[Bug ada/28180] New: FAIL: gdb.ada/interface.exp: print s (timeout)

[Bug ada/28180] New: FAIL: gdb.ada/interface.exp: print s (timeout)

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=28180

            Bug ID: 28180
           Summary: FAIL: gdb.ada/interface.exp: print s (timeout)
           Product: gdb
           Version: HEAD
            Status: NEW
          Severity: normal
          Priority: P2
         Component: ada
          Assignee: unassigned at sourceware dot org
          Reporter: vries at gcc dot gnu.org
  Target Milestone: ---

With current master I noticed this timeout:
...
(gdb) PASS: gdb.ada/interface.exp: print r
print s^M
Multiple matches for s^M
[0] cancel^M
[1] s at
/home/vries/gdb_versions/devel/binutils-gdb.git/gdb/testsuite/gdb.ada/interface/foo.adb:20^M
[2] s at
/home/vries/gdb_versions/devel/binutils-gdb.git/gdb/testsuite/gdb.ada/interface/foo.adb:?^M
> FAIL: gdb.ada/interface.exp: print s (timeout)
...

Bisects to:
...
commit ba8694b650b60c29126fd958575ffa1ca4f6c415 (HEAD)
Author: Tom Tromey <tromey@adacore.com>
Date:   Thu Jul 1 08:55:15 2021 -0600

    Handle type qualifier for enumeration name

    Pierre-Marie noticed that the Ada expression "TYPE'(NAME)" resolved
    incorrectly when "TYPE" was an enumeration type.  Here, "NAME" should
    be unambiguous.

    This patch fixes this problem.  Note that the patch is not perfect --
    it does not give an error if TYPE is an enumeration type but NAME is
    not an enumerator but does have some other meaning in scope.  Fixing
    this proved difficult, and so I've left it out.
...

Fails with gcc-7.5.0, 8.5.0, passes with gcc-9.3.1, gcc-10.3.1, gcc-11.1.1.

-- 
You are receiving this mail because:
You are on the CC list for the bug.

[Bug ada/28180] FAIL: gdb.ada/interface.exp: print s (timeout)

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=28180

Tom de Vries <vries at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |tromey at sourceware dot org

-- 
You are receiving this mail because:
You are on the CC list for the bug.

[Bug ada/28180] FAIL: gdb.ada/interface.exp: print s (timeout)

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=28180

--- Comment #1 from Tom de Vries <vries at gcc dot gnu.org> ---
Same for:
...
(gdb) PASS: gdb.ada/tagged.exp: print segm
ptype obj^M
Multiple matches for obj^M
[0] cancel^M
[1] obj at
/home/vries/gdb_versions/devel/binutils-gdb.git/gdb/testsuite/gdb.ada/tagged/foo.adb:20^M
[2] obj at
/home/vries/gdb_versions/devel/binutils-gdb.git/gdb/testsuite/gdb.ada/tagged/foo.adb:?^M
> FAIL: gdb.ada/tagged.exp: ptype obj (timeout)
...

-- 
You are receiving this mail because:
You are on the CC list for the bug.

[Bug ada/28180] FAIL: gdb.ada/interface.exp: print s (timeout)

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=28180

Tom Tromey <tromey at sourceware dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Assignee|unassigned at sourceware dot org   |tromey at sourceware dot org

-- 
You are receiving this mail because:
You are on the CC list for the bug.

[Bug ada/28180] FAIL: gdb.ada/interface.exp: print s (timeout)

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=28180

--- Comment #2 from Tom Tromey <tromey at sourceware dot org> ---
(In reply to Tom de Vries from comment #0)

> [1] s at
> /home/vries/gdb_versions/devel/binutils-gdb.git/gdb/testsuite/gdb.ada/
> interface/foo.adb:20^M
> [2] s at
> /home/vries/gdb_versions/devel/binutils-gdb.git/gdb/testsuite/gdb.ada/
> interface/foo.adb:?^M

The second location is pretty weird.
I suspect this is just some kind of debuginfo problem
with the older compiler.

> Same for:
> ...
> > FAIL: gdb.ada/tagged.exp: ptype obj (timeout)

Is it the same compiler versions that fail here?
I can't test it readily but I can send a patch to disable
these tests with an older gcc.

-- 
You are receiving this mail because:
You are on the CC list for the bug.

[Bug ada/28180] FAIL: gdb.ada/interface.exp: print s (timeout)

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=28180

--- Comment #3 from Tom de Vries <vries at gcc dot gnu.org> ---
(In reply to Tom de Vries from comment #0)
> With current master I noticed this timeout:
> ...
> (gdb) PASS: gdb.ada/interface.exp: print r
> print s^M
> Multiple matches for s^M
> [0] cancel^M
> [1] s at
> /home/vries/gdb_versions/devel/binutils-gdb.git/gdb/testsuite/gdb.ada/
> interface/foo.adb:20^M
> [2] s at
> /home/vries/gdb_versions/devel/binutils-gdb.git/gdb/testsuite/gdb.ada/
> interface/foo.adb:?^M
> > FAIL: gdb.ada/interface.exp: print s (timeout)
> ...

Doing a bit of investigation, we see:
...
Breakpoint 1, foo () at
/home/vries/gdb_versions/devel/binutils-gdb.git/gdb/testsuite/gdb.ada/interface/foo.adb:22
22         Do_Nothing (R);  -- STOP
(gdb) info locals
r = (x => 1, y => 2, w => 3, h => 4)
<G6b_LAST> = 8
<foo__G6b___U> = 8
s = (x => 1, y => 2, w => 3, h => 4)
s = 0x7fffffffd890
...

So both "s" are local variables.

That makes it easy to find in the dwarf.

We have:
...
 <2><1204>: Abbrev Number: 31 (DW_TAG_variable)
    <1205>   DW_AT_name        : (indirect string, offset: 0x13e6): s.14
    <1209>   DW_AT_type        : <0x1213>
    <120d>   DW_AT_artificial  : 1
    <120d>   DW_AT_location    : 5 byte block: 91 e0 7d 23 18   (DW_OP_fbreg:
-288; DW_OP_plus_uconst: 24)
...
and:
...
 <3><1249>: Abbrev Number: 33 (DW_TAG_variable) 
    <124a>   DW_AT_name        : s
    <124c>   DW_AT_decl_file   : 1
    <124d>   DW_AT_decl_line   : 20
    <124e>   DW_AT_type        : <0x146d>
    <1252>   DW_AT_location    : 6 byte block: 91 e0 7d 23 18 6        
(DW_OP_fbreg: -288; DW_OP_plus_uconst: 24; DW_OP_deref)
...

I suppose the first is the unexpected one.  It has DW_AT_artificial, but is
still put into the symbol table because it has a DW_AT_name.

This patch:
...
diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c
index acabee3315f..44327ecbd9a 100644
--- a/gdb/dwarf2/read.c
+++ b/gdb/dwarf2/read.c
@@ -21585,6 +21585,9 @@ new_symbol (struct die_info *die, struct type *type,
struct dwarf2_
cu *cu,
   if (name)
     {
       int suppress_add = 0;
+      attr = dwarf2_attr (die, DW_AT_artificial, cu);
+      if (attr != nullptr)
+       suppress_add = 1;

       if (space)
        sym = space;
...
gets us:
...
$ gdb -q -batch  outputs/gdb.ada/interface/foo -ex "b foo.adb:22" -ex r -ex "p
s"
Breakpoint 1 at 0x404455: file foo.adb, line 22.

Breakpoint 1, foo () at foo.adb:22
22         Do_Nothing (R);  -- STOP
warning: Unknown upper bound, using 1.
$1 = (x => 1, y => 2, w => 3, h => 4)
...
but with the warning because foo__G6b___U (which is another artificial
variable) cannot be evaluated.

Hmm, so ada uses named artifical variables that need to be in the symbol table
in order to evaluate them, but they should be ignored in terms of gdb commands
that investigate source constructs like "p s".  That seems to be the root
cause.

-- 
You are receiving this mail because:
You are on the CC list for the bug.

[Bug ada/28180] FAIL: gdb.ada/interface.exp: print s (timeout)

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=28180

--- Comment #4 from Tom de Vries <vries at gcc dot gnu.org> ---
This allows the test-case to pass:
...
diff --git a/gdb/ada-lang.c b/gdb/ada-lang.c
index 6680a4fd657..e3bfcd8aa9f 100644
--- a/gdb/ada-lang.c
+++ b/gdb/ada-lang.c
@@ -3539,6 +3539,16 @@ ada_resolve_variable (struct symbol *sym, const struct
block *block,

         candidates.end ());
     }

+  candidates.erase
+    (std::remove_if
+     (candidates.begin (),
+      candidates.end (),
+      [] (block_symbol &bsym)
+      {
+       return bsym.symbol->artificial;
+      }),
+     candidates.end ());
+
   int i;
   if (candidates.empty ())
     error (_("No definition found for %s"), sym->print_name ());
diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c
index acabee3315f..bff615d31ee 100644
--- a/gdb/dwarf2/read.c
+++ b/gdb/dwarf2/read.c
@@ -21592,6 +21592,10 @@ new_symbol (struct die_info *die, struct type *type,
struct dwarf2
_cu *cu,
        sym = new (&objfile->objfile_obstack) symbol;
       OBJSTAT (objfile, n_syms++);

+      attr = dwarf2_attr (die, DW_AT_artificial, cu);
+      if (attr != nullptr)
+       sym->artificial = 1;
+
       /* Cache this symbol's name and the name's demangled form (if any).  */
       sym->set_language (cu->per_cu->lang, &objfile->objfile_obstack);
       /* Fortran does not have mangling standard and the mangling does differ
diff --git a/gdb/symtab.h b/gdb/symtab.h
index fd8dd62a406..b028586e50f 100644
--- a/gdb/symtab.h
+++ b/gdb/symtab.h
@@ -536,6 +536,8 @@ struct general_symbol_info
      valid.  */
   unsigned int ada_mangled : 1;

+  unsigned int artificial : 1;
+
   /* Which section is this symbol in?  This is an index into
      section_offsets for this objfile.  Negative means that the symbol
      does not get relocated relative to a section.  */
@@ -1131,6 +1133,7 @@ struct symbol : public general_symbol_info, public
allocate_on_obstac
k
       language_specific.obstack = nullptr;
       m_language = language_unknown;
       ada_mangled = 0;
+      artificial = 0;
       m_section = -1;
       /* GCC 4.8.5 (on CentOS 7) does not correctly compile class-
         initialization of unions, so we initialize it manually here.  */
...
and passes gdb.ada/*.exp.

-- 
You are receiving this mail because:
You are on the CC list for the bug.

[Bug ada/28180] FAIL: gdb.ada/interface.exp: print s (timeout)

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=28180

--- Comment #5 from Tom de Vries <vries at gcc dot gnu.org> ---
(In reply to Tom de Vries from comment #0)
> Fails with gcc-7.5.0, 8.5.0, passes with gcc-9.3.1, gcc-10.3.1, gcc-11.1.1.

Which bisects to:
...
commit d70ba0c10dec6968d178303709204fdde3d8892f (refs/bisect/bad)
Author: Eric Botcazou <ebotcazou@adacore.com>
Date:   Sun Jun 17 11:36:58 2018 +0000

    gimplify.c (nonlocal_vlas): Delete.
...
submitted here (
https://gcc.gnu.org/pipermail/gcc-patches/2018-June/500683.html ).

-- 
You are receiving this mail because:
You are on the CC list for the bug.

[Bug ada/28180] FAIL: gdb.ada/interface.exp: print s (timeout)

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=28180

--- Comment #6 from Tom de Vries <vries at gcc dot gnu.org> ---
(In reply to Tom Tromey from comment #2)
> (In reply to Tom de Vries from comment #0)
> 
> > [1] s at
> > /home/vries/gdb_versions/devel/binutils-gdb.git/gdb/testsuite/gdb.ada/
> > interface/foo.adb:20^M
> > [2] s at
> > /home/vries/gdb_versions/devel/binutils-gdb.git/gdb/testsuite/gdb.ada/
> > interface/foo.adb:?^M
> 
> The second location is pretty weird.

AFAICT, due to the corresponding artificial variable in dwarf having no
location info.

> I suspect this is just some kind of debuginfo problem
> with the older compiler.
> 

I cannot tell whether the change in debug info is incorrect -> correct, or just
different.

Either way, the patch from comment 4 seems to be able to handle this.

> > Same for:
> > ...
> > > FAIL: gdb.ada/tagged.exp: ptype obj (timeout)
> 
> Is it the same compiler versions that fail here?

Yes.

> I can't test it readily but I can send a patch to disable
> these tests with an older gcc.

Any thoughts on the patch ?

-- 
You are receiving this mail because:
You are on the CC list for the bug.

[Bug ada/28180] FAIL: gdb.ada/interface.exp: print s (timeout)

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=28180

--- Comment #7 from Tom de Vries <vries at gcc dot gnu.org> ---
Created attachment 13594
  --> https://sourceware.org/bugzilla/attachment.cgi?id=13594&action=edit
foo.gz

Reproduce:
...
$ gunzip foo.gz 
$ gdb -q -batch ./foo -ex "b foo.adb:22" -ex r -ex "p s"
Breakpoint 1 at 0x404455: file
/home/vries/gdb_versions/devel/binutils-gdb.git/gdb/testsuite/gdb.ada/interface/foo.adb,
line 22.

Breakpoint 1, foo () at
/home/vries/gdb_versions/devel/binutils-gdb.git/gdb/testsuite/gdb.ada/interface/foo.adb:22
22         Do_Nothing (R);  -- STOP
Multiple matches for s
[0] cancel
[1] s at
/home/vries/gdb_versions/devel/binutils-gdb.git/gdb/testsuite/gdb.ada/interface/foo.adb:20
[2] s at
/home/vries/gdb_versions/devel/binutils-gdb.git/gdb/testsuite/gdb.ada/interface/foo.adb:?
> 
...

-- 
You are receiving this mail because:
You are on the CC list for the bug.

[Bug ada/28180] FAIL: gdb.ada/interface.exp: print s (timeout)

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=28180

Tom Tromey <tromey at sourceware dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |brobecke at sourceware dot org

--- Comment #8 from Tom Tromey <tromey at sourceware dot org> ---
(In reply to Tom de Vries from comment #3)

> Hmm, so ada uses named artifical variables that need to be in the symbol
> table in order to evaluate them, but they should be ignored in terms of gdb
> commands that investigate source constructs like "p s".  That seems to be
> the root cause.

Yeah, Ada uses a special setup where some debug info is expressed via
magic symbol names.  The Ada compiler is moving away from this --
gcc recently switched its default to "minimal encodings", but even with
this in place there are still some things that require this treatment.


> Any thoughts on the patch ?

Unless there's some strong need, my inclination would be to not do anything
special to support older versions of the compiler.  We're trying to move
everything to "real DWARF", at least to the extent that this is possible.

Joel is away right now, but I'll CC him to see what he thinks.

-- 
You are receiving this mail because:
You are on the CC list for the bug.

[Bug ada/28180] FAIL: gdb.ada/interface.exp: print s (timeout)

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=28180

--- Comment #9 from Tom de Vries <vries at gcc dot gnu.org> ---
(In reply to Tom Tromey from comment #8)
> (In reply to Tom de Vries from comment #3)
> 
> > Hmm, so ada uses named artifical variables that need to be in the symbol
> > table in order to evaluate them, but they should be ignored in terms of gdb
> > commands that investigate source constructs like "p s".  That seems to be
> > the root cause.
> 
> Yeah, Ada uses a special setup where some debug info is expressed via
> magic symbol names.  The Ada compiler is moving away from this --
> gcc recently switched its default to "minimal encodings", but even with
> this in place there are still some things that require this treatment.
> 
> 
> > Any thoughts on the patch ?
> 
> Unless there's some strong need, my inclination would be to not do anything
> special to support older versions of the compiler.  We're trying to move
> everything to "real DWARF", at least to the extent that this is possible.
> 
> Joel is away right now, but I'll CC him to see what he thinks.

FTR, I can live with an xfail.  But it's good to note that with the latest gcc
version, the compiler still produces this type of variables (not s.14, but
others, f.i. <G6b_LAST>), and an xfail should explain why s.14 is incorrect
compiler output, and <G6b_LAST> correct compiler output.

-- 
You are receiving this mail because:
You are on the CC list for the bug.

[Bug ada/28180] FAIL: gdb.ada/interface.exp: print s (timeout)

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=28180

--- Comment #10 from Tom Tromey <tromey at sourceware dot org> ---
(In reply to Tom de Vries from comment #4)
> This allows the test-case to pass:
> ...

I was digging through local code recently and I found out that AdaCore
has a patch that does something along these lines.
There's a function:

/* Return non-zero if STR should be suppressed in info listings.  */

static int
is_suppressed_name (const char *str)


then a macro that ends up calling that:

#define SYMBOL_PRINTING_SUPPRESSED(symbol)                              \
  (current_language->la_language == language_ada                        \
   && ada_suppress_symbol_printing (symbol))


Then iterate_over_block_locals does:

  ALL_BLOCK_SYMBOLS (b, iter, sym)
    {
      if (SYMBOL_PRINTING_SUPPRESSED (sym))
        continue;

This code dates to 2007; I don't know if it's ever been sent upstream.

I'm building gcc 8 to see if I can reproduce this.
Maybe the answer is your patch after all, or maybe upstreaming this local one.

-- 
You are receiving this mail because:
You are on the CC list for the bug.

[Bug ada/28180] FAIL: gdb.ada/interface.exp: print s (timeout)

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=28180

--- Comment #11 from Tom Tromey <tromey at sourceware dot org> ---
> I'm building gcc 8 to see if I can reproduce this.

Well, I couldn't build it on this machine,
so I'm not sure what to do now.
If I package up the local change, could you try it out?

-- 
You are receiving this mail because:
You are on the CC list for the bug.

[Bug ada/28180] FAIL: gdb.ada/interface.exp: print s (timeout)

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=28180

--- Comment #12 from Tom de Vries <vries at gcc dot gnu.org> ---
(In reply to Tom Tromey from comment #11)
> > I'm building gcc 8 to see if I can reproduce this.
> 
> Well, I couldn't build it on this machine,
> so I'm not sure what to do now.
> If I package up the local change, could you try it out?

Sure. [ Though I'm on vacation now, so limited to ubuntu 18.04.5, and possibly
not able to do a quick response. ]

-- 
You are receiving this mail because:
You are on the CC list for the bug.

[Bug ada/28180] FAIL: gdb.ada/interface.exp: print s (timeout)

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=28180

--- Comment #13 from Tom de Vries <vries at gcc dot gnu.org> ---
(In reply to Tom Tromey from comment #10)
> This code dates to 2007; I don't know if it's ever been sent upstream.
> 

Perhaps https://sourceware.org/pipermail/gdb-patches/2008-January/054994.html
?

-- 
You are receiving this mail because:
You are on the CC list for the bug.

[Bug ada/28180] FAIL: gdb.ada/interface.exp: print s (timeout)

[brobecker at gnat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=28180

Joel Brobecker <brobecker at gnat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |brobecker at gnat dot com

--- Comment #14 from Joel Brobecker <brobecker at gnat dot com> ---
> Perhaps https://sourceware.org/pipermail/gdb-patches/2008-January/054994.html
> ?

That's exactly it. We tried to submit that code way back then, and Daniel
suggested a better route. Unfortunately, we never found the time to work on
that since then...

-- 
You are receiving this mail because:
You are on the CC list for the bug.

[Bug ada/28180] FAIL: gdb.ada/interface.exp: print s (timeout)

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=28180

--- Comment #15 from Tom Tromey <tromey at sourceware dot org> ---
Daniel's suggestion is basically Tom's patch in comment #4,
so I think we ought to go with that.

-- 
You are receiving this mail because:
You are on the CC list for the bug.

[Bug ada/28180] FAIL: gdb.ada/interface.exp: print s (timeout)

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=28180

--- Comment #16 from Tom de Vries <vries at gcc dot gnu.org> ---
https://sourceware.org/pipermail/gdb-patches/2021-August/181605.html

-- 
You are receiving this mail because:
You are on the CC list for the bug.

[Bug ada/28180] FAIL: gdb.ada/interface.exp: print s (timeout)

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=28180

Tom de Vries <vries at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
             Status|NEW                         |RESOLVED
   Target Milestone|---                         |12.1

--- Comment #17 from Tom de Vries <vries at gcc dot gnu.org> ---
Fixed by commit
https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=2c71f639a04fad36b5f7b255909ede09b63afdf9

-- 
You are receiving this mail because:
You are on the CC list for the bug.

[Bug ada/28180] FAIL: gdb.ada/interface.exp: print s (timeout)

[sam at gentoo dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=28180

Sam James <sam at gentoo dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           See Also|                            |https://sourceware.org/bugz
                   |                            |illa/show_bug.cgi?id=31463

-- 
You are receiving this mail because:
You are on the CC list for the bug.