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[Ada] AI12-0287 Legality Rules for null exclusions in renaming are too fierce 

2020-06-08  Arnaud Charlet  <charlet@adacore.com>

gcc/ada/

	* sem_ch12.adb (Instantiate_Object): Relax rules related to null
	exclusions and generic objects. Handle all anonymous types
	consistently and not just E_Anonymous_Access_Type.
	* sem_ch8.adb (Analyze_Object_Renaming): Change wording so that
	it applies to both renamings and instantiations to avoid
	confusion.
This commit is contained in:
Arnaud Charlet 2020-02-16 07:16:45 -05:00 committed by Pierre-Marie de Rodat
parent 58c4038810
commit b4aa6e2978
2 changed files with 25 additions and 19 deletions
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34
gcc/ada/sem_ch12.adb
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@ -11279,10 +11279,9 @@ package body Sem_Ch12 is
-- access type.
if Ada_Version < Ada_2005
or else Ekind (Base_Type (Ftyp)) /=
E_Anonymous_Access_Type
or else Ekind (Base_Type (Etype (Actual))) /=
E_Anonymous_Access_Type
or else Ekind (Base_Type (Ftyp)) not in Anonymous_Access_Kind
or else Ekind (Base_Type (Etype (Actual)))
not in Anonymous_Access_Kind
then
Error_Msg_NE
("type of actual does not match type of&", Actual, Gen_Obj);
@ -11477,15 +11476,19 @@ package body Sem_Ch12 is
Actual_Decl := Parent (Entity (Actual));
end if;
-- Ada 2005 (AI-423): For a formal object declaration with a null
-- exclusion or an access definition that has a null exclusion: If the
-- actual matching the formal object declaration denotes a generic
-- formal object of another generic unit G, and the instantiation
-- containing the actual occurs within the body of G or within the body
-- of a generic unit declared within the declarative region of G, then
-- the declaration of the formal object of G must have a null exclusion.
-- Otherwise, the subtype of the actual matching the formal object
-- declaration shall exclude null.
-- Ada 2005 (AI-423) refined by AI12-0287:
-- For an object_renaming_declaration with a null_exclusion or an
-- access_definition that has a null_exclusion, the subtype of the
-- object_name shall exclude null. In addition, if the
-- object_renaming_declaration occurs within the body of a generic unit
-- G or within the body of a generic unit declared within the
-- declarative region of generic unit G, then:
-- * if the object_name statically denotes a generic formal object of
-- mode in out of G, then the declaration of that object shall have a
-- null_exclusion;
-- * if the object_name statically denotes a call of a generic formal
-- function of G, then the declaration of the result of that function
-- shall have a null_exclusion.
if Ada_Version >= Ada_2005
and then Present (Actual_Decl)
@ -11494,6 +11497,11 @@ package body Sem_Ch12 is
and then Nkind (Analyzed_Formal) = N_Formal_Object_Declaration
and then not Has_Null_Exclusion (Actual_Decl)
and then Has_Null_Exclusion (Analyzed_Formal)
and then Ekind (Defining_Identifier (Analyzed_Formal))
= E_Generic_In_Out_Parameter
and then ((In_Generic_Scope (Entity (Actual))
and then In_Package_Body (Scope (Entity (Actual))))
or else not Can_Never_Be_Null (Etype (Actual)))
then
Error_Msg_Sloc := Sloc (Analyzed_Formal);
Error_Msg_N

10
gcc/ada/sem_ch8.adb
View File

@ -1278,7 +1278,7 @@ package body Sem_Ch8 is
then
if not Can_Never_Be_Null (Etype (Nam_Ent)) then
Error_Msg_N
("renamed formal does not exclude `NULL` "
("object does not exclude `NULL` "
& "(RM 8.5.1(4.6/2))", N);
elsif In_Package_Body (Scope (Id)) then
@ -1292,7 +1292,7 @@ package body Sem_Ch8 is
elsif not Can_Never_Be_Null (Etype (Nam_Ent)) then
Error_Msg_N
("renamed object does not exclude `NULL` "
("object does not exclude `NULL` "
& "(RM 8.5.1(4.6/2))", N);
-- An instance is illegal if it contains a renaming that
@ -1309,8 +1309,7 @@ package body Sem_Ch8 is
N_Raise_Constraint_Error
then
Error_Msg_N
("renamed actual does not exclude `NULL` "
& "(RM 8.5.1(4.6/2))", N);
("actual does not exclude `NULL` (RM 8.5.1(4.6/2))", N);
-- Finally, if there is a null exclusion, the subtype mark
-- must not be null-excluding.
@ -1328,8 +1327,7 @@ package body Sem_Ch8 is
and then not Can_Never_Be_Null (Etype (Nam_Ent))
then
Error_Msg_N
("renamed object does not exclude `NULL` "
& "(RM 8.5.1(4.6/2))", N);
("object does not exclude `NULL` (RM 8.5.1(4.6/2))", N);
elsif Has_Null_Exclusion (N)
and then No (Access_Definition (N))