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1 | ------------------------------------------------------------------------------ |
2 | -- -- | |
3 | -- GNAT COMPILER COMPONENTS -- | |
4 | -- -- | |
5 | -- S E M _ C H 1 3 -- | |
6 | -- -- | |
7 | -- S p e c -- | |
996ae0b0 | 8 | -- -- |
1d005acc | 9 | -- Copyright (C) 1992-2019, Free Software Foundation, Inc. -- |
996ae0b0 RK |
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- -- | |
b5c84c3c | 13 | -- ware Foundation; either version 3, or (at your option) any later ver- -- |
996ae0b0 RK |
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 -- | |
b5c84c3c RD |
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. -- | |
996ae0b0 RK |
20 | -- -- |
21 | -- GNAT was originally developed by the GNAT team at New York University. -- | |
71ff80dc | 22 | -- Extensive contributions were provided by Ada Core Technologies Inc. -- |
996ae0b0 RK |
23 | -- -- |
24 | ------------------------------------------------------------------------------ | |
25 | ||
105b5e65 | 26 | with Table; |
996ae0b0 RK |
27 | with Types; use Types; |
28 | with Uintp; use Uintp; | |
29 | ||
30 | package Sem_Ch13 is | |
31 | procedure Analyze_At_Clause (N : Node_Id); | |
32 | procedure Analyze_Attribute_Definition_Clause (N : Node_Id); | |
33 | procedure Analyze_Enumeration_Representation_Clause (N : Node_Id); | |
34 | procedure Analyze_Free_Statement (N : Node_Id); | |
3ff38f33 | 35 | procedure Analyze_Freeze_Entity (N : Node_Id); |
3cd4a210 | 36 | procedure Analyze_Freeze_Generic_Entity (N : Node_Id); |
996ae0b0 RK |
37 | procedure Analyze_Record_Representation_Clause (N : Node_Id); |
38 | procedure Analyze_Code_Statement (N : Node_Id); | |
39 | ||
eaba57fb RD |
40 | procedure Analyze_Aspect_Specifications (N : Node_Id; E : Entity_Id); |
41 | -- This procedure is called to analyze aspect specifications for node N. E | |
42 | -- is the corresponding entity declared by the declaration node N. Callers | |
43 | -- should check that Has_Aspects (N) is True before calling this routine. | |
0f1a6a0b | 44 | |
e9d08fd7 | 45 | procedure Analyze_Aspects_On_Subprogram_Body_Or_Stub (N : Node_Id); |
caf07df9 AC |
46 | -- Analyze the aspect specifications of [generic] subprogram body or stub |
47 | -- N. Callers should check that Has_Aspects (N) is True before calling the | |
48 | -- routine. This routine diagnoses misplaced aspects that should appear on | |
49 | -- the initial declaration of N and offers suggestions for replacements. | |
50 | ||
a9a5b8ac RD |
51 | procedure Adjust_Record_For_Reverse_Bit_Order (R : Entity_Id); |
52 | -- Called from Freeze where R is a record entity for which reverse bit | |
52b70b1b TQ |
53 | -- order is specified and there is at least one component clause. Note: |
54 | -- component positions are normally adjusted as per AI95-0133, unless | |
55 | -- -gnatd.p is used to restore original Ada 95 mode. | |
8a95f4e8 RD |
56 | |
57 | procedure Check_Record_Representation_Clause (N : Node_Id); | |
58 | -- This procedure completes the analysis of a record representation clause | |
59 | -- N. It is called at freeze time after adjustment of component clause bit | |
60 | -- positions for possible non-standard bit order. In the case of Ada 2005 | |
61 | -- (machine scalar) mode, this adjustment can make substantial changes, so | |
62 | -- some checks, in particular for component overlaps cannot be done at the | |
63 | -- time the record representation clause is first seen, but must be delayed | |
64 | -- till freeze time, and in particular is called after calling the above | |
65 | -- procedure for adjusting record bit positions for reverse bit order. | |
a9a5b8ac | 66 | |
996ae0b0 RK |
67 | procedure Initialize; |
68 | -- Initialize internal tables for new compilation | |
69 | ||
cf28c974 RD |
70 | procedure Kill_Rep_Clause (N : Node_Id); |
71 | -- This procedure is called for a rep clause N when we are in -gnatI mode | |
39678b1c | 72 | -- (Ignore_Rep_Clauses). It replaces the node N with a null statement. This |
cf28c974 RD |
73 | -- is only called if Ignore_Rep_Clauses is True. |
74 | ||
996ae0b0 RK |
75 | procedure Set_Enum_Esize (T : Entity_Id); |
76 | -- This routine sets the Esize field for an enumeration type T, based | |
77 | -- on the current representation information available for T. Note that | |
78 | -- the setting of the RM_Size field is not affected. This routine also | |
79 | -- initializes the alignment field to zero. | |
80 | ||
81 | function Minimum_Size | |
82 | (T : Entity_Id; | |
0da2c8ac | 83 | Biased : Boolean := False) return Nat; |
15ce9ca2 | 84 | -- Given an elementary type, determines the minimum number of bits required |
996ae0b0 RK |
85 | -- to represent all values of the type. This function may not be called |
86 | -- with any other types. If the flag Biased is set True, then the minimum | |
87 | -- size calculation that biased representation is used in the case of a | |
88 | -- discrete type, e.g. the range 7..8 gives a minimum size of 4 with | |
89 | -- Biased set to False, and 1 with Biased set to True. Note that the | |
90 | -- biased parameter only has an effect if the type is not biased, it | |
91 | -- causes Minimum_Size to indicate the minimum size of an object with | |
92 | -- the given type, of the size the type would have if it were biased. If | |
93 | -- the type is already biased, then Minimum_Size returns the biased size, | |
94 | -- regardless of the setting of Biased. Also, fixed-point types are never | |
4b92fd3c ST |
95 | -- biased in the current implementation. If the size is not known at |
96 | -- compile time, this function returns 0. | |
996ae0b0 | 97 | |
fbf5a39b AC |
98 | procedure Check_Constant_Address_Clause (Expr : Node_Id; U_Ent : Entity_Id); |
99 | -- Expr is an expression for an address clause. This procedure checks | |
100 | -- that the expression is constant, in the limited sense that it is safe | |
101 | -- to evaluate it at the point the object U_Ent is declared, rather than | |
102 | -- at the point of the address clause. The condition for this to be true | |
103 | -- is that the expression has no variables, no constants declared after | |
104 | -- U_Ent, and no calls to non-pure functions. If this condition is not | |
105 | -- met, then an appropriate error message is posted. This check is applied | |
106 | -- at the point an object with an address clause is frozen, as well as for | |
107 | -- address clauses for tasks and entries. | |
108 | ||
996ae0b0 RK |
109 | procedure Check_Size |
110 | (N : Node_Id; | |
111 | T : Entity_Id; | |
112 | Siz : Uint; | |
113 | Biased : out Boolean); | |
114 | -- Called when size Siz is specified for subtype T. This subprogram checks | |
115 | -- that the size is appropriate, posting errors on node N as required. | |
81a5b587 AC |
116 | -- This check is effective for elementary types and bit-packed arrays. |
117 | -- For other non-elementary types, a check is only made if an explicit | |
118 | -- size has been given for the type (and the specified size must match). | |
119 | -- The parameter Biased is set False if the size specified did not require | |
996ae0b0 RK |
120 | -- the use of biased representation, and True if biased representation |
121 | -- was required to meet the size requirement. Note that Biased is only | |
122 | -- set if the type is not currently biased, but biasing it is the only | |
123 | -- way to meet the requirement. If the type is currently biased, then | |
124 | -- this biased size is used in the initial check, and Biased is False. | |
81a5b587 AC |
125 | -- If the size is too small, and an error message is given, then both |
126 | -- Esize and RM_Size are reset to the allowed minimum value in T. | |
996ae0b0 | 127 | |
0da2c8ac | 128 | function Rep_Item_Too_Early (T : Entity_Id; N : Node_Id) return Boolean; |
82d4f390 RD |
129 | -- Called at start of processing a representation clause/pragma. Used to |
130 | -- check that the representation item is not being applied to an incomplete | |
131 | -- type or to a generic formal type or a type derived from a generic formal | |
132 | -- type. Returns False if no such error occurs. If this error does occur, | |
133 | -- appropriate error messages are posted on node N, and True is returned. | |
996ae0b0 | 134 | |
e477d718 AC |
135 | generic |
136 | with procedure Replace_Type_Reference (N : Node_Id); | |
137 | procedure Replace_Type_References_Generic (N : Node_Id; T : Entity_Id); | |
138 | -- This is used to scan an expression for a predicate or invariant aspect | |
139 | -- replacing occurrences of the name of the subtype to which the aspect | |
140 | -- applies with appropriate references to the parameter of the predicate | |
141 | -- function or invariant procedure. The procedure passed as a generic | |
142 | -- parameter does the actual replacement of node N, which is either a | |
143 | -- simple direct reference to T, or a selected component that represents | |
144 | -- an appropriately qualified occurrence of T. | |
145 | ||
996ae0b0 RK |
146 | function Rep_Item_Too_Late |
147 | (T : Entity_Id; | |
148 | N : Node_Id; | |
0da2c8ac | 149 | FOnly : Boolean := False) return Boolean; |
996ae0b0 | 150 | -- Called at the start of processing a representation clause or a |
82d4f390 RD |
151 | -- representation pragma. Used to check that a representation item for |
152 | -- entity T does not appear too late (according to the rules in RM 13.1(9) | |
153 | -- and RM 13.1(10)). N is the associated node, which in the pragma case | |
154 | -- is the pragma or representation clause itself, used for placing error | |
155 | -- messages if the item is too late. | |
996ae0b0 RK |
156 | -- |
157 | -- Fonly is a flag that causes only the freezing rule (para 9) to be | |
82d4f390 RD |
158 | -- applied, and the tests of para 10 are skipped. This is appropriate for |
159 | -- both subtype related attributes (Alignment and Size) and for stream | |
160 | -- attributes, which, although certainly not subtype related attributes, | |
161 | -- clearly should not be subject to the para 10 restrictions (see | |
162 | -- AI95-00137). Similarly, we also skip the para 10 restrictions for | |
868e30a5 | 163 | -- the Storage_Size case where they also clearly do not apply, and for |
f3d0f304 | 164 | -- Stream_Convert which is in the same category as the stream attributes. |
996ae0b0 | 165 | -- |
82d4f390 RD |
166 | -- If the rep item is too late, an appropriate message is output and True |
167 | -- is returned, which is a signal that the caller should abandon processing | |
168 | -- for the item. If the item is not too late, then False is returned, and | |
169 | -- the caller can continue processing the item. | |
996ae0b0 RK |
170 | -- |
171 | -- If no error is detected, this call also as a side effect links the | |
172 | -- representation item onto the head of the representation item chain | |
173 | -- (referenced by the First_Rep_Item field of the entity). | |
174 | -- | |
82d4f390 RD |
175 | -- Note: Rep_Item_Too_Late must be called with the underlying type in the |
176 | -- case of a private or incomplete type. The protocol is to first check for | |
177 | -- Rep_Item_Too_Early using the initial entity, then take the underlying | |
178 | -- type, then call Rep_Item_Too_Late on the result. | |
c159409f AC |
179 | -- |
180 | -- Note: Calls to Rep_Item_Too_Late are ignored for the case of attribute | |
181 | -- definition clauses which have From_Aspect_Specification set. This is | |
182 | -- because such clauses are linked on to the Rep_Item chain in procedure | |
183 | -- Sem_Ch13.Analyze_Aspect_Specifications. See that procedure for details. | |
996ae0b0 RK |
184 | |
185 | function Same_Representation (Typ1, Typ2 : Entity_Id) return Boolean; | |
186 | -- Given two types, where the two types are related by possible derivation, | |
187 | -- determines if the two types have the same representation, or different | |
188 | -- representations, requiring the special processing for representation | |
189 | -- change. A False result is possible only for array, enumeration or | |
190 | -- record types. | |
191 | ||
192 | procedure Validate_Unchecked_Conversion | |
193 | (N : Node_Id; | |
194 | Act_Unit : Entity_Id); | |
195 | -- Validate a call to unchecked conversion. N is the node for the actual | |
196 | -- instantiation, which is used only for error messages. Act_Unit is the | |
f3d57416 | 197 | -- entity for the instantiation, from which the actual types etc. for this |
996ae0b0 RK |
198 | -- instantiation can be determined. This procedure makes an entry in a |
199 | -- table and/or generates an N_Validate_Unchecked_Conversion node. The | |
200 | -- actual checking is done in Validate_Unchecked_Conversions or in the | |
201 | -- back end as required. | |
202 | ||
203 | procedure Validate_Unchecked_Conversions; | |
c9d2e84b | 204 | -- This routine is called after calling the back end to validate unchecked |
105b5e65 AC |
205 | -- conversions for size and alignment appropriateness. The reason it is |
206 | -- called that late is to take advantage of any back-annotation of size | |
c9d2e84b | 207 | -- and alignment performed by the back end. |
996ae0b0 | 208 | |
2642f998 RD |
209 | procedure Validate_Address_Clauses; |
210 | -- This is called after the back end has been called (and thus after the | |
211 | -- alignments of objects have been back annotated). It goes through the | |
212 | -- table of saved address clauses checking for suspicious alignments and | |
213 | -- if necessary issuing warnings. | |
214 | ||
105b5e65 AC |
215 | procedure Validate_Independence; |
216 | -- This is called after the back end has been called (and thus after the | |
217 | -- layout of components has been back annotated). It goes through the | |
218 | -- table of saved pragma Independent[_Component] entries, checking that | |
308e6f3a | 219 | -- independence can be achieved, and if necessary issuing error messages. |
105b5e65 AC |
220 | |
221 | ------------------------------------- | |
222 | -- Table for Validate_Independence -- | |
223 | ------------------------------------- | |
224 | ||
225 | -- If a legal pragma Independent or Independent_Components is given for | |
226 | -- an entity, then an entry is made in this table, to be checked by a | |
227 | -- call to Validate_Independence after back annotation of layout is done. | |
228 | ||
229 | type Independence_Check_Record is record | |
230 | N : Node_Id; | |
231 | -- The pragma Independent or Independent_Components | |
232 | ||
233 | E : Entity_Id; | |
234 | -- The entity to which it applies | |
235 | end record; | |
236 | ||
237 | package Independence_Checks is new Table.Table ( | |
238 | Table_Component_Type => Independence_Check_Record, | |
239 | Table_Index_Type => Int, | |
240 | Table_Low_Bound => 1, | |
241 | Table_Initial => 20, | |
242 | Table_Increment => 200, | |
243 | Table_Name => "Independence_Checks"); | |
244 | ||
47e11d08 AC |
245 | ----------------------------------- |
246 | -- Handling of Aspect Visibility -- | |
247 | ----------------------------------- | |
248 | ||
249 | -- The visibility of aspects is tricky. First, the visibility is delayed | |
250 | -- to the freeze point. This is not too complicated, what we do is simply | |
251 | -- to leave the aspect "laying in wait" for the freeze point, and at that | |
b98e2969 | 252 | -- point materialize and analyze the corresponding attribute definition |
47e11d08 AC |
253 | -- clause or pragma. There is some special processing for preconditions |
254 | -- and postonditions, where the pragmas themselves deal with the required | |
255 | -- delay, but basically the approach is the same, delay analysis of the | |
256 | -- expression to the freeze point. | |
257 | ||
258 | -- Much harder is the requirement for diagnosing cases in which an early | |
259 | -- freeze causes a change in visibility. Consider: | |
260 | ||
261 | -- package AspectVis is | |
262 | -- R_Size : constant Integer := 32; | |
263 | -- | |
264 | -- package Inner is | |
265 | -- type R is new Integer with | |
266 | -- Size => R_Size; | |
267 | -- F : R; -- freezes | |
268 | -- R_Size : constant Integer := 64; | |
269 | -- S : constant Integer := R'Size; -- 32 not 64 | |
270 | -- end Inner; | |
271 | -- end AspectVis; | |
272 | ||
273 | -- Here the 32 not 64 shows what would be expected if this program were | |
274 | -- legal, since the evaluation of R_Size has to be done at the freeze | |
275 | -- point and gets the outer definition not the inner one. | |
276 | ||
277 | -- But the language rule requires this program to be diagnosed as illegal | |
278 | -- because the visibility changes between the freeze point and the end of | |
279 | -- the declarative region. | |
280 | ||
281 | -- To meet this requirement, we first note that the Expression field of the | |
282 | -- N_Aspect_Specification node holds the raw unanalyzed expression, which | |
283 | -- will get used in processing the aspect. At the time of analyzing the | |
284 | -- N_Aspect_Specification node, we create a complete copy of the expression | |
285 | -- and store it in the entity field of the Identifier (an odd usage, but | |
286 | -- the identifier is not used except to identify the aspect, so its Entity | |
287 | -- field is otherwise unused, and we are short of room in the node). | |
288 | ||
289 | -- This copy stays unanalyzed up to the freeze point, where we analyze the | |
290 | -- resulting pragma or attribute definition clause, except that in the | |
291 | -- case of invariants and predicates, we mark occurrences of the subtype | |
292 | -- name as having the entity of the subprogram parameter, so that they | |
293 | -- will not cause trouble in the following steps. | |
294 | ||
295 | -- Then at the freeze point, we create another copy of this unanalyzed | |
296 | -- expression. By this time we no longer need the Expression field for | |
297 | -- other purposes, so we can store it there. Now we have two copies of | |
298 | -- the original unanalyzed expression. One of them gets preanalyzed at | |
299 | -- the freeze point to capture the visibility at the freeze point. | |
300 | ||
301 | -- Now when we hit the freeze all at the end of the declarative part, if | |
302 | -- we come across a frozen entity with delayed aspects, we still have one | |
303 | -- copy of the unanalyzed expression available in the node, and we again | |
304 | -- do a preanalysis using that copy and the visibility at the end of the | |
305 | -- declarative part. Now we have two preanalyzed expression (preanalysis | |
306 | -- is good enough, since we are only interested in referenced entities). | |
307 | -- One captures the visibility at the freeze point, the other captures the | |
308 | -- visibility at the end of the declarative part. We see if the entities | |
309 | -- in these two expressions are the same, by seeing if the two expressions | |
310 | -- are fully conformant, and if not, issue appropriate error messages. | |
311 | ||
a90bd866 | 312 | -- Quite an awkward approach, but this is an awkard requirement |
47e11d08 | 313 | |
8a0320ad | 314 | procedure Analyze_Aspects_At_Freeze_Point (E : Entity_Id); |
15e934bf AC |
315 | -- Analyze all the delayed aspects for entity E at freezing point. This |
316 | -- includes dealing with inheriting delayed aspects from the parent type | |
317 | -- in the case where a derived type is frozen. | |
8a0320ad | 318 | |
47e11d08 AC |
319 | procedure Check_Aspect_At_Freeze_Point (ASN : Node_Id); |
320 | -- Performs the processing described above at the freeze point, ASN is the | |
321 | -- N_Aspect_Specification node for the aspect. | |
322 | ||
323 | procedure Check_Aspect_At_End_Of_Declarations (ASN : Node_Id); | |
324 | -- Performs the processing described above at the freeze all point, and | |
325 | -- issues appropriate error messages if the visibility has indeed changed. | |
326 | -- Again, ASN is the N_Aspect_Specification node for the aspect. | |
dc3af7e2 AC |
327 | |
328 | procedure Inherit_Aspects_At_Freeze_Point (Typ : Entity_Id); | |
329 | -- Given an entity Typ that denotes a derived type or a subtype, this | |
330 | -- routine performs the inheritance of aspects at the freeze point. | |
dd2bf554 | 331 | |
f06f5f6b AC |
332 | procedure Resolve_Aspect_Expressions (E : Entity_Id); |
333 | -- Name resolution of an aspect expression happens at the end of the | |
334 | -- current declarative part or at the freeze point for the entity, | |
335 | -- whichever comes first. For declarations in the visible part of a | |
336 | -- package, name resolution takes place before analysis of the private | |
337 | -- part even though the freeze point of the entity may appear later. | |
338 | ||
dd2bf554 ES |
339 | procedure Validate_Iterable_Aspect (Typ : Entity_Id; ASN : Node_Id); |
340 | -- For SPARK 2014 formal containers. The expression has the form of an | |
82d4f390 RD |
341 | -- aggregate, and each entry must denote a function with the proper syntax |
342 | -- for First, Next, and Has_Element. Optionally an Element primitive may | |
343 | -- also be defined. | |
344 | ||
77a40ec1 AC |
345 | procedure Install_Discriminants (E : Entity_Id); |
346 | -- Make visible the discriminants of type entity E | |
347 | ||
77a40ec1 AC |
348 | procedure Uninstall_Discriminants (E : Entity_Id); |
349 | -- Remove visibility to the discriminants of type entity E | |
350 | ||
996ae0b0 | 351 | end Sem_Ch13; |