------------------------------------------------------------------------------ -- -- -- GNAT COMPILER COMPONENTS -- -- -- -- S E M _ D I S P -- -- -- -- S p e c -- -- -- -- Copyright (C) 1992-2018, 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. -- -- -- ------------------------------------------------------------------------------ -- This package contains routines involved in tagged types and dynamic -- dispatching. with Types; use Types; package Sem_Disp is procedure Check_Controlling_Formals (Typ : Entity_Id; Subp : Entity_Id); -- Check that all controlling parameters of Subp are of type Typ, that -- defaults for controlling parameters are tag-indeterminate, and that the -- nominal subtype of the parameters and result statically match the first -- subtype of the controlling type. Issues appropriate error messages if -- any of these requirements is not met. procedure Check_Dispatching_Call (N : Node_Id); -- Check if the call N is a dispatching call. The subprogram is known to be -- a dispatching operation. The call is dispatching if all the controlling -- actuals are dynamically tagged. This procedure is called after overload -- resolution, so the call is known to be unambiguous. procedure Check_Dispatching_Operation (Subp, Old_Subp : Entity_Id); -- Add Subp to the list of primitive operations of the corresponding type -- if it has a parameter of this type and is defined at a proper place for -- primitive operations (new primitives are only defined in package spec, -- overridden operation can be defined in any scope). If Old_Subp is not -- Empty we are in the overriding case. If the tagged type associated with -- Subp is a concurrent type (case that occurs when the type is declared -- in a generic because the analysis of generics disables generation of the -- corresponding record) then this routine does not add Subp to the list of -- primitive operations but leaves Subp decorated as dispatching operation -- to enable checks associated with the Object.Operation notation. procedure Check_Operation_From_Incomplete_Type (Subp : Entity_Id; Typ : Entity_Id); -- If a primitive operation was defined for the incomplete view of the -- type, and the full type declaration is a derived type definition, -- the operation may override an inherited one. -- Need more description here, what are the parameters, and what does -- this call actually do??? procedure Check_Operation_From_Private_View (Subp, Old_Subp : Entity_Id); -- Add Old_Subp to the list of primitive operations of the corresponding -- tagged type if it is the full view of a private tagged type. The Alias -- of Old_Subp is adjusted to point to the inherited procedure of the -- full view because it is always this one which has to be called. -- What is Subp used for??? function Covered_Interface_Op (Prim : Entity_Id) return Entity_Id; -- Returns the interface primitive that Prim covers, when its controlling -- type has progenitors. function Find_Controlling_Arg (N : Node_Id) return Node_Id; -- Returns the actual controlling argument if N is dynamically tagged, and -- Empty if it is not dynamically tagged. function Find_Dispatching_Type (Subp : Entity_Id) return Entity_Id; -- Check whether the subprogram Subp is dispatching, and find the tagged -- type of the controlling argument or arguments. Returns Empty if Subp -- is not a dispatching operation. function Find_Primitive_Covering_Interface (Tagged_Type : Entity_Id; Iface_Prim : Entity_Id) return Entity_Id; -- Search the homonym chain for the primitive of Tagged_Type that covers -- Iface_Prim. The homonym chain traversal is required to catch primitives -- associated with the partial view of private types when processing the -- corresponding full view. If the entity is not found, then search for it -- in the list of primitives of Tagged_Type. This latter search is needed -- when the interface primitive is covered by a private subprogram. If the -- primitive has not been covered yet then return the entity that will be -- overridden when the primitive is covered (that is, return the entity -- whose alias attribute references the interface primitive). If none of -- these entities is found then return Empty. type Subprogram_List is array (Nat range <>) of Entity_Id; -- Type returned by Inherited_Subprograms function generic with function Find_DT (Subp : Entity_Id) return Entity_Id; package Inheritance_Utilities is -- This package provides generic versions of inheritance utilities -- provided here. These versions are used in GNATprove backend to adapt -- these utilities to GNATprove specific version of visibility of types. function Inherited_Subprograms (S : Entity_Id; No_Interfaces : Boolean := False; Interfaces_Only : Boolean := False; One_Only : Boolean := False) return Subprogram_List; function Is_Overriding_Subprogram (E : Entity_Id) return Boolean; end Inheritance_Utilities; function Inherited_Subprograms (S : Entity_Id; No_Interfaces : Boolean := False; Interfaces_Only : Boolean := False; One_Only : Boolean := False) return Subprogram_List; -- Given the spec of a subprogram, this function gathers any inherited -- subprograms from direct inheritance or via interfaces. The result is an -- array of Entity_Ids of the specs of inherited subprograms. Returns a -- null array if passed an Empty spec id. Note that the returned array -- only includes subprograms and generic subprograms (and excludes any -- other inherited entities, in particular enumeration literals). If -- No_Interfaces is True, only return inherited subprograms not coming -- from an interface. If Interfaces_Only is True, only return inherited -- subprograms from interfaces. Otherwise, subprograms inherited directly -- come first, starting with the closest ancestors, and are followed by -- subprograms inherited from interfaces. At most one of No_Interfaces -- and Interfaces_Only should be True. -- -- If One_Only is set, the search is discontinued as soon as one entry -- is found. In this case the resulting array is either null or contains -- exactly one element. function Is_Dynamically_Tagged (N : Node_Id) return Boolean; -- Used to determine whether a call is dispatching, i.e. if it is -- an expression of a class_Wide type, or a call to a function with -- controlling result where at least one operand is dynamically tagged. -- Also used to determine whether an entity has a class-wide type, or a -- function call that dispatches on the result. Used to verify that all the -- dependent expressions in a conditional expression are equally tagged. function Is_Null_Interface_Primitive (E : Entity_Id) return Boolean; -- Returns True if E is a null procedure that is an interface primitive function Is_Overriding_Subprogram (E : Entity_Id) return Boolean; -- Returns True if E is an overriding subprogram function Is_Tag_Indeterminate (N : Node_Id) return Boolean; -- Returns true if the expression N is tag-indeterminate. An expression -- is tag-indeterminate if it is a call that dispatches on result, and all -- controlling operands are also indeterminate. Such a function call may -- inherit a tag from an enclosing call. procedure Override_Dispatching_Operation (Tagged_Type : Entity_Id; Prev_Op : Entity_Id; New_Op : Entity_Id; Is_Wrapper : Boolean := False); -- Replace an implicit dispatching operation of the type Tagged_Type -- with an explicit one. Prev_Op is an inherited primitive operation which -- is overridden by the explicit declaration of New_Op. Is_Wrapper is -- True when New_Op is an internally generated wrapper of a controlling -- function. The caller checks that Tagged_Type is indeed a tagged type. procedure Propagate_Tag (Control : Node_Id; Actual : Node_Id); -- If a function call is tag-indeterminate, its controlling argument is -- found in the context: either an enclosing call, or the left-hand side -- of the enclosing assignment statement. The tag must be propagated -- recursively to the tag-indeterminate actuals of the call. -- Need clear description of the parameters Control and Actual, especially -- since the comments above refer to actuals in the plural ??? end Sem_Disp;