SUSPEND_FUN
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.MULTIPLE_VARARG_PARAMETERS
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.MUST_BE_INITIALIZED
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.MUST_BE_INITIALIZED_OR_BE_ABSTRACT
@@ -1987,6 +1988,10 @@ object FirErrorsDefaultMessages : BaseDiagnosticRendererFactory() {
             MODIFIER_FORM_FOR_NON_BUILT_IN_SUSPEND,
             "Calls having a form of ''suspend {}'' are deprecated because ''suspend'' in the context will have a meaning of a modifier. Add empty argument list to the call: ''suspend() { ... }''"
         )
+        map.put(
+            MODIFIER_FORM_FOR_NON_BUILT_IN_SUSPEND_FUN,
+            "Calls having a form of ''suspend fun'' are deprecated because ''suspend'' in the context will have a meaning of a modifier. Surround the argument of the call with parens: ''suspend(fun() { ... })''"
+        )
         map.put(RETURN_FOR_BUILT_IN_SUSPEND, "Using implicit label for this lambda is prohibited")
 
         // Label

compiler/testData/diagnostics/testsWithStdLib/coroutines/nonModifierFormForBuiltInWithFun.fir.kt

@@ -1,29 +0,0 @@
-// SKIP_TXT
-
-infix fun Int.suspend(c: () -> Unit) { c() }
-
-fun bar() {
-    1 <!MODIFIER_FORM_FOR_NON_BUILT_IN_SUSPEND!>suspend<!> fun() {
-        println()
-    }
-
-    1 <!SYNTAX!>@Ann suspend fun()<!> {
-        println()
-    }
-
-    1 <!MODIFIER_FORM_FOR_NON_BUILT_IN_SUSPEND!>suspend<!> @Ann fun() {
-        println()
-    }
-}
-
-@Target(AnnotationTarget.EXPRESSION)
-@Retention(AnnotationRetention.SOURCE)
-annotation class Ann
-
-fun main(suspend: WLambdaInvoke) {
-    1 <!MODIFIER_FORM_FOR_NON_BUILT_IN_SUSPEND!>suspend<!> fun() {}
-}
-
-class WLambdaInvoke {
-    operator fun Int.invoke(l: () -> Unit) {}
-}

compiler/testData/diagnostics/testsWithStdLib/coroutines/nonModifierFormForBuiltInWithFun.kt

@@ -1,3 +1,4 @@
+// FIR_IDENTICAL
 // SKIP_TXT
 
 infix fun Int.suspend(c: () -> Unit) { c() }