Do not mark comment next to reachable child as unreachable

compiler/frontend/src/org/jetbrains/jet/lang/cfg/UnreachableCode.kt

@@ -26,6 +26,7 @@ import com.intellij.psi.PsiWhiteSpace
 import java.util.ArrayList
 import org.jetbrains.jet.lexer.JetTokens
 import com.intellij.psi.util.PsiTreeUtil
+import com.intellij.psi.PsiComment
 
 trait UnreachableCode {
     val elements: Set<JetElement>
@@ -70,7 +71,9 @@ class UnreachableCodeImpl(
     }
 
     fun List<PsiElement>.removeReachableElementsWithMeaninglessSiblings(): List<PsiElement> {
-        fun PsiElement.isMeaningless() = this is PsiWhiteSpace || this.getNode()?.getElementType() == JetTokens.COMMA
+        fun PsiElement.isMeaningless() = this is PsiWhiteSpace
+                || this.getNode()?.getElementType() == JetTokens.COMMA
+                || this is PsiComment
 
         val childrenToRemove = HashSet<PsiElement>()
         fun collectSiblingsIfMeaningless(elementIndex: Int, direction: Int) {

compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/commentsInDeadCode.kt

@@ -0,0 +1,22 @@
+package a
+
+fun test1() {
+    <!UNREACHABLE_CODE!>bar(<!>
+        11,
+        todo(),//comment1
+        <!UNREACHABLE_CODE!>""//comment2
+    )<!>
+}
+
+fun test2() {
+    <!UNREACHABLE_CODE!>bar(<!>11, todo()/*comment1*/, <!UNREACHABLE_CODE!>""/*comment2*/)<!>
+}
+fun test3() {
+    <!UNREACHABLE_CODE!>bar(<!>11, @l(todo()/*comment*/), <!UNREACHABLE_CODE!>"")<!>
+}
+
+fun todo() = throw Exception()
+
+fun bar(<!UNUSED_PARAMETER!>i<!>: Int, <!UNUSED_PARAMETER!>s<!>: String, <!UNUSED_PARAMETER!>a<!>: Any) {}
+
+

compiler/tests/org/jetbrains/jet/checkers/JetDiagnosticsTestGenerated.java

@@ -1451,6 +1451,11 @@ public class JetDiagnosticsTestGenerated extends AbstractJetDiagnosticsTest {
                     doTest("compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/commasAndWhitespaces.kt");
                 }
                 
+                @TestMetadata("commentsInDeadCode.kt")
+                public void testCommentsInDeadCode() throws Exception {
+                    doTest("compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/commentsInDeadCode.kt");
+                }
+                
                 @TestMetadata("deadCallInInvokeCall.kt")
                 public void testDeadCallInInvokeCall() throws Exception {
                     doTest("compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/deadCallInInvokeCall.kt");