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ada: Fix spurious error in checking of SPARK elaboration

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The problem is that the computation of early call regions skips freeze nodes
but scenarios involving procedures declared as actions of these freeze nodes
are taken into account.  As a consequence if a subprogram body, typically of
an expression function, is placed just after a freeze node, its early call
region depends on whether the construct just before the freeze node can be
preelaborated or not; in other words, the legality of calls made from the
actions of this freeze node to the subprogram depends on what happens ahead
of the freeze node, which may be totally unrelated to the situation.

This change disables the ABE diagnostics in this case, as is done in a few
other similar cases leading to bogus errors too.

gcc/ada/

	* sem_elab.adb (Processing_In_State): Add Within_Freezing_Actions
	component.
	(Process_Conditional_ABE_Call): Compute its value.
	(Process_Conditional_ABE_Call_SPARK): For a call and a target in
	the main unit, do not emit any ABE diagnostics if the call occurs
	in a freezing actions context.
This commit is contained in:
Eric Botcazou 2022-12-02 10:21:25 +01:00 • committed by Marc Poulhiès
parent ea588d41f3
commit 0cb36c85ab
1 changed files with 23 additions and 1 deletions
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24
gcc/ada/sem_elab.adb
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@ -881,6 +881,10 @@ package body Sem_Elab is
-- The subprogram body traversal mode. Once set, this value should not
-- be changed.
Within_Freezing_Actions : Boolean := False;
-- This flag is set when the Processing phase is currently examining a
-- scenario which was reached from the actions of a freeze node.
Within_Generic : Boolean := False;
-- This flag is set when the Processing phase is currently within a
-- generic unit.
@ -5353,6 +5357,7 @@ package body Sem_Elab is
Subp_Id : constant Entity_Id := Target (Call_Rep);
Subp_Rep : constant Target_Rep_Id :=
Target_Representation_Of (Subp_Id, In_State);
Body_Decl : constant Node_Id := Body_Declaration (Subp_Rep);
Subp_Decl : constant Node_Id := Spec_Declaration (Subp_Rep);
SPARK_Rules_On : constant Boolean :=
@ -5452,6 +5457,16 @@ package body Sem_Elab is
or else not Elaboration_Warnings_OK (Call_Rep)
or else not Elaboration_Warnings_OK (Subp_Rep);
-- The call occurs in freezing actions context when a prior scenario
-- is already in that mode, or when the target is a subprogram whose
-- body has been generated as a freezing action. Update the state of
-- the Processing phase to reflect this.
New_In_State.Within_Freezing_Actions :=
New_In_State.Within_Freezing_Actions
or else (Present (Body_Decl)
and then Nkind (Parent (Body_Decl)) = N_Freeze_Entity);
-- The call occurs in an initial condition context when a prior
-- scenario is already in that mode, or when the target is an
-- Initial_Condition procedure. Update the state of the Processing
@ -5502,7 +5517,7 @@ package body Sem_Elab is
In_State => New_In_State);
Traverse_Conditional_ABE_Body
(N => Body_Declaration (Subp_Rep),
(N => Body_Decl,
In_State => New_In_State);
end Process_Conditional_ABE_Call;
@ -5721,6 +5736,13 @@ package body Sem_Elab is
if In_State.Suppress_Warnings then
null;
-- Do not emit any ABE diagnostics when the call occurs in a
-- freezing actions context because this leads to incorrect
-- diagnostics.
elsif In_State.Within_Freezing_Actions then
null;
-- Do not emit any ABE diagnostics when the call occurs in an
-- initial condition context because this leads to incorrect
-- diagnostics.