[pushed/ob] cplus_demangle_fill_component: Handle DEMANGLE_COMPONENT_RVALUE_REFERENCE (Re: [PATCH] libiberty: Initialize d_printing in all cplus_demangle_* functions.)

[Pedro Alves]

[added back gcc-patches, obvious libiberty patch below]

On 03/14/2017 10:50 AM, Pedro Alves wrote:
> On 03/14/2017 09:04 AM, Mark Wielaard wrote:
> 
>> That looks good. But note that there is one behavioral change.
>> cplus_demangle_fill_component is defined as:
>>
>> /* Fill in most component types with a left subtree and a right
>>subtree.  Returns non-zero on success, zero on failure, such as an
>>unrecognized or inappropriate component type.  */
>>
>> And gdb/cp-name-parser.y fill_comp does:
>>
>>   i = cplus_demangle_fill_component (ret, d_type, lhs, rhs);
>>   gdb_assert (i);
>>
>> So you have an extra sanity check. Where before you might have silently
>> created a bogus demangle_component. Which I assume is what you want.
> 
> Indeed, and I think it is.
> 
>> But it might depend on what gdb_assert precisely does 
> 
> gdb_assert triggers the infamous:
> 
>  A problem internal to GDB has been detected,
>  further debugging may prove unreliable.
>  Quit this debugging session? (y or n) 
> 
>> and if the parser input is normally "sane" or not.
> 
> The only thing that is validated is that we don't create
> a component with a left/right subtree when that doesn't make sense
> for the component type.  I think trying to create such a component
> would be a parser/grammar/production bug, even with invalid input.
> 
> I had run into that assert in fill_comp yesterday actually, with a slightly
> different/larger patch.  At first I saw the cplus_demangle_fill_component
> declaration in demangle.h, but didn't see the implementation in 
> cp-demangle.c, and
> thought that was just some oversight/left over.  So I though I'd add one.  I 
> factored
> out a cplus_demangle_fill_component out of cp-demangle.c:d_make_comp, 
> following the
> same pattern used by the other cplus_demangle_fill* / d_make* function pairs. 
>  
> Only after did I notice that actually, there's an implementation of
> cplus_demangle_fill_component in cplus-demint.c...  AFAICS, that's only
> used by GDB.  No other tool in the binutils-gdb repo, nor GCC's repo uses it, 
> AFAICS.
> So I figured that I'd remove the cplus-demint.c implementation, in favor of
> the new implementation in cp-demangle.c based on d_make_comp.  And _that_ ran 
> into the
> assertion, because the implementations are exactly the same.  GDB fills in 
> some types with
> NULL left components and fills them in later.  For example, for 
> DEMANGLE_COMPONENT_POINTER:
> 
>  ptr_operator   :   '*' qualifiers_opt
> -   { $$.comp = make_empty (DEMANGLE_COMPONENT_POINTER);
> - $$.comp->u.s_binary.left = 
> $$.comp->u.s_binary.right = NULL;
> +   { $$.comp = fill_comp (DEMANGLE_COMPONENT_POINTER, 
> NULL, NULL);
>   $$.last = _left ($$.comp);
>   $$.comp = d_qualify ($$.comp, $2, 0); }
> 
> Note how cp-demangle.c:d_make_comp's validations are stricter than 
> cp-demint.c:cplus_demangle_fill_component's.  The former only allows 
> lazy-filling for a few cases:
> 
> [...]
>   /* These are allowed to have no parameters--in some cases they
>will be filled in later.  */
> case DEMANGLE_COMPONENT_FUNCTION_TYPE:
> [...]
> 
> While cp-demint.c:cplus_demangle_fill_component, the version that
> GDB uses, allows that in all cases.  IOW, passing in a NULL left/right subtree
> to cplus_demangle_fill_component when the component type expects one is OK, 
> assuming
> that the caller will fill them in afterwards.  I crossed checked the types in
> the new fill_comp calls with the checks inside cplus_demangle_fill_component 
> now,
> and I believe they're all OK.
> 
> Maybe it'd be possible to avoid this lazy filling in, but I didn't
> bother trying.

Funny enough, I was going to apply the gdb patch today, but 
gdb meanwhile gained a new make_empty call for
DEMANGLE_COMPONENT_RVALUE_REFERENCE, and making that new code
use fill_comp/cplus_demangle_fill_component too triggered the
sanity check discussed above...  This is just a latent bug
being exposed now.

I've pushed the obvious patch below to both gcc trunk and binutils-gdb master.

>From b1a42fdfa31937d7e05df34afee970ac0ad239e1 Mon Sep 17 00:00:00 2001
From: Pedro Alves 
Date: Mon, 27 Mar 2017 13:56:49 +0100
Subject: [PATCH] cplus_demangle_fill_component: Handle
 DEMANGLE_COMPONENT_RVALUE_REFERENCE

This patch almost a decade ago:

...
2007-08-31  Douglas Gregor  

* cp-demangle.c (d_dump): Handle
DEMANGLE_COMPONENT_RVALUE_REFERENCE.
(d_make_comp): Ditto.
...

... missed doing the same change to cplus_demangle_fill_component that
was done to d_make_comp.  I.e., teach it to only validate that we're
not passing in a "right" subtree.  GDB has recently (finally) learned
about rvalue references, and a change to make it use
cplus_demangle_fill_component more ran into an assertion because of
this.

(GDB is the only user of 

Re: [PATCH] libiberty: Initialize d_printing in all cplus_demangle_* functions.

[Pedro Alves]

On 03/13/2017 06:29 PM, Mark Wielaard wrote:

> O, sorry. I should have let Nick known about the gdb regressions I found.
> Besides this patch gdb needs the following one-liner fix:
> 
> diff --git a/gdb/cp-name-parser.y b/gdb/cp-name-parser.y
> index fd1e949..5278c05 100644
> --- a/gdb/cp-name-parser.y
> +++ b/gdb/cp-name-parser.y
> @@ -201,6 +201,7 @@ make_empty (enum demangle_component_type d_type)
>  {
>struct demangle_component *ret = d_grab ();
>ret->type = d_type;
> +  ret->d_printing = 0;
>return ret;
>  }

Should gdb be memsetting instead to avoid having to know about
libiberty's "internals"?  Either version is pre-approved for GDB.

Thanks,
Pedro Alves

Re: [PATCH] libiberty: Initialize d_printing in all cplus_demangle_* functions.

[Mark Wielaard]

On Mon, Mar 13, 2017 at 07:11:50PM +0100, Markus Trippelsdorf wrote:
> On 2017.03.12 at 23:05 +0100, Mark Wielaard wrote:
> > While integrating the d_printing recursion guard change into gdb I
> > noticed we forgot to initialize the demangle_component d_printing
> > field in cplus_demangle_fill_{name,extended_operator,ctor,dtor}.
> > As is done in cplus_demangle_fill_{component,builtin_type,operator}.
> > It happened to work because in gcc all demangle_components were
> > allocated through d_make_empty. But gdb has its own allocation
> > mechanism (as might other users).
> 
> Nick has synced the binutils-gdb repro with gcc's. 
> I think you should commit your fix as obvious.

Ian just approved it and I checked it in. gcc svn r246105.

> And it would be nice if Nick could sync again, after your patch went in.

O, sorry. I should have let Nick known about the gdb regressions I found.
Besides this patch gdb needs the following one-liner fix:

diff --git a/gdb/cp-name-parser.y b/gdb/cp-name-parser.y
index fd1e949..5278c05 100644
--- a/gdb/cp-name-parser.y
+++ b/gdb/cp-name-parser.y
@@ -201,6 +201,7 @@ make_empty (enum demangle_component_type d_type)
 {
   struct demangle_component *ret = d_grab ();
   ret->type = d_type;
+  ret->d_printing = 0;
   return ret;
 }
 

Cheers,

Mark

Re: [PATCH] libiberty: Initialize d_printing in all cplus_demangle_* functions.

[Markus Trippelsdorf]

On 2017.03.12 at 23:05 +0100, Mark Wielaard wrote:
> While integrating the d_printing recursion guard change into gdb I
> noticed we forgot to initialize the demangle_component d_printing
> field in cplus_demangle_fill_{name,extended_operator,ctor,dtor}.
> As is done in cplus_demangle_fill_{component,builtin_type,operator}.
> It happened to work because in gcc all demangle_components were
> allocated through d_make_empty. But gdb has its own allocation
> mechanism (as might other users).

Nick has synced the binutils-gdb repro with gcc's. 
I think you should commit your fix as obvious.

And it would be nice if Nick could sync again, after your patch went in.

-- 
Markus

Re: [PATCH] libiberty: Initialize d_printing in all cplus_demangle_* functions.

[Ian Lance Taylor via gcc-patches]

On Sun, Mar 12, 2017 at 3:05 PM, Mark Wielaard  wrote:
> While integrating the d_printing recursion guard change into gdb I
> noticed we forgot to initialize the demangle_component d_printing
> field in cplus_demangle_fill_{name,extended_operator,ctor,dtor}.
> As is done in cplus_demangle_fill_{component,builtin_type,operator}.
> It happened to work because in gcc all demangle_components were
> allocated through d_make_empty. But gdb has its own allocation
> mechanism (as might other users).
>
> libiberty/ChangeLog:
>
>* cp-demangle.c (cplus_demangle_fill_name): Initialize
>demangle_component d_printing.
>(cplus_demangle_fill_extended_operator): Likewise.
>(cplus_demangle_fill_ctor): Likewise.
>(cplus_demangle_fill_dtor): Likewise.

This is OK.

Thanks.

Ian

[PATCH] libiberty: Initialize d_printing in all cplus_demangle_* functions.

[Mark Wielaard]

While integrating the d_printing recursion guard change into gdb I
noticed we forgot to initialize the demangle_component d_printing
field in cplus_demangle_fill_{name,extended_operator,ctor,dtor}.
As is done in cplus_demangle_fill_{component,builtin_type,operator}.
It happened to work because in gcc all demangle_components were
allocated through d_make_empty. But gdb has its own allocation
mechanism (as might other users).

libiberty/ChangeLog:

   * cp-demangle.c (cplus_demangle_fill_name): Initialize
   demangle_component d_printing.
   (cplus_demangle_fill_extended_operator): Likewise.
   (cplus_demangle_fill_ctor): Likewise.
   (cplus_demangle_fill_dtor): Likewise.
---
 libiberty/ChangeLog | 8 
 libiberty/cp-demangle.c | 4 
 2 files changed, 12 insertions(+)

diff --git a/libiberty/ChangeLog b/libiberty/ChangeLog
index e93e327..b513fce 100644
--- a/libiberty/ChangeLog
+++ b/libiberty/ChangeLog
@@ -1,3 +1,11 @@
+2017-03-12  Mark Wielaard  
+
+   * cp-demangle.c (cplus_demangle_fill_name): Initialize
+   demangle_component d_printing.
+   (cplus_demangle_fill_extended_operator): Likewise.
+   (cplus_demangle_fill_ctor): Likewise.
+   (cplus_demangle_fill_dtor): Likewise.
+
 2017-03-08  Mark Wielaard  
 
PR demangler/70909
diff --git a/libiberty/cp-demangle.c b/libiberty/cp-demangle.c
index 341a418..04832ff 100644
--- a/libiberty/cp-demangle.c
+++ b/libiberty/cp-demangle.c
@@ -854,6 +854,7 @@ cplus_demangle_fill_name (struct demangle_component *p, 
const char *s, int len)
 {
   if (p == NULL || s == NULL || len == 0)
 return 0;
+  p->d_printing = 0;
   p->type = DEMANGLE_COMPONENT_NAME;
   p->u.s_name.s = s;
   p->u.s_name.len = len;
@@ -869,6 +870,7 @@ cplus_demangle_fill_extended_operator (struct 
demangle_component *p, int args,
 {
   if (p == NULL || args < 0 || name == NULL)
 return 0;
+  p->d_printing = 0;
   p->type = DEMANGLE_COMPONENT_EXTENDED_OPERATOR;
   p->u.s_extended_operator.args = args;
   p->u.s_extended_operator.name = name;
@@ -888,6 +890,7 @@ cplus_demangle_fill_ctor (struct demangle_component *p,
   || (int) kind < gnu_v3_complete_object_ctor
   || (int) kind > gnu_v3_object_ctor_group)
 return 0;
+  p->d_printing = 0;
   p->type = DEMANGLE_COMPONENT_CTOR;
   p->u.s_ctor.kind = kind;
   p->u.s_ctor.name = name;
@@ -907,6 +910,7 @@ cplus_demangle_fill_dtor (struct demangle_component *p,
   || (int) kind < gnu_v3_deleting_dtor
   || (int) kind > gnu_v3_object_dtor_group)
 return 0;
+  p->d_printing = 0;
   p->type = DEMANGLE_COMPONENT_DTOR;
   p->u.s_dtor.kind = kind;
   p->u.s_dtor.name = name;
-- 
1.8.3.1