FIR: fix API mode checker for local functions

analysis/low-level-api-fir/tests/org/jetbrains/kotlin/analysis/low/level/api/fir/diagnostic/compiler/based/DiagnosisCompilerTestFE10TestdataTestGenerated.java

@@ -30261,6 +30261,12 @@ public class DiagnosisCompilerTestFE10TestdataTestGenerated extends AbstractDiag
                 runTest("compiler/testData/diagnostics/tests/testsWithExplicitApi/interfaces.kt");
             }
 
+            @Test
+            @TestMetadata("localFunctions.kt")
+            public void testLocalFunctions() throws Exception {
+                runTest("compiler/testData/diagnostics/tests/testsWithExplicitApi/localFunctions.kt");
+            }
+
             @Test
             @TestMetadata("mustBeEffectivelyPublic.kt")
             public void testMustBeEffectivelyPublic() throws Exception {

compiler/fir/analysis-tests/tests-gen/org/jetbrains/kotlin/test/runners/FirOldFrontendDiagnosticsTestGenerated.java

@@ -30261,6 +30261,12 @@ public class FirOldFrontendDiagnosticsTestGenerated extends AbstractFirDiagnosti
                 runTest("compiler/testData/diagnostics/tests/testsWithExplicitApi/interfaces.kt");
             }
 
+            @Test
+            @TestMetadata("localFunctions.kt")
+            public void testLocalFunctions() throws Exception {
+                runTest("compiler/testData/diagnostics/tests/testsWithExplicitApi/localFunctions.kt");
+            }
+
             @Test
             @TestMetadata("mustBeEffectivelyPublic.kt")
             public void testMustBeEffectivelyPublic() throws Exception {

compiler/fir/analysis-tests/tests-gen/org/jetbrains/kotlin/test/runners/FirOldFrontendDiagnosticsWithLightTreeTestGenerated.java

@@ -30261,6 +30261,12 @@ public class FirOldFrontendDiagnosticsWithLightTreeTestGenerated extends Abstrac
                 runTest("compiler/testData/diagnostics/tests/testsWithExplicitApi/interfaces.kt");
             }
 
+            @Test
+            @TestMetadata("localFunctions.kt")
+            public void testLocalFunctions() throws Exception {
+                runTest("compiler/testData/diagnostics/tests/testsWithExplicitApi/localFunctions.kt");
+            }
+
             @Test
             @TestMetadata("mustBeEffectivelyPublic.kt")
             public void testMustBeEffectivelyPublic() throws Exception {

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

@@ -386,7 +386,7 @@ object DIAGNOSTICS_LIST : DiagnosticList("FirErrors") {
             parameter<String>("message")
         }
 
-        val NO_EXPLICIT_VISIBILITY_IN_API_MODE by warning<KtDeclaration>(PositioningStrategy.DECLARATION_START_TO_NAME)
+        val NO_EXPLICIT_VISIBILITY_IN_API_MODE by error<KtDeclaration>(PositioningStrategy.DECLARATION_START_TO_NAME)
         val NO_EXPLICIT_VISIBILITY_IN_API_MODE_WARNING by warning<KtDeclaration>(PositioningStrategy.DECLARATION_START_TO_NAME)
 
         val NO_EXPLICIT_RETURN_TYPE_IN_API_MODE by error<KtDeclaration>(PositioningStrategy.DECLARATION_NAME)

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

@@ -288,7 +288,7 @@ object FirErrors {
     val WRONG_MODIFIER_CONTAINING_DECLARATION by error2<PsiElement, KtModifierKeywordToken, String>()
     val DEPRECATED_MODIFIER_CONTAINING_DECLARATION by warning2<PsiElement, KtModifierKeywordToken, String>()
     val INAPPLICABLE_OPERATOR_MODIFIER by error1<PsiElement, String>(SourceElementPositioningStrategies.OPERATOR_MODIFIER)
-    val NO_EXPLICIT_VISIBILITY_IN_API_MODE by warning0<KtDeclaration>(SourceElementPositioningStrategies.DECLARATION_START_TO_NAME)
+    val NO_EXPLICIT_VISIBILITY_IN_API_MODE by error0<KtDeclaration>(SourceElementPositioningStrategies.DECLARATION_START_TO_NAME)
     val NO_EXPLICIT_VISIBILITY_IN_API_MODE_WARNING by warning0<KtDeclaration>(SourceElementPositioningStrategies.DECLARATION_START_TO_NAME)
     val NO_EXPLICIT_RETURN_TYPE_IN_API_MODE by error0<KtDeclaration>(SourceElementPositioningStrategies.DECLARATION_NAME)
     val NO_EXPLICIT_RETURN_TYPE_IN_API_MODE_WARNING by warning0<KtDeclaration>(SourceElementPositioningStrategies.DECLARATION_NAME)

compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/syntax/FirExplicitApiDeclarationChecker.kt

@@ -76,6 +76,8 @@ object FirExplicitApiDeclarationChecker : FirDeclarationSyntaxChecker<FirDeclara
      * 4. Getters and setters (because getters can't change visibility and setter-only explicit visibility looks ugly)
      * 5. Properties of annotations in public API
      * 6. Value parameter declaration
+     * 7. An anonymous function
+     * 8. A local named function
      *
      * TODO: Do we need something like @PublicApiFile to disable (or invert) this inspection per-file?
      */
@@ -86,7 +88,9 @@ object FirExplicitApiDeclarationChecker : FirDeclarationSyntaxChecker<FirDeclara
             // 4
             is FirPropertyAccessor,
             // 6
-            is FirValueParameter -> true
+            is FirValueParameter,
+            // 7
+            is FirAnonymousFunction -> true
             is FirCallableDeclaration -> {
                 val containingClass = context.containingDeclarations.lastOrNull() as? FirRegularClass
                 // 2, 5
@@ -97,8 +101,8 @@ object FirExplicitApiDeclarationChecker : FirDeclarationSyntaxChecker<FirDeclara
                     return true
                 }
 
-                // 3
+                // 3, 8
-                declaration.isOverride
+                declaration.isOverride || declaration.isLocalMember
             }
             else -> false
         }

compiler/testData/diagnostics/tests/testsWithExplicitApi/localFunctions.kt

@@ -0,0 +1,18 @@
+// FIR_IDENTICAL
+<!NO_EXPLICIT_VISIBILITY_IN_API_MODE!>fun run<!>(b: () -> Unit) {}
+
+<!NO_EXPLICIT_VISIBILITY_IN_API_MODE!>fun test<!>() {
+    run {
+
+    }
+
+    fun localFun() {}
+    localFun()
+    run(::localFun)
+
+    val localFun2 = fun() {}
+    run(localFun2)
+
+    val lambda = {}
+    run(lambda)
+}

compiler/testData/diagnostics/tests/testsWithExplicitApi/localFunctions.txt

@@ -0,0 +1,4 @@
+package
+
+public fun run(/*0*/ b: () -> kotlin.Unit): kotlin.Unit
+public fun test(): kotlin.Unit

compiler/tests-common-new/tests-gen/org/jetbrains/kotlin/test/runners/DiagnosticTestGenerated.java

@@ -30357,6 +30357,12 @@ public class DiagnosticTestGenerated extends AbstractDiagnosticTest {
                 runTest("compiler/testData/diagnostics/tests/testsWithExplicitApi/interfaces.kt");
             }
 
+            @Test
+            @TestMetadata("localFunctions.kt")
+            public void testLocalFunctions() throws Exception {
+                runTest("compiler/testData/diagnostics/tests/testsWithExplicitApi/localFunctions.kt");
+            }
+
             @Test
             @TestMetadata("mustBeEffectivelyPublic.kt")
             public void testMustBeEffectivelyPublic() throws Exception {