ada: Enforce matching of extra formals

ada: Enforce matching of extra formals

This patch enforces matching of extra formals in overridden subprograms,
subprogram renamings, and subprograms to which attributes 'Access,
'Unchecked_Access, or 'Unrestricted_Access is applied (for these access
cases the subprogram is checked against its corresponding subprogram
type). This enforcement is an internal consistency check, not an
implementation of some language legality rule.

gcc/ada/

	* debug.adb
	(Debug_Flag_Underscore_XX): Switch -gnatd_X used temporarily to allow
	disabling extra formal checks.
	* exp_attr.adb
	(Expand_N_Attribute_Reference [access types]): Add extra formals
	to the subprogram referenced in the prefix of 'Unchecked_Access,
	'Unrestricted_Access or 'Access; required to check that its extra
	formals match the extra formals of the corresponding subprogram type.
	* exp_ch3.adb
	(Stream_Operation_OK): Declaration moved to the public part of the
	package.
	(Validate_Tagged_Type_Extra_Formals): New subprogram.
	(Expand_Freeze_Record_Type): Improve the code that takes care of
	adding the extra formals of dispatching primitives; extended to
	add also the extra formals to renamings of dispatching primitives.
	* exp_ch3.ads
	(Stream_Operation_OK): Declaration moved from the package body.
	* exp_ch6.adb
	(Check_BIP_Actuals): Complete documentation.
	(Has_BIP_Extra_Formal): Subprogram declaration moved to the public
	part of the package. In addition, a parameter has been added to
	disable an assertion that requires its use with frozen entities.
	(Duplicate_Params_Without_Extra_Actuals): New subprogram.
	(Check_Subprogram_Variant): Emit the call without duplicating the
	extra formals since they will be added when the call is analyzed.
	(Expand_Call_Helper): Ensure that the called subprogram has all its
	extra formals, enforce assertion checking extra formals on thunks,
	and mark calls from thunks as processed-BIP-calls to avoid adding
	their extra formals twice.
	(Is_Build_In_Place_Function): Return False for entities with foreign
	convention.
	(Is_Build_In_Place_Function_Call): Return True also for not BIP functions
	that have BIP formals since the extra actuals are required.
	(Make_Build_In_Place_Call_In_Object_Declaration): Occurrences of
	Is_Return_Object replaced by the local variable Is_OK_Return_Object
	that evaluates to False for scopes with foreign convention.
	(Might_Have_Tasks): Fix check of class-wide limited record types.
	(Needs_BIP_Task_Actuals): Remove assertion to allow calling this
	function in more contexts; in addition it returns False for functions
	returning objects with foreign convention.
	(Needs_BIP_Finalization_Master): Likewise.
	(Needs_BIP_Alloc_Form): Likewise.
	(Validate_Subprogram_Calls): Check that the number of actuals (including
	extra actuals) of calls in the subtree N match their corresponding
	formals.
	* exp_ch6.ads
	(Has_BIP_Extra_Formal): Subprogram declaration moved to the public
	part of the package. In addition, a parameter has been added to
	disable an assertion that requires its use with frozen entities.
	(Is_Build_In_Place_Function_Call): Complete documentation.
	(Validate_Subprogram_Calls): Check that the number of actuals (including
	extra actuals) of calls in the subtree N match their corresponding
	formals.
	* freeze.adb
	(Check_Itype): Add extra formals to anonymous access subprogram itypes.
	(Freeze_Expression): Improve code that disables the addition of extra
	formals to functions with foreign convention.
	(Check_Extra_Formals): Moved to package Sem_Ch6 as Extra_Formals_OK.
	(Freeze_Subprogram): Add extra formals to non-dispatching subprograms.
	* frontend.adb
	(Frontend): Validate all the subprogram calls; it can be disabled using
	switch -gnatd_X
	* sem_ch3.adb
	(Access_Subprogram_Declaration): Defer the addition of extra formals to
	the freezing point so that we know the convention.
	(Check_Anonymous_Access_Component): Likewise.
	(Derive_Subprogram): Fix documentation.
	* sem_ch6.adb
	(Has_Reliable_Extra_Formals): New subprogram.
	(Check_Anonymous_Return): Fix check of access to class-wide limited
	record types.
	(Check_Untagged_Equality): Placed in alphabetical order.
	(Extra_Formals_OK): Subprogram moved from freeze.adb.
	(Extra_Formals_Match_OK): New subprogram.
	(Has_BIP_Formals): New subprogram.
	(Has_Extra_Formals): New subprograms.
	(Needs_Accessibility_Check_Extra): New subprogram.
	(Parent_Subprogram): New subprogram.
	(Add_Extra_Formal): Minor code cleanup.
	(Create_Extra_Formals): Enforce matching extra formals on overridden
	and aliased entities.
	* sem_ch6.ads
	(Extra_Formals_Match_OK): New subprogram.
	(Extra_Formals_OK): Subprogram moved from freeze.adb.
	* sem_eval.adb
	(Compile_Time_Known_Value): Improve predicate to avoid assertion
	failure; found working on this ticket; this change does not
	affect the behavior of the compiler because this subprogram
	has an exception handler that returns False when the assertion
	fails.
	* sem_util.adb
	(Needs_Result_Accessibility_Level): Do not return False for dispatching
	operations compiled with Ada_Version < 2012 since they they may be
	overridden by primitives compiled with Ada_Version >= Ada_2012.