Re: PING: Re: [PATCH] c++: provide #include hint for missing includes [PR110164]

[Jason Merrill <jason@redhat.com>]

On 6/22/23 11:50, Marek Polacek wrote:
> On Wed, Jun 21, 2023 at 04:44:00PM -0400, David Malcolm via Gcc-patches wrote:
>> I'd like to ping this C++ FE patch for review:
>>      https://gcc.gnu.org/pipermail/gcc-patches/2023-June/621779.html
> 
> Not an approval, but LGTM, though some nits below:
>   
>> On Wed, 2023-06-14 at 20:28 -0400, David Malcolm wrote:
>>> PR c++/110164 notes that in cases where we have a forward decl
>>> of a std library type such as:
>>>
>>> std::array<int, 10> x;
>>>
>>> we omit this diagnostic:
>>>
>>> error: aggregate ‘std::array<int, 10> x’ has incomplete type and cannot be defined
>>>
>>> This patch adds this hint to the diagnostic:
>>>
>>> note: ‘std::array’ is defined in header ‘<array>’; this is probably fixable by adding ‘#include <array>’
>>>
>>> Successfully bootstrapped & regrtested on x86_64-pc-linux-gnu.
>>> OK for trunk?
>>>
>>> gcc/cp/ChangeLog:
>>>          PR c++/110164
>>>          * cp-name-hint.h (maybe_suggest_missing_header): New decl.
>>>          * decl.cc: Define INCLUDE_MEMORY.  Add include of
>>>          "cp/cp-name-hint.h".
>>>          (start_decl_1): Call maybe_suggest_missing_header.
>>>          * name-lookup.cc (maybe_suggest_missing_header): Remove "static".
>>>
>>> gcc/testsuite/ChangeLog:
>>>          PR c++/110164
>>>          * g++.dg/missing-header-pr110164.C: New test.
>>> ---
>>>   gcc/cp/cp-name-hint.h                          |  3 +++
>>>   gcc/cp/decl.cc                                 | 10 ++++++++++
>>>   gcc/cp/name-lookup.cc                          |  2 +-
>>>   gcc/testsuite/g++.dg/missing-header-pr110164.C | 10 ++++++++++
>>>   4 files changed, 24 insertions(+), 1 deletion(-)
>>>   create mode 100644 gcc/testsuite/g++.dg/missing-header-pr110164.C
>>>
>>> diff --git a/gcc/cp/cp-name-hint.h b/gcc/cp/cp-name-hint.h
>>> index bfa7c53c8f6..e2387e23d1f 100644
>>> --- a/gcc/cp/cp-name-hint.h
>>> +++ b/gcc/cp/cp-name-hint.h
>>> @@ -32,6 +32,9 @@ along with GCC; see the file COPYING3.  If not see
>>>   
>>>   extern name_hint suggest_alternatives_for (location_t, tree, bool);
>>>   extern name_hint suggest_alternatives_in_other_namespaces (location_t, tree);
>>> +extern name_hint maybe_suggest_missing_header (location_t location,
>>> +                                              tree name,
>>> +                                              tree scope);
> 
> The enclosing decls omit the parameter names; if you do that, it may
> fit on one line.
> 
>>>   extern name_hint suggest_alternative_in_explicit_scope (location_t, tree, tree);
>>>   extern name_hint suggest_alternative_in_scoped_enum (tree, tree);
>>>   
>>> diff --git a/gcc/cp/decl.cc b/gcc/cp/decl.cc
>>> index a672e4844f1..504b08ec250 100644
>>> --- a/gcc/cp/decl.cc
>>> +++ b/gcc/cp/decl.cc
>>> @@ -27,6 +27,7 @@ along with GCC; see the file COPYING3.  If not see
>>>      line numbers.  For example, the CONST_DECLs for enum values.  */
>>>   
>>>   #include "config.h"
>>> +#define INCLUDE_MEMORY
>>>   #include "system.h"
>>>   #include "coretypes.h"
>>>   #include "target.h"
>>> @@ -46,6 +47,7 @@ along with GCC; see the file COPYING3.  If not see
>>>   #include "c-family/c-objc.h"
>>>   #include "c-family/c-pragma.h"
>>>   #include "c-family/c-ubsan.h"
>>> +#include "cp/cp-name-hint.h"
>>>   #include "debug.h"
>>>   #include "plugin.h"
>>>   #include "builtins.h"
>>> @@ -5995,7 +5997,11 @@ start_decl_1 (tree decl, bool initialized)
>>>          ;                       /* An auto type is ok.  */
>>>         else if (TREE_CODE (type) != ARRAY_TYPE)
>>>          {
>>> +         auto_diagnostic_group d;
>>>            error ("variable %q#D has initializer but incomplete type", decl);
>>> +         maybe_suggest_missing_header (input_location,
>>> +                                       TYPE_IDENTIFIER (type),
>>> +                                       TYPE_CONTEXT (type));
> 
> Maybe CP_TYPE_CONTEXT?
> 
>>>            type = TREE_TYPE (decl) = error_mark_node;
>>>          }
>>>         else if (!COMPLETE_TYPE_P (complete_type (TREE_TYPE (type))))
>>> @@ -6011,8 +6017,12 @@ start_decl_1 (tree decl, bool initialized)
>>>          gcc_assert (CLASS_PLACEHOLDER_TEMPLATE (type));
>>>         else
>>>          {
>>> +         auto_diagnostic_group d;
>>>            error ("aggregate %q#D has incomplete type and cannot be defined",
>>>                   decl);
>>> +         maybe_suggest_missing_header (input_location,
>>> +                                       TYPE_IDENTIFIER (type),
>>> +                                       TYPE_CONTEXT (type));
> 
> Here as well.
> 
>>>            /* Change the type so that assemble_variable will give
>>>               DECL an rtl we can live with: (mem (const_int 0)).  */
>>>            type = TREE_TYPE (decl) = error_mark_node;
>>> diff --git a/gcc/cp/name-lookup.cc b/gcc/cp/name-lookup.cc
>>> index 6ac58a35b56..917b481c163 100644
>>> --- a/gcc/cp/name-lookup.cc
>>> +++ b/gcc/cp/name-lookup.cc
>>> @@ -6796,7 +6796,7 @@ maybe_suggest_missing_std_header (location_t location, tree name)
>>>      for NAME within SCOPE at LOCATION, or an empty name_hint if this isn't
>>>      applicable.  */
>>>   
>>> -static name_hint
>>> +name_hint
>>>   maybe_suggest_missing_header (location_t location, tree name, tree scope)
>>>   {
>>>     if (scope == NULL_TREE)
>>> diff --git a/gcc/testsuite/g++.dg/missing-header-pr110164.C b/gcc/testsuite/g++.dg/missing-header-pr110164.C
>>> new file mode 100644
>>> index 00000000000..15980071c38
>>> --- /dev/null
>>> +++ b/gcc/testsuite/g++.dg/missing-header-pr110164.C
> 
> Can we put the new test into g++.dg/diagnostic/?

OK with the tweaks Marek suggests.

Jason