[C++ Patch] PR 84644 ("internal compiler error: in warn_misplaced_attr_for_class_type, at cp/decl.c:4718")

[C++ Patch] PR 84644 ("internal compiler error: in warn_misplaced_attr_for_class_type, at cp/decl.c:4718")

[Paolo Carlini]

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Hi,

here we ICE when, at the end of check_tag_decl we pass a DECLTYPE_TYPE 
to warn_misplaced_attr_for_class_type. I think the right fix is 
rejecting earlier a decltype with no declarator as a declaration that 
doesn't declare anything (note: all the compilers I have at hand agree). 
Tested x86_64-linux.

Thanks, Paolo.

////////////////////


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/cp
2018-10-15  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/84644
	* decl.c (check_tag_decl): A decltype with no declarator
	doesn't declare anything.

/testsuite
2018-10-15  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/84644
	* g++.dg/cpp0x/decltype68.C: New.
	* g++.dg/cpp0x/decltype-33838.C: Adjust.

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Index: cp/decl.c
===================================================================
--- cp/decl.c	(revision 265158)
+++ cp/decl.c	(working copy)
@@ -4793,6 +4793,7 @@ check_tag_decl (cp_decl_specifier_seq *declspecs,
   if (declspecs->type
       && TYPE_P (declspecs->type)
       && ((TREE_CODE (declspecs->type) != TYPENAME_TYPE
+	   && TREE_CODE (declspecs->type) != DECLTYPE_TYPE
 	   && MAYBE_CLASS_TYPE_P (declspecs->type))
 	  || TREE_CODE (declspecs->type) == ENUMERAL_TYPE))
     declared_type = declspecs->type;
Index: testsuite/g++.dg/cpp0x/decltype-33838.C
===================================================================
--- testsuite/g++.dg/cpp0x/decltype-33838.C	(revision 265158)
+++ testsuite/g++.dg/cpp0x/decltype-33838.C	(working copy)
@@ -2,5 +2,5 @@
 // PR c++/33838
 template<typename T> struct A
 {
-  __decltype (T* foo()); // { dg-error "expected|no arguments|accept" }
+  __decltype (T* foo()); // { dg-error "expected|no arguments|declaration" }
 };
Index: testsuite/g++.dg/cpp0x/decltype68.C
===================================================================
--- testsuite/g++.dg/cpp0x/decltype68.C	(nonexistent)
+++ testsuite/g++.dg/cpp0x/decltype68.C	(working copy)
@@ -0,0 +1,7 @@
+// PR c++/84644
+// { dg-do compile { target c++11 } }
+
+template<int a>
+struct b {
+  decltype(a) __attribute__((break));  // { dg-error "declaration does not declare anything" }
+};

Re: [C++ Patch] PR 84644 ("internal compiler error: in warn_misplaced_attr_for_class_type, at cp/decl.c:4718")

[Jason Merrill]

On 10/15/18 12:45 PM, Paolo Carlini wrote:
>         && ((TREE_CODE (declspecs->type) != TYPENAME_TYPE
> +	   && TREE_CODE (declspecs->type) != DECLTYPE_TYPE
>   	   && MAYBE_CLASS_TYPE_P (declspecs->type))

I would think that the MAYBE_CLASS_TYPE_P here should be CLASS_TYPE_P, 
and then we can remove the TYPENAME_TYPE check.  Or do we want to allow 
template type parameters for some reason?

Jason

Re: [C++ Patch] PR 84644 ("internal compiler error: in warn_misplaced_attr_for_class_type, at cp/decl.c:4718")

[Paolo Carlini]

Hi,

On 24/10/18 22:41, Jason Merrill wrote:
> On 10/15/18 12:45 PM, Paolo Carlini wrote:
>>         && ((TREE_CODE (declspecs->type) != TYPENAME_TYPE
>> +       && TREE_CODE (declspecs->type) != DECLTYPE_TYPE
>>          && MAYBE_CLASS_TYPE_P (declspecs->type))
>
> I would think that the MAYBE_CLASS_TYPE_P here should be CLASS_TYPE_P, 
> and then we can remove the TYPENAME_TYPE check.  Or do we want to 
> allow template type parameters for some reason?

Indeed, it would be nice to just use OVERLOAD_TYPE_P. However it seems 
we at least want to let through TEMPLATE_TYPE_PARMs representing 'auto' 
- otherwise Dodji's check a few lines below which fixed c++/51473 
doesn't work anymore - and also BOUND_TEMPLATE_TEMPLATE_PARM, otherwise 
we regress on template/spec32.C and template/ttp22.C because we don't 
diagnose the shadowing anymore. Thus, I would say either we keep on 
using MAYBE_CLASS_TYPE_P or we pick what we need, possibly we add a comment?

Thanks, Paolo.

Re: [C++ Patch] PR 84644 ("internal compiler error: in warn_misplaced_attr_for_class_type, at cp/decl.c:4718")

[Jason Merrill]

On Fri, Oct 26, 2018 at 4:52 AM Paolo Carlini <paolo.carlini@oracle.com> wrote:
> On 24/10/18 22:41, Jason Merrill wrote:
> > On 10/15/18 12:45 PM, Paolo Carlini wrote:
> >>         && ((TREE_CODE (declspecs->type) != TYPENAME_TYPE
> >> +       && TREE_CODE (declspecs->type) != DECLTYPE_TYPE
> >>          && MAYBE_CLASS_TYPE_P (declspecs->type))
> >
> > I would think that the MAYBE_CLASS_TYPE_P here should be CLASS_TYPE_P,
> > and then we can remove the TYPENAME_TYPE check.  Or do we want to
> > allow template type parameters for some reason?
>
> Indeed, it would be nice to just use OVERLOAD_TYPE_P. However it seems
> we at least want to let through TEMPLATE_TYPE_PARMs representing 'auto'
> - otherwise Dodji's check a few lines below which fixed c++/51473
> doesn't work anymore - and also BOUND_TEMPLATE_TEMPLATE_PARM, otherwise
> we regress on template/spec32.C and template/ttp22.C because we don't
> diagnose the shadowing anymore. Thus, I would say either we keep on
> using MAYBE_CLASS_TYPE_P or we pick what we need, possibly we add a comment?

Aha.  I guess the answer is not to restrict that test any more, but
instead to fix the code further down so it gives a proper diagnostic
rather than call warn_misplaced_attr_for_class_type.

Jason

Re: [C++ Patch] PR 84644 ("internal compiler error: in warn_misplaced_attr_for_class_type, at cp/decl.c:4718")

[Paolo Carlini]

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Hi,

On 26/10/18 17:18, Jason Merrill wrote:
> On Fri, Oct 26, 2018 at 4:52 AM Paolo Carlini <paolo.carlini@oracle.com> wrote:
>> On 24/10/18 22:41, Jason Merrill wrote:
>>> On 10/15/18 12:45 PM, Paolo Carlini wrote:
>>>>          && ((TREE_CODE (declspecs->type) != TYPENAME_TYPE
>>>> +       && TREE_CODE (declspecs->type) != DECLTYPE_TYPE
>>>>           && MAYBE_CLASS_TYPE_P (declspecs->type))
>>> I would think that the MAYBE_CLASS_TYPE_P here should be CLASS_TYPE_P,
>>> and then we can remove the TYPENAME_TYPE check.  Or do we want to
>>> allow template type parameters for some reason?
>> Indeed, it would be nice to just use OVERLOAD_TYPE_P. However it seems
>> we at least want to let through TEMPLATE_TYPE_PARMs representing 'auto'
>> - otherwise Dodji's check a few lines below which fixed c++/51473
>> doesn't work anymore - and also BOUND_TEMPLATE_TEMPLATE_PARM, otherwise
>> we regress on template/spec32.C and template/ttp22.C because we don't
>> diagnose the shadowing anymore. Thus, I would say either we keep on
>> using MAYBE_CLASS_TYPE_P or we pick what we need, possibly we add a comment?
> Aha.  I guess the answer is not to restrict that test any more, but
> instead to fix the code further down so it gives a proper diagnostic
> rather than call warn_misplaced_attr_for_class_type.

I see. Thus something like the below? It passes testing on x86_64-linux.

Thanks! Paolo.

/////////////


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Index: cp/decl.c
===================================================================
--- cp/decl.c	(revision 265510)
+++ cp/decl.c	(working copy)
@@ -4798,9 +4798,10 @@ check_tag_decl (cp_decl_specifier_seq *declspecs,
     declared_type = declspecs->type;
   else if (declspecs->type == error_mark_node)
     error_p = true;
-  if (declared_type == NULL_TREE && ! saw_friend && !error_p)
+  if ((!declared_type || TREE_CODE (declared_type) == DECLTYPE_TYPE)
+      && ! saw_friend && !error_p)
     permerror (input_location, "declaration does not declare anything");
-  else if (declared_type != NULL_TREE && type_uses_auto (declared_type))
+  else if (declared_type && type_uses_auto (declared_type))
     {
       error_at (declspecs->locations[ds_type_spec],
 		"%<auto%> can only be specified for variables "
@@ -4884,7 +4885,8 @@ check_tag_decl (cp_decl_specifier_seq *declspecs,
 		  "%<constexpr%> cannot be used for type declarations");
     }
 
-  if (declspecs->attributes && warn_attributes && declared_type)
+  if (declspecs->attributes && warn_attributes && declared_type
+      && TREE_CODE (declared_type) != DECLTYPE_TYPE)
     {
       location_t loc;
       if (!CLASS_TYPE_P (declared_type)
Index: testsuite/g++.dg/cpp0x/decltype-33838.C
===================================================================
--- testsuite/g++.dg/cpp0x/decltype-33838.C	(revision 265510)
+++ testsuite/g++.dg/cpp0x/decltype-33838.C	(working copy)
@@ -2,5 +2,5 @@
 // PR c++/33838
 template<typename T> struct A
 {
-  __decltype (T* foo()); // { dg-error "expected|no arguments|accept" }
+  __decltype (T* foo()); // { dg-error "expected|no arguments|declaration" }
 };
Index: testsuite/g++.dg/cpp0x/decltype68.C
===================================================================
--- testsuite/g++.dg/cpp0x/decltype68.C	(nonexistent)
+++ testsuite/g++.dg/cpp0x/decltype68.C	(working copy)
@@ -0,0 +1,7 @@
+// PR c++/84644
+// { dg-do compile { target c++11 } }
+
+template<int a>
+struct b {
+  decltype(a) __attribute__((break));  // { dg-error "declaration does not declare anything" }
+};

Re: [C++ Patch] PR 84644 ("internal compiler error: in warn_misplaced_attr_for_class_type, at cp/decl.c:4718")

[Jason Merrill]

On 10/26/18 2:02 PM, Paolo Carlini wrote:
> On 26/10/18 17:18, Jason Merrill wrote:
>> On Fri, Oct 26, 2018 at 4:52 AM Paolo Carlini 
>> <paolo.carlini@oracle.com> wrote:
>>> On 24/10/18 22:41, Jason Merrill wrote:
>>>> On 10/15/18 12:45 PM, Paolo Carlini wrote:
>>>>>          && ((TREE_CODE (declspecs->type) != TYPENAME_TYPE
>>>>> +       && TREE_CODE (declspecs->type) != DECLTYPE_TYPE
>>>>>           && MAYBE_CLASS_TYPE_P (declspecs->type))
>>>> I would think that the MAYBE_CLASS_TYPE_P here should be CLASS_TYPE_P,
>>>> and then we can remove the TYPENAME_TYPE check.  Or do we want to
>>>> allow template type parameters for some reason?
>>> Indeed, it would be nice to just use OVERLOAD_TYPE_P. However it seems
>>> we at least want to let through TEMPLATE_TYPE_PARMs representing 'auto'
>>> - otherwise Dodji's check a few lines below which fixed c++/51473
>>> doesn't work anymore - and also BOUND_TEMPLATE_TEMPLATE_PARM, otherwise
>>> we regress on template/spec32.C and template/ttp22.C because we don't
>>> diagnose the shadowing anymore. Thus, I would say either we keep on
>>> using MAYBE_CLASS_TYPE_P or we pick what we need, possibly we add a 
>>> comment?
>> Aha.  I guess the answer is not to restrict that test any more, but
>> instead to fix the code further down so it gives a proper diagnostic
>> rather than call warn_misplaced_attr_for_class_type.
> 
> I see. Thus something like the below? It passes testing on x86_64-linux.

> +  if ((!declared_type || TREE_CODE (declared_type) == DECLTYPE_TYPE)
> +      && ! saw_friend && !error_p)
>      permerror (input_location, "declaration does not declare anything");

I see no reason to make this specific to decltype.  Maybe move this 
diagnostic into the final 'else' block with the other declspec 
diagnostics and not look at declared_type at all?

> +  if (declspecs->attributes && warn_attributes && declared_type
> +      && TREE_CODE (declared_type) != DECLTYPE_TYPE)

I think we do want to give a diagnostic about useless attributes, not 
skip it.

Jason

Re: [C++ Patch] PR 84644 ("internal compiler error: in warn_misplaced_attr_for_class_type, at cp/decl.c:4718")

[Paolo Carlini]

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Hi,

On 30/10/18 21:37, Jason Merrill wrote:
> On 10/26/18 2:02 PM, Paolo Carlini wrote:
>> On 26/10/18 17:18, Jason Merrill wrote:
>>> On Fri, Oct 26, 2018 at 4:52 AM Paolo Carlini 
>>> <paolo.carlini@oracle.com> wrote:
>>>> On 24/10/18 22:41, Jason Merrill wrote:
>>>>> On 10/15/18 12:45 PM, Paolo Carlini wrote:
>>>>>>          && ((TREE_CODE (declspecs->type) != TYPENAME_TYPE
>>>>>> +       && TREE_CODE (declspecs->type) != DECLTYPE_TYPE
>>>>>>           && MAYBE_CLASS_TYPE_P (declspecs->type))
>>>>> I would think that the MAYBE_CLASS_TYPE_P here should be 
>>>>> CLASS_TYPE_P,
>>>>> and then we can remove the TYPENAME_TYPE check.  Or do we want to
>>>>> allow template type parameters for some reason?
>>>> Indeed, it would be nice to just use OVERLOAD_TYPE_P. However it seems
>>>> we at least want to let through TEMPLATE_TYPE_PARMs representing 
>>>> 'auto'
>>>> - otherwise Dodji's check a few lines below which fixed c++/51473
>>>> doesn't work anymore - and also BOUND_TEMPLATE_TEMPLATE_PARM, 
>>>> otherwise
>>>> we regress on template/spec32.C and template/ttp22.C because we don't
>>>> diagnose the shadowing anymore. Thus, I would say either we keep on
>>>> using MAYBE_CLASS_TYPE_P or we pick what we need, possibly we add a 
>>>> comment?
>>> Aha.  I guess the answer is not to restrict that test any more, but
>>> instead to fix the code further down so it gives a proper diagnostic
>>> rather than call warn_misplaced_attr_for_class_type.
>>
>> I see. Thus something like the below? It passes testing on x86_64-linux.
>
>> +  if ((!declared_type || TREE_CODE (declared_type) == DECLTYPE_TYPE)
>> +      && ! saw_friend && !error_p)
>>      permerror (input_location, "declaration does not declare 
>> anything");
>
> I see no reason to make this specific to decltype.  Maybe move this 
> diagnostic into the final 'else' block with the other declspec 
> diagnostics and not look at declared_type at all?

I'm not sure to fully understand: if we do that we still want to at 
least minimally check that declared_type is null, like we already do, 
and then we simply accept the new testcase. Is that Ok? Because, as I 
probably mentioned at some point, all the other compilers I have at hand 
issue a "does not declare anything" diagnostic, and we likewise do that 
for the legacy __typeof. Not looking into declared_type *at all* doesn't 
work with plain class types and enums, of course. Or you meant something 
entirely different??

>> +  if (declspecs->attributes && warn_attributes && declared_type
>> +      && TREE_CODE (declared_type) != DECLTYPE_TYPE)
>
> I think we do want to give a diagnostic about useless attributes, not 
> skip it.

Agreed. FWIW the attached tests fine.

Thanks, Paolo.

///////////////////


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Index: decl.c
===================================================================
--- decl.c	(revision 265636)
+++ decl.c	(working copy)
@@ -4798,9 +4798,7 @@ check_tag_decl (cp_decl_specifier_seq *declspecs,
     declared_type = declspecs->type;
   else if (declspecs->type == error_mark_node)
     error_p = true;
-  if (declared_type == NULL_TREE && ! saw_friend && !error_p)
-    permerror (input_location, "declaration does not declare anything");
-  else if (declared_type != NULL_TREE && type_uses_auto (declared_type))
+  if (declared_type && type_uses_auto (declared_type))
     {
       error_at (declspecs->locations[ds_type_spec],
 		"%<auto%> can only be specified for variables "
@@ -4842,7 +4840,9 @@ check_tag_decl (cp_decl_specifier_seq *declspecs,
 
   else
     {
-      if (decl_spec_seq_has_spec_p (declspecs, ds_inline))
+      if (!declared_type && ! saw_friend && !error_p)
+	permerror (input_location, "declaration does not declare anything");
+      else if (decl_spec_seq_has_spec_p (declspecs, ds_inline))
 	error_at (declspecs->locations[ds_inline],
 		  "%<inline%> can only be specified for functions");
       else if (decl_spec_seq_has_spec_p (declspecs, ds_virtual))
@@ -4909,7 +4909,7 @@ check_tag_decl (cp_decl_specifier_seq *declspecs,
 		    "no attribute can be applied to "
 		    "an explicit instantiation");
 	}
-      else
+      else if (TREE_CODE (declared_type) != DECLTYPE_TYPE)
 	warn_misplaced_attr_for_class_type (loc, declared_type);
     }
 

Re: [C++ Patch] PR 84644 ("internal compiler error: in warn_misplaced_attr_for_class_type, at cp/decl.c:4718")

[Jason Merrill]

On 10/30/18 9:22 PM, Paolo Carlini wrote:
> Hi,
> 
> On 30/10/18 21:37, Jason Merrill wrote:
>> On 10/26/18 2:02 PM, Paolo Carlini wrote:
>>> On 26/10/18 17:18, Jason Merrill wrote:
>>>> On Fri, Oct 26, 2018 at 4:52 AM Paolo Carlini 
>>>> <paolo.carlini@oracle.com> wrote:
>>>>> On 24/10/18 22:41, Jason Merrill wrote:
>>>>>> On 10/15/18 12:45 PM, Paolo Carlini wrote:
>>>>>>>          && ((TREE_CODE (declspecs->type) != TYPENAME_TYPE
>>>>>>> +       && TREE_CODE (declspecs->type) != DECLTYPE_TYPE
>>>>>>>           && MAYBE_CLASS_TYPE_P (declspecs->type))
>>>>>> I would think that the MAYBE_CLASS_TYPE_P here should be 
>>>>>> CLASS_TYPE_P,
>>>>>> and then we can remove the TYPENAME_TYPE check.  Or do we want to
>>>>>> allow template type parameters for some reason?
>>>>> Indeed, it would be nice to just use OVERLOAD_TYPE_P. However it seems
>>>>> we at least want to let through TEMPLATE_TYPE_PARMs representing 
>>>>> 'auto'
>>>>> - otherwise Dodji's check a few lines below which fixed c++/51473
>>>>> doesn't work anymore - and also BOUND_TEMPLATE_TEMPLATE_PARM, 
>>>>> otherwise
>>>>> we regress on template/spec32.C and template/ttp22.C because we don't
>>>>> diagnose the shadowing anymore. Thus, I would say either we keep on
>>>>> using MAYBE_CLASS_TYPE_P or we pick what we need, possibly we add a 
>>>>> comment?
>>>> Aha.  I guess the answer is not to restrict that test any more, but
>>>> instead to fix the code further down so it gives a proper diagnostic
>>>> rather than call warn_misplaced_attr_for_class_type.
>>>
>>> I see. Thus something like the below? It passes testing on x86_64-linux.
>>
>>> +  if ((!declared_type || TREE_CODE (declared_type) == DECLTYPE_TYPE)
>>> +      && ! saw_friend && !error_p)
>>>      permerror (input_location, "declaration does not declare 
>>> anything");
>>
>> I see no reason to make this specific to decltype.  Maybe move this 
>> diagnostic into the final 'else' block with the other declspec 
>> diagnostics and not look at declared_type at all?
> 
> I'm not sure to fully understand: if we do that we still want to at 
> least minimally check that declared_type is null, like we already do, 
> and then we simply accept the new testcase. Is that Ok? Because, as I 
> probably mentioned at some point, all the other compilers I have at hand 
> issue a "does not declare anything" diagnostic, and we likewise do that 
> for the legacy __typeof. Not looking into declared_type *at all* doesn't 
> work with plain class types and enums, of course. Or you meant something 
> entirely different??
> 
>>> +  if (declspecs->attributes && warn_attributes && declared_type
>>> +      && TREE_CODE (declared_type) != DECLTYPE_TYPE)
>>
>> I think we do want to give a diagnostic about useless attributes, not 
>> skip it.
> 
> Agreed. FWIW the attached tests fine.

The problem here is that the code toward the bottom expects 
"declared_type" to be the tagged type declared by a declaration with no 
declarator, and in this testcase it's ending up as a DECLTYPE_TYPE.

I think once we've checked for 'auto' we don't want declared_type to be 
anything that isn't OVERLOAD_TYPE_P.  We can arrange that either by 
checking for 'auto' first and then changing the code that sets 
declared_type to use OVERLOAD_TYPE_P, or by clearing declared_type after 
checking for 'auto' if it isn't OVERLOAD_TYPE_P.

Jason

Re: [C++ Patch] PR 84644 ("internal compiler error: in warn_misplaced_attr_for_class_type, at cp/decl.c:4718")

[Paolo Carlini]

Hi,

On 13/12/18 22:03, Jason Merrill wrote:
> On 10/30/18 9:22 PM, Paolo Carlini wrote:
>> Hi,
>>
>> On 30/10/18 21:37, Jason Merrill wrote:
>>> On 10/26/18 2:02 PM, Paolo Carlini wrote:
>>>> On 26/10/18 17:18, Jason Merrill wrote:
>>>>> On Fri, Oct 26, 2018 at 4:52 AM Paolo Carlini 
>>>>> <paolo.carlini@oracle.com> wrote:
>>>>>> On 24/10/18 22:41, Jason Merrill wrote:
>>>>>>> On 10/15/18 12:45 PM, Paolo Carlini wrote:
>>>>>>>>          && ((TREE_CODE (declspecs->type) != TYPENAME_TYPE
>>>>>>>> +       && TREE_CODE (declspecs->type) != DECLTYPE_TYPE
>>>>>>>>           && MAYBE_CLASS_TYPE_P (declspecs->type))
>>>>>>> I would think that the MAYBE_CLASS_TYPE_P here should be 
>>>>>>> CLASS_TYPE_P,
>>>>>>> and then we can remove the TYPENAME_TYPE check.  Or do we want to
>>>>>>> allow template type parameters for some reason?
>>>>>> Indeed, it would be nice to just use OVERLOAD_TYPE_P. However it 
>>>>>> seems
>>>>>> we at least want to let through TEMPLATE_TYPE_PARMs representing 
>>>>>> 'auto'
>>>>>> - otherwise Dodji's check a few lines below which fixed c++/51473
>>>>>> doesn't work anymore - and also BOUND_TEMPLATE_TEMPLATE_PARM, 
>>>>>> otherwise
>>>>>> we regress on template/spec32.C and template/ttp22.C because we 
>>>>>> don't
>>>>>> diagnose the shadowing anymore. Thus, I would say either we keep on
>>>>>> using MAYBE_CLASS_TYPE_P or we pick what we need, possibly we add 
>>>>>> a comment?
>>>>> Aha.  I guess the answer is not to restrict that test any more, but
>>>>> instead to fix the code further down so it gives a proper diagnostic
>>>>> rather than call warn_misplaced_attr_for_class_type.
>>>>
>>>> I see. Thus something like the below? It passes testing on 
>>>> x86_64-linux.
>>>
>>>> +  if ((!declared_type || TREE_CODE (declared_type) == DECLTYPE_TYPE)
>>>> +      && ! saw_friend && !error_p)
>>>>      permerror (input_location, "declaration does not declare 
>>>> anything");
>>>
>>> I see no reason to make this specific to decltype.  Maybe move this 
>>> diagnostic into the final 'else' block with the other declspec 
>>> diagnostics and not look at declared_type at all?
>>
>> I'm not sure to fully understand: if we do that we still want to at 
>> least minimally check that declared_type is null, like we already do, 
>> and then we simply accept the new testcase. Is that Ok? Because, as I 
>> probably mentioned at some point, all the other compilers I have at 
>> hand issue a "does not declare anything" diagnostic, and we likewise 
>> do that for the legacy __typeof. Not looking into declared_type *at 
>> all* doesn't work with plain class types and enums, of course. Or you 
>> meant something entirely different??
>>
>>>> +  if (declspecs->attributes && warn_attributes && declared_type
>>>> +      && TREE_CODE (declared_type) != DECLTYPE_TYPE)
>>>
>>> I think we do want to give a diagnostic about useless attributes, 
>>> not skip it.
>>
>> Agreed. FWIW the attached tests fine.
>
> The problem here is that the code toward the bottom expects 
> "declared_type" to be the tagged type declared by a declaration with 
> no declarator, and in this testcase it's ending up as a DECLTYPE_TYPE.
>
> I think once we've checked for 'auto' we don't want declared_type to 
> be anything that isn't OVERLOAD_TYPE_P.  We can arrange that either by 
> checking for 'auto' first and then changing the code that sets 
> declared_type to use OVERLOAD_TYPE_P, or by clearing declared_type 
> after checking for 'auto' if it isn't OVERLOAD_TYPE_P.

Thanks. I'm slowly catching up on this issue... Any suggestion about 
BOUND_TEMPLATE_TEMPLATE_PARM? If we don't let through such tree nodes - 
which are MAYBE_CLASS_TYPE_P and aren't OVERLOAD_TYPE_P - we regress on 
template/spec32.C, we don't reject it anymore.,

Paolo.

Re: [C++ Patch] PR 84644 ("internal compiler error: in warn_misplaced_attr_for_class_type, at cp/decl.c:4718")

[Jason Merrill]

On 12/14/18 1:44 PM, Paolo Carlini wrote:
> Hi,
> 
> On 13/12/18 22:03, Jason Merrill wrote:
>> On 10/30/18 9:22 PM, Paolo Carlini wrote:
>>> Hi,
>>>
>>> On 30/10/18 21:37, Jason Merrill wrote:
>>>> On 10/26/18 2:02 PM, Paolo Carlini wrote:
>>>>> On 26/10/18 17:18, Jason Merrill wrote:
>>>>>> On Fri, Oct 26, 2018 at 4:52 AM Paolo Carlini 
>>>>>> <paolo.carlini@oracle.com> wrote:
>>>>>>> On 24/10/18 22:41, Jason Merrill wrote:
>>>>>>>> On 10/15/18 12:45 PM, Paolo Carlini wrote:
>>>>>>>>>          && ((TREE_CODE (declspecs->type) != TYPENAME_TYPE
>>>>>>>>> +       && TREE_CODE (declspecs->type) != DECLTYPE_TYPE
>>>>>>>>>           && MAYBE_CLASS_TYPE_P (declspecs->type))
>>>>>>>> I would think that the MAYBE_CLASS_TYPE_P here should be 
>>>>>>>> CLASS_TYPE_P,
>>>>>>>> and then we can remove the TYPENAME_TYPE check.  Or do we want to
>>>>>>>> allow template type parameters for some reason?
>>>>>>> Indeed, it would be nice to just use OVERLOAD_TYPE_P. However it 
>>>>>>> seems
>>>>>>> we at least want to let through TEMPLATE_TYPE_PARMs representing 
>>>>>>> 'auto'
>>>>>>> - otherwise Dodji's check a few lines below which fixed c++/51473
>>>>>>> doesn't work anymore - and also BOUND_TEMPLATE_TEMPLATE_PARM, 
>>>>>>> otherwise
>>>>>>> we regress on template/spec32.C and template/ttp22.C because we 
>>>>>>> don't
>>>>>>> diagnose the shadowing anymore. Thus, I would say either we keep on
>>>>>>> using MAYBE_CLASS_TYPE_P or we pick what we need, possibly we add 
>>>>>>> a comment?
>>>>>> Aha.  I guess the answer is not to restrict that test any more, but
>>>>>> instead to fix the code further down so it gives a proper diagnostic
>>>>>> rather than call warn_misplaced_attr_for_class_type.
>>>>>
>>>>> I see. Thus something like the below? It passes testing on 
>>>>> x86_64-linux.
>>>>
>>>>> +  if ((!declared_type || TREE_CODE (declared_type) == DECLTYPE_TYPE)
>>>>> +      && ! saw_friend && !error_p)
>>>>>      permerror (input_location, "declaration does not declare 
>>>>> anything");
>>>>
>>>> I see no reason to make this specific to decltype.  Maybe move this 
>>>> diagnostic into the final 'else' block with the other declspec 
>>>> diagnostics and not look at declared_type at all?
>>>
>>> I'm not sure to fully understand: if we do that we still want to at 
>>> least minimally check that declared_type is null, like we already do, 
>>> and then we simply accept the new testcase. Is that Ok? Because, as I 
>>> probably mentioned at some point, all the other compilers I have at 
>>> hand issue a "does not declare anything" diagnostic, and we likewise 
>>> do that for the legacy __typeof. Not looking into declared_type *at 
>>> all* doesn't work with plain class types and enums, of course. Or you 
>>> meant something entirely different??
>>>
>>>>> +  if (declspecs->attributes && warn_attributes && declared_type
>>>>> +      && TREE_CODE (declared_type) != DECLTYPE_TYPE)
>>>>
>>>> I think we do want to give a diagnostic about useless attributes, 
>>>> not skip it.
>>>
>>> Agreed. FWIW the attached tests fine.
>>
>> The problem here is that the code toward the bottom expects 
>> "declared_type" to be the tagged type declared by a declaration with 
>> no declarator, and in this testcase it's ending up as a DECLTYPE_TYPE.
>>
>> I think once we've checked for 'auto' we don't want declared_type to 
>> be anything that isn't OVERLOAD_TYPE_P.  We can arrange that either by 
>> checking for 'auto' first and then changing the code that sets 
>> declared_type to use OVERLOAD_TYPE_P, or by clearing declared_type 
>> after checking for 'auto' if it isn't OVERLOAD_TYPE_P.
> 
> Thanks. I'm slowly catching up on this issue... Any suggestion about 
> BOUND_TEMPLATE_TEMPLATE_PARM? If we don't let through such tree nodes - 
> which are MAYBE_CLASS_TYPE_P and aren't OVERLOAD_TYPE_P - we regress on 
> template/spec32.C, we don't reject it anymore.

If we clear declared_type for a BOUND_TEMPLATE_TEMPLATE_PARM, we should 
get the "does not declare anything" error.

Jason

Re: [C++ Patch] PR 84644 ("internal compiler error: in warn_misplaced_attr_for_class_type, at cp/decl.c:4718")

[Paolo Carlini]

[-- Attachment #1: Type: text/plain, Size: 4488 bytes --]

Hi,

On 14/12/18 21:19, Jason Merrill wrote:
> On 12/14/18 1:44 PM, Paolo Carlini wrote:
>> Hi,
>>
>> On 13/12/18 22:03, Jason Merrill wrote:
>>> On 10/30/18 9:22 PM, Paolo Carlini wrote:
>>>> Hi,
>>>>
>>>> On 30/10/18 21:37, Jason Merrill wrote:
>>>>> On 10/26/18 2:02 PM, Paolo Carlini wrote:
>>>>>> On 26/10/18 17:18, Jason Merrill wrote:
>>>>>>> On Fri, Oct 26, 2018 at 4:52 AM Paolo Carlini 
>>>>>>> <paolo.carlini@oracle.com> wrote:
>>>>>>>> On 24/10/18 22:41, Jason Merrill wrote:
>>>>>>>>> On 10/15/18 12:45 PM, Paolo Carlini wrote:
>>>>>>>>>>          && ((TREE_CODE (declspecs->type) != TYPENAME_TYPE
>>>>>>>>>> +       && TREE_CODE (declspecs->type) != DECLTYPE_TYPE
>>>>>>>>>>           && MAYBE_CLASS_TYPE_P (declspecs->type))
>>>>>>>>> I would think that the MAYBE_CLASS_TYPE_P here should be 
>>>>>>>>> CLASS_TYPE_P,
>>>>>>>>> and then we can remove the TYPENAME_TYPE check. Or do we want to
>>>>>>>>> allow template type parameters for some reason?
>>>>>>>> Indeed, it would be nice to just use OVERLOAD_TYPE_P. However 
>>>>>>>> it seems
>>>>>>>> we at least want to let through TEMPLATE_TYPE_PARMs 
>>>>>>>> representing 'auto'
>>>>>>>> - otherwise Dodji's check a few lines below which fixed c++/51473
>>>>>>>> doesn't work anymore - and also BOUND_TEMPLATE_TEMPLATE_PARM, 
>>>>>>>> otherwise
>>>>>>>> we regress on template/spec32.C and template/ttp22.C because we 
>>>>>>>> don't
>>>>>>>> diagnose the shadowing anymore. Thus, I would say either we 
>>>>>>>> keep on
>>>>>>>> using MAYBE_CLASS_TYPE_P or we pick what we need, possibly we 
>>>>>>>> add a comment?
>>>>>>> Aha.  I guess the answer is not to restrict that test any more, but
>>>>>>> instead to fix the code further down so it gives a proper 
>>>>>>> diagnostic
>>>>>>> rather than call warn_misplaced_attr_for_class_type.
>>>>>>
>>>>>> I see. Thus something like the below? It passes testing on 
>>>>>> x86_64-linux.
>>>>>
>>>>>> +  if ((!declared_type || TREE_CODE (declared_type) == 
>>>>>> DECLTYPE_TYPE)
>>>>>> +      && ! saw_friend && !error_p)
>>>>>>      permerror (input_location, "declaration does not declare 
>>>>>> anything");
>>>>>
>>>>> I see no reason to make this specific to decltype.  Maybe move 
>>>>> this diagnostic into the final 'else' block with the other 
>>>>> declspec diagnostics and not look at declared_type at all?
>>>>
>>>> I'm not sure to fully understand: if we do that we still want to at 
>>>> least minimally check that declared_type is null, like we already 
>>>> do, and then we simply accept the new testcase. Is that Ok? 
>>>> Because, as I probably mentioned at some point, all the other 
>>>> compilers I have at hand issue a "does not declare anything" 
>>>> diagnostic, and we likewise do that for the legacy __typeof. Not 
>>>> looking into declared_type *at all* doesn't work with plain class 
>>>> types and enums, of course. Or you meant something entirely 
>>>> different??
>>>>
>>>>>> +  if (declspecs->attributes && warn_attributes && declared_type
>>>>>> +      && TREE_CODE (declared_type) != DECLTYPE_TYPE)
>>>>>
>>>>> I think we do want to give a diagnostic about useless attributes, 
>>>>> not skip it.
>>>>
>>>> Agreed. FWIW the attached tests fine.
>>>
>>> The problem here is that the code toward the bottom expects 
>>> "declared_type" to be the tagged type declared by a declaration with 
>>> no declarator, and in this testcase it's ending up as a DECLTYPE_TYPE.
>>>
>>> I think once we've checked for 'auto' we don't want declared_type to 
>>> be anything that isn't OVERLOAD_TYPE_P.  We can arrange that either 
>>> by checking for 'auto' first and then changing the code that sets 
>>> declared_type to use OVERLOAD_TYPE_P, or by clearing declared_type 
>>> after checking for 'auto' if it isn't OVERLOAD_TYPE_P.
>>
>> Thanks. I'm slowly catching up on this issue... Any suggestion about 
>> BOUND_TEMPLATE_TEMPLATE_PARM? If we don't let through such tree nodes 
>> - which are MAYBE_CLASS_TYPE_P and aren't OVERLOAD_TYPE_P - we 
>> regress on template/spec32.C, we don't reject it anymore.
> If we clear declared_type for a BOUND_TEMPLATE_TEMPLATE_PARM, we 
> should get the "does not declare anything" error.

Ah, now I see, I didn't realize that we would also change the errors we 
issue for those testcases. Thus the below is finishing testing, appears 
to work fine.

Thanks, Paolo.

///////////////////


[-- Attachment #2: patch_84644_3 --]
[-- Type: text/plain, Size: 3075 bytes --]

Index: cp/decl.c
===================================================================
--- cp/decl.c	(revision 267131)
+++ cp/decl.c	(working copy)
@@ -4803,9 +4803,8 @@ check_tag_decl (cp_decl_specifier_seq *declspecs,
     declared_type = declspecs->type;
   else if (declspecs->type == error_mark_node)
     error_p = true;
-  if (declared_type == NULL_TREE && ! saw_friend && !error_p)
-    permerror (input_location, "declaration does not declare anything");
-  else if (declared_type != NULL_TREE && type_uses_auto (declared_type))
+
+  if (type_uses_auto (declared_type))
     {
       error_at (declspecs->locations[ds_type_spec],
 		"%<auto%> can only be specified for variables "
@@ -4812,6 +4811,12 @@ check_tag_decl (cp_decl_specifier_seq *declspecs,
 		"or function declarations");
       return error_mark_node;
     }
+
+  if (declared_type && !OVERLOAD_TYPE_P (declared_type))
+    declared_type = NULL_TREE;
+
+  if (!declared_type && !saw_friend && !error_p)
+    permerror (input_location, "declaration does not declare anything");
   /* Check for an anonymous union.  */
   else if (declared_type && RECORD_OR_UNION_CODE_P (TREE_CODE (declared_type))
 	   && TYPE_UNNAMED_P (declared_type))
Index: testsuite/g++.dg/cpp0x/decltype-33838.C
===================================================================
--- testsuite/g++.dg/cpp0x/decltype-33838.C	(revision 267127)
+++ testsuite/g++.dg/cpp0x/decltype-33838.C	(working copy)
@@ -2,5 +2,5 @@
 // PR c++/33838
 template<typename T> struct A
 {
-  __decltype (T* foo()); // { dg-error "expected|no arguments|accept" }
+  __decltype (T* foo()); // { dg-error "expected|no arguments|declaration" }
 };
Index: testsuite/g++.dg/cpp0x/decltype68.C
===================================================================
--- testsuite/g++.dg/cpp0x/decltype68.C	(nonexistent)
+++ testsuite/g++.dg/cpp0x/decltype68.C	(working copy)
@@ -0,0 +1,7 @@
+// PR c++/84644
+// { dg-do compile { target c++11 } }
+
+template<int a>
+struct b {
+  decltype(a) __attribute__((break));  // { dg-error "declaration does not declare anything" }
+};
Index: testsuite/g++.dg/template/spec32.C
===================================================================
--- testsuite/g++.dg/template/spec32.C	(revision 267127)
+++ testsuite/g++.dg/template/spec32.C	(working copy)
@@ -2,5 +2,5 @@
 
 struct A
 {
-  template<template<int> class B> struct B<0>;  // { dg-error "name of class shadows" }
+  template<template<int> class B> struct B<0>;  // { dg-error "declaration does not declare anything" }
 };
Index: testsuite/g++.dg/template/ttp22.C
===================================================================
--- testsuite/g++.dg/template/ttp22.C	(revision 267127)
+++ testsuite/g++.dg/template/ttp22.C	(working copy)
@@ -2,7 +2,7 @@
 // { dg-do compile }
 
 template<template<int> class A>
-class A<0>;  // { dg-error "shadows template template parameter" }
+class A<0>;  // { dg-error "declaration does not declare anything" }
 
 template<template<int> class B>
 class B<0> {};  // { dg-error "shadows template template parameter" }

Re: [C++ Patch] PR 84644 ("internal compiler error: in warn_misplaced_attr_for_class_type, at cp/decl.c:4718")

[Jason Merrill]

On 12/14/18 4:33 PM, Paolo Carlini wrote:
> Hi,
> 
> On 14/12/18 21:19, Jason Merrill wrote:
>> On 12/14/18 1:44 PM, Paolo Carlini wrote:
>>> Hi,
>>>
>>> On 13/12/18 22:03, Jason Merrill wrote:
>>>> On 10/30/18 9:22 PM, Paolo Carlini wrote:
>>>>> Hi,
>>>>>
>>>>> On 30/10/18 21:37, Jason Merrill wrote:
>>>>>> On 10/26/18 2:02 PM, Paolo Carlini wrote:
>>>>>>> On 26/10/18 17:18, Jason Merrill wrote:
>>>>>>>> On Fri, Oct 26, 2018 at 4:52 AM Paolo Carlini 
>>>>>>>> <paolo.carlini@oracle.com> wrote:
>>>>>>>>> On 24/10/18 22:41, Jason Merrill wrote:
>>>>>>>>>> On 10/15/18 12:45 PM, Paolo Carlini wrote:
>>>>>>>>>>>          && ((TREE_CODE (declspecs->type) != TYPENAME_TYPE
>>>>>>>>>>> +       && TREE_CODE (declspecs->type) != DECLTYPE_TYPE
>>>>>>>>>>>           && MAYBE_CLASS_TYPE_P (declspecs->type))
>>>>>>>>>> I would think that the MAYBE_CLASS_TYPE_P here should be 
>>>>>>>>>> CLASS_TYPE_P,
>>>>>>>>>> and then we can remove the TYPENAME_TYPE check. Or do we want to
>>>>>>>>>> allow template type parameters for some reason?
>>>>>>>>> Indeed, it would be nice to just use OVERLOAD_TYPE_P. However 
>>>>>>>>> it seems
>>>>>>>>> we at least want to let through TEMPLATE_TYPE_PARMs 
>>>>>>>>> representing 'auto'
>>>>>>>>> - otherwise Dodji's check a few lines below which fixed c++/51473
>>>>>>>>> doesn't work anymore - and also BOUND_TEMPLATE_TEMPLATE_PARM, 
>>>>>>>>> otherwise
>>>>>>>>> we regress on template/spec32.C and template/ttp22.C because we 
>>>>>>>>> don't
>>>>>>>>> diagnose the shadowing anymore. Thus, I would say either we 
>>>>>>>>> keep on
>>>>>>>>> using MAYBE_CLASS_TYPE_P or we pick what we need, possibly we 
>>>>>>>>> add a comment?
>>>>>>>> Aha.  I guess the answer is not to restrict that test any more, but
>>>>>>>> instead to fix the code further down so it gives a proper 
>>>>>>>> diagnostic
>>>>>>>> rather than call warn_misplaced_attr_for_class_type.
>>>>>>>
>>>>>>> I see. Thus something like the below? It passes testing on 
>>>>>>> x86_64-linux.
>>>>>>
>>>>>>> +  if ((!declared_type || TREE_CODE (declared_type) == 
>>>>>>> DECLTYPE_TYPE)
>>>>>>> +      && ! saw_friend && !error_p)
>>>>>>>      permerror (input_location, "declaration does not declare 
>>>>>>> anything");
>>>>>>
>>>>>> I see no reason to make this specific to decltype.  Maybe move 
>>>>>> this diagnostic into the final 'else' block with the other 
>>>>>> declspec diagnostics and not look at declared_type at all?
>>>>>
>>>>> I'm not sure to fully understand: if we do that we still want to at 
>>>>> least minimally check that declared_type is null, like we already 
>>>>> do, and then we simply accept the new testcase. Is that Ok? 
>>>>> Because, as I probably mentioned at some point, all the other 
>>>>> compilers I have at hand issue a "does not declare anything" 
>>>>> diagnostic, and we likewise do that for the legacy __typeof. Not 
>>>>> looking into declared_type *at all* doesn't work with plain class 
>>>>> types and enums, of course. Or you meant something entirely 
>>>>> different??
>>>>>
>>>>>>> +  if (declspecs->attributes && warn_attributes && declared_type
>>>>>>> +      && TREE_CODE (declared_type) != DECLTYPE_TYPE)
>>>>>>
>>>>>> I think we do want to give a diagnostic about useless attributes, 
>>>>>> not skip it.
>>>>>
>>>>> Agreed. FWIW the attached tests fine.
>>>>
>>>> The problem here is that the code toward the bottom expects 
>>>> "declared_type" to be the tagged type declared by a declaration with 
>>>> no declarator, and in this testcase it's ending up as a DECLTYPE_TYPE.
>>>>
>>>> I think once we've checked for 'auto' we don't want declared_type to 
>>>> be anything that isn't OVERLOAD_TYPE_P.  We can arrange that either 
>>>> by checking for 'auto' first and then changing the code that sets 
>>>> declared_type to use OVERLOAD_TYPE_P, or by clearing declared_type 
>>>> after checking for 'auto' if it isn't OVERLOAD_TYPE_P.
>>>
>>> Thanks. I'm slowly catching up on this issue... Any suggestion about 
>>> BOUND_TEMPLATE_TEMPLATE_PARM? If we don't let through such tree nodes 
>>> - which are MAYBE_CLASS_TYPE_P and aren't OVERLOAD_TYPE_P - we 
>>> regress on template/spec32.C, we don't reject it anymore.
>> If we clear declared_type for a BOUND_TEMPLATE_TEMPLATE_PARM, we 
>> should get the "does not declare anything" error.
> 
> Ah, now I see, I didn't realize that we would also change the errors we 
> issue for those testcases. Thus the below is finishing testing, appears 
> to work fine.

OK.

Jason