opt.ads: Elaboration warnings are now on by default.

opt.ads: Elaboration warnings are now on by default.

2017-11-16  Hristian Kirtchev  <kirtchev@adacore.com>

	* opt.ads: Elaboration warnings are now on by default. Add a comment
	explaining why this is needed.
	* sem_ch9.adb (Analyze_Requeue): Preserve the status of elaboration
	warnings.
	* sem_ch12.adb (Analyze_Package_Instantiation): Preserve the status of
	elaboration warnings.
	(Analyze_Subprogram_Instantiation): Preserve the status of elaboration
	warnings.
	* sem_elab.adb: Update the structure of Call_Attributes and
	Instantiation_Attributes.
	(Build_Call_Marker): Propagate the status of elaboration warnings from
	the call to the marker.
	(Extract_Call_Attributes): Extract the status of elaboration warnings.
	(Extract_Instantiation_Attributes): Extract the status of elaboration
	warnings.
	(Process_Conditional_ABE_Activation_Impl): Elaboration diagnostics are
	now dependent on the status of elaboration warnings.
	(Process_Conditional_ABE_Call_Ada): Elaboration diagnostics are now
	dependent on the status of elaboration warnings.
	(Process_Conditional_ABE_Instantiation_Ada): Elaboration diagnostics
	are now dependent on the status of elaboration warnings.
	(Process_Guaranteed_ABE_Activation_Impl): Remove pragma Unreferenced
	for formal Call_Attrs. Elaboration diagnostics are now dependent on the
	status of elaboration warnings.
	(Process_Guaranteed_ABE_Call): Elaboration diagnostics are now
	dependent on the status of elaboration warnings.
	(Process_Guaranteed_ABE_Instantiation): Elaboration diagnostics are now
	dependent on the status of elaboration warnings.
	* sem_prag.adb (Analyze_Pragma): Remove the unjustified warning
	concerning pragma Elaborate.
	* sem_res.adb (Resolve_Call): Preserve the status of elaboration
	warnings.
	(Resolve_Entry_Call): Propagate flag Is_Elaboration_Warnings_OK_Node
	from the procedure call to the entry call.
	* sem_util.adb (Mark_Elaboration_Attributes): Add formal parameter
	Warnings.
	(Mark_Elaboration_Attributes_Node): Preserve the status of elaboration
	warnings
	* sem_util.ads (Mark_Elaboration_Attributes): Add formal parameter
	Warnings. Update the comment on usage.
	* sinfo.adb (Is_Dispatching_Call): Update to use Flag6.
	(Is_Elaboration_Warnings_OK_Node): New routine.
	(Set_Is_Dispatching_Call): Update to use Flag6.
	(Set_Is_Elaboration_Warnings_OK_Node): New routine.
	* sinfo.ads: Attribute Is_Dispatching_Call now uses Flag6. Add new
	attribute Is_Elaboration_Warnings_OK_Node along with occurrences
	in nodes.
	(Is_Elaboration_Warnings_OK_Node): New routine along with pragma
	Inline.
	(Set_Is_Elaboration_Warnings_OK_Node): New routine along with pragma
	Inline.
	* doc/gnat_ugn/elaboration_order_handling_in_gnat.rst: Update various
	sections to indicate how to suppress elaboration warnings.  Document
	switches -gnatwl and -gnatwL.
	* gnat_ugn.texi: Regenerate.

From-SVN: r254819