K2: drop obsolete TODO about multiple WasExperimental

In certain situations like constructor calls, it's possible
to have different WasExperimental/SinceKotlin pairs associated
with one use-site, e.g. a constructor call is associated both
with a constructor declaration and a class declaration.
However, looks like it make no sense to handle this situation
in FirSinceKotlinHelpers, because FirOptInUsageBaseChecker already
handles them.

#KT-59825 Fixed

analysis/low-level-api-fir/tests/org/jetbrains/kotlin/analysis/low/level/api/fir/diagnostic/compiler/based/DiagnosticCompilerTestFE10TestdataTestGenerated.java

@@ -43118,6 +43118,12 @@ public class DiagnosticCompilerTestFE10TestdataTestGenerated extends AbstractDia
                 runTest("compiler/testData/diagnostics/testsWithStdLib/experimental/wasExperimental.kt");
             }
 
+            @Test
+            @TestMetadata("wasExperimentalCombined.kt")
+            public void testWasExperimentalCombined() throws Exception {
+                runTest("compiler/testData/diagnostics/testsWithStdLib/experimental/wasExperimentalCombined.kt");
+            }
+
             @Test
             @TestMetadata("wrongTargetsWithoutExplicitTarget.kt")
             public void testWrongTargetsWithoutExplicitTarget() throws Exception {

analysis/low-level-api-fir/tests/org/jetbrains/kotlin/analysis/low/level/api/fir/diagnostic/compiler/based/LLFirPreresolvedReversedDiagnosticCompilerFE10TestDataTestGenerated.java

@@ -43118,6 +43118,12 @@ public class LLFirPreresolvedReversedDiagnosticCompilerFE10TestDataTestGenerated
                 runTest("compiler/testData/diagnostics/testsWithStdLib/experimental/wasExperimental.kt");
             }
 
+            @Test
+            @TestMetadata("wasExperimentalCombined.kt")
+            public void testWasExperimentalCombined() throws Exception {
+                runTest("compiler/testData/diagnostics/testsWithStdLib/experimental/wasExperimentalCombined.kt");
+            }
+
             @Test
             @TestMetadata("wrongTargetsWithoutExplicitTarget.kt")
             public void testWrongTargetsWithoutExplicitTarget() throws Exception {

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

@@ -40998,6 +40998,12 @@ public class FirLightTreeOldFrontendDiagnosticsTestGenerated extends AbstractFir
                 runTest("compiler/testData/diagnostics/testsWithStdLib/experimental/wasExperimental.kt");
             }
 
+            @Test
+            @TestMetadata("wasExperimentalCombined.kt")
+            public void testWasExperimentalCombined() throws Exception {
+                runTest("compiler/testData/diagnostics/testsWithStdLib/experimental/wasExperimentalCombined.kt");
+            }
+
             @Test
             @TestMetadata("wrongTargetsWithoutExplicitTarget.kt")
             public void testWrongTargetsWithoutExplicitTarget() throws Exception {

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

@@ -41118,6 +41118,12 @@ public class FirPsiOldFrontendDiagnosticsTestGenerated extends AbstractFirPsiDia
                 runTest("compiler/testData/diagnostics/testsWithStdLib/experimental/wasExperimental.kt");
             }
 
+            @Test
+            @TestMetadata("wasExperimentalCombined.kt")
+            public void testWasExperimentalCombined() throws Exception {
+                runTest("compiler/testData/diagnostics/testsWithStdLib/experimental/wasExperimentalCombined.kt");
+            }
+
             @Test
             @TestMetadata("wrongTargetsWithoutExplicitTarget.kt")
             public void testWrongTargetsWithoutExplicitTarget() throws Exception {

compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/FirSinceKotlinHelpers.kt

@@ -68,7 +68,6 @@ private fun FirDeclaration.getOwnSinceKotlinVersion(session: FirSession): FirSin
         )
         val apiVersion = ((sinceKotlinSingleArgument as? FirConstExpression<*>)?.value as? String)?.let(ApiVersion.Companion::parse)
         if (apiVersion != null) {
-            // TODO, KT-59825: combine wasExperimentalMarkerClasses in case of several associated declarations with the same maximal API version
             if (result == null || apiVersion > result!!.apiVersion) {
                 result = FirSinceKotlinValue(apiVersion, loadWasExperimentalMarkerClasses(session))
             }

compiler/testData/diagnostics/testsWithStdLib/experimental/wasExperimentalCombined.fir.kt

@@ -0,0 +1,52 @@
+// API_VERSION: 1.8
+// !DIAGNOSTICS: -INVISIBLE_MEMBER -INVISIBLE_REFERENCE
+
+@RequiresOptIn
+@Retention(AnnotationRetention.BINARY)
+annotation class ClassMarker
+
+@RequiresOptIn
+@Retention(AnnotationRetention.BINARY)
+annotation class ConstructorMarker
+
+@RequiresOptIn
+@Retention(AnnotationRetention.BINARY)
+annotation class TypeAliasMarker
+
+@SinceKotlin("1.9")
+@WasExperimental(ClassMarker::class)
+class C {
+    @SinceKotlin("1.9")
+    @WasExperimental(ConstructorMarker::class)
+    constructor() {}
+}
+
+@SinceKotlin("1.9")
+@WasExperimental(TypeAliasMarker::class)
+typealias T = <!OPT_IN_USAGE_ERROR!>C<!>
+
+@ClassMarker
+fun test1() {
+    <!OPT_IN_USAGE_ERROR!>C<!>()
+}
+
+@ConstructorMarker
+fun test2() {
+    <!OPT_IN_USAGE_ERROR!>C<!>()
+}
+
+@ClassMarker
+@ConstructorMarker
+fun test3() {
+    C()
+}
+
+@ClassMarker
+fun test4(t: <!OPT_IN_USAGE_ERROR!>T<!>) {}
+
+@TypeAliasMarker
+fun test5(t: <!OPT_IN_USAGE_ERROR!>T<!>) {}
+
+@ClassMarker
+@TypeAliasMarker
+fun test6(t: T) {}

compiler/testData/diagnostics/testsWithStdLib/experimental/wasExperimentalCombined.kt

@@ -0,0 +1,52 @@
+// API_VERSION: 1.8
+// !DIAGNOSTICS: -INVISIBLE_MEMBER -INVISIBLE_REFERENCE
+
+@RequiresOptIn
+@Retention(AnnotationRetention.BINARY)
+annotation class ClassMarker
+
+@RequiresOptIn
+@Retention(AnnotationRetention.BINARY)
+annotation class ConstructorMarker
+
+@RequiresOptIn
+@Retention(AnnotationRetention.BINARY)
+annotation class TypeAliasMarker
+
+@SinceKotlin("1.9")
+@WasExperimental(ClassMarker::class)
+class C {
+    @SinceKotlin("1.9")
+    @WasExperimental(ConstructorMarker::class)
+    constructor() {}
+}
+
+@SinceKotlin("1.9")
+@WasExperimental(TypeAliasMarker::class)
+typealias T = <!OPT_IN_USAGE_ERROR!>C<!>
+
+@ClassMarker
+fun test1() {
+    <!UNRESOLVED_REFERENCE!>C<!>()
+}
+
+@ConstructorMarker
+fun test2() {
+    <!OPT_IN_USAGE_ERROR!>C<!>()
+}
+
+@ClassMarker
+@ConstructorMarker
+fun test3() {
+    C()
+}
+
+@ClassMarker
+fun test4(t: <!OPT_IN_USAGE_ERROR!>T<!>) {}
+
+@TypeAliasMarker
+fun test5(t: <!OPT_IN_USAGE_ERROR!>T<!>) {}
+
+@ClassMarker
+@TypeAliasMarker
+fun test6(t: T) {}

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

@@ -43112,6 +43112,12 @@ public class DiagnosticTestGenerated extends AbstractDiagnosticTest {
                 runTest("compiler/testData/diagnostics/testsWithStdLib/experimental/wasExperimental.kt");
             }
 
+            @Test
+            @TestMetadata("wasExperimentalCombined.kt")
+            public void testWasExperimentalCombined() throws Exception {
+                runTest("compiler/testData/diagnostics/testsWithStdLib/experimental/wasExperimentalCombined.kt");
+            }
+
             @Test
             @TestMetadata("wrongTargetsWithoutExplicitTarget.kt")
             public void testWrongTargetsWithoutExplicitTarget() throws Exception {