WIP: Feature/dead code improve

src/main/java/com/github/_1c_syntax/bsl/languageserver/cfg/ControlFlowGraph.java

@@ -34,7 +34,7 @@ public class ControlFlowGraph extends DefaultDirectedGraph<CfgVertex, CfgEdge> {
   @Getter
   private ExitVertex exitPoint;
 
-  ControlFlowGraph() {
+  public ControlFlowGraph() {
     super(CfgEdge.class);
     exitPoint = new ExitVertex();
     addVertex(exitPoint);

src/main/java/com/github/_1c_syntax/bsl/languageserver/diagnostics/UnreachableCodeDiagnostic.java

@@ -21,6 +21,8 @@
  */
 package com.github._1c_syntax.bsl.languageserver.diagnostics;
 
+import com.github._1c_syntax.bsl.languageserver.cfg.CfgBuildingParseTreeVisitor;
+import com.github._1c_syntax.bsl.languageserver.cfg.ExitVertex;
 import com.github._1c_syntax.bsl.languageserver.diagnostics.metadata.DiagnosticMetadata;
 import com.github._1c_syntax.bsl.languageserver.diagnostics.metadata.DiagnosticSeverity;
 import com.github._1c_syntax.bsl.languageserver.diagnostics.metadata.DiagnosticTag;
@@ -37,6 +39,7 @@
 import java.util.ArrayDeque;
 import java.util.ArrayList;
 import java.util.Collections;
+import java.util.Comparator;
 import java.util.Deque;
 import java.util.List;
 import java.util.stream.Collectors;
@@ -110,6 +113,59 @@ private void savePreprocessorRange(Deque<ParseTree> nodes, BSLParser.Preprocesso
     }
   }
 
+  @Override
+  public ParseTree visitSubCodeBlock(BSLParser.SubCodeBlockContext ctx) {
+    errorRanges.clear();
+    super.visitSubCodeBlock(ctx);
+    appendUnreachableCode(ctx.codeBlock());
+    return ctx;
+  }
+
+  @Override
+  public ParseTree visitFileCodeBlock(BSLParser.FileCodeBlockContext ctx) {
+    errorRanges.clear();
+    super.visitFileCodeBlock(ctx);
+    appendUnreachableCode(ctx.codeBlock());
+    return ctx;
+  }
+
+  private void appendUnreachableCode(BSLParser.CodeBlockContext ctx) {
+    var builder = new CfgBuildingParseTreeVisitor();
+    builder.producePreprocessorConditions(true);
+    builder.produceLoopIterations(false);
+    builder.determineAdjacentDeadCode(false);
+
+    var graph = builder.buildGraph(ctx);
+    var deadCode = graph.vertexSet().stream()
+      .filter(vertex -> vertex != graph.getEntryPoint() && vertex.getClass() != ExitVertex.class)
+      .filter(vertex -> graph.inDegreeOf(vertex) == 0)
+      .flatMap(vertex -> vertex.getAst().stream())
+      .sorted(Comparator.comparingInt(bslParserRuleContext -> bslParserRuleContext.getStart().getLine()))
+      .map(Ranges::create)
+      .collect(Collectors.toList());
+
+
+    var newRanges = new ArrayList<Range>();
+    for (var range : deadCode) {
+      var alreadyDetected = false;
+      for (Range detectedRange : errorRanges) {
+        var pos = new Position(range.getStart().getLine(), range.getStart().getCharacter());
+        if (Ranges.containsPosition(detectedRange, pos)) {
+          alreadyDetected = true;
+          break;
+        }
+      }
+      if(!alreadyDetected) {
+        newRanges.add(range);
+      }
+    }
+
+    for (var range : newRanges) {
+      diagnosticStorage.addDiagnostic(range);
+    }
+
+  }
+
   @Override
   public ParseTree visitContinueStatement(BSLParser.ContinueStatementContext ctx) {
     findAndAddDiagnostic(ctx);

src/test/java/com/github/_1c_syntax/bsl/languageserver/diagnostics/UnreachableCodeDiagnosticTest.java

@@ -38,7 +38,7 @@ class UnreachableCodeDiagnosticTest extends AbstractDiagnosticTest<UnreachableCo
   void test() {
     List<Diagnostic> diagnostics = getDiagnostics();
 
-    assertThat(diagnostics).hasSize(15);
+    assertThat(diagnostics).hasSize(16);
     assertThat(diagnostics, true)
       .hasRange(12, 12, 20)
       .hasRange(21, 12, 20)
@@ -52,9 +52,10 @@ void test() {
       .hasRange(102, 8, 17)
       .hasRange(108, 16, 111, 29)
       .hasRange(138, 4, 16)
-      .hasRange(161, 4, 13)
-      .hasRange(166, 4, 168, 13)
-      .hasRange(172, 0, 9);
+      .hasRange(163, 4, 22)
+      .hasRange(171, 4, 13)
+      .hasRange(176, 4, 178, 13)
+      .hasRange(182, 0, 9);
   }
 
   @Test

src/test/resources/diagnostics/UnreachableCodeDiagnostic.bsl

@@ -154,6 +154,16 @@
 КонецФункции
 #КонецОбласти
 
+Функция ДосрочныйВыход()
+    Если А Тогда
+        Возврат 1;
+    Иначе
+        Возврат 2;
+    КонецЕсли;
+
+    ТутОшибка = Истина; // <- недостижимый код
+КонецФункции
+
 #Если Сервер Тогда
    Возврат;
 #Иначе
@@ -170,4 +180,4 @@
 КонецЕсли;
 
 Возврат;
-Метод2();   // Ошибка: После Возврат
+Метод2();   // Ошибка: После Возврат