This patch adds another suggestion to the elaboration order diagnostics. An elaboration circularity involving a task activation may be resolved through pragma Restrictions (No_Entry_Calls_In_Elaboration_Code).
------------
-- Source --
------------
-- no_entry_calls.txt
pragma Restrictions (No_Entry_Calls_In_Elaboration_Code);
-- a.ads
package A is
task type Task_Typ is
entry Start;
end Task_Typ;
procedure Proc;
end A;
-- a.adb
with B;
package body A is
task body Task_Typ is
begin
accept Start;
B.Proc;
end Task_Typ;
Elab : Task_Typ;
procedure Proc is null;
end A;
-- b.ads
package B is
procedure Proc;
end B;
-- b.adb
with A;
package body B is
procedure Proc is
begin
A.Proc;
end Proc;
end B;
-- main.adb
with A;
-- +--> A spec B spec
-- | ^ ^ ^
-- | | with | |
-- | sbb | +----------------+ | sbb
-- | | | |
-- | | | Invocation |
-- | A body ------------> B body
-- | ^ | |
-- | | Invocation | |
-- | +------------------+ |
-- | |
-- | Invocation |
-- +---------------------------+
--
-- The cycle is:
--
-- A body --> A body
procedure Main is begin null; end Main;
----------------------------
-- Compilation and output --
----------------------------
$ gnatmake -f -q main.adb -gnatd_F
$ gnatmake -f -q main.adb -gnatec=no_entry_calls.txt
error: Elaboration circularity detected
info:
info: Reason:
info:
info: unit "a (body)" depends on its own elaboration
info:
info: Circularity:
info:
info: unit "a (body)" invokes a construct of unit "a (body)" at
elaboration time
info: path 1:
info: elaboration of unit "a (body)"
info: activation of local task declared at "a.ads":2:14
info: call to subprogram "proc" declared at "b.ads":2:14
info: call to subprogram "proc" declared at "a.ads":6:14
info:
info: Suggestions:
info:
info: use pragma Restrictions (No_Entry_Calls_In_Elaboration_Code)
info: use the dynamic elaboration model (compiler switch -gnatE)
info:
gnatmake: *** bind failed.
Tested on x86_64-pc-linux-gnu, committed on trunk
2019-07-09 Hristian Kirtchev <kirtc...@adacore.com>
gcc/ada/
* bindo.ads: Move type Precedence_Kind from the private to the
visible part of the unit.
* bindo-augmentors.adb: Remove the use of global data as it is
bad practice.
(Augment_Library_Graph): Update the parameter profile.
(Is_Visited, Set_Is_Visited): Remove.
(Visit_Elaboration_Root, Visit_Elaboration_Roots): Update the
parameter profile and comment on usage.
(Visit_Vertex): Likewise. Also keep track of which invocation
edge activates a task.
* bindo-augmentors.ads (Augment_Library_Graph): Update the
parameter profile and comment on usage.
* bindo-builders.adb (Create_Forced_Edge,
Create_Spec_And_Body_Edge, Create_With_Edge): Update the call to
Add_Edge.
* bindo-diagnostics.adb: Add with end use clauses for Restrict
and Rident.
(Output_Dynamic_Model_Suggestions): Remove.
(Output_Invocation_Related_Suggestions): New routine.
(Output_Suggestions): Output all invocation-related suggestions
together.
* bindo-elaborators.adb: Remove types Comparator_Ptr and
Predicate_Ptr.
(Find_Best_Vertex): Update the parameter profile.
* bindo-graphs.adb (Activates_Task): New routine.
(Add_Body_Before_Spec_Edge): Update the call to
Add_Edge_With_Return.
(Add_Edge): Update the parameter profile and the call to
Add_Edge_With_Return.
(Add_Edge_With_Return): Update the parameter profile and comment
on usage.
(At_Least_One_Edge_Satisfies): New routine.
(Contains_Elaborate_All_Edge): Reimplement.
(Contains_Static_Successor_Edge, Contains_Task_Activation): New
routine.
(Contains_Weak_Static_Successor): Remove.
(Is_Static_Successor_Edge): New routine.
* bindo-graphs.ads: Add types LGE_Predicate_Ptr,
LGV_Comparator_Ptr, and LGV_Predicate_Ptr. Update type
Library_Graph_Edge_Attributes to capture whether an invocation
edge activates a task. Update the value of
No_Library_Graph_Edge_Attributes.
(Activates_Task): Update the parameter profile and comment on
usage.
(Contains_Static_Successor_Edge, Contains_Task_Activation): New
routines.
(Contains_Weak_Static_Successor): Remove.
* doc/gnat_ugn/elaboration_order_handling_in_gnat.rst:
Update the documentation to reflect the new task-related advice.
* gnat_ugn.texi: Regenerate.
patch.diff.gz
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