[FIR] Report conflicts for constructors of top-level classes

^KT-59880

compiler/fir/analysis-tests/testData/resolve/diagnostics/explicitDelegationCallRequired.kt

@@ -7,8 +7,8 @@ class B : A {
     constructor(z: String) : this()
 }
 
-<!SUPERTYPE_INITIALIZED_WITHOUT_PRIMARY_CONSTRUCTOR!>class C : A(20) {
-    <!EXPLICIT_DELEGATION_CALL_REQUIRED!>constructor()<!>
+<!SUPERTYPE_INITIALIZED_WITHOUT_PRIMARY_CONSTRUCTOR!>class <!CONFLICTING_OVERLOADS!>C<!> : A(20) {
+    <!CONFLICTING_OVERLOADS, EXPLICIT_DELEGATION_CALL_REQUIRED!>constructor()<!>
     constructor(z: String) : <!OVERLOAD_RESOLUTION_AMBIGUITY!>this<!>()
 }<!>
 

compiler/fir/analysis-tests/testData/resolve/diagnostics/supertypeInitializedWithoutPrimaryConstructor.kt

@@ -6,6 +6,6 @@ class D : <!NO_VALUE_FOR_PARAMETER, SUPERTYPE_NOT_INITIALIZED!>C<!>
 class E : C(10)
 class F() : C(10)
 
-<!SUPERTYPE_INITIALIZED_WITHOUT_PRIMARY_CONSTRUCTOR!>class G : C(10) {
-    constructor() : super(1)
+<!SUPERTYPE_INITIALIZED_WITHOUT_PRIMARY_CONSTRUCTOR!>class <!CONFLICTING_OVERLOADS!>G<!> : C(10) {
+    <!CONFLICTING_OVERLOADS!>constructor()<!> : super(1)
 }<!>

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

@@ -161,6 +161,19 @@ fun FirDeclarationCollector<FirBasedSymbol<*>>.collectClassMembers(klass: FirReg
         }
     }
 
+    // Constructors of nested classes
+    // are collected when checking the outer
+    // class: this is because they may clash
+    // with functions from this outer class,
+    // so we should avoid checking them twice.
+    if (context.isTopLevel) {
+        scope.processDeclaredConstructors {
+            if (it.isCollectable() && it.isVisibleInClass(klass)) {
+                collect(it, FirRedeclarationPresenter.represent(it, klass), functionDeclarations)
+            }
+        }
+    }
+
     val visitedProperties = mutableSetOf<FirVariableSymbol<*>>()
 
     scope.collectLeafProperties().forEach {

compiler/testData/diagnostics/tests/secondaryConstructors/headerSupertypeInitialization.fir.kt

@@ -1,5 +1,5 @@
 // !DIAGNOSTICS: -UNUSED_PARAMETER
 open class B(x: Int)
-<!SUPERTYPE_INITIALIZED_WITHOUT_PRIMARY_CONSTRUCTOR!>class A : B(1) {
-    constructor(): super(1)
+<!SUPERTYPE_INITIALIZED_WITHOUT_PRIMARY_CONSTRUCTOR!>class <!CONFLICTING_OVERLOADS!>A<!> : B(1) {
+    <!CONFLICTING_OVERLOADS!>constructor()<!>: super(1)
 }<!>

compiler/testData/diagnostics/tests/secondaryConstructors/redeclarations.fir.kt

@@ -1,27 +0,0 @@
-// !DIAGNOSTICS: -UNUSED_PARAMETER
-
-class A(x: String = "", y: String = "") {
-    constructor(x: String, y: String): <!OVERLOAD_RESOLUTION_AMBIGUITY!>this<!>(x, y)
-    constructor(): <!OVERLOAD_RESOLUTION_AMBIGUITY!>this<!>("", "")
-    constructor(): <!OVERLOAD_RESOLUTION_AMBIGUITY!>this<!>("", "")
-}
-
-class B {
-    <!CONFLICTING_OVERLOADS!>constructor(x: Int)<!>
-}
-
-<!CONFLICTING_OVERLOADS!>fun B(x: Int)<!> {}
-
-class Outer {
-    class A<!CONFLICTING_OVERLOADS!>(x: String = "", y: String = "")<!> {
-        <!CONFLICTING_OVERLOADS!>constructor(x: String, y: String)<!>: <!OVERLOAD_RESOLUTION_AMBIGUITY!>this<!>(x, y)
-        <!CONFLICTING_OVERLOADS!>constructor()<!>: <!OVERLOAD_RESOLUTION_AMBIGUITY!>this<!>("", "")
-        <!CONFLICTING_OVERLOADS!>constructor()<!>: <!OVERLOAD_RESOLUTION_AMBIGUITY!>this<!>("", "")
-    }
-
-    class B {
-        <!CONFLICTING_OVERLOADS!>constructor(x: Int)<!>
-    }
-
-    <!CONFLICTING_OVERLOADS!>fun B(x: Int)<!> {}
-}

compiler/testData/diagnostics/tests/secondaryConstructors/redeclarations.kt

@@ -1,3 +1,4 @@
+// FIR_IDENTICAL
 // !DIAGNOSTICS: -UNUSED_PARAMETER
 
 class A<!CONFLICTING_OVERLOADS!>(x: String = "", y: String = "")<!> {