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/*

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 *  matiec - a compiler for the programming languages defined in IEC 61131-3

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 *

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 *  Copyright (C) 2009-2012  Mario de Sousa (msousa@fe.up.pt)

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 *  Copyright (C) 2012       Manuele Conti (manuele.conti@sirius-es.it)

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 *  Copyright (C) 2012       Matteo Facchinetti (matteo.facchinetti@sirius-es.it)

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 *

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 *  This program is free software: you can redistribute it and/or modify

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 *  it under the terms of the GNU General Public License as published by

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 *  the Free Software Foundation, either version 3 of the License, or

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 *  (at your option) any later version.

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 *

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 *  This program is distributed in the hope that it will be useful,

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 *  but WITHOUT ANY WARRANTY; without even the implied warranty of

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 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

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 *  GNU General Public License for more details.

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 *

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 *  You should have received a copy of the GNU General Public License

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 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.

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 *

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 *

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 * This code is made available on the understanding that it will not be

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 * used in safety-critical situations without a full and competent review.

    24

 */

    25

    26

/*

    27

 * An IEC 61131-3 compiler.

    28

 *

    29

 * Based on the

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 * FINAL DRAFT - IEC 61131-3, 2nd Ed. (2001-12-10)

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 *

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 */

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    34

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/* NOTE: The algorithm implemented here assumes that candidate datatype lists have already been filled!

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 *       BEFORE running this visitor, be sure to CALL the fill_candidate_datatype_c visitor!

    37

 */

    38

    39

    40

/*

    41

 *  Choose, from the list of all the possible datatypes each expression may take, the single datatype that it will in fact take.

    42

 *  The resulting (chosen) datatype, will be stored in the symbol_c.datatype variable, leaving the candidate datatype list untouched!

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 * 

    44

 *  For rvalue expressions, this decision will be based on the datatype of the lvalue expression.

    45

 *  For lvalue expressions, the candidate datatype list should have a single entry.

    46

 * 

    47

 *  For example, the very simple literal '0' in 'foo := 0', may represent a:

    48

 *    BOOL, BYTE, WORD, DWORD, LWORD, USINT, SINT, UINT, INT, UDINT, DINT, ULINT, LINT (as well as the SAFE versions of these data tyes too!)

    49

 * 

    50

 *  In this class, the datatype of '0' will be set to the same datatype as the 'foo' variable.

    51

 *  If the intersection of the candidate datatype lists of the left and right side expressions is empty, 

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 *  then a datatype error has been found, and the datatype is either left at NULL, or set to a pointer of an invalid_type_name_c object!

    53

 */

    54

    55

    56

#include "narrow_candidate_datatypes.hh"

    57

#include "datatype_functions.hh"

    58

#include <typeinfo>

    59

#include <list>

    60

#include <string>

    61

#include <string.h>

    62

#include <strings.h>

    63

    64

    65

/* set to 1 to see debug info during execution */

    66

static int debug = 0;

    67

    68

narrow_candidate_datatypes_c::narrow_candidate_datatypes_c(symbol_c *ignore) {

    69

}

    70

    71

narrow_candidate_datatypes_c::~narrow_candidate_datatypes_c(void) {

    72

}

    73

    74

    75

/* Only set the symbol's desired datatype to 'datatype' if that datatype is in the candidate_datatype list */

    76

static void set_datatype(symbol_c *datatype, symbol_c *symbol) {

    77

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	/* If we are trying to set to the undefined type, and the symbol's datatype has already been set to something else, 

    79

	 * we abort the compoiler as I don't think this should ever occur. 

    80

	 * NOTE: In order to handle JMPs to labels that come before the JMP itself, we run the narrow algorithm twice.

    81

	 *       This means that this situation may legally occur, so we cannot abort the compiler here!

    82

	 */

    83

// 	if ((NULL == datatype) && (NULL != symbol->datatype)) ERROR;

    84

 	if ((NULL == datatype) && (NULL != symbol->datatype)) return;

    85

	if ((NULL == datatype) && (NULL == symbol->datatype)) return;

    86

    87

	if (search_in_candidate_datatype_list(datatype, symbol->candidate_datatypes) < 0)

    88

		symbol->datatype = &(search_constant_type_c::invalid_type_name);   

    89

	else {

    90

		if (NULL == symbol->datatype)   

    91

			/* not yet set to anything, so we set it to the requested data type */

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			symbol->datatype = datatype; 

    93

		else {

    94

			/* had already been set previously to some data type. Let's check if they are the same! */

    95

			if (!is_type_equal(symbol->datatype, datatype))

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				symbol->datatype = &(search_constant_type_c::invalid_type_name);

    97

// 			else 

    98

				/* we leave it unchanged, as it is the same as the requested data type! */

    99

		}

   100

	}

   101

}

   102

   103

   104

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/* Only set the symbol's desired datatype to 'datatype' if that datatype is in the candidate_datatype list */

   106

// static void set_datatype_in_prev_il_instructions(symbol_c *datatype, std::vector <symbol_c *> prev_il_instructions) {

   107

static void set_datatype_in_prev_il_instructions(symbol_c *datatype, il_instruction_c *symbol) {

   108

	if (NULL == symbol) ERROR;

   109

	for (unsigned int i = 0; i < symbol->prev_il_instruction.size(); i++)

   110

		set_datatype(datatype, symbol->prev_il_instruction[i]);

   111

}

   112

   113

   114

   115

bool narrow_candidate_datatypes_c::is_widening_compatible(const struct widen_entry widen_table[], symbol_c *left_type, symbol_c *right_type, symbol_c *result_type, bool *deprecated_status) {

   116

	/* NOTE: According to our algorithm, left_type and right_type should never by NULL (if they are, we have an internal compiler error!

   117

	 *       However, result_type may be NULL if the code has a data type semantic error!

   118

	 */

   119

	if ((NULL == left_type) || (NULL == right_type) || (NULL == result_type))

   120

		return false;

   121

   122

	for (int k = 0; NULL != widen_table[k].left;  k++) {

   123

		if        ((typeid(*left_type)   == typeid(*widen_table[k].left))

   124

		        && (typeid(*right_type)  == typeid(*widen_table[k].right))

   125

			&& (typeid(*result_type) == typeid(*widen_table[k].result))) {

   126

			if (NULL != deprecated_status)

   127

				*deprecated_status = (widen_table[k].status == widen_entry::deprecated);

   128

			return true;

   129

		}

   130

	}

   131

	return false;

   132

}

   133

   134

/*

   135

 * All parameters being passed to the called function MUST be in the parameter list to which f_call points to!

   136

 * This means that, for non formal function calls in IL, de current (default value) must be artificially added to the

   137

 * beginning of the parameter list BEFORE calling handle_function_call().

   138

 */

   139

void narrow_candidate_datatypes_c::narrow_nonformal_call(symbol_c *f_call, symbol_c *f_decl, int *ext_parm_count) {

   140

	symbol_c *call_param_value,  *param_type;

   141

	identifier_c *param_name;

   142

	function_param_iterator_c       fp_iterator(f_decl);

   143

	function_call_param_iterator_c fcp_iterator(f_call);

   144

	int extensible_parameter_highest_index = -1;

   145

	unsigned int i;

   146

   147

	if (NULL != ext_parm_count) *ext_parm_count = -1;

   148

   149

	/* Iterating through the non-formal parameters of the function call */

   150

	while((call_param_value = fcp_iterator.next_nf()) != NULL) {

   151

		/* Obtaining the type of the value being passed in the function call */

   152

		/* Iterate to the next parameter of the function being called.

   153

		 * Get the name of that parameter, and ignore if EN or ENO.

   154

		 */

   155

		do {

   156

			param_name = fp_iterator.next();

   157

			/* If there is no other parameter declared, then we are passing too many parameters... */

   158

			/* This error should have been caught in fill_candidate_datatypes_c, but may occur here again when we handle FB invocations! 

   159

			 * In this case, we carry on analysing the code in order to be able to provide relevant error messages

   160

			 * for that code too!

   161

			 */

   162

			if(param_name == NULL) break;

   163

		} while ((strcmp(param_name->value, "EN") == 0) || (strcmp(param_name->value, "ENO") == 0));

   164

   165

		/* Set the desired datatype for this parameter, and call it recursively. */

   166

		/* Note that if the call has more parameters than those declared in the function/FB declaration,

   167

		 * we may be setting this to NULL!

   168

		 */

   169

		symbol_c *desired_datatype = base_type(fp_iterator.param_type());

   170

		if ((NULL != param_name) && (NULL == desired_datatype)) ERROR;

   171

		if ((NULL == param_name) && (NULL != desired_datatype)) ERROR;

   172

   173

		/* NOTE: When we are handling a nonformal function call made from IL, the first parameter is the 'default' or 'current'

   174

		 *       il value. However, a pointer to a copy of the prev_il_instruction is pre-pended into the operand list, so 

   175

		 *       the call 

   176

		 *       call_param_value->accept(*this);

   177

		 *       may actually be calling an object of the base symbol_c .

   178

		 */

   179

		set_datatype(desired_datatype, call_param_value);

   180

		call_param_value->accept(*this);

   181

   182

		if (NULL != param_name) 

   183

			if (extensible_parameter_highest_index < fp_iterator.extensible_param_index())

   184

				extensible_parameter_highest_index = fp_iterator.extensible_param_index();

   185

	}

   186

	/* In the case of a call to an extensible function, we store the highest index 

   187

	 * of the extensible parameters this particular call uses, in the symbol_c object

   188

	 * of the function call itself!

   189

	 * In calls to non-extensible functions, this value will be set to -1.

   190

	 * This information is later used in stage4 to correctly generate the

   191

	 * output code.

   192

	 */

   193

	if ((NULL != ext_parm_count) && (extensible_parameter_highest_index >=0) /* if call to extensible function */)

   194

		*ext_parm_count = 1 + extensible_parameter_highest_index - fp_iterator.first_extensible_param_index();

   195

}

   196

   197

   198

   199

void narrow_candidate_datatypes_c::narrow_formal_call(symbol_c *f_call, symbol_c *f_decl, int *ext_parm_count) {

   200

	symbol_c *call_param_value, *call_param_name, *param_type;

   201

	symbol_c *verify_duplicate_param;

   202

	identifier_c *param_name;

   203

	function_param_iterator_c       fp_iterator(f_decl);

   204

	function_call_param_iterator_c fcp_iterator(f_call);

   205

	int extensible_parameter_highest_index = -1;

   206

	identifier_c *extensible_parameter_name;

   207

	unsigned int i;

   208

   209

	if (NULL != ext_parm_count) *ext_parm_count = -1;

   210

	/* Iterating through the formal parameters of the function call */

   211

	while((call_param_name = fcp_iterator.next_f()) != NULL) {

   212

   213

		/* Obtaining the value being passed in the function call */

   214

		call_param_value = fcp_iterator.get_current_value();

   215

		/* the following should never occur. If it does, then we have a bug in our code... */

   216

		if (NULL == call_param_value) ERROR;

   217

   218

		/* Find the corresponding parameter in function declaration */

   219

		param_name = fp_iterator.search(call_param_name);

   220

   221

		/* Set the desired datatype for this parameter, and call it recursively. */

   222

		/* NOTE: When handling a FB call, this narrow_formal_call() may be called to analyse

   223

		 *       an invalid FB call (call with parameters that do not exist on the FB declaration).

   224

		 *       For this reason, the param_name may come out as NULL!

   225

		 */

   226

		symbol_c *desired_datatype = base_type(fp_iterator.param_type());

   227

		if ((NULL != param_name) && (NULL == desired_datatype)) ERROR;

   228

		if ((NULL == param_name) && (NULL != desired_datatype)) ERROR;

   229

   230

		/* set the desired data type for this parameter */

   231

		set_datatype(desired_datatype, call_param_value);

   232

		/* And recursively call that parameter/expression, so it can propagate that info */

   233

		call_param_value->accept(*this);

   234

   235

		/* set the extensible_parameter_highest_index, which will be needed in stage 4 */

   236

		/* This value says how many extensible parameters are being passed to the standard function */

   237

		if (NULL != param_name) 

   238

			if (extensible_parameter_highest_index < fp_iterator.extensible_param_index())

   239

				extensible_parameter_highest_index = fp_iterator.extensible_param_index();

   240

	}

   241

	/* call is compatible! */

   242

   243

	/* In the case of a call to an extensible function, we store the highest index 

   244

	 * of the extensible parameters this particular call uses, in the symbol_c object

   245

	 * of the function call itself!

   246

	 * In calls to non-extensible functions, this value will be set to -1.

   247

	 * This information is later used in stage4 to correctly generate the

   248

	 * output code.

   249

	 */

   250

	if ((NULL != ext_parm_count) && (extensible_parameter_highest_index >=0) /* if call to extensible function */)

   251

		*ext_parm_count = 1 + extensible_parameter_highest_index - fp_iterator.first_extensible_param_index();

   252

}

   253

   254

   255

/*

   256

typedef struct {

   257

  symbol_c *function_name,

   258

  symbol_c *nonformal_operand_list,

   259

  symbol_c *   formal_operand_list,

   260

   261

  std::vector <symbol_c *> &candidate_functions,  

   262

  symbol_c &*called_function_declaration,

   263

  int      &extensible_param_count

   264

} generic_function_call_t;

   265

*/

   266

void narrow_candidate_datatypes_c::narrow_function_invocation(symbol_c *fcall, generic_function_call_t fcall_data) {

   267

	/* set the called_function_declaration. */

   268

	fcall_data.called_function_declaration = NULL;

   269

   270

	/* set the called_function_declaration taking into account the datatype that we need to return */

   271

	for(unsigned int i = 0; i < fcall->candidate_datatypes.size(); i++) {

   272

		if (is_type_equal(fcall->candidate_datatypes[i], fcall->datatype)) {

   273

			fcall_data.called_function_declaration = fcall_data.candidate_functions[i];

   274

			break;

   275

		}

   276

	}

   277

   278

	/* NOTE: If we can't figure out the declaration of the function being called, this is not 

   279

	 *       necessarily an internal compiler error. It could be because the symbol->datatype is NULL

   280

	 *       (because the ST code being analysed has an error _before_ this function invocation).

   281

	 *       However, we don't just give, up, we carry on recursivly analysing the code, so as to be

   282

	 *       able to print out any error messages related to the parameters being passed in this function 

   283

	 *       invocation.

   284

	 */

   285

	/* if (NULL == symbol->called_function_declaration) ERROR; */

   286

	if (fcall->candidate_datatypes.size() == 1) {

   287

		/* If only one function declaration, then we use that (even if symbol->datatypes == NULL)

   288

		 * so we can check for errors in the expressions used to pass parameters in this

   289

		 * function invocation.

   290

		 */

   291

		fcall_data.called_function_declaration = fcall_data.candidate_functions[0];

   292

	}

   293

   294

	/* If an overloaded function is being invoked, and we cannot determine which version to use,

   295

	 * then we can not meaningfully verify the expressions used inside that function invocation.

   296

	 * We simply give up!

   297

	 */

   298

	if (NULL == fcall_data.called_function_declaration)

   299

		return;

   300

   301

	if (NULL != fcall_data.nonformal_operand_list)  narrow_nonformal_call(fcall, fcall_data.called_function_declaration, &(fcall_data.extensible_param_count));

   302

	if (NULL != fcall_data.   formal_operand_list)     narrow_formal_call(fcall, fcall_data.called_function_declaration, &(fcall_data.extensible_param_count));

   303

   304

	return;

   305

}

   306

   307

   308

   309

   310

/* narrow implicit FB call in IL.

   311

 * e.g.  CLK ton_var

   312

 *        CU counter_var

   313

 *

   314

 * The algorithm will be to build a fake il_fb_call_c equivalent to the implicit IL FB call, and let 

   315

 * the visit(il_fb_call_c *) method handle it!

   316

 */

   317

void *narrow_candidate_datatypes_c::narrow_implicit_il_fb_call(symbol_c *il_instruction, const char *param_name, symbol_c *&called_fb_declaration) {

   318

   319

	/* set the datatype of the il_operand, this is, the FB being called! */

   320

	if (NULL != il_operand) {

   321

		/* only set it if it is in the candidate datatypes list! */  

   322

		set_datatype(called_fb_declaration, il_operand);

   323

		il_operand->accept(*this);

   324

	}

   325

	symbol_c *fb_decl = il_operand->datatype;

   326

   327

	if (0 == fake_prev_il_instruction->prev_il_instruction.size()) {

   328

		/* This IL implicit FB call (e.g. CLK ton_var) is not preceded by another IL instruction

   329

		 * (or list of instructions) that will set the IL current/default value.

   330

		 * We cannot proceed verifying type compatibility of something that does not exist.

   331

		 */

   332

		return NULL;

   333

	}

   334

   335

	if (NULL == fb_decl) {

   336

		/* the il_operand is a not FB instance */

   337

		/* so we simply pass on the required datatype to the prev_il_instructions */

   338

		/* The invalid FB invocation will be caught in the print_datatypes_error_c by analysing NULL value in il_operand->datatype! */

   339

		set_datatype_in_prev_il_instructions(il_instruction->datatype, fake_prev_il_instruction);

   340

		return NULL;

   341

	}

   342

   343

   344

	/* The value being passed to the 'param_name' parameter is actually the prev_il_instruction.

   345

	 * However, we do not place that object directly in the fake il_param_list_c that we will be

   346

	 * creating, since the visit(il_fb_call_c *) method will recursively call every object in that list.

   347

	 * The il_prev_intruction object will be visited once we have handled this implici IL FB call

   348

	 * (called from the instruction_list_c for() loop that works backwards). We DO NOT want to visit it twice.

   349

	 * (Anyway, if we let the visit(il_fb_call_c *) recursively visit the current prev_il_instruction, this pointer

   350

	 * would be changed to the IL instruction coming before the current prev_il_instruction! => things would get all messed up!)

   351

	 * The easiest way to work around this is to simply use a new object, and copy the relevant details to that object!

   352

	 */

   353

	symbol_c param_value = *fake_prev_il_instruction; /* copy the candidate_datatypes list ! */

   354

   355

	identifier_c variable_name(param_name);

   356

	// SYM_REF1(il_assign_operator_c, variable_name)

   357

	il_assign_operator_c il_assign_operator(&variable_name);  

   358

	// SYM_REF3(il_param_assignment_c, il_assign_operator, il_operand, simple_instr_list)

   359

	il_param_assignment_c il_param_assignment(&il_assign_operator, &param_value/*il_operand*/, NULL);

   360

	il_param_list_c il_param_list;

   361

	il_param_list.add_element(&il_param_assignment);

   362

	// SYM_REF4(il_fb_call_c, il_call_operator, fb_name, il_operand_list, il_param_list, symbol_c *called_fb_declaration)

   363

	CAL_operator_c CAL_operator;

   364

	il_fb_call_c il_fb_call(&CAL_operator, il_operand, NULL, &il_param_list);

   365

   366

	/* A FB call does not return any datatype, but the IL instructions that come after this

   367

	 * FB call may require a specific datatype in the il current/default variable, 

   368

	 * so we must pass this information up to the IL instruction before the FB call, since it will

   369

	 * be that IL instruction that will be required to produce the desired dtataype.

   370

	 *

   371

	 * The above will be done by the visit(il_fb_call_c *) method, so we must make sure to

   372

	 * correctly set up the il_fb_call.datatype variable!

   373

	 */

   374

	il_fb_call.called_fb_declaration = called_fb_declaration;

   375

	il_fb_call.accept(*this);

   376

   377

	/* set the required datatype of the previous IL instruction! */

   378

	/* NOTE:

   379

	 * When handling these implicit IL calls, the parameter_value being passed to the FB parameter

   380

	 * is actually the prev_il_instruction.

   381

	 * 

   382

	 * However, since the FB call does not change the value in the current/default IL variable, this value

   383

	 * must also be used ny the IL instruction coming after this FB call.

   384

	 *

   385

	 * This means that we have two consumers/users for the same value. 

   386

	 * We must therefore check whether the datatype required by the IL instructions following this FB call 

   387

	 * is the same as that required for the first parameter. If not, then we have a semantic error,

   388

	 * and we set it to invalid_type_name.

   389

	 *

   390

	 * However, we only do that if:

   391

	 *  - The IL instruction that comes after this IL FB call actually asked this FB call for a specific 

   392

	 *     datatype in the current/default vairable, once this IL FB call returns.

   393

	 *     However, sometimes, (for e.g., this FB call is the last in the IL list) the subsequent FB to not aks this

   394

	 *     FB call for any datatype. In that case, then the datatype required to pass to the first parameter of the

   395

	 *     FB call must be left unchanged!

   396

	 */

   397

	if ((NULL == il_instruction->datatype) || (is_type_equal(param_value.datatype, il_instruction->datatype))) {

   398

		set_datatype_in_prev_il_instructions(param_value.datatype, fake_prev_il_instruction);

   399

	} else {

   400

		set_datatype_in_prev_il_instructions(&search_constant_type_c::invalid_type_name, fake_prev_il_instruction);

   401

	}

   402

	return NULL;

   403

}

   404

   405

   406

/* a helper function... */

   407

symbol_c *narrow_candidate_datatypes_c::base_type(symbol_c *symbol) {

   408

	/* NOTE: symbol == NULL is valid. It will occur when, for e.g., an undefined/undeclared symbolic_variable is used

   409

	 *       in the code.

   410

	 */

   411

	if (symbol == NULL) return NULL;

   412

	return (symbol_c *)symbol->accept(search_base_type);	

   413

}

   414

   415

/*********************/

   416

/* B 1.2 - Constants */

   417

/*********************/

   418

   419

/**********************/

   420

/* B 1.3 - Data types */

   421

/**********************/

   422

/********************************/

   423

/* B 1.3.3 - Derived data types */

   424

/********************************/

   425

/* simple_specification ASSIGN constant */

   426

// SYM_REF2(simple_spec_init_c, simple_specification, constant)

   427

void *narrow_candidate_datatypes_c::visit(simple_spec_init_c *symbol) {

   428

	if (symbol->candidate_datatypes.size() == 1)

   429

	  symbol->datatype = symbol->candidate_datatypes[0];

   430

   431

	if (symbol->simple_specification->candidate_datatypes.size() == 1)

   432

	  symbol->simple_specification->datatype = symbol->simple_specification->candidate_datatypes[0];

   433

   434

	if (NULL != symbol->constant) {

   435

		set_datatype(symbol->datatype, symbol->constant);

   436

		symbol->constant->accept(*this);

   437

	}

   438

	return NULL;

   439

}

   440

   441

   442

   443

/*  signed_integer DOTDOT signed_integer */

   444

// SYM_REF2(subrange_c, lower_limit, upper_limit)

   445

void *narrow_candidate_datatypes_c::visit(subrange_c *symbol) {

   446

	symbol->lower_limit->datatype = symbol->datatype;

   447

	symbol->lower_limit->accept(*this);

   448

	symbol->upper_limit->datatype = symbol->datatype;

   449

	symbol->upper_limit->accept(*this);

   450

	return NULL;

   451

}

   452

   453

   454

/*********************/

   455

/* B 1.4 - Variables */

   456

/*********************/

   457

   458

/********************************************/

   459

/* B 1.4.1 - Directly Represented Variables */

   460

/********************************************/

   461

   462

/*************************************/

   463

/* B 1.4.2 - Multi-element variables */

   464

/*************************************/

   465

/*  subscripted_variable '[' subscript_list ']' */

   466

// SYM_REF2(array_variable_c, subscripted_variable, subscript_list)

   467

void *narrow_candidate_datatypes_c::visit(array_variable_c *symbol) {

   468

	/* we need to check the data types of the expressions used for the subscripts... */

   469

	symbol->subscript_list->accept(*this);

   470

	return NULL;

   471

}

   472

   473

   474

/* subscript_list ',' subscript */

   475

// SYM_LIST(subscript_list_c)

   476

void *narrow_candidate_datatypes_c::visit(subscript_list_c *symbol) {

   477

	for (int i = 0; i < symbol->n; i++) {

   478

		for (unsigned int k = 0; k < symbol->elements[i]->candidate_datatypes.size(); k++) {

   479

			if (is_ANY_INT_type(symbol->elements[i]->candidate_datatypes[k]))

   480

				symbol->elements[i]->datatype = symbol->elements[i]->candidate_datatypes[k];

   481

		}

   482

		symbol->elements[i]->accept(*this);

   483

	}

   484

	return NULL;  

   485

}

   486

   487

   488

   489

   490

/******************************************/

   491

/* B 1.4.3 - Declaration & Initialisation */

   492

/******************************************/

   493

   494

void *narrow_candidate_datatypes_c::visit(var1_list_c *symbol) {

   495

#if 0   /* We don't really need to set the datatype of each variable. We just check the declaration itself! */

   496

  for(int i = 0; i < symbol->n; i++) {

   497

    if (symbol->elements[i]->candidate_datatypes.size() == 1)

   498

      symbol->elements[i]->datatype = symbol->elements[i]->candidate_datatypes[0];

   499

  }

   500

#endif

   501

  return NULL;