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------------------------------------------------------------------------------

--                                                                          --

--                         GNAT COMPILER COMPONENTS                         --

--                                                                          --

--                             S E M _ U T I L                              --

--                                                                          --

--                                 S p e c                                  --

--                                                                          --

--          Copyright (C) 1992-2009, Free Software Foundation, Inc.         --

--                                                                          --

-- GNAT is free software;  you can  redistribute it  and/or modify it under --

-- terms of the  GNU General Public License as published  by the Free Soft- --

-- ware  Foundation;  either version 3,  or (at your option) any later ver- --

-- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --

-- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --

-- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License --

-- for  more details.  You should have  received  a copy of the GNU General --

-- Public License  distributed with GNAT; see file COPYING3.  If not, go to --

-- http://www.gnu.org/licenses for a complete copy of the license.          --

--                                                                          --

-- GNAT was originally developed  by the GNAT team at  New York University. --

-- Extensive contributions were provided by Ada Core Technologies Inc.      --

--                                                                          --

------------------------------------------------------------------------------

--  Package containing utility procedures used throughout the semantics

with Einfo;  use Einfo;

with Namet;  use Namet;

with Nmake;  use Nmake;

with Snames; use Snames;

with Types;  use Types;

with Uintp;  use Uintp;

with Urealp; use Urealp;

package Sem_Util is

   function Abstract_Interface_List (Typ : Entity_Id) return List_Id;

   --  Given a type that implements interfaces look for its associated

   --  definition node and return its list of interfaces.

   procedure Add_Access_Type_To_Process (E : Entity_Id; A : Entity_Id);

   --  Add A to the list of access types to process when expanding the

   --  freeze node of E.

   procedure Add_Global_Declaration (N : Node_Id);

   --  These procedures adds a declaration N at the library level, to be

   --  elaborated before any other code in the unit. It is used for example

   --  for the entity that marks whether a unit has been elaborated. The

   --  declaration is added to the Declarations list of the Aux_Decls_Node

   --  for the current unit. The declarations are added in the current scope,

   --  so the caller should push a new scope as required before the call.

   function Alignment_In_Bits (E : Entity_Id) return Uint;

   --  If the alignment of the type or object E is currently known to the

   --  compiler, then this function returns the alignment value in bits.

   --  Otherwise Uint_0 is returned, indicating that the alignment of the

   --  entity is not yet known to the compiler.

   procedure Apply_Compile_Time_Constraint_Error

     (N      : Node_Id;

      Msg    : String;

      Reason : RT_Exception_Code;

      Ent    : Entity_Id  := Empty;

      Typ    : Entity_Id  := Empty;

      Loc    : Source_Ptr := No_Location;

      Rep    : Boolean    := True;

      Warn   : Boolean    := False);

   --  N is a subexpression which will raise constraint error when evaluated

   --  at runtime. Msg is a message that explains the reason for raising the

   --  exception. The last character is ? if the message is always a warning,

   --  even in Ada 95, and is not a ? if the message represents an illegality

   --  (because of violation of static expression rules) in Ada 95 (but not

   --  in Ada 83). Typically this routine posts all messages at the Sloc of

   --  node N. However, if Loc /= No_Location, Loc is the Sloc used to output

   --  the message. After posting the appropriate message, and if the flag

   --  Rep is set, this routine replaces the expression with an appropriate

   --  N_Raise_Constraint_Error node using the given Reason code. This node

   --  is then marked as being static if the original node is static, but

   --  sets the flag Raises_Constraint_Error, preventing further evaluation.

   --  The error message may contain a } or & insertion character. This

   --  normally references Etype (N), unless the Ent argument is given

   --  explicitly, in which case it is used instead. The type of the raise

   --  node that is built is normally Etype (N), but if the Typ parameter

   --  is present, this is used instead. Warn is normally False. If it is

   --  True then the message is treated as a warning even though it does

   --  not end with a ? (this is used when the caller wants to parametrize

   --  whether an error or warning is given.

   function Build_Actual_Subtype

     (T : Entity_Id;

      N : Node_Or_Entity_Id) return Node_Id;

   --  Build an anonymous subtype for an entity or expression, using the

   --  bounds of the entity or the discriminants of the enclosing record.

   --  T is the type for which the actual subtype is required, and N is either

   --  a defining identifier, or any subexpression.

   function Build_Actual_Subtype_Of_Component

     (T : Entity_Id;

      N : Node_Id) return Node_Id;

   --  Determine whether a selected component has a type that depends on

   --  discriminants, and build actual subtype for it if so.

   function Build_Default_Subtype

     (T : Entity_Id;

      N : Node_Id) return Entity_Id;

   --  If T is an unconstrained type with defaulted discriminants, build a

   --  subtype constrained by the default values, insert the subtype

   --  declaration in the tree before N, and return the entity of that

   --  subtype. Otherwise, simply return T.

   function Build_Discriminal_Subtype_Of_Component

     (T : Entity_Id) return Node_Id;

   --  Determine whether a record component has a type that depends on

   --  discriminants, and build actual subtype for it if so.

   procedure Build_Elaboration_Entity (N : Node_Id; Spec_Id : Entity_Id);

   --  Given a compilation unit node N, allocate an elaboration boolean for

   --  the compilation unit, and install it in the Elaboration_Entity field

   --  of Spec_Id, the entity for the compilation unit.

   function Cannot_Raise_Constraint_Error (Expr : Node_Id) return Boolean;

   --  Returns True if the expression cannot possibly raise Constraint_Error.

   --  The response is conservative in the sense that a result of False does

   --  not necessarily mean that CE could be raised, but a response of True

   --  means that for sure CE cannot be raised.

   procedure Check_Dynamically_Tagged_Expression

     (Expr        : Node_Id;

      Typ         : Entity_Id;

      Related_Nod : Node_Id);

   --  Check wrong use of dynamically tagged expression

   procedure Check_Fully_Declared (T : Entity_Id; N : Node_Id);

   --  Verify that the full declaration of type T has been seen. If not,

   --  place error message on node N. Used in  object declarations, type

   --  conversions, qualified expressions.

   procedure Check_Nested_Access (Ent : Entity_Id);

   --  Check whether Ent denotes an entity declared in an uplevel scope, which

   --  is accessed inside a nested procedure, and set Has_Up_Level_Access flag

   --  accordingly. This is currently only enabled for VM_Target /= No_VM.

   procedure Check_Potentially_Blocking_Operation (N : Node_Id);

   --  N is one of the statement forms that is a potentially blocking

   --  operation. If it appears within a protected action, emit warning.

   procedure Check_Unprotected_Access

     (Context : Node_Id;

      Expr    : Node_Id);

   --  Check whether the expression is a pointer to a protected component,

   --  and the context is external to the protected operation, to warn against

   --  a possible unlocked access to data.

   procedure Check_VMS (Construct : Node_Id);

   --  Check that this the target is OpenVMS, and if so, return with

   --  no effect, otherwise post an error noting this can only be used

   --  with OpenVMS ports. The argument is the construct in question

   --  and is used to post the error message.

   procedure Collect_Interfaces

     (T               : Entity_Id;

      Ifaces_List     : out Elist_Id;

      Exclude_Parents : Boolean := False;

      Use_Full_View   : Boolean := True);

   --  Ada 2005 (AI-251): Collect whole list of abstract interfaces that are

   --  directly or indirectly implemented by T. Exclude_Parents is used to

   --  avoid the addition of inherited interfaces to the generated list.

   --  Use_Full_View is used to collect the interfaces using the full-view

   --  (if available).

   procedure Collect_Interface_Components

     (Tagged_Type     : Entity_Id;

      Components_List : out Elist_Id);

   --  Ada 2005 (AI-251): Collect all the tag components associated with the

   --  secondary dispatch tables of a tagged type.

   procedure Collect_Interfaces_Info

     (T               : Entity_Id;

      Ifaces_List     : out Elist_Id;

      Components_List : out Elist_Id;

      Tags_List       : out Elist_Id);

   --  Ada 2005 (AI-251): Collect all the interfaces associated with T plus

   --  the record component and tag associated with each of these interfaces.

   --  On exit Ifaces_List, Components_List and Tags_List have the same number

   --  of elements, and elements at the same position on these tables provide

   --  information on the same interface type.

   function Collect_Primitive_Operations (T : Entity_Id) return Elist_Id;

   --  Called upon type derivation and extension. We scan the declarative

   --  part in  which the type appears, and collect subprograms that have

   --  one subsidiary subtype of the type. These subprograms can only

   --  appear after the type itself.

   function Compile_Time_Constraint_Error

     (N    : Node_Id;

      Msg  : String;

      Ent  : Entity_Id  := Empty;

      Loc  : Source_Ptr := No_Location;

      Warn : Boolean    := False) return Node_Id;

   --  This is similar to Apply_Compile_Time_Constraint_Error in that it

   --  generates a warning (or error) message in the same manner, but it does

   --  not replace any nodes. For convenience, the function always returns its

   --  first argument. The message is a warning if the message ends with ?, or

   --  we are operating in Ada 83 mode, or if the Warn parameter is set to

   --  True.

   procedure Conditional_Delay (New_Ent, Old_Ent : Entity_Id);

   --  Sets the Has_Delayed_Freeze flag of New if the Delayed_Freeze flag

   --  of Old is set and Old has no yet been Frozen (i.e. Is_Frozen is false);

   function Copy_Parameter_List (Subp_Id : Entity_Id) return List_Id;

   --  Utility to create a parameter profile for a new subprogram spec, when

   --  the subprogram has a body that acts as spec. This is done for some cases

   --  of inlining, and for private protected ops. Also used to create bodies

   --  for stubbed subprograms.

   function Current_Entity (N : Node_Id) return Entity_Id;

   --  Find the currently visible definition for a given identifier, that is to

   --  say the first entry in the visibility chain for the Chars of N.

   function Current_Entity_In_Scope (N : Node_Id) return Entity_Id;

   --  Find whether there is a previous definition for identifier N in the

   --  current scope. Because declarations for a scope are not necessarily

   --  contiguous (e.g. for packages) the first entry on the visibility chain

   --  for N is not necessarily in the current scope.

   function Current_Scope return Entity_Id;

   --  Get entity representing current scope

   function Current_Subprogram return Entity_Id;

   --  Returns current enclosing subprogram. If Current_Scope is a subprogram,

   --  then that is what is returned, otherwise the Enclosing_Subprogram of the

   --  Current_Scope is returned. The returned value is Empty if this is called

   --  from a library package which is not within any subprogram.

   function Defining_Entity (N : Node_Id) return Entity_Id;

   --  Given a declaration N, returns the associated defining entity. If

   --  the declaration has a specification, the entity is obtained from

   --  the specification. If the declaration has a defining unit name,

   --  then the defining entity is obtained from the defining unit name

   --  ignoring any child unit prefixes.

   function Denotes_Discriminant

     (N                : Node_Id;

      Check_Concurrent : Boolean := False) return Boolean;

   --  Returns True if node N is an Entity_Name node for a discriminant.

   --  If the flag Check_Concurrent is true, function also returns true

   --  when N denotes the discriminal of the discriminant of a concurrent

   --  type. This is necessary to disable some optimizations on private

   --  components of protected types, and constraint checks on entry

   --  families constrained by discriminants.

   function Denotes_Same_Object (A1, A2 : Node_Id) return Boolean;

   function Denotes_Same_Prefix (A1, A2 : Node_Id) return Boolean;

   --  Functions to detect suspicious overlapping between actuals in a call,

   --  when one of them is writable. The predicates are those proposed in

   --  AI05-0144, to detect dangerous order dependence in complex calls.

   --  I would add a parameter Warn which enables more extensive testing of

   --  cases as we find appropriate when we are only warning ??? Or perhaps

   --  return an indication of (Error, Warn, OK) ???

   function Denotes_Variable (N : Node_Id) return Boolean;

   --  Returns True if node N denotes a single variable without parentheses

   function Depends_On_Discriminant (N : Node_Id) return Boolean;

   --  Returns True if N denotes a discriminant or if N is a range, a subtype

   --  indication or a scalar subtype where one of the bounds is a

   --  discriminant.

   function Designate_Same_Unit

     (Name1 : Node_Id;

      Name2 : Node_Id) return  Boolean;

   --  Return true if Name1 and Name2 designate the same unit name;

   --  each of these names is supposed to be a selected component name,

   --  an expanded name, a defining program unit name or an identifier

   function Enclosing_Generic_Body

     (N : Node_Id) return Node_Id;

   --  Returns the Node_Id associated with the innermost enclosing

   --  generic body, if any. If none, then returns Empty.

   function Enclosing_Generic_Unit

     (N : Node_Id) return Node_Id;

   --  Returns the Node_Id associated with the innermost enclosing

   --  generic unit, if any. If none, then returns Empty.

   function Enclosing_Lib_Unit_Entity return Entity_Id;

   --  Returns the entity of enclosing N_Compilation_Unit Node which is the

   --  root of the current scope (which must not be Standard_Standard, and

   --  the caller is responsible for ensuring this condition).

   function Enclosing_Lib_Unit_Node (N : Node_Id) return Node_Id;

   --  Returns the enclosing N_Compilation_Unit Node that is the root

   --  of a subtree containing N.

   function Enclosing_Subprogram (E : Entity_Id) return Entity_Id;

   --  Utility function to return the Ada entity of the subprogram enclosing

   --  the entity E, if any. Returns Empty if no enclosing subprogram.

   procedure Ensure_Freeze_Node (E : Entity_Id);

   --  Make sure a freeze node is allocated for entity E. If necessary,

   --  build and initialize a new freeze node and set Has_Delayed_Freeze

   --  true for entity E.

   procedure Enter_Name (Def_Id : Entity_Id);

   --  Insert new name in symbol table of current scope with check for

   --  duplications (error message is issued if a conflict is found)

   --  Note: Enter_Name is not used for overloadable entities, instead

   --  these are entered using Sem_Ch6.Enter_Overloadable_Entity.

   procedure Explain_Limited_Type (T : Entity_Id; N : Node_Id);

   --  This procedure is called after issuing a message complaining

   --  about an inappropriate use of limited type T. If useful, it

   --  adds additional continuation lines to the message explaining

   --  why type T is limited. Messages are placed at node N.

   procedure Find_Actual

     (N      : Node_Id;

      Formal : out Entity_Id;

      Call   : out Node_Id);

   --  Determines if the node N is an actual parameter of a procedure call. If

   --  so, then Formal points to the entity for the formal (whose Ekind is one

   --  of E_In_Parameter, E_Out_Parameter, E_In_Out_Parameter) and Call is set

   --  to the node for the corresponding call. If the node N is not an actual

   --  parameter, or is an actual parameter of a function call, then Formal and

   --  Call are set to Empty.

   function Find_Corresponding_Discriminant

     (Id   : Node_Id;

      Typ  : Entity_Id) return Entity_Id;

   --  Because discriminants may have different names in a generic unit

   --  and in an instance, they are resolved positionally when possible.

   --  A reference to a discriminant carries the discriminant that it

   --  denotes when analyzed. Subsequent uses of this id on a different

   --  type denote the discriminant at the same position in this new type.

   procedure Find_Overlaid_Entity

     (N   : Node_Id;

      Ent : out Entity_Id;

      Off : out Boolean);

   --  The node N should be an address representation clause. Determines if the

   --  target expression is the address of an entity with an optional offset.

   --  If so, Ent is set to the entity and, if there is an offset, Off is set

   --  to True, otherwise to False. If N is not an address representation

   --  clause, or if it is not possible to determine that the address is of

   --  this form, then Ent is set to Empty, and Off is set to False.

   function Find_Parameter_Type (Param : Node_Id) return Entity_Id;

   --  Return the type of formal parameter Param as determined by its

   --  specification.

   function Find_Static_Alternative (N : Node_Id) return Node_Id;

   --  N is a case statement whose expression is a compile-time value.

   --  Determine the alternative chosen, so that the code of non-selected

   --  alternatives, and the warnings that may apply to them, are removed.

   function First_Actual (Node : Node_Id) return Node_Id;

   --  Node is an N_Function_Call or N_Procedure_Call_Statement node. The

   --  result returned is the first actual parameter in declaration order

   --  (not the order of parameters as they appeared in the source, which

   --  can be quite different as a result of the use of named parameters).

   --  Empty is returned for a call with no parameters. The procedure for

   --  iterating through the actuals in declaration order is to use this

   --  function to find the first actual, and then use Next_Actual to obtain

   --  the next actual in declaration order. Note that the value returned

   --  is always the expression (not the N_Parameter_Association nodes

   --  even if named association is used).

   function Full_Qualified_Name (E : Entity_Id) return String_Id;

   --  Generates the string literal corresponding to the E's full qualified

   --  name in upper case. An ASCII.NUL is appended as the last character.

   --  The names in the string are generated by Namet.Get_Decoded_Name_String.

   procedure Gather_Components

     (Typ           : Entity_Id;

      Comp_List     : Node_Id;

      Governed_By   : List_Id;

      Into          : Elist_Id;

      Report_Errors : out Boolean);

   --  The purpose of this procedure is to gather the valid components in a

   --  record type according to the values of its discriminants, in order to

   --  validate the components of a record aggregate.

   --

   --    Typ is the type of the aggregate when its constrained discriminants

   --      need to be collected, otherwise it is Empty.

   --

   --    Comp_List is an N_Component_List node.

   --

   --    Governed_By is a list of N_Component_Association nodes, where each

   --     choice list contains the name of a discriminant and the expression

   --     field gives its value. The values of the discriminants governing

   --     the (possibly nested) variant parts in Comp_List are found in this

   --     Component_Association List.

   --

   --    Into is the list where the valid components are appended. Note that

   --     Into need not be an Empty list. If it's not, components are attached

   --     to its tail.

   --

   --    Report_Errors is set to True if the values of the discriminants are

   --     non-static.

   --

   --  This procedure is also used when building a record subtype. If the

   --  discriminant constraint of the subtype is static, the components of the

   --  subtype are only those of the variants selected by the values of the

   --  discriminants. Otherwise all components of the parent must be included

   --  in the subtype for semantic analysis.

   function Get_Actual_Subtype (N : Node_Id) return Entity_Id;

   --  Given a node for an expression, obtain the actual subtype of the

   --  expression. In the case of a parameter where the formal is an

   --  unconstrained array or discriminated type, this will be the

   --  previously constructed subtype of the actual. Note that this is

   --  not quite the "Actual Subtype" of the RM, since it is always

   --  a constrained type, i.e. it is the subtype of the value of the

   --  actual. The actual subtype is also returned in other cases where

   --  it has already been constructed for an object. Otherwise the

   --  expression type is returned unchanged, except for the case of an

   --  unconstrained array type, where an actual subtype is created, using

   --  Insert_Actions if necessary to insert any associated actions.

   function Get_Actual_Subtype_If_Available (N : Node_Id) return Entity_Id;

   --  This is like Get_Actual_Subtype, except that it never constructs an

   --  actual subtype. If an actual subtype is already available, i.e. the

   --  Actual_Subtype field of the corresponding entity is set, then it is

   --  returned. Otherwise the Etype of the node is returned.

   function Get_Default_External_Name (E : Node_Or_Entity_Id) return Node_Id;

   --  This is used to construct the string literal node representing a

   --  default external name, i.e. one that is constructed from the name

   --  of an entity, or (in the case of extended DEC import/export pragmas,

   --  an identifier provided as the external name. Letters in the name are

   --  according to the setting of Opt.External_Name_Default_Casing.

   function Get_Generic_Entity (N : Node_Id) return Entity_Id;

   --  Returns the true generic entity in an instantiation. If the name in

   --  the instantiation is a renaming, the function returns the renamed

   --  generic.

   procedure Get_Index_Bounds (N : Node_Id; L, H : out Node_Id);

   --  This procedure assigns to L and H respectively the values of the

   --  low and high bounds of node N, which must be a range, subtype

   --  indication, or the name of a scalar subtype. The result in L, H

   --  may be set to Error if there was an earlier error in the range.

   function Get_Enum_Lit_From_Pos

     (T   : Entity_Id;

      Pos : Uint;

      Loc : Source_Ptr) return Entity_Id;

   --  This function obtains the E_Enumeration_Literal entity for the

   --  specified value from the enumeration type or subtype T. The

   --  second argument is the Pos value, which is assumed to be in range.

   --  The third argument supplies a source location for constructed

   --  nodes returned by this function.

   procedure Get_Library_Unit_Name_String (Decl_Node : Node_Id);

   --  Retrieve the fully expanded name of the library unit declared by

   --  Decl_Node into the name buffer.

   function Get_Name_Entity_Id (Id : Name_Id) return Entity_Id;

   --  An entity value is associated with each name in the name table. The

   --  Get_Name_Entity_Id function fetches the Entity_Id of this entity,

   --  which is the innermost visible entity with the given name. See the

   --  body of Sem_Ch8 for further details on handling of entity visibility.

   function Get_Pragma_Id (N : Node_Id) return Pragma_Id;

   pragma Inline (Get_Pragma_Id);

   --  Obtains the Pragma_Id from the Chars field of Pragma_Identifier (N)

   function Get_Referenced_Object (N : Node_Id) return Node_Id;

   --  Given a node, return the renamed object if the node represents a renamed

   --  object, otherwise return the node unchanged. The node may represent an

   --  arbitrary expression.

   function Get_Renamed_Entity (E : Entity_Id) return Entity_Id;

   --  Given an entity for an exception, package, subprogram or generic unit,

   --  returns the ultimately renamed entity if this is a renaming. If this is

   --  not a renamed entity, returns its argument. It is an error to call this

   --  with any other kind of entity.

   function Get_Subprogram_Entity (Nod : Node_Id) return Entity_Id;

   --  Nod is either a procedure call statement, or a function call, or

   --  an accept statement node. This procedure finds the Entity_Id of the

   --  related subprogram or entry and returns it, or if no subprogram can

   --  be found, returns Empty.

   function Get_Subprogram_Body (E : Entity_Id) return Node_Id;

   --  Given the entity for a subprogram (E_Function or E_Procedure),

   --  return the corresponding N_Subprogram_Body node. If the corresponding

   --  body of the declaration is missing (as for an imported subprogram)

   --  return Empty.

   function Get_Task_Body_Procedure (E : Entity_Id) return Node_Id;

   pragma Inline (Get_Task_Body_Procedure);

   --  Given an entity for a task type or subtype, retrieves the

   --  Task_Body_Procedure field from the corresponding task type

   --  declaration.

   function Has_Access_Values (T : Entity_Id) return Boolean;

   --  Returns true if type or subtype T is an access type, or has a component

   --  (at any recursive level) that is an access type. This is a conservative

   --  predicate, if it is not known whether or not T contains access values

   --  (happens for generic formals in some cases), then False is returned.

   --  Note that tagged types return False. Even though the tag is implemented

   --  as an access type internally, this function tests only for access types

   --  known to the programmer. See also Has_Tagged_Component.

   type Alignment_Result is (Known_Compatible, Unknown, Known_Incompatible);

   --  Result of Has_Compatible_Alignment test, description found below. Note

   --  that the values are arranged in increasing order of problematicness.

   function Has_Compatible_Alignment

     (Obj  : Entity_Id;

      Expr : Node_Id) return Alignment_Result;

   --  Obj is an object entity, and expr is a node for an object reference. If

   --  the alignment of the object referenced by Expr is known to be compatible

   --  with the alignment of Obj (i.e. is larger or the same), then the result

   --  is Known_Compatible. If the alignment of the object referenced by Expr

   --  is known to be less than the alignment of Obj, then Known_Incompatible

   --  is returned. If neither condition can be reliably established at compile

   --  time, then Unknown is returned. This is used to determine if alignment

   --  checks are required for address clauses, and also whether copies must

   --  be made when objects are passed by reference.

   --

   --  Note: Known_Incompatible does not mean that at run time the alignment

   --  of Expr is known to be wrong for Obj, just that it can be determined

   --  that alignments have been explicitly or implicitly specified which

   --  are incompatible (whereas Unknown means that even this is not known).

   --  The appropriate reaction of a caller to Known_Incompatible is to treat

   --  it as Unknown, but issue a warning that there may be an alignment error.

   function Has_Declarations (N : Node_Id) return Boolean;

   --  Determines if the node can have declarations

   function Has_Discriminant_Dependent_Constraint

     (Comp : Entity_Id) return Boolean;

   --  Returns True if and only if Comp has a constrained subtype

   --  that depends on a discriminant.

   function Has_Infinities (E : Entity_Id) return Boolean;

   --  Determines if the range of the floating-point type E includes

   --  infinities. Returns False if E is not a floating-point type.

   function Has_Interfaces

     (T             : Entity_Id;

      Use_Full_View : Boolean := True) return Boolean;

   --  Where T is a concurrent type or a record type, returns true if T covers

   --  any abstract interface types. In case of private types the argument

   --  Use_Full_View controls if the check is done using its full view (if

   --  available).

   function Has_Null_Exclusion (N : Node_Id) return Boolean;

   --  Determine whether node N has a null exclusion

   function Has_Overriding_Initialize (T : Entity_Id) return Boolean;

   --  Predicate to determine whether a controlled type has a user-defined

   --  Initialize primitive, which makes the type not preelaborable.

   function Has_Preelaborable_Initialization (E : Entity_Id) return Boolean;

   --  Return True iff type E has preelaborable initialization as defined in

   --  Ada 2005 (see AI-161 for details of the definition of this attribute).

   function Has_Private_Component (Type_Id : Entity_Id) return Boolean;

   --  Check if a type has a (sub)component of a private type that has not

   --  yet received a full declaration.

   function Has_Stream (T : Entity_Id) return Boolean;

   --  Tests if type T is derived from Ada.Streams.Root_Stream_Type, or

   --  in the case of a composite type, has a component for which this

   --  predicate is True, and if so returns True. Otherwise a result of

   --  False means that there is no Stream type in sight. For a private

   --  type, the test is applied to the underlying type (or returns False

   --  if there is no underlying type).

   function Has_Tagged_Component (Typ : Entity_Id) return Boolean;

   --  Returns True if Typ is a composite type (array or record) which is

   --  either itself a tagged type, or has a component (recursively) which is

   --  a tagged type. Returns False for non-composite type, or if no tagged

   --  component is present. This function is used to check if '=' has to be

   --  expanded into a bunch component comparisons.

   function Implements_Interface

     (Typ_Ent         : Entity_Id;

      Iface_Ent       : Entity_Id;

      Exclude_Parents : Boolean := False) return Boolean;

   --  Returns true if the Typ implements interface Iface

   function In_Instance return Boolean;

   --  Returns True if the current scope is within a generic instance

   function In_Instance_Body return Boolean;

   --  Returns True if current scope is within the body of an instance, where

   --  several semantic checks (e.g. accessibility checks) are relaxed.

   function In_Instance_Not_Visible return Boolean;

   --  Returns True if current scope is with the private part or the body of

   --  an instance. Other semantic checks are suppressed in this context.

   function In_Instance_Visible_Part return Boolean;

   --  Returns True if current scope is within the visible part of a package

   --  instance, where several additional semantic checks apply.

   function In_Package_Body return Boolean;

   --  Returns True if current scope is within a package body

   function In_Parameter_Specification (N : Node_Id) return Boolean;

   --  Returns True if node N belongs to a parameter specification

   function In_Subprogram_Or_Concurrent_Unit return Boolean;

   --  Determines if the current scope is within a subprogram compilation

   --  unit (inside a subprogram declaration, subprogram body, or generic

   --  subprogram declaration) or within a task or protected body. The test

   --  is for appearing anywhere within such a construct (that is it does not

   --  need to be directly within).

   function In_Visible_Part (Scope_Id : Entity_Id) return Boolean;

   --  Determine whether a declaration occurs within the visible part of a

   --  package specification. The package must be on the scope stack, and the

   --  corresponding private part must not.

   procedure Insert_Explicit_Dereference (N : Node_Id);

   --  In a context that requires a composite or subprogram type and where a

   --  prefix is an access type, rewrite the access type node N (which is the

   --  prefix, e.g. of an indexed component) as an explicit dereference.

   procedure Inspect_Deferred_Constant_Completion (Decls : List_Id);

   --  Examine all deferred constants in the declaration list Decls and check

   --  whether they have been completed by a full constant declaration or an

   --  Import pragma. Emit the error message if that is not the case.

   function Is_AAMP_Float (E : Entity_Id) return Boolean;

   --  Defined for all type entities. Returns True only for the base type of

   --  float types with AAMP format. The particular format is determined by the

   --  Digits_Value value which is 6 for the 32-bit floating point type, or 9

   --  for the 48-bit type. This is not an attribute function (like VAX_Float)

   --  in order to not use up an extra flag and to prevent the dependency of

   --  Einfo on Targparm which would be required for a synthesized attribute.

   function Is_Actual_Out_Parameter (N : Node_Id) return Boolean;

   --  Determines if N is an actual parameter of out mode in a subprogram call

   function Is_Actual_Parameter (N : Node_Id) return Boolean;

   --  Determines if N is an actual parameter in a subprogram call

   function Is_Aliased_View (Obj : Node_Id) return Boolean;

   --  Determine if Obj is an aliased view, i.e. the name of an

   --  object to which 'Access or 'Unchecked_Access can apply.

   function Is_Ancestor_Package

     (E1 : Entity_Id;

      E2 : Entity_Id) return Boolean;

   --  Determine whether package E1 is an ancestor of E2

   function Is_Atomic_Object (N : Node_Id) return Boolean;

   --  Determines if the given node denotes an atomic object in the sense

   --  of the legality checks described in RM C.6(12).

   function Is_Coextension_Root (N : Node_Id) return Boolean;

   --  Determine whether node N is an allocator which acts as a coextension

   --  root.

   function Is_Controlling_Limited_Procedure

     (Proc_Nam : Entity_Id) return Boolean;

   --  Ada 2005 (AI-345): Determine whether Proc_Nam is a primitive procedure

   --  of a limited interface with a controlling first parameter.

   function Is_CPP_Constructor_Call (N : Node_Id) return Boolean;

   --  Returns True if N is a call to a CPP constructor

   function Is_Dependent_Component_Of_Mutable_Object

     (Object : Node_Id) return Boolean;

   --  Returns True if Object is the name of a subcomponent that depends on

   --  discriminants of a variable whose nominal subtype is unconstrained and

   --  not indefinite, and the variable is not aliased. Otherwise returns

   --  False. The nodes passed to this function are assumed to denote objects.

   function Is_Dereferenced (N : Node_Id) return Boolean;

   --  N is a subexpression node of an access type. This function returns true

   --  if N appears as the prefix of a node that does a dereference of the

   --  access value (selected/indexed component, explicit dereference or a

   --  slice), and false otherwise.

   function Is_Descendent_Of (T1 : Entity_Id; T2 : Entity_Id) return Boolean;

   --  Returns True if type T1 is a descendent of type T2, and false otherwise.

   --  This is the RM definition, a type is a descendent of another type if it

   --  is the same type or is derived from a descendent of the other type.

   function Is_Concurrent_Interface (T : Entity_Id) return Boolean;

   --  First determine whether type T is an interface and then check whether

   --  it is of protected, synchronized or task kind.

   function Is_False (U : Uint) return Boolean;

   --  The argument is a Uint value which is the Boolean'Pos value of a

   --  Boolean operand (i.e. is either 0 for False, or 1 for True). This

   --  function simply tests if it is False (i.e. zero)

   function Is_Fixed_Model_Number (U : Ureal; T : Entity_Id) return Boolean;

   --  Returns True iff the number U is a model number of the fixed-

   --  point type T, i.e. if it is an exact multiple of Small.

   function Is_Fully_Initialized_Type (Typ : Entity_Id) return Boolean;

   --  Typ is a type entity. This function returns true if this type is fully

   --  initialized, meaning that an object of the type is fully initialized.

   --  Note that initialization resulting from use of pragma Normalized_Scalars

   --  does not count. Note that this is only used for the purpose of issuing

   --  warnings for objects that are potentially referenced uninitialized. This

   --  means that the result returned is not crucial, but should err on the

   --  side of thinking things are fully initialized if it does not know.

   function Is_Inherited_Operation (E : Entity_Id) return Boolean;

   --  E is a subprogram. Return True is E is an implicit operation inherited

   --  by a derived type declarations.

   function Is_LHS (N : Node_Id) return Boolean;

   --  Returns True iff N is used as Name in an assignment statement.

   function Is_Library_Level_Entity (E : Entity_Id) return Boolean;

   --  A library-level declaration is one that is accessible from Standard,

   --  i.e. a library unit or an entity declared in a library package.

   function Is_Local_Variable_Reference (Expr : Node_Id) return Boolean;

   --  Determines whether Expr is a reference to a variable or IN OUT mode

   --  parameter of the current enclosing subprogram.

   --  Why are OUT parameters not considered here ???

   function Is_Object_Reference (N : Node_Id) return Boolean;

   --  Determines if the tree referenced by N represents an object. Both

   --  variable and constant objects return True (compare Is_Variable).

   function Is_OK_Variable_For_Out_Formal (AV : Node_Id) return Boolean;

   --  Used to test if AV is an acceptable formal for an OUT or IN OUT

   --  formal. Note that the Is_Variable function is not quite the right

   --  test because this is a case in which conversions whose expression

   --  is a variable (in the Is_Variable sense) with a non-tagged type

   --  target are considered view conversions and hence variables.

   function Is_Partially_Initialized_Type (Typ : Entity_Id) return Boolean;

   --  Typ is a type entity. This function returns true if this type is partly

   --  initialized, meaning that an object of the type is at least partly

   --  initialized (in particular in the record case, that at least one

   --  component has an initialization expression). Note that initialization

   --  resulting from the use of pragma Normalized_Scalars does not count.

   function Is_Potentially_Persistent_Type (T : Entity_Id) return Boolean;

   --  Determines if type T is a potentially persistent type. A potentially

   --  persistent type is defined (recursively) as a scalar type, a non-tagged

   --  record whose components are all of a potentially persistent type, or an

   --  array with all static constraints whose component type is potentially

   --  persistent. A private type is potentially persistent if the full type

   --  is potentially persistent.

   function Is_Protected_Self_Reference (N : Node_Id) return Boolean;

   --  Return True if node N denotes a protected type name which represents

   --  the current instance of a protected object according to RM 9.4(21/2).

   function Is_RCI_Pkg_Spec_Or_Body (Cunit : Node_Id) return Boolean;

   --  Return True if a compilation unit is the specification or the

   --  body of a remote call interface package.

   function Is_Remote_Access_To_Class_Wide_Type (E : Entity_Id) return Boolean;

   --  Return True if E is a remote access-to-class-wide type

   function Is_Remote_Access_To_Subprogram_Type (E : Entity_Id) return Boolean;

   --  Return True if E is a remote access to subprogram type

   function Is_Remote_Call (N : Node_Id) return Boolean;

   --  Return True if N denotes a potentially remote call

   function Is_Renamed_Entry (Proc_Nam : Entity_Id) return Boolean;

   --  Return True if Proc_Nam is a procedure renaming of an entry

   function Is_Selector_Name (N : Node_Id) return Boolean;

   --  Given an N_Identifier node N, determines if it is a Selector_Name.

   --  As described in Sinfo, Selector_Names are special because they

   --  represent use of the N_Identifier node for a true identifier, when

   --  normally such nodes represent a direct name.

   function Is_Statement (N : Node_Id) return Boolean;

   --  Check if the node N is a statement node. Note that this includes

   --  the case of procedure call statements (unlike the direct use of

   --  the N_Statement_Other_Than_Procedure_Call subtype from Sinfo).

   --  Note that a label is *not* a statement, and will return False.

   function Is_Synchronized_Tagged_Type (E : Entity_Id) return Boolean;

   --  Returns True if E is a synchronized tagged type (AARM 3.9.4 (6/2))

   function Is_Transfer (N : Node_Id) return Boolean;

   --  Returns True if the node N is a statement which is known to cause

   --  an unconditional transfer of control at runtime, i.e. the following

   --  statement definitely will not be executed.

   function Is_True (U : Uint) return Boolean;

   --  The argument is a Uint value which is the Boolean'Pos value of a

   --  Boolean operand (i.e. is either 0 for False, or 1 for True). This

   --  function simply tests if it is True (i.e. non-zero)

   function Is_Value_Type (T : Entity_Id) return Boolean;

   --  Returns true if type T represents a value type. This is only relevant to

   --  CIL, will always return false for other targets. A value type is a CIL

   --  object that is accessed directly, as opposed to the other CIL objects

   --  that are accessed through managed pointers.