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* Re: [PATCH 2/2 v2] Ada: Finalization of constrained subtypes of unconstrained synchronized private extensions
@ 2023-09-13 21:37 Gary Dismukes
  2023-09-15 16:38 ` Gary Dismukes
  0 siblings, 1 reply; 6+ messages in thread
From: Gary Dismukes @ 2023-09-13 21:37 UTC (permalink / raw)
  To: Richard Wai; +Cc: gcc-patches, Eric Botcazou, Arnaud Charlet, Stephen Baird

Hi Richard,

I hope you're doing well.

I'm just following up on the patch (second version) that you sent us
recently for the problem you ran into with the generation of the
address finalization routine for synchronized private extensions.

Thanks very much for finding this fix and submitting your patch.
Your patch looks good, and we'll look into applying that to the
compiler, though no guarantees about when it will be added.  

Best regards,
  Gary Dismukes


^ permalink raw reply	[flat|nested] 6+ messages in thread
* [PATCH 1/2] Ada: Synchronized private extensions are always limited
@ 2023-08-10  4:55 Richard Wai
  2023-08-23 14:24 ` [PATCH 2/2 v2] Ada: Finalization of constrained subtypes of unconstrained synchronized private extensions Richard Wai
  0 siblings, 1 reply; 6+ messages in thread
From: Richard Wai @ 2023-08-10  4:55 UTC (permalink / raw)
  To: gcc-patches
  Cc: 'Eric Botcazou', 'Arnaud Charlet',
	'Stephen Baird'


[-- Attachment #1.1: Type: text/plain, Size: 3732 bytes --]

GNAT currently considers a synchronized private extension that derives from
an interface to be limited only when said interface is a concurrent
interface. However it is of course legal for a synchronized private
extension to derive from a limited interface. In this case GNAT fails to
correctly determine that the private extension is limited.

 

This causes two separate problems that makes discriminated types in such a
case impossible:

1.	GNAT inappropriately rejects compilation, claiming default
discriminants on such a private extension are illegal.
2.	GNAT fails to generate the expected discriminals for the
unconstrained discriminanted case, leading to the corresponding
discriminants of the "corresponding record" of the underlying concurrent
type to have no identifiers, and thus compilation fails.

 

Fairly simple fix. If "synchronized" appears in the private extension
declaration, it is limited. This is explicit in the RM as well (7.3(6/2)).

 

Fixing this bug uncovered of a related bug wrt. TSS address finalizer
generation for constrained subtypes of synchronized private extensions with
no default discriminants. That patch is to follow separately.

 

Patch file is attached.

 

--  Begin change log entry --

 

ada: Private extensions with the keyword "synchronized" are always limited.

 

GNAT was relying on synchronized private type extensions deriving from a
concurrent interface to determine its limitedness. This does not cover the
case where such an extension derives a limited interface. RM-7.6(6/2) makes
is clear that "synchronized" in a private extension implies the derived type
is limited. GNAT should explicitly check for the presence of "synchronized"
in a private extension declaration, and it should have the same effect as
the presence of "limited".

 

gcc/ada/

                * sem_ch3.adb (Build_Derived_Record_Type): Treat presence of
keyword "synchronized" the same as "limited" when determining if a private
extension is limited.

 

-- End change log entry --

 

This patch was bootstrapped on x86_64-*-freebsd13.2. Two new test cases were
added. Note that 4 gnat test cases fail currently on master and are
unrelated to this patch.

 

Check-ada output of this patch:

                                === acats tests ===

Running chapter a ...

Running chapter c2 ...

Running chapter c3 ...

Running chapter c4 ...

Running chapter c5 ...

Running chapter c6 ...

Running chapter c7 ...

Running chapter c8 ...

Running chapter c9 ...

Running chapter ca ...

Running chapter cb ...

Running chapter cc ...

Running chapter cd ...

Running chapter ce ...

Running chapter cxa ...

Running chapter cxb ...

Running chapter cxf ...

Running chapter cxg ...

Running chapter cxh ...

Running chapter cz ...

Running chapter d ...

Running chapter e ...

Running chapter l ...

                                === acats Summary ===

# of expected passes                       2328

# of unexpected failures 0

 

Native configuration is x86_64-unknown-freebsd13.2

 

                                === gnat tests ===

 

Schedule of variations:

    unix

 

Running target unix

FAIL: gnat.dg/specs/alignment2.ads  (test for warnings, line 14)

FAIL: gnat.dg/specs/alignment2.ads  (test for warnings, line 20)

FAIL: gnat.dg/specs/alignment2.ads  (test for warnings, line 38)

FAIL: gnat.dg/specs/alignment2.ads  (test for warnings, line 42)

 

                                === gnat Summary ===

 

# of expected passes                       3402

# of unexpected failures                4

# of expected failures                      23

# of unsupported tests                   10

gnatmake version 14.0.0 20230809 (experimental)

 

 

Richard Wai

ANNEXI-STRAYLINE


[-- Attachment #2: ada-synchronized-private-types-are-limited.patch --]
[-- Type: application/octet-stream, Size: 5895 bytes --]

From f87d0da43296b87cd242380a4077a167e5ea1291 Mon Sep 17 00:00:00 2001
From: Richard Wai <richard@annexi-strayline.com>
Date: Wed, 9 Aug 2023 01:54:48 -0400
Subject: [PATCH 1/2] ada: Consider that any synchronized private extension is
 always a limited type, even if it inherits from a non-concurrent interface.
 Add two regression tests for two separate problems that arose

---
 gcc/ada/sem_ch3.adb                           | 12 +++--
 .../gnat.dg/sync_tag_discriminals.adb         | 51 +++++++++++++++++++
 gcc/testsuite/gnat.dg/sync_tag_limited.adb    | 50 ++++++++++++++++++
 3 files changed, 110 insertions(+), 3 deletions(-)
 create mode 100644 gcc/testsuite/gnat.dg/sync_tag_discriminals.adb
 create mode 100644 gcc/testsuite/gnat.dg/sync_tag_limited.adb

diff --git a/gcc/ada/sem_ch3.adb b/gcc/ada/sem_ch3.adb
index 042ace01724..48731a7bf04 100644
--- a/gcc/ada/sem_ch3.adb
+++ b/gcc/ada/sem_ch3.adb
@@ -9494,9 +9494,15 @@ package body Sem_Ch3 is
 
       --  AI-419: Limitedness is not inherited from an interface parent, so to
       --  be limited in that case the type must be explicitly declared as
-      --  limited. However, task and protected interfaces are always limited.
-
-      if Limited_Present (Type_Def) then
+      --  limited, or synchronized. While task and protected interfaces are
+      --  always limited, a synchronized private extension might not inherit
+      --  from such interfaces, and so we also need to recognize the
+      --  explicit limitedness implied by a synchronized private extension
+      --  the does not derive from a synchronized interface (see RM-7.3(6/2)).
+
+      if Limited_Present (Type_Def)
+        or else Synchronized_Present (Type_Def)
+      then
          Set_Is_Limited_Record (Derived_Type);
 
       elsif Is_Limited_Record (Parent_Type)
diff --git a/gcc/testsuite/gnat.dg/sync_tag_discriminals.adb b/gcc/testsuite/gnat.dg/sync_tag_discriminals.adb
new file mode 100644
index 00000000000..b105acf6e98
--- /dev/null
+++ b/gcc/testsuite/gnat.dg/sync_tag_discriminals.adb
@@ -0,0 +1,51 @@
+-- This test is related to sync_tag_limited in that previous versions of GNAT
+-- failed to consider a synchronized private extension as limited if it was
+-- not derrived from a synchronized interface (i.e. a limited interface). Since
+-- such a private type would not be considered limited, GNAT would fail to
+-- correctly build the expected discriminals later needed by the creation of
+-- the concurrent type's "corresponding record type", leading to a compilation
+-- error where the discriminants of the corresponding record type had no
+-- identifiers.
+--
+-- This test is in addition to sync_tag_limited because the sync_tag_limited
+-- would fail for "legality" reasons (default discriminants not allowed for
+-- a non-limited taged type). It is also an opportunity to ensure that non-
+-- defaulted discriminated synchronized private extensions work as expected.
+
+--  { dg-do compile }
+
+procedure Sync_Tag_Discriminals is
+   
+   package Ifaces is
+      
+      type Test_Interface is limited interface;
+      
+      procedure Interface_Action (Test: in out Test_Interface) is abstract;
+      
+   end Ifaces;
+   
+   
+   package Implementation is
+      type Test_Implementation
+        (Constraint: Positive) is
+        synchronized new Ifaces.Test_Interface with private;
+      
+   private
+      protected type Test_Implementation
+        (Constraint: Positive)
+      is new Ifaces.Test_Interface with
+      
+         overriding procedure Interface_Action;
+         
+      end Test_Implementation;
+   end Implementation;
+   
+   package body Implementation is
+      protected body Test_Implementation is
+         procedure Interface_Action is null;
+      end;
+   end Implementation;
+   
+begin
+   null;
+end Sync_Tag_Discriminals;
diff --git a/gcc/testsuite/gnat.dg/sync_tag_limited.adb b/gcc/testsuite/gnat.dg/sync_tag_limited.adb
new file mode 100644
index 00000000000..608f10662a3
--- /dev/null
+++ b/gcc/testsuite/gnat.dg/sync_tag_limited.adb
@@ -0,0 +1,50 @@
+--  Synchronized tagged types created by a private extension with the keyword
+--  'synchronized' shall be seen as an (immutably) limited tagged type, and
+--  should therefore accept default disciminant spectifications.
+--  This was a bug in earlier versions of GNAT, whereby GNAT erroneously
+--  relied on a parent synchronized interface to determine limitedness
+--  of a synchronized private extension. The problem being that a synchronized
+--  private extension can derive a non-synchronized interface (specifically a
+--  limited interface), Yet the RM makes it clear (7.3(6/2)) that such
+--  synchronized private extensions are always limited.
+--
+--  Ergo: Default discriminants are of course legal on any synchronized private
+--  extension.
+
+--  { dg-do compile }
+
+procedure Sync_Tag_Limited is
+   
+   package Ifaces is
+      
+      type Test_Interface is limited interface;
+      
+      procedure Interface_Action (Test: in out Test_Interface) is abstract;
+      
+   end Ifaces;
+   
+   
+   package Implementation is
+      type Test_Implementation
+        (Constraint: Positive := 1) is
+        synchronized new Ifaces.Test_Interface with private;
+      
+   private
+      protected type Test_Implementation
+        (Constraint: Positive := 1)
+      is new Ifaces.Test_Interface with
+      
+         overriding procedure Interface_Action;
+         
+      end Test_Implementation;
+   end Implementation;
+   
+   package body Implementation is
+      protected body Test_Implementation is
+         procedure Interface_Action is null;
+      end;
+   end Implementation;
+   
+begin
+   null;
+end Sync_Tag_Limited;
-- 
2.40.1


^ permalink raw reply	[flat|nested] 6+ messages in thread

end of thread, other threads:[~2023-09-19 12:08 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2023-09-13 21:37 [PATCH 2/2 v2] Ada: Finalization of constrained subtypes of unconstrained synchronized private extensions Gary Dismukes
2023-09-15 16:38 ` Gary Dismukes
     [not found]   ` <010d018aa45631b4-d2c02a5f-44ef-4dbe-b8c1-bd53686aff72-000000@ca-central-1.amazonses.com>
2023-09-18 13:43     ` [PATCH 2/2 v3] " Arnaud Charlet
2023-09-19  3:35       ` Richard Wai
2023-09-19 12:08         ` [COMMITTED] ada: TSS finalize address subprogram generation for constrained Marc Poulhiès
  -- strict thread matches above, loose matches on Subject: below --
2023-08-10  4:55 [PATCH 1/2] Ada: Synchronized private extensions are always limited Richard Wai
2023-08-23 14:24 ` [PATCH 2/2 v2] Ada: Finalization of constrained subtypes of unconstrained synchronized private extensions Richard Wai

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