1------------------------------------------------------------------------------ 2-- -- 3-- GNAT COMPILER COMPONENTS -- 4-- -- 5-- S E M _ D I S P -- 6-- -- 7-- S p e c -- 8-- -- 9-- Copyright (C) 1992-2021, Free Software Foundation, Inc. -- 10-- -- 11-- GNAT is free software; you can redistribute it and/or modify it under -- 12-- terms of the GNU General Public License as published by the Free Soft- -- 13-- ware Foundation; either version 3, or (at your option) any later ver- -- 14-- sion. GNAT is distributed in the hope that it will be useful, but WITH- -- 15-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY -- 16-- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License -- 17-- for more details. You should have received a copy of the GNU General -- 18-- Public License distributed with GNAT; see file COPYING3. If not, go to -- 19-- http://www.gnu.org/licenses for a complete copy of the license. -- 20-- -- 21-- GNAT was originally developed by the GNAT team at New York University. -- 22-- Extensive contributions were provided by Ada Core Technologies Inc. -- 23-- -- 24------------------------------------------------------------------------------ 25 26-- This package contains routines involved in tagged types and dynamic 27-- dispatching. 28 29with Types; use Types; 30package Sem_Disp is 31 32 procedure Check_Controlling_Formals (Typ : Entity_Id; Subp : Entity_Id); 33 -- Check that all controlling parameters of Subp are of type Typ, that 34 -- defaults for controlling parameters are tag-indeterminate, and that the 35 -- nominal subtype of the parameters and result statically match the first 36 -- subtype of the controlling type. Issues appropriate error messages if 37 -- any of these requirements is not met. 38 39 procedure Check_Dispatching_Call (N : Node_Id); 40 -- Check if the call N is a dispatching call. The subprogram is known to be 41 -- a dispatching operation. The call is dispatching if all the controlling 42 -- actuals are dynamically tagged. This procedure is called after overload 43 -- resolution, so the call is known to be unambiguous. 44 45 procedure Check_Dispatching_Operation (Subp, Old_Subp : Entity_Id); 46 -- Add Subp to the list of primitive operations of the corresponding type 47 -- if it has a parameter of this type and is defined at a proper place for 48 -- primitive operations (new primitives are only defined in package spec, 49 -- overridden operation can be defined in any scope). If Old_Subp is not 50 -- Empty we are in the overriding case. If the tagged type associated with 51 -- Subp is a concurrent type (case that occurs when the type is declared 52 -- in a generic because the analysis of generics disables generation of the 53 -- corresponding record) then this routine does not add Subp to the list of 54 -- primitive operations but leaves Subp decorated as dispatching operation 55 -- to enable checks associated with the Object.Operation notation. 56 57 procedure Check_Operation_From_Incomplete_Type 58 (Subp : Entity_Id; 59 Typ : Entity_Id); 60 -- If a primitive subprogram Subp was defined for the incomplete view of 61 -- Typ, and the full type declaration is a derived type, then Subp may 62 -- override a subprogram inherited from the parent type. In that case, 63 -- the inherited subprogram will have been hidden by the current one at 64 -- the point of the type derivation, so it does not appear in the list 65 -- of primitive operations of the type, and this procedure inserts the 66 -- overriding subprogram in the the full type's list of primitives by 67 -- iterating over the list for the parent type. If instead Subp is a new 68 -- primitive, then it's simply appended to the primitive list. 69 70 procedure Check_Operation_From_Private_View (Subp, Old_Subp : Entity_Id); 71 -- No action performed if Subp is not an alias of a dispatching operation. 72 -- Add Old_Subp (if not already present) to the list of primitives of the 73 -- tagged type T of Subp if T is the full view of a private tagged type. 74 -- The Alias of Old_Subp is adjusted to point to the inherited procedure 75 -- of the full view because it is always this one which has to be called. 76 77 function Covered_Interface_Primitives (Prim : Entity_Id) return Elist_Id; 78 -- Returns all the interface primitives covered by Prim, when its 79 -- controlling type has progenitors. 80 81 function Covered_Interface_Op (Prim : Entity_Id) return Entity_Id; 82 -- Returns the interface primitive that Prim covers, when its controlling 83 -- type has progenitors. 84 85 function Find_Controlling_Arg (N : Node_Id) return Node_Id; 86 -- Returns the actual controlling argument if N is dynamically tagged, and 87 -- Empty if it is not dynamically tagged. 88 89 function Find_Dispatching_Type (Subp : Entity_Id) return Entity_Id; 90 -- Check whether the subprogram Subp is dispatching, and find the tagged 91 -- type of the controlling argument or arguments. Returns Empty if Subp 92 -- is not a dispatching operation. 93 94 function Find_Primitive_Covering_Interface 95 (Tagged_Type : Entity_Id; 96 Iface_Prim : Entity_Id) return Entity_Id; 97 -- Search the homonym chain for the primitive of Tagged_Type that covers 98 -- Iface_Prim. The homonym chain traversal is required to catch primitives 99 -- associated with the partial view of private types when processing the 100 -- corresponding full view. If the entity is not found, then search for it 101 -- in the list of primitives of Tagged_Type. This latter search is needed 102 -- when the interface primitive is covered by a private subprogram. If the 103 -- primitive has not been covered yet then return the entity that will be 104 -- overridden when the primitive is covered (that is, return the entity 105 -- whose alias attribute references the interface primitive). If none of 106 -- these entities is found then return Empty. 107 108 type Subprogram_List is array (Nat range <>) of Entity_Id; 109 -- Type returned by Inherited_Subprograms function 110 111 generic 112 with function Find_DT (Subp : Entity_Id) return Entity_Id; 113 package Inheritance_Utilities is 114 115 -- This package provides generic versions of inheritance utilities 116 -- provided here. These versions are used in GNATprove backend to adapt 117 -- these utilities to GNATprove specific version of visibility of types. 118 119 function Inherited_Subprograms 120 (S : Entity_Id; 121 No_Interfaces : Boolean := False; 122 Interfaces_Only : Boolean := False; 123 One_Only : Boolean := False) return Subprogram_List; 124 125 function Is_Overriding_Subprogram (E : Entity_Id) return Boolean; 126 end Inheritance_Utilities; 127 128 function Inherited_Subprograms 129 (S : Entity_Id; 130 No_Interfaces : Boolean := False; 131 Interfaces_Only : Boolean := False; 132 One_Only : Boolean := False) return Subprogram_List; 133 -- Given the spec of a subprogram, this function gathers any inherited 134 -- subprograms from direct inheritance or via interfaces. The result is an 135 -- array of Entity_Ids of the specs of inherited subprograms. Returns a 136 -- null array if passed an Empty spec id. Note that the returned array 137 -- only includes subprograms and generic subprograms (and excludes any 138 -- other inherited entities, in particular enumeration literals). If 139 -- No_Interfaces is True, only return inherited subprograms not coming 140 -- from an interface. If Interfaces_Only is True, only return inherited 141 -- subprograms from interfaces. Otherwise, subprograms inherited directly 142 -- come first, starting with the closest ancestors, and are followed by 143 -- subprograms inherited from interfaces. At most one of No_Interfaces 144 -- and Interfaces_Only should be True. 145 -- 146 -- If One_Only is set, the search is discontinued as soon as one entry 147 -- is found. In this case the resulting array is either null or contains 148 -- exactly one element. 149 150 function Is_Dynamically_Tagged (N : Node_Id) return Boolean; 151 -- Used to determine whether a call is dispatching, i.e. if it is 152 -- an expression of a class_Wide type, or a call to a function with 153 -- controlling result where at least one operand is dynamically tagged. 154 -- Also used to determine whether an entity has a class-wide type, or a 155 -- function call that dispatches on the result. Used to verify that all the 156 -- dependent expressions in a conditional expression are equally tagged. 157 158 function Is_Null_Interface_Primitive (E : Entity_Id) return Boolean; 159 -- Returns True if E is a null procedure that is an interface primitive 160 161 function Is_Overriding_Subprogram (E : Entity_Id) return Boolean; 162 -- Returns True if E is an overriding subprogram and False otherwise, in 163 -- particular for an inherited subprogram. 164 165 function Is_Tag_Indeterminate (N : Node_Id) return Boolean; 166 -- Returns true if the expression N is tag-indeterminate. An expression 167 -- is tag-indeterminate if it is a call that dispatches on result, and all 168 -- controlling operands are also indeterminate. Such a function call may 169 -- inherit a tag from an enclosing call. 170 171 procedure Override_Dispatching_Operation 172 (Tagged_Type : Entity_Id; 173 Prev_Op : Entity_Id; 174 New_Op : Entity_Id); 175 -- Replace an implicit dispatching operation of the type Tagged_Type 176 -- with an explicit one. Prev_Op is an inherited primitive operation which 177 -- is overridden by the explicit declaration of New_Op. 178 179 procedure Propagate_Tag (Control : Node_Id; Actual : Node_Id); 180 -- If a function call given by Actual is tag-indeterminate, its controlling 181 -- argument is found in the context, given by Control: either from an 182 -- operand of an enclosing call, or the left-hand side of the enclosing 183 -- assignment statement. The tag of Control will be propagated recursively 184 -- to Actual and to its tag-indeterminate operands, if any. 185 186end Sem_Disp; 187