K2: add ACCIDENTAL_OVERRIDE_CLASH_BY_JVM_SIGNATURE for clashing functions

This diagnostic is reported on an explicitly-declared function which
overrides a regular Java function with the same signature as a hidden
one from the same scope.

#KT-64846 Fixed

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

@@ -5099,6 +5099,15 @@ internal val KT_DIAGNOSTIC_CONVERTER = KtDiagnosticConverterBuilder.buildConvert
             token,
         )
     }
+    add(FirJvmErrors.ACCIDENTAL_OVERRIDE_CLASH_BY_JVM_SIGNATURE) { firDiagnostic ->
+        AccidentalOverrideClashByJvmSignatureImpl(
+            firSymbolBuilder.functionLikeBuilder.buildFunctionSymbol(firDiagnostic.a),
+            firDiagnostic.b,
+            firSymbolBuilder.functionLikeBuilder.buildFunctionSymbol(firDiagnostic.c),
+            firDiagnostic as KtPsiDiagnostic,
+            token,
+        )
+    }
     add(FirJvmErrors.JAVA_TYPE_MISMATCH) { firDiagnostic ->
         JavaTypeMismatchImpl(
             firSymbolBuilder.typeBuilder.buildKtType(firDiagnostic.a),

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

@@ -3548,6 +3548,13 @@ sealed interface KtFirDiagnostic<PSI : PsiElement> : KtDiagnosticWithPsi<PSI> {
         val base: KtCallableSymbol
     }
 
+    interface AccidentalOverrideClashByJvmSignature : KtFirDiagnostic<KtNamedFunction> {
+        override val diagnosticClass get() = AccidentalOverrideClashByJvmSignature::class
+        val hidden: KtFunctionLikeSymbol
+        val overrideDescription: String
+        val regular: KtFunctionLikeSymbol
+    }
+
     interface JavaTypeMismatch : KtFirDiagnostic<KtExpression> {
         override val diagnosticClass get() = JavaTypeMismatch::class
         val expectedType: KtType

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

@@ -4281,6 +4281,14 @@ internal class WrongNullabilityForJavaOverrideImpl(
     token: KtLifetimeToken,
 ) : KtAbstractFirDiagnostic<PsiElement>(firDiagnostic, token), KtFirDiagnostic.WrongNullabilityForJavaOverride
 
+internal class AccidentalOverrideClashByJvmSignatureImpl(
+    override val hidden: KtFunctionLikeSymbol,
+    override val overrideDescription: String,
+    override val regular: KtFunctionLikeSymbol,
+    firDiagnostic: KtPsiDiagnostic,
+    token: KtLifetimeToken,
+) : KtAbstractFirDiagnostic<KtNamedFunction>(firDiagnostic, token), KtFirDiagnostic.AccidentalOverrideClashByJvmSignature
+
 internal class JavaTypeMismatchImpl(
     override val expectedType: KtType,
     override val actualType: KtType,