[JS FIR] Rework JS_NAME_CLASH diagnostic for constructors

- Fix a false positive JS_NAME_CLASH report on constructors
   from different classes but with the same JsName.
 - Allow the same JsName for class constructors and other top-level
   declarations. This behavior differs from K1, but it is correct
   since there is no real name clash in the generated JS code.

^KT-64867 Fixed

compiler/fir/checkers/checkers.js/src/org/jetbrains/kotlin/fir/analysis/js/checkers/declaration/FirJsNameClashClassMembersChecker.kt

@@ -17,6 +17,7 @@ import org.jetbrains.kotlin.fir.analysis.js.checkers.FirJsStableName
 import org.jetbrains.kotlin.fir.declarations.FirClass
 import org.jetbrains.kotlin.fir.declarations.FirClassLikeDeclaration
 import org.jetbrains.kotlin.fir.declarations.FirDeclarationOrigin
+import org.jetbrains.kotlin.fir.declarations.constructors
 import org.jetbrains.kotlin.fir.declarations.utils.isFinal
 import org.jetbrains.kotlin.fir.scopes.*
 import org.jetbrains.kotlin.fir.symbols.FirBasedSymbol
@@ -118,6 +119,7 @@ object FirJsNameClashClassMembersChecker : FirClassChecker() {
 
             val scope = declaration.symbol.unsubstitutedScope(context)
 
+            scope.processDeclaredConstructors(allSymbols::add)
             addAllSymbolsFrom(scope.collectAllFunctions())
             addAllSymbolsFrom(scope.collectAllProperties())
 

compiler/fir/checkers/checkers.js/src/org/jetbrains/kotlin/fir/analysis/js/checkers/declaration/FirJsNameClashFileTopLevelDeclarationsChecker.kt

@@ -35,11 +35,6 @@ object FirJsNameClashFileTopLevelDeclarationsChecker : FirFileChecker() {
         val topLevelDeclarationsWithStableName = mutableMapOf<String, MutableList<FirJsStableName>>()
         for (topLevelDeclaration in declaration.declarations) {
             topLevelDeclarationsWithStableName.addStableName(topLevelDeclaration.symbol, context)
-            if (topLevelDeclaration is FirClass) {
-                for (classConstructor in topLevelDeclaration.constructors(context.session)) {
-                    topLevelDeclarationsWithStableName.addStableName(classConstructor, context)
-                }
-            }
         }
         for ((name, stableNames) in topLevelDeclarationsWithStableName.entries) {
             for (symbol in stableNames) {

compiler/testData/diagnostics/testsWithJsStdLib/name/topLevelMethodAndJsNameConstructor.fir.kt

@@ -0,0 +1,11 @@
+// FIR_DIFFERENCE
+// K1 performs a check for legacy JS BE; however, this is not relevant for IR BE because in the generated JS code,
+// there is no name clash between the constructor with JsName and the other top-level declarations with the same JsName.
+// Keep K1 as it is, but for K2, implement a more relevant check without the clash.
+package foo
+
+class A(val x: String) {
+    @JsName("aa") constructor(x: Int) : this("int $x")
+}
+
+fun aa() {}

compiler/testData/diagnostics/testsWithJsStdLib/name/topLevelMethodAndJsNameConstructor.kt

@@ -1,4 +1,7 @@
-// FIR_IDENTICAL
+// FIR_DIFFERENCE
+// K1 performs a check for legacy JS BE; however, this is not relevant for IR BE because in the generated JS code,
+// there is no name clash between the constructor with JsName and the other top-level declarations with the same JsName.
+// Keep K1 as it is, but for K2, implement a more relevant check without the clash.
 package foo
 
 class A(val x: String) {