gcc/ada/sem_ch6.ads

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT COMPILER COMPONENTS                         --
   4 --                                                                          --
   5 --                              S E M _ C H 6                               --
   6 --                                                                          --
   7 --                                 S p e c                                  --
   8 --                                                                          --
   9 --          Copyright (C) 1992-2023, 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 with Types; use Types;
  27 package Sem_Ch6 is
  28
  29    type Conformance_Type is
  30      (Type_Conformant, Mode_Conformant, Subtype_Conformant, Fully_Conformant);
  31    pragma Ordered (Conformance_Type);
  32    --  Conformance type used in conformance checks between specs and bodies,
  33    --  and for overriding. The literals match the RM definitions of the
  34    --  corresponding terms. This is an ordered type, since each conformance
  35    --  type is stronger than the ones preceding it.
  36
  37    procedure Analyze_Abstract_Subprogram_Declaration (N : Node_Id);
  38    procedure Analyze_Expression_Function             (N : Node_Id);
  39    procedure Analyze_Extended_Return_Statement       (N : Node_Id);
  40    procedure Analyze_Function_Call                   (N : Node_Id);
  41    procedure Analyze_Operator_Symbol                 (N : Node_Id);
  42    procedure Analyze_Parameter_Association           (N : Node_Id);
  43    procedure Analyze_Procedure_Call                  (N : Node_Id);
  44    procedure Analyze_Return_When_Statement           (N : Node_Id);
  45    procedure Analyze_Simple_Return_Statement         (N : Node_Id);
  46    procedure Analyze_Subprogram_Declaration          (N : Node_Id);
  47    procedure Analyze_Subprogram_Body                 (N : Node_Id);
  48
  49    function Analyze_Subprogram_Specification (N : Node_Id) return Entity_Id;
  50    --  Analyze subprogram specification in both subprogram declarations
  51    --  and body declarations. Returns the defining entity for the
  52    --  specification N.
  53
  54    function Can_Override_Operator (Subp : Entity_Id) return Boolean;
  55    --  Returns true if Subp can override a predefined operator
  56
  57    procedure Check_Conventions (Typ : Entity_Id);
  58    --  Ada 2005 (AI-430): Check that the conventions of all inherited and
  59    --  overridden dispatching operations of type Typ are consistent with their
  60    --  respective counterparts.
  61
  62    procedure Check_Delayed_Subprogram (Designator : Entity_Id);
  63    --  Designator can be a E_Subprogram_Type, E_Procedure or E_Function. If a
  64    --  type in its profile depends on a private type without a full
  65    --  declaration, indicate that the subprogram or type is delayed.
  66
  67    procedure Check_Discriminant_Conformance
  68      (N        : Node_Id;
  69       Prev     : Entity_Id;
  70       Prev_Loc : Node_Id);
  71    --  Check that the discriminants of a full type N fully conform to the
  72    --  discriminants of the corresponding partial view Prev. Prev_Loc indicates
  73    --  the source location of the partial view, which may be different than
  74    --  Prev in the case of private types.
  75
  76    procedure Check_Formal_Subprogram_Conformance
  77      (New_Id  : Entity_Id;
  78       Old_Id  : Entity_Id;
  79       Err_Loc : Node_Id := Empty);
  80    --  Check RM 6.3.1(17/3): the profile of a generic formal subprogram is not
  81    --  subtype conformant with any other profile and post an error message if
  82    --  either New_Id or Old_Id denotes a formal subprogram, with the flag being
  83    --  placed on the Err_Loc node if it is specified, and on New_Id if not. See
  84    --  also spec of Check_Fully_Conformant below for New_Id and Old_Id usage.
  85
  86    procedure Check_Fully_Conformant
  87      (New_Id  : Entity_Id;
  88       Old_Id  : Entity_Id;
  89       Err_Loc : Node_Id := Empty);
  90    --  Check that two callable entities (subprograms, entries, literals)
  91    --  are fully conformant, post error message if not (RM 6.3.1(17)) with
  92    --  the flag being placed on the Err_Loc node if it is specified, and
  93    --  on the appropriate component of the New_Id construct if not. Note:
  94    --  when checking spec/body conformance, New_Id must be the body entity
  95    --  and Old_Id is the spec entity (the code in the implementation relies
  96    --  on this ordering, and in any case, this makes sense, since if flags
  97    --  are to be placed on the construct, they clearly belong on the body.
  98
  99    procedure Check_Mode_Conformant
 100      (New_Id   : Entity_Id;
 101       Old_Id   : Entity_Id;
 102       Err_Loc  : Node_Id := Empty;
 103       Get_Inst : Boolean := False);
 104    --  Check that two callable entities (subprograms, entries, literals)
 105    --  are mode conformant, post error message if not (RM 6.3.1(15)) with
 106    --  the flag being placed on the Err_Loc node if it is specified, and
 107    --  on the appropriate component of the New_Id construct if not. The
 108    --  argument Get_Inst is set to True when this is a check against a
 109    --  formal access-to-subprogram type, indicating that mapping of types
 110    --  is needed.
 111
 112    procedure Check_Overriding_Indicator
 113      (Subp            : Entity_Id;
 114       Overridden_Subp : Entity_Id;
 115       Is_Primitive    : Boolean);
 116    --  Verify the consistency of an overriding_indicator given for subprogram
 117    --  declaration, body, renaming, or instantiation. Overridden_Subp is set
 118    --  if the scope where we are introducing the subprogram contains a
 119    --  type-conformant subprogram that becomes hidden by the new subprogram.
 120    --  Is_Primitive indicates whether the subprogram is primitive.
 121
 122    procedure Check_Subtype_Conformant
 123      (New_Id                   : Entity_Id;
 124       Old_Id                   : Entity_Id;
 125       Err_Loc                  : Node_Id := Empty;
 126       Skip_Controlling_Formals : Boolean := False;
 127       Get_Inst                 : Boolean := False);
 128    --  Check that two callable entities (subprograms, entries, literals)
 129    --  are subtype conformant, post error message if not (RM 6.3.1(16)),
 130    --  the flag being placed on the Err_Loc node if it is specified, and
 131    --  on the appropriate component of the New_Id construct if not.
 132    --  Skip_Controlling_Formals is True when checking the conformance of
 133    --  a subprogram that implements an interface operation. In that case,
 134    --  only the non-controlling formals can (and must) be examined. The
 135    --  argument Get_Inst is set to True when this is a check against a
 136    --  formal access-to-subprogram type, indicating that mapping of types
 137    --  is needed.
 138
 139    procedure Check_Synchronized_Overriding
 140      (Def_Id          : Entity_Id;
 141       Overridden_Subp : out Entity_Id);
 142    --  First determine if Def_Id is an entry or a subprogram either defined in
 143    --  the scope of a task or protected type, or that is a primitive of such
 144    --  a type. Check whether Def_Id overrides a subprogram of an interface
 145    --  implemented by the synchronized type, returning the overridden entity
 146    --  or Empty.
 147
 148    procedure Check_Type_Conformant
 149      (New_Id  : Entity_Id;
 150       Old_Id  : Entity_Id;
 151       Err_Loc : Node_Id := Empty);
 152    --  Check that two callable entities (subprograms, entries, literals)
 153    --  are type conformant, post error message if not (RM 6.3.1(14)) with
 154    --  the flag being placed on the Err_Loc node if it is specified, and
 155    --  on the appropriate component of the New_Id construct if not.
 156
 157    function Conforming_Types
 158      (T1       : Entity_Id;
 159       T2       : Entity_Id;
 160       Ctype    : Conformance_Type;
 161       Get_Inst : Boolean := False) return Boolean;
 162    --  Check that the types of two formal parameters are conforming. In most
 163    --  cases this is just a name comparison, but within an instance it involves
 164    --  generic actual types, and in the presence of anonymous access types
 165    --  it must examine the designated types. The argument Get_Inst is set to
 166    --  True when this is a check against a formal access-to-subprogram type,
 167    --  indicating that mapping of types is needed.
 168
 169    procedure Create_Extra_Formals (E : Entity_Id);
 170    --  For each parameter of a subprogram or entry that requires an additional
 171    --  formal (such as for access parameters and indefinite discriminated
 172    --  parameters), creates the appropriate formal and attach it to its
 173    --  associated parameter. Each extra formal will also be appended to
 174    --  the end of Subp's parameter list (with each subsequent extra formal
 175    --  being attached to the preceding extra formal).
 176
 177    function Extra_Formals_Match_OK
 178      (E     : Entity_Id;
 179       Ref_E : Entity_Id) return Boolean;
 180    --  Return True if the extra formals of the given entities match. E is a
 181    --  subprogram, and Ref_E is the reference entity that will be used to check
 182    --  the extra formals of E: a subprogram type or another subprogram. For
 183    --  example, if E is a dispatching primitive of a tagged type then Ref_E
 184    --  may be the overridden primitive of its parent type or its ultimate
 185    --  renamed entity; however, if E is a subprogram to which 'Access is
 186    --  applied then Ref_E is its corresponding subprogram type. Used in
 187    --  assertions.
 188
 189    function Extra_Formals_OK (E : Entity_Id) return Boolean;
 190    --  Return True if the decoration of the attributes associated with extra
 191    --  formals are properly set. Used in assertions.
 192
 193    function Find_Corresponding_Spec
 194      (N          : Node_Id;
 195       Post_Error : Boolean := True) return Entity_Id;
 196    --  Use the subprogram specification in the body to retrieve the previous
 197    --  subprogram declaration, if any.
 198
 199    function Fully_Conformant (New_Id, Old_Id : Entity_Id) return Boolean;
 200    --  Determine whether two callable entities (subprograms, entries,
 201    --  literals) are fully conformant (RM 6.3.1(17))
 202
 203    function Fully_Conformant_Expressions
 204      (Given_E1 : Node_Id;
 205       Given_E2 : Node_Id;
 206       Report   : Boolean := False) return Boolean;
 207    --  Determines if two (non-empty) expressions are fully conformant
 208    --  as defined by (RM 6.3.1(18-21))
 209
 210    function Fully_Conformant_Discrete_Subtypes
 211       (Given_S1 : Node_Id;
 212        Given_S2 : Node_Id) return Boolean;
 213    --  Determines if two subtype definitions are fully conformant. Used
 214    --  for entry family conformance checks (RM 6.3.1 (24)).
 215
 216    function Has_BIP_Formals (E : Entity_Id) return Boolean;
 217    --  Determines if a given entity has build-in-place formals
 218
 219    procedure Install_Entity (E : Entity_Id);
 220    --  Place a single entity on the visibility chain
 221
 222    procedure Install_Formals (Id : Entity_Id);
 223    --  On entry to a subprogram body, make the formals visible. Note that
 224    --  simply placing the subprogram on the scope stack is not sufficient:
 225    --  the formals must become the current entities for their names. This
 226    --  procedure is also used to get visibility to the formals when analyzing
 227    --  preconditions and postconditions appearing in the spec.
 228
 229    function Is_Interface_Conformant
 230      (Tagged_Type : Entity_Id;
 231       Iface_Prim  : Entity_Id;
 232       Prim        : Entity_Id) return Boolean;
 233    --  Returns true if both primitives have a matching name (including support
 234    --  for names of inherited private primitives --which have suffix 'P'), they
 235    --  are type conformant, and Prim is defined in the scope of Tagged_Type.
 236    --  Special management is done for functions returning interfaces.
 237
 238    procedure List_Inherited_Pre_Post_Aspects (E : Entity_Id);
 239    --  E is the entity for a subprogram or generic subprogram spec. This call
 240    --  lists all inherited Pre/Post aspects if List_Inherited_Pre_Post is True.
 241
 242    procedure May_Need_Actuals (Fun : Entity_Id);
 243    --  Flag functions that can be called without parameters, i.e. those that
 244    --  have no parameters, or those for which defaults exist for all parameters
 245    --  Used for subprogram declarations and for access subprogram declarations,
 246    --  where they apply to the anonymous designated type. On return the flag
 247    --  Set_Needs_No_Actuals is set appropriately in Fun.
 248
 249    function Mode_Conformant (New_Id, Old_Id : Entity_Id) return Boolean;
 250    --  Determine whether two callable entities (subprograms, entries,
 251    --  literals) are mode conformant (RM 6.3.1(15))
 252
 253    procedure New_Overloaded_Entity
 254      (S            : Entity_Id;
 255       Derived_Type : Entity_Id := Empty);
 256    --  Process new overloaded entity. Overloaded entities are created by
 257    --  enumeration type declarations, subprogram specifications, entry
 258    --  declarations, and (implicitly) by type derivations. If Derived_Type
 259    --  is non-empty then this is a subprogram derived for that type.
 260
 261    procedure Process_Formals (T : List_Id; Related_Nod : Node_Id);
 262    --  Enter the formals in the scope of the subprogram or entry, and
 263    --  analyze default expressions if any. The implicit types created for
 264    --  access parameter are attached to the Related_Nod which comes from the
 265    --  context.
 266
 267    procedure Reference_Body_Formals (Spec : Entity_Id; Bod : Entity_Id);
 268    --  If there is a separate spec for a subprogram or generic subprogram, the
 269    --  formals of the body are treated as references to the corresponding
 270    --  formals of the spec. This reference does not count as an actual use of
 271    --  the formal, in order to diagnose formals that are unused in the body.
 272    --  This procedure is also used in renaming_as_body declarations, where
 273    --  the formals of the specification must be treated as body formals that
 274    --  correspond to the previous subprogram declaration, and not as new
 275    --  entities with their defining entry in the cross-reference information.
 276
 277    procedure Set_Actual_Subtypes (N : Node_Id; Subp : Entity_Id);
 278    --  If the formals of a subprogram are unconstrained, build a subtype
 279    --  declaration that uses the bounds or discriminants of the actual to
 280    --  construct an actual subtype for them. This is an optimization that
 281    --  is done only in some cases where the actual subtype cannot change
 282    --  during execution of the subprogram. By setting the actual subtype
 283    --  once, we avoid recomputing it unnecessarily.
 284
 285    procedure Set_Formal_Mode (Formal_Id : Entity_Id);
 286    --  Set proper Ekind to reflect formal mode (in, out, in out)
 287
 288    function Subtype_Conformant
 289      (New_Id                   : Entity_Id;
 290       Old_Id                   : Entity_Id;
 291       Skip_Controlling_Formals : Boolean := False) return Boolean;
 292    --  Determine whether two callable entities (subprograms, entries, literals)
 293    --  are subtype conformant (RM 6.3.1(16)). Skip_Controlling_Formals is True
 294    --  when checking the conformance of a subprogram that implements an
 295    --  interface operation. In that case, only the non-controlling formals
 296    --  can (and must) be examined.
 297
 298    function Type_Conformant
 299      (New_Id                   : Entity_Id;
 300       Old_Id                   : Entity_Id;
 301       Skip_Controlling_Formals : Boolean := False) return Boolean;
 302    --  Determine whether two callable entities (subprograms, entries, literals)
 303    --  are type conformant (RM 6.3.1(14)). Skip_Controlling_Formals is True
 304    --  when checking the conformance of a subprogram that implements an
 305    --  interface operation. In that case, only the non-controlling formals
 306    --  can (and must) be examined.
 307
 308    procedure Valid_Operator_Definition (Designator : Entity_Id);
 309    --  Verify that an operator definition has the proper number of formals
 310
 311 end Sem_Ch6;