[Ada] Synchronization of SPARK implementation against reference manual

[Arnaud Charlet <charlet at adacore dot com>]

This patch updates the implementation of various SPARK features by removing
obsolete checks based on old rules and introduces new cheks to satisfy the
latest version of the SPARK reference manual. The tools now produce superior
error messages that reference various SPARK manual sections where possible.

Tested on x86_64-pc-linux-gnu, committed on trunk

2014-01-27  Hristian Kirtchev  <kirtchev@adacore.com>

	* einfo.adb (Is_Input_Only_State): Removed.
	(Is_Non_Volatile_State): Removed.
	(Is_Output_State): Removed.
	* einfo.ads (Is_Input_Only_State): Remove attribute and
	subprogram. Update related entity.
	(Is_Non_Volatile_State):
	Remove attribute and subprogram. Update related entity.
	(Is_Output_State): Removed attribute and subprogram. Update
	related entity.
	* exp_ch6.adb (Expand_Subprogram_Contract): Update comment on
	generated code.
	* sem_ch3.adb (Analyze_Declarations): Analyze the contract of
	an object, not just variables.
	(Analyze_Object_Contract): New routine.
	(Analyze_Variable_Contract): Removed.
	(Process_Discriminants): Detect an illegal use of volatile
	discriminant in SPARK mode.
	* sem_ch5.adb (Analyze_Iterator_Specification):
	Detect an illegal use of volatile loop variable.
	(Analyze_Loop_Parameter_Specification): Detect an illegal use
	of volatile loop variable.
	* sem_ch6.adb (Process_Formals): Update the volatile object
	detection. Detect an illegal formal of mode IN OUT or OUT in
	SPARK mode. Enhance the error messages with references.
	* sem_ch12.adb (Instantiate_Object): Update the volatile object
	detection. Enhance the error messages with references.
	* sem_prag.adb (Analyze_Abstract_State): Enhance the error
	messages with references.
	(Analyze_Contract_Case): Enhance the error messages with references.
	(Analyze_External_Property): Call Check_Duplicate_Property to process
	an external property.
	(Analyze_External_Property_In_Decl_Part): New routine.
	(Analyze_External_State_In_Decl_Part): Removed.
	(Analyze_Global_Item): Detect an illegal
	use of a volatile constant. Detect an illegal use
	of a variable with enabled Effective_Reads. Enhance
	the error messages with references. Remove obsolete
	checks concerning Input_Only and Output_Only states.
	(Analyze_Initialization_Item): Enhance the error messages
	with references.
	(Analyze_Initializes_In_Decl_Part): Do not
	collect the states and variables when the initialization list
	is null.
	(Analyze_Input_Item): Enhance the error messages with references.
	(Analyze_Input_Output): Enhance the error messages with references.
	(Analyze_Pragma): Enhance the error messages with references.
	(Analyze_Refinement_Clause): Code reformatting.
	(Analyze_Refined_Depends_In_Decl_Part):
	Rename global variable Global to Reg_Global and update all
	occurrences. Add local variables D7 and D8. Update the error
	messages with references. Update the call to Collect_Global_Items.
	(Analyze_Refined_Global_In_Decl_Part): Add local variables
	Has_Proof_In_State, Proof_In_Constits and Proof_In_Items. Update
	the call to Collect_Global_Items.  Account for a Proof_In state
	in null / useless refinement checks. Verify the coverage of
	Proof_In states.
	(Check_Dependency_Clause): Remove local variable
	Out_Constits. Remove the retrieval and removal of constituents
	for an Output_Only state. Remove the reporting of unused
	Output_Only state constituents.
	(Check_Duplicate_Mode): Enhance
	the error message with a reference.
	(Check_Duplicate_Property): New routine.
	(Check_Duplicate_Option): Enhance the error message with a reference.
	(Check_External_Properties): Enhance the error message with a reference.
	(Check_Function_Return): Enhance the error message with a reference.
	(Check_In_Out_States): Update
	comment on usage. Add a specialized error message for Proof_In
	constituents. Enhance the error message with a reference.
	(Check_Input_States): Update comment on usage. Account for
	possible Proof_In constituents. Enhance the error message
	with a areference.
	(Check_Matching_Constituent): Enhance the error message with a
	reference.
	(Check_Matching_State): Enchance the error message with a reference.
	(Check_Mode): Add local variable From_Global. Update the call to
	Find_Mode.  Emit more precise error messages concerning extra items
	(Check_Mode_Restriction_In_Enclosing_Context): Consider
	pragma Refined_Global.	Enhance the error message with a
	reference.
	(Check_Mode_Restriction_In_Function): Enhance the error message with
	a reference.
	(Check_Output_States): Update comment on usage. Add local variable
	Posted.  Account for possible Proof_In constituents. Produce a detailed
	list of missing constituents.
	(Check_Proof_In_States): New routine.
	(Check_Refined_Global_Item): Handle Proof_In
	constituents. Enchance the error message with a reference.
	(Collect_Global_Items): Add formal parameters Proof_In_Items
	and Has_Proof_In_State. Update the comment on usage. Account
	for Proof_In items.
	(Create_Or_Modify_Clause): Enchance
	the error message with a reference.
	(Find_Mode): Add
	formal parameter From_Global. Update the comment on usage.
	Detect when the mode is governed by pragma [Refined_]Global.
	(Output_Constituents): Removed.
	(Report_Extra_Constituents):
	Report extra Proof_In constituents.
	(Report_Unused_Constituents): Removed.
	(Usage_Error): Code reformatting. Enhance the error
	messages with reference.
	* sem_prag.ads (Analyze_External_Property_In_Decl_Part): New routine.
	(Analyze_External_State_In_Decl_Part): Removed.
	* sem_res.adb (Resolve_Actuals): Update the volatile object
	detection. Enhance the error message with a reference.
	(Resolve_Entity_Name): Update the volatile object
	detection. Enhance the error message with a reference.
	* sem_util.adb (Is_Refined_State): Add a guard to avoid a crash.
	(Is_SPARK_Volatile_Object): New routine.
	(Has_Volatile_Component): New routine.
	* sem_util.ads (Is_Delegate): Alphabetized.
	(Is_SPARK_Volatile_Object): New routine.
	(Has_Volatile_Component): New routine.
	* snames.ads-tmpl: Remove names Name_Input_Only and Name_Output_Only.

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