Instance `COPY` empty-`EXTEND` bug

[g5t]

In the grammar rules for COMPONENT duplicate = COPY(source)

McCode/mccode/src/instrument.y

Lines 1280 to 1314 in 03e2db0

	instref: "COPY" '(' compref ')' actuallist /* make a copy of a previous instance, with def+set */
	{
	struct comp_inst *comp_src;
	struct comp_inst *comp;
	comp_src = $3;
	palloc(comp);
	comp->def = comp_src->def;
	comp->extend = comp_src->extend;
	comp->group = comp_src->group;
	comp->jump = comp_src->jump;
	comp->when = comp_src->when;
	/* now catenate src and actual parameters */
	comp->actuals= symtab_create();
	symtab_cat(comp->actuals, $5);
	symtab_cat(comp->actuals, comp_src->actuals);
	comp->metadata = metadata_list_copy(comp_src->metadata);
	$$ = comp;
	}
	| "COPY" '(' compref ')'
	{
	struct comp_inst *comp_src;
	struct comp_inst *comp;
	comp_src = $3;
	palloc(comp);
	comp->defpar = comp_src->defpar;
	comp->setpar = comp_src->setpar;
	comp->def = comp_src->def;
	comp->extend = comp_src->extend;
	comp->group = comp_src->group;
	comp->jump = comp_src->jump;
	comp->when = comp_src->when;
	comp->actuals= comp_src->actuals;
	comp->metadata = metadata_list_copy(comp_src->metadata);
	$$ = comp;
	}

the resulting instance's extend is set to be the same as the source instance.

When translating and compiling the example instrument RTP_Laue.instr warnings are issued to alert the user that a copied component instance's EXTEND block is overwritten:

-----------------------------------------------------------
WARNING: Existing (COPY) EXTEND block in COMPONENT image_plate_eff:
  EXTEND %{
    /* take into account ZnS scintillator efficiency */
    double eff=0.5;
    double v=sqrt(vx*vx+vy*vy+vz*vz);
    p *= 1.0-exp(3960.0/v*log(1.0-eff/100.0));
  %}

is overwritten by:
  EXTEND %{
  %}
-----------------------------------------------------------

-----------------------------------------------------------
WARNING: Existing (COPY) EXTEND block in COMPONENT image_plate_scattered:
  EXTEND %{
    /* take into account ZnS scintillator efficiency */
    double eff=0.5;
    double v=sqrt(vx*vx+vy*vy+vz*vz);
    p *= 1.0-exp(3960.0/v*log(1.0-eff/100.0));
  %}

is overwritten by:
  EXTEND %{
  %}
-----------------------------------------------------------

despite the file not specifying any extra EXTEND on the copies

McCode/mcstas-comps/examples/TRIGA/RTP_Laue/RTP_Laue.instr

Lines 110 to 126 in 03e2db0

	/* image plate/film with efficiency */
	COMPONENT image_plate_ideal = Monitor_nD(xwidth=.3, yheight=.3,
	options="x y", bins=1000)
	AT (0,0,.1) RELATIVE detector_axis
	EXTEND %{
	/* take into account ZnS scintillator efficiency */
	double eff=0.5;
	double v=sqrt(vx*vx+vy*vy+vz*vz);
	p *= 1.0-exp(3960.0/v*log(1.0-eff/100.0));
	%}
	COMPONENT image_plate_eff = COPY(image_plate_ideal)
	AT (0,0,.1+1e-3) RELATIVE detector_axis
	COMPONENT image_plate_scattered = COPY(image_plate_ideal)
	WHEN(sample_scattered)
	AT (0,0,.1+1e-3) RELATIVE detector_axis

This seems to have been recognized previously, as some example instruments work around the problem by defining identical EXTEND blocks on copied component instances, e.g.,

McCode/mcstas-comps/examples/ILL/ILL_H22_D1B/ILL_H22_D1B.instr

Lines 225 to 254 in 03e2db0

	COMPONENT Cryo_1 = PowderN(reflections="Al.laz",
	radius = 0.061, thickness = 0.001, yheight = 0.10,
	concentric = 1, d_phi=RAD2DEG*atan(R_h/L3),
	p_inc=Inc_Cryo, p_transmit=Trans_Cryo)
	AT (0,0,L2) RELATIVE mono_out
	EXTEND
	%{
	flag_env+=SCATTERED;
	%}
	COMPONENT Cryo_2 = COPY(Cryo_1)(radius = 0.0545, thickness = 0.001)
	AT (0,0,L2) RELATIVE mono_out
	EXTEND
	%{
	flag_env+=SCATTERED;
	%}
	COMPONENT Cryo_3 = COPY(Cryo_1)(radius = 0.039, thickness = 0.001)
	AT (0,0,L2) RELATIVE mono_out
	EXTEND
	%{
	flag_env+=SCATTERED;
	%}
	COMPONENT Cryo_4 = COPY(Cryo_1)(radius = 0.036, thickness = 0.001)
	AT (0,0,L2) RELATIVE mono_out
	EXTEND
	%{
	flag_env+=SCATTERED;
	%}

From the warning messages, the problem seems to arise from the line number check in

McCode/mccode/src/instrument.y

Lines 1419 to 1443 in 03e2db0

	if ($13->linenum) {
	#ifdef GENERATE_C
	if (comp->extend->linenum>0) {
	fprintf(stderr, "\n-----------------------------------------------------------\n");
	fprintf(stderr, "WARNING: Existing (COPY) EXTEND block in COMPONENT %s:\n", comp->name);
	List_handle liter = list_iterate(comp->extend->lines);
	List_handle liter2 = list_iterate($13->lines);
	char *line, *line2;
	fprintf(stderr, " EXTEND %%{\n");
	while((line = list_next(liter))) {
	fprintf(stderr, " %s",line);
	}
	list_iterate_end(liter);
	fprintf(stderr, " %%}\n");
	fprintf(stderr, "\nis overwritten by:\n");
	fprintf(stderr, " EXTEND %%{\n");
	while((line2 = list_next(liter2))) {
	fprintf(stderr, " %s",line2);
	}
	list_iterate_end(liter2);
	fprintf(stderr, " %%}\n-----------------------------------------------------------\n");
	}
	#endif
	comp->extend= $13; /* EXTEND block*/
	}

but the actual 'empty code block' initializer sets that to -1

McCode/mccode/src/cogen.c.in

Lines 258 to 269 in 03e2db0

	struct code_block *
	codeblock_new(void)
	{
	struct code_block *cb;
	palloc(cb);
	cb->filename = NULL;
	cb->quoted_filename = NULL;
	cb->linenum = -1;
	cb->lines = list_create();
	return cb;
	}

so if ($13->linenum) is always true (unless if something else sets that to zero somewhere).