Program: 11009
Project: 11009
Buggy source:
@Override public Object visitQuery(@NotNull cqlParser.QueryContext ctx){
  QueryContext queryContext=new QueryContext();
  libraryBuilder.pushQueryContext(queryContext);
  try {
    List<AliasedQuerySource> sources;
    queryContext.enterSourceClause();
    try {
      sources=(List<AliasedQuerySource>)visit(ctx.sourceClause());
    }
  finally {
      queryContext.exitSourceClause();
    }
    queryContext.addQuerySources(sources);
    boolean expressionContextPushed=false;
    if (libraryBuilder.inPopulationContext() && queryContext.referencesPatientContext()) {
      libraryBuilder.pushExpressionContext("String_Node_Str");
      expressionContextPushed=true;
    }
    try {
      List<LetClause> dfcx=ctx.letClause() != null ? (List<LetClause>)visit(ctx.letClause()) : null;
      List<RelationshipClause> qicx=new ArrayList<>();
      if (ctx.queryInclusionClause() != null) {
        for (        cqlParser.QueryInclusionClauseContext queryInclusionClauseContext : ctx.queryInclusionClause()) {
          qicx.add((RelationshipClause)visit(queryInclusionClauseContext));
        }
      }
      Expression where=ctx.whereClause() != null ? (Expression)visit(ctx.whereClause()) : null;
      if (dateRangeOptimization && where != null) {
        for (        AliasedQuerySource aqs : sources) {
          where=optimizeDateRangeInQuery(where,aqs);
        }
      }
      ReturnClause ret=ctx.returnClause() != null ? (ReturnClause)visit(ctx.returnClause()) : null;
      if ((ret == null) && (sources.size() > 1)) {
        ret=of.createReturnClause().withDistinct(true);
        Tuple returnExpression=of.createTuple();
        TupleType returnType=new TupleType();
        for (        AliasedQuerySource aqs : sources) {
          TupleElement element=of.createTupleElement().withName(aqs.getAlias()).withValue(of.createAliasRef().withName(aqs.getAlias()));
          element.getValue().setResultType(aqs.getResultType());
          element.setResultType(element.getValue().getResultType());
          returnType.addElement(new TupleTypeElement(element.getName(),element.getResultType()));
          returnExpression.getElement().add(element);
        }
        returnExpression.setResultType(queryContext.isSingular() ? returnType : new ListType(returnType));
        ret.setExpression(returnExpression);
        ret.setResultType(returnExpression.getResultType());
      }
      queryContext.removeQuerySources(sources);
      if (dfcx != null) {
        queryContext.removeLetClauses(dfcx);
      }
      DataType queryResultType=ret == null ? sources.get(0).getResultType() : ret.getResultType();
      queryContext.setResultElementType(queryContext.isSingular() ? null : ((ListType)queryResultType).getElementType());
      SortClause sort=null;
      if (ctx.sortClause() != null) {
        if (queryContext.isSingular()) {
          throw new IllegalArgumentException("String_Node_Str");
        }
        queryContext.enterSortClause();
        try {
          sort=(SortClause)visit(ctx.sortClause());
          for (          SortByItem sortByItem : sort.getBy()) {
            if (sortByItem instanceof ByDirection) {
              libraryBuilder.verifyComparable(queryContext.getResultElementType());
            }
 else {
              libraryBuilder.verifyComparable(sortByItem.getResultType());
            }
          }
        }
  finally {
          queryContext.exitSortClause();
        }
      }
      Query query=of.createQuery().withSource(sources).withLet(dfcx).withRelationship(qicx).withWhere(where).withReturn(ret).withSort(sort);
      query.setResultType(queryResultType);
      return query;
    }
  finally {
      if (expressionContextPushed) {
        libraryBuilder.popExpressionContext();
      }
    }
  }
  finally {
    libraryBuilder.popQueryContext();
  }
}

Fixed version (ground truth):
@Override public Object visitQuery(@NotNull cqlParser.QueryContext ctx){
  QueryContext queryContext=new QueryContext();
  libraryBuilder.pushQueryContext(queryContext);
  try {
    List<AliasedQuerySource> sources;
    queryContext.enterSourceClause();
    try {
      sources=(List<AliasedQuerySource>)visit(ctx.sourceClause());
    }
  finally {
      queryContext.exitSourceClause();
    }
    queryContext.addQuerySources(sources);
    boolean expressionContextPushed=false;
    if (libraryBuilder.inPopulationContext() && queryContext.referencesPatientContext()) {
      libraryBuilder.pushExpressionContext("String_Node_Str");
      expressionContextPushed=true;
    }
    try {
      List<LetClause> dfcx=ctx.letClause() != null ? (List<LetClause>)visit(ctx.letClause()) : null;
      List<RelationshipClause> qicx=new ArrayList<>();
      if (ctx.queryInclusionClause() != null) {
        for (        cqlParser.QueryInclusionClauseContext queryInclusionClauseContext : ctx.queryInclusionClause()) {
          qicx.add((RelationshipClause)visit(queryInclusionClauseContext));
        }
      }
      Expression where=ctx.whereClause() != null ? (Expression)visit(ctx.whereClause()) : null;
      if (dateRangeOptimization && where != null) {
        for (        AliasedQuerySource aqs : sources) {
          where=optimizeDateRangeInQuery(where,aqs);
        }
      }
      ReturnClause ret=ctx.returnClause() != null ? (ReturnClause)visit(ctx.returnClause()) : null;
      if ((ret == null) && (sources.size() > 1)) {
        ret=of.createReturnClause().withDistinct(true);
        Tuple returnExpression=of.createTuple();
        TupleType returnType=new TupleType();
        for (        AliasedQuerySource aqs : sources) {
          TupleElement element=of.createTupleElement().withName(aqs.getAlias()).withValue(of.createAliasRef().withName(aqs.getAlias()));
          DataType sourceType=aqs.getResultType() instanceof ListType ? ((ListType)aqs.getResultType()).getElementType() : aqs.getResultType();
          element.getValue().setResultType(sourceType);
          element.setResultType(element.getValue().getResultType());
          returnType.addElement(new TupleTypeElement(element.getName(),element.getResultType()));
          returnExpression.getElement().add(element);
        }
        returnExpression.setResultType(queryContext.isSingular() ? returnType : new ListType(returnType));
        ret.setExpression(returnExpression);
        ret.setResultType(returnExpression.getResultType());
      }
      queryContext.removeQuerySources(sources);
      if (dfcx != null) {
        queryContext.removeLetClauses(dfcx);
      }
      DataType queryResultType=ret == null ? sources.get(0).getResultType() : ret.getResultType();
      queryContext.setResultElementType(queryContext.isSingular() ? null : ((ListType)queryResultType).getElementType());
      SortClause sort=null;
      if (ctx.sortClause() != null) {
        if (queryContext.isSingular()) {
          throw new IllegalArgumentException("String_Node_Str");
        }
        queryContext.enterSortClause();
        try {
          sort=(SortClause)visit(ctx.sortClause());
          for (          SortByItem sortByItem : sort.getBy()) {
            if (sortByItem instanceof ByDirection) {
              libraryBuilder.verifyComparable(queryContext.getResultElementType());
            }
 else {
              libraryBuilder.verifyComparable(sortByItem.getResultType());
            }
          }
        }
  finally {
          queryContext.exitSortClause();
        }
      }
      Query query=of.createQuery().withSource(sources).withLet(dfcx).withRelationship(qicx).withWhere(where).withReturn(ret).withSort(sort);
      query.setResultType(queryResultType);
      return query;
    }
  finally {
      if (expressionContextPushed) {
        libraryBuilder.popExpressionContext();
      }
    }
  }
  finally {
    libraryBuilder.popQueryContext();
  }
}