------------------------------------------------------------------------------ -- -- -- GNAT COMPILER COMPONENTS -- -- -- -- S E M _ A U X -- -- -- -- S p e c -- -- -- -- Copyright (C) 1992-2015, 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. -- -- -- -- As a special exception, if other files instantiate generics from this -- -- unit, or you link this unit with other files to produce an executable, -- -- this unit does not by itself cause the resulting executable to be -- -- covered by the GNU General Public License. This exception does not -- -- however invalidate any other reasons why the executable file might be -- -- covered by the GNU Public 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 compiler, -- and also by ASIS so dependencies are limited to ASIS included packages. -- Historical note. Many of the routines here were originally in Einfo, but -- Einfo is supposed to be a relatively low level package dealing with the -- content of entities in the tree, so this package is used for routines that -- require more than minimal semantic knowledge. with Alloc; use Alloc; with Namet; use Namet; with Table; with Types; use Types; with Sinfo; use Sinfo; package Sem_Aux is -------------------------------- -- Obsolescent Warnings Table -- -------------------------------- -- This table records entities for which a pragma Obsolescent with a -- message argument has been processed. type OWT_Record is record Ent : Entity_Id; -- The entity to which the pragma applies Msg : String_Id; -- The string containing the message end record; package Obsolescent_Warnings is new Table.Table ( Table_Component_Type => OWT_Record, Table_Index_Type => Int, Table_Low_Bound => 0, Table_Initial => Alloc.Obsolescent_Warnings_Initial, Table_Increment => Alloc.Obsolescent_Warnings_Increment, Table_Name => "Obsolescent_Warnings"); procedure Initialize; -- Called at the start of compilation of each new main source file to -- initialize the allocation of the Obsolescent_Warnings table. Note that -- Initialize must not be called if Tree_Read is used. procedure Tree_Read; -- Initializes Obsolescent_Warnings table from current tree file using the -- relevant Table.Tree_Read routine. procedure Tree_Write; -- Writes out Obsolescent_Warnings table to current tree file using the -- relevant Table.Tree_Write routine. ----------------- -- Subprograms -- ----------------- function Ancestor_Subtype (Typ : Entity_Id) return Entity_Id; -- The argument Id is a type or subtype entity. If the argument is a -- subtype then it returns the subtype or type from which the subtype was -- obtained, otherwise it returns Empty. function Available_View (Ent : Entity_Id) return Entity_Id; -- Ent denotes an abstract state or a type that may come from a limited -- with clause. Return the non-limited view of Ent if there is one or Ent -- if this is not the case. function Constant_Value (Ent : Entity_Id) return Node_Id; -- Ent is a variable, constant, named integer, or named real entity. This -- call obtains the initialization expression for the entity. Will return -- Empty for a deferred constant whose full view is not available or -- in some other cases of internal entities, which cannot be treated as -- constants from the point of view of constant folding. Empty is also -- returned for variables with no initialization expression. function Corresponding_Unsigned_Type (Typ : Entity_Id) return Entity_Id; -- Typ is a signed integer subtype. This routine returns the standard -- unsigned type with the same Esize as the implementation base type of -- Typ, e.g. Long_Integer => Long_Unsigned. function Enclosing_Dynamic_Scope (Ent : Entity_Id) return Entity_Id; -- For any entity, Ent, returns the closest dynamic scope in which the -- entity is declared or Standard_Standard for library-level entities. function First_Discriminant (Typ : Entity_Id) return Entity_Id; -- Typ is a type with discriminants. The discriminants are the first -- entities declared in the type, so normally this is equivalent to -- First_Entity. The exception arises for tagged types, where the tag -- itself is prepended to the front of the entity chain, so the -- First_Discriminant function steps past the tag if it is present. -- The caller is responsible for checking that the type has discriminants. -- When called on a private type with unknown discriminants, the function -- always returns Empty. function First_Stored_Discriminant (Typ : Entity_Id) return Entity_Id; -- Typ is a type with discriminants. Gives the first discriminant stored -- in an object of this type. In many cases, these are the same as the -- normal visible discriminants for the type, but in the case of renamed -- discriminants, this is not always the case. -- -- For tagged types, and untagged types which are root types or derived -- types but which do not rename discriminants in their root type, the -- stored discriminants are the same as the actual discriminants of the -- type, and hence this function is the same as First_Discriminant. -- -- For derived untagged types that rename discriminants in the root type -- this is the first of the discriminants that occur in the root type. To -- be precise, in this case stored discriminants are entities attached to -- the entity chain of the derived type which are a copy of the -- discriminants of the root type. Furthermore their Is_Completely_Hidden -- flag is set since although they are actually stored in the object, they -- are not in the set of discriminants that is visible in the type. -- -- For derived untagged types, the set of stored discriminants are the real -- discriminants from Gigi's standpoint, i.e. those that will be stored in -- actual objects of the type. function First_Subtype (Typ : Entity_Id) return Entity_Id; -- Applies to all types and subtypes. For types, yields the first subtype -- of the type. For subtypes, yields the first subtype of the base type of -- the subtype. function First_Tag_Component (Typ : Entity_Id) return Entity_Id; -- Typ must be a tagged record type. This function returns the Entity for -- the first _Tag field in the record type. function Get_Binary_Nkind (Op : Entity_Id) return Node_Kind; -- Op must be an entity with an Ekind of E_Operator. This function returns -- the Nkind value that would be used to construct a binary operator node -- referencing this entity. It is an error to call this function if Ekind -- (Op) /= E_Operator. function Get_Low_Bound (E : Entity_Id) return Node_Id; -- For an index subtype or string literal subtype, return its low bound function Get_Unary_Nkind (Op : Entity_Id) return Node_Kind; -- Op must be an entity with an Ekind of E_Operator. This function returns -- the Nkind value that would be used to construct a unary operator node -- referencing this entity. It is an error to call this function if Ekind -- (Op) /= E_Operator. function Get_Rep_Item (E : Entity_Id; Nam : Name_Id; Check_Parents : Boolean := True) return Node_Id; -- Searches the Rep_Item chain for a given entity E, for an instance of a -- rep item (pragma, attribute definition clause, or aspect specification) -- whose name matches the given name Nam. If Check_Parents is False then it -- only returns rep item that has been directly specified for E (and not -- inherited from its parents, if any). If one is found, it is returned, -- otherwise Empty is returned. A special case is that when Nam is -- Name_Priority, the call will also find Interrupt_Priority. function Get_Rep_Item (E : Entity_Id; Nam1 : Name_Id; Nam2 : Name_Id; Check_Parents : Boolean := True) return Node_Id; -- Searches the Rep_Item chain for a given entity E, for an instance of a -- rep item (pragma, attribute definition clause, or aspect specification) -- whose name matches one of the given names Nam1 or Nam2. If Check_Parents -- is False then it only returns rep item that has been directly specified -- for E (and not inherited from its parents, if any). If one is found, it -- is returned, otherwise Empty is returned. A special case is that when -- one of the given names is Name_Priority, the call will also find -- Interrupt_Priority. function Get_Rep_Pragma (E : Entity_Id; Nam : Name_Id; Check_Parents : Boolean := True) return Node_Id; -- Searches the Rep_Item chain for a given entity E, for an instance of a -- representation pragma whose name matches the given name Nam. If -- Check_Parents is False then it only returns representation pragma that -- has been directly specified for E (and not inherited from its parents, -- if any). If one is found and if it is the first rep item in the list -- that matches Nam, it is returned, otherwise Empty is returned. A special -- case is that when Nam is Name_Priority, the call will also find -- Interrupt_Priority. function Get_Rep_Pragma (E : Entity_Id; Nam1 : Name_Id; Nam2 : Name_Id; Check_Parents : Boolean := True) return Node_Id; -- Searches the Rep_Item chain for a given entity E, for an instance of a -- representation pragma whose name matches one of the given names Nam1 or -- Nam2. If Check_Parents is False then it only returns representation -- pragma that has been directly specified for E (and not inherited from -- its parents, if any). If one is found and if it is the first rep item in -- the list that matches one of the given names, it is returned, otherwise -- Empty is returned. A special case is that when one of the given names is -- Name_Priority, the call will also find Interrupt_Priority. function Has_Rep_Item (E : Entity_Id; Nam : Name_Id; Check_Parents : Boolean := True) return Boolean; -- Searches the Rep_Item chain for the given entity E, for an instance of a -- rep item (pragma, attribute definition clause, or aspect specification) -- with the given name Nam. If Check_Parents is False then it only checks -- for a rep item that has been directly specified for E (and not inherited -- from its parents, if any). If found then True is returned, otherwise -- False indicates that no matching entry was found. function Has_Rep_Item (E : Entity_Id; Nam1 : Name_Id; Nam2 : Name_Id; Check_Parents : Boolean := True) return Boolean; -- Searches the Rep_Item chain for the given entity E, for an instance of a -- rep item (pragma, attribute definition clause, or aspect specification) -- with the given names Nam1 or Nam2. If Check_Parents is False then it -- only checks for a rep item that has been directly specified for E (and -- not inherited from its parents, if any). If found then True is returned, -- otherwise False indicates that no matching entry was found. function Has_Rep_Pragma (E : Entity_Id; Nam : Name_Id; Check_Parents : Boolean := True) return Boolean; -- Searches the Rep_Item chain for the given entity E, for an instance of a -- representation pragma with the given name Nam. If Check_Parents is False -- then it only checks for a representation pragma that has been directly -- specified for E (and not inherited from its parents, if any). If found -- and if it is the first rep item in the list that matches Nam then True -- is returned, otherwise False indicates that no matching entry was found. function Has_Rep_Pragma (E : Entity_Id; Nam1 : Name_Id; Nam2 : Name_Id; Check_Parents : Boolean := True) return Boolean; -- Searches the Rep_Item chain for the given entity E, for an instance of a -- representation pragma with the given names Nam1 or Nam2. If -- Check_Parents is False then it only checks for a rep item that has been -- directly specified for E (and not inherited from its parents, if any). -- If found and if it is the first rep item in the list that matches one of -- the given names then True is returned, otherwise False indicates that no -- matching entry was found. function Has_External_Tag_Rep_Clause (T : Entity_Id) return Boolean; -- Defined in tagged types. Set if an External_Tag rep. clause has been -- given for this type. Use to avoid the generation of the default -- External_Tag. -- -- Note: we used to use an entity flag for this purpose, but that was wrong -- because it was not propagated from the private view to the full view. We -- could have added that propagation, but it would have been an annoying -- irregularity compared to other representation aspects, and the cost of -- looking up the aspect when needed is small. function Has_Unconstrained_Elements (T : Entity_Id) return Boolean; -- True if T has discriminants and is unconstrained, or is an array type -- whose element type Has_Unconstrained_Elements. function Has_Variant_Part (Typ : Entity_Id) return Boolean; -- Return True if the first subtype of Typ is a discriminated record type -- which has a variant part. False otherwise. function In_Generic_Body (Id : Entity_Id) return Boolean; -- Determine whether entity Id appears inside a generic body function Initialization_Suppressed (Typ : Entity_Id) return Boolean; pragma Inline (Initialization_Suppressed); -- Returns True if initialization should be suppressed for the given type -- or subtype. This is true if Suppress_Initialization is set either for -- the subtype itself, or for the corresponding base type. function Is_Body (N : Node_Id) return Boolean; -- Determine whether an arbitrary node denotes a body function Is_By_Copy_Type (Ent : Entity_Id) return Boolean; -- Ent is any entity. Returns True if Ent is a type entity where the type -- is required to be passed by copy, as defined in (RM 6.2(3)). function Is_By_Reference_Type (Ent : Entity_Id) return Boolean; -- Ent is any entity. Returns True if Ent is a type entity where the type -- is required to be passed by reference, as defined in (RM 6.2(4-9)). function Is_Definite_Subtype (T : Entity_Id) return Boolean; -- T is a type entity. Returns True if T is a definite subtype. -- Indefinite subtypes are unconstrained arrays, unconstrained -- discriminated types without defaulted discriminants, class-wide types, -- and types with unknown discriminants. Definite subtypes are all others -- (elementary, constrained composites (including the case of records -- without discriminants), and types with defaulted discriminants). function Is_Derived_Type (Ent : Entity_Id) return Boolean; -- Determines if the given entity Ent is a derived type. Result is always -- false if argument is not a type. function Is_Generic_Formal (E : Entity_Id) return Boolean; -- Determine whether E is a generic formal parameter. In particular this is -- used to set the visibility of generic formals of a generic package -- declared with a box or with partial parameterization. function Is_Immutably_Limited_Type (Ent : Entity_Id) return Boolean; -- Implements definition in Ada 2012 RM-7.5 (8.1/3). This differs from the -- following predicate in that an untagged record with immutably limited -- components is NOT by itself immutably limited. This matters, e.g. when -- checking the legality of an access to the current instance. function Is_Limited_View (Ent : Entity_Id) return Boolean; -- Ent is any entity. True for a type that is "inherently" limited (i.e. -- cannot become nonlimited). From the Ada 2005 RM-7.5(8.1/2), "a type with -- a part that is of a task, protected, or explicitly limited record type". -- These are the types that are defined as return-by-reference types in Ada -- 95 (see RM95-6.5(11-16)). In Ada 2005, these are the types that require -- build-in-place for function calls. Note that build-in-place is allowed -- for other types, too. This is also used for identifying pure procedures -- whose calls should not be eliminated (RM 10.2.1(18/2)). function Is_Limited_Type (Ent : Entity_Id) return Boolean; -- Ent is any entity. Returns true if Ent is a limited type (limited -- private type, limited interface type, task type, protected type, -- composite containing a limited component, or a subtype of any of -- these types). This older routine overlaps with the previous one, this -- should be cleaned up??? function Nearest_Ancestor (Typ : Entity_Id) return Entity_Id; -- Given a subtype Typ, this function finds out the nearest ancestor from -- which constraints and predicates are inherited. There is no simple link -- for doing this, consider: -- -- subtype R is Integer range 1 .. 10; -- type T is new R; -- -- In this case the nearest ancestor is R, but the Etype of T'Base will -- point to R'Base, so we have to go rummaging in the declarations to get -- this information. It is used for making sure we freeze this before we -- freeze Typ, and also for retrieving inherited predicate information. -- For the case of base types or first subtypes, there is no useful entity -- to return, so Empty is returned. -- -- Note: this is similar to Ancestor_Subtype except that it also deals -- with the case of derived types. function Nearest_Dynamic_Scope (Ent : Entity_Id) return Entity_Id; -- This is similar to Enclosing_Dynamic_Scope except that if Ent is itself -- a dynamic scope, then it is returned. Otherwise the result is the same -- as that returned by Enclosing_Dynamic_Scope. function Next_Tag_Component (Tag : Entity_Id) return Entity_Id; -- Tag must be an entity representing a _Tag field of a tagged record. -- The result returned is the next _Tag field in this record, or Empty -- if this is the last such field. function Number_Components (Typ : Entity_Id) return Nat; -- Typ is a record type, yields number of components (including -- discriminants) in type. function Number_Discriminants (Typ : Entity_Id) return Pos; -- Typ is a type with discriminants, yields number of discriminants in type function Object_Type_Has_Constrained_Partial_View (Typ : Entity_Id; Scop : Entity_Id) return Boolean; -- Return True if type of object has attribute Has_Constrained_Partial_View -- set to True; in addition, within a generic body, return True if subtype -- of the object is a descendant of an untagged generic formal private or -- derived type, and the subtype is not an unconstrained array subtype -- (RM 3.3(23.10/3)). function Package_Body (E : Entity_Id) return Node_Id; -- Given an entity for a package (spec or body), return the corresponding -- package body if any, or else Empty. function Package_Spec (E : Entity_Id) return Node_Id; -- Given an entity for a package spec, return the corresponding package -- spec if any, or else Empty. function Package_Specification (E : Entity_Id) return Node_Id; -- Given an entity for a package, return the corresponding package -- specification. function Subprogram_Body (E : Entity_Id) return Node_Id; -- Given an entity for a subprogram (spec or body), return the -- corresponding subprogram body if any, or else Empty. function Subprogram_Body_Entity (E : Entity_Id) return Entity_Id; -- Given an entity for a subprogram (spec or body), return the entity -- corresponding to the subprogram body, which may be the same as E or -- Empty if no body is available. function Subprogram_Spec (E : Entity_Id) return Node_Id; -- Given an entity for a subprogram spec, return the corresponding -- subprogram spec if any, or else Empty. function Subprogram_Specification (E : Entity_Id) return Node_Id; -- Given an entity for a subprogram, return the corresponding subprogram -- specification. If the entity is an inherited subprogram without -- specification itself, return the specification of the inherited -- subprogram. function Ultimate_Alias (Prim : Entity_Id) return Entity_Id; pragma Inline (Ultimate_Alias); -- Return the last entity in the chain of aliased entities of Prim. If Prim -- has no alias return Prim. function Unit_Declaration_Node (Unit_Id : Entity_Id) return Node_Id; -- Unit_Id is the simple name of a program unit, this function returns the -- corresponding xxx_Declaration node for the entity. Also applies to the -- body entities for subprograms, tasks and protected units, in which case -- it returns the subprogram, task or protected body node for it. The unit -- may be a child unit with any number of ancestors. end Sem_Aux;