[FIR] Forbid multiple labels per statement

^KT-53629: Fixed

compiler/testData/diagnostics/tests/controlStructures/nestedLoopsWithMultipleLabels.fir.kt

@@ -0,0 +1,10 @@
+// K2: See KT-65342
+
+fun test() {
+    <!MULTIPLE_LABELS_ARE_FORBIDDEN!>a@<!> b@ while(true) {
+        val f = {
+            return@a
+        }
+        break@b
+    }
+}

compiler/testData/diagnostics/tests/controlStructures/nestedLoopsWithMultipleLabels.kt

@@ -1,4 +1,5 @@
-// FIR_IDENTICAL
+// K2: See KT-65342
+
 fun test() {
     a@ b@ while(true) {
         val f = {

compiler/testData/diagnostics/tests/controlStructures/notAFunctionLabel_after.fir.kt

@@ -30,12 +30,12 @@ fun testAnnotatedLambdaLabel() =
     }
 
 fun testLambdaMultipleLabels1() =
-    lambda1@ lambda2@ {
+    <!MULTIPLE_LABELS_ARE_FORBIDDEN!>lambda1@<!> lambda2@ {
         <!NOT_A_FUNCTION_LABEL!>return@lambda1<!>
     }
 
 fun testLambdaMultipleLabels2() =
-    lambda1@ lambda2@ {
+    <!MULTIPLE_LABELS_ARE_FORBIDDEN!>lambda1@<!> lambda2@ {
         return@lambda2
     }
 
@@ -62,7 +62,7 @@ fun testHighOrderFunctionCallLabelInReturn() {
 }
 
 fun testMultipleLabelsWithNestedLambda() {
-    l1@ l2@{
+    <!MULTIPLE_LABELS_ARE_FORBIDDEN!>l1@<!> l2@{
         {
             <!NOT_A_FUNCTION_LABEL!>return@l1<!>
         }

compiler/testData/diagnostics/tests/controlStructures/notAFunctionLabel_before.fir.kt

@@ -30,12 +30,12 @@ fun testAnnotatedLambdaLabel() =
     }
 
 fun testLambdaMultipleLabels1() =
-    lambda1@ lambda2@ {
+    <!MULTIPLE_LABELS_ARE_FORBIDDEN!>lambda1@<!> lambda2@ {
         <!NOT_A_FUNCTION_LABEL!>return@lambda1<!>
     }
 
 fun testLambdaMultipleLabels2() =
-    lambda1@ lambda2@ {
+    <!MULTIPLE_LABELS_ARE_FORBIDDEN!>lambda1@<!> lambda2@ {
         return@lambda2
     }
 
@@ -62,7 +62,7 @@ fun testHighOrderFunctionCallLabelInReturn() {
 }
 
 fun testMultipleLabelsWithNestedLambda() {
-    l1@ l2@{
+    <!MULTIPLE_LABELS_ARE_FORBIDDEN!>l1@<!> l2@{
         {
             <!NOT_A_FUNCTION_LABEL!>return@l1<!>
         }

compiler/testData/diagnostics/tests/inline/labelsAndNonInlineUsage.fir.kt

@@ -1,4 +1,4 @@
-// !DIAGNOSTICS: -REDUNDANT_LABEL_WARNING -UNDERSCORE_IS_RESERVED
+// !DIAGNOSTICS: -REDUNDANT_LABEL_WARNING -UNDERSCORE_IS_RESERVED -MULTIPLE_LABELS_ARE_FORBIDDEN
 
 // See KT-65337
 // !DIAGNOSTICS: -UNRESOLVED_REFERENCE

compiler/testData/diagnostics/tests/inline/labelsAndNonInlineUsage.kt

@@ -1,4 +1,4 @@
-// !DIAGNOSTICS: -REDUNDANT_LABEL_WARNING -UNDERSCORE_IS_RESERVED
+// !DIAGNOSTICS: -REDUNDANT_LABEL_WARNING -UNDERSCORE_IS_RESERVED -MULTIPLE_LABELS_ARE_FORBIDDEN
 
 // See KT-65337
 // !DIAGNOSTICS: -UNRESOLVED_REFERENCE

compiler/testData/diagnostics/tests/inline/parenthesized.fir.kt

@@ -23,5 +23,5 @@ inline fun inlineFunWithInvoke2(s: (p: Int) -> Unit) {
 
 inline fun propagation(s: (p: Int) -> Unit) {
     inlineFunWithInvoke((label@ s))
-    inlineFunWithInvoke((label2@ label@ s))
+    inlineFunWithInvoke((<!MULTIPLE_LABELS_ARE_FORBIDDEN!>label2@<!> label@ s))
 }

compiler/testData/diagnostics/tests/labels/multipleLabels.fir.kt

@@ -0,0 +1,37 @@
+// !DIAGNOSTICS: -REDUNDANT_LABEL_WARNING
+
+fun foo1() {
+    <!MULTIPLE_LABELS_ARE_FORBIDDEN!>l2@<!> l1@ do {
+    } while (true)
+}
+
+fun foo2() {
+    <!MULTIPLE_LABELS_ARE_FORBIDDEN!>l4@<!> <!UNDERSCORE_IS_RESERVED!>_<!>@ <!MULTIPLE_LABELS_ARE_FORBIDDEN!>l3@<!> <!UNDERSCORE_IS_RESERVED!>__<!>@ <!MULTIPLE_LABELS_ARE_FORBIDDEN!>l2@<!> l1@ while (true) {
+    }
+}
+
+fun foo3() {
+    <!MULTIPLE_LABELS_ARE_FORBIDDEN!>l2@<!> l1@ 42
+}
+
+fun foo4() {
+    l1@ do {
+        l4@ { false }
+    } while (true)
+}
+
+fun foo5() {
+    <!MULTIPLE_LABELS_ARE_FORBIDDEN!>l2@<!> l1@ do {
+        l4@ { false }
+    } while (true)
+}
+
+fun foo6() {
+    <!MULTIPLE_LABELS_ARE_FORBIDDEN!>l2@<!> l1@ do {
+        l4@ l3@{ true }
+    } while (true)
+}
+
+fun foo7() {
+    <!MULTIPLE_LABELS_ARE_FORBIDDEN!>l3@<!> <!MULTIPLE_LABELS_ARE_FORBIDDEN!>l2@<!> l1@ fun bar() {}
+}

compiler/testData/diagnostics/tests/labels/multipleLabels.kt

@@ -0,0 +1,37 @@
+// !DIAGNOSTICS: -REDUNDANT_LABEL_WARNING
+
+fun foo1() {
+    l2@ l1@ do {
+    } while (true)
+}
+
+fun foo2() {
+    l4@ <!UNDERSCORE_IS_RESERVED!>_<!>@ l3@ <!UNDERSCORE_IS_RESERVED!>__<!>@ l2@ l1@ while (true) {
+    }
+}
+
+fun foo3() {
+    l2@ l1@ 42
+}
+
+fun foo4() {
+    l1@ do {
+        l4@ { false }
+    } while (true)
+}
+
+fun foo5() {
+    l2@ l1@ do {
+        l4@ { false }
+    } while (true)
+}
+
+fun foo6() {
+    l2@ l1@ do {
+        l4@ l3@{ true }
+    } while (true)
+}
+
+fun foo7() {
+    l3@ l2@ l1@ fun bar() {}
+}

compiler/testData/diagnostics/tests/regressions/TypeMismatchOnUnaryOperations.fir.kt

@@ -1,3 +1,5 @@
+// K2: See KT-65342
+
 fun main() {
     val a : Int? = null;
     var v = 1
@@ -9,7 +11,7 @@ fun main() {
     val h1 : String = <!INITIALIZER_TYPE_MISMATCH!>--v<!>;
     val i : String = <!INITIALIZER_TYPE_MISMATCH, TYPE_MISMATCH!>!true<!>;
     val j : String = <!INITIALIZER_TYPE_MISMATCH!>foo@ true<!>;
-    val k : String = <!INITIALIZER_TYPE_MISMATCH!>foo@ bar@ true<!>;
+    val k : String = <!MULTIPLE_LABELS_ARE_FORBIDDEN!>foo@<!> bar@ true;
     val l : String = <!INITIALIZER_TYPE_MISMATCH!>-1<!>;
     val m : String = <!INITIALIZER_TYPE_MISMATCH!>+1<!>;
 }

compiler/testData/diagnostics/tests/regressions/TypeMismatchOnUnaryOperations.kt

@@ -1,3 +1,5 @@
+// K2: See KT-65342
+
 fun main() {
     val a : Int? = null;
     var v = 1