[PATCH 1/2] PR c++/91436 fix C++ dialect for std::make_unique fix-it hint

[PATCH 1/2] PR c++/91436 fix C++ dialect for std::make_unique fix-it hint

[Jonathan Wakely]

[-- Attachment #1: Type: text/plain, Size: 476 bytes --]

The std::make_unique function wasn't added until C++14, and neither was
the std::complex_literals namespace.

gcc/cp:

	PR c++/91436
	* name-lookup.c (get_std_name_hint): Fix min_dialect field for
	complex_literals and make_unique entries.

gcc/testsuite:

	PR c++/91436
	* g++.dg/lookup/missing-std-include-5.C: Limit test to C++14 and up.
	* g++.dg/lookup/missing-std-include-6.C: Don't check make_unique in
	test that runs for C++11.


Tested x86_64-linux. OK for trunk?



[-- Attachment #2: patch.txt --]
[-- Type: text/plain, Size: 3109 bytes --]

commit b58e771fe21ae380200fdec00aa899d4b15b73d5
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Tue Aug 13 13:25:39 2019 +0100

    PR c++/91436 fix C++ dialect for std::make_unique fix-it hint
    
    The std::make_unique function wasn't added until C++14, and neither was
    the std::complex_literals namespace.
    
    gcc/cp:
    
            PR c++/91436
            * name-lookup.c (get_std_name_hint): Fix min_dialect field for
            complex_literals and make_unique entries.
    
    gcc/testsuite:
    
            PR c++/91436
            * g++.dg/lookup/missing-std-include-5.C: Limit test to C++14 and up.
            * g++.dg/lookup/missing-std-include-6.C: Don't check make_unique in
            test that runs for C++11.

diff --git a/gcc/cp/name-lookup.c b/gcc/cp/name-lookup.c
index 9f278220df3..96b2d90540d 100644
--- a/gcc/cp/name-lookup.c
+++ b/gcc/cp/name-lookup.c
@@ -5557,7 +5557,7 @@ get_std_name_hint (const char *name)
     {"bitset", "<bitset>", cxx11},
     /* <complex>.  */
     {"complex", "<complex>", cxx98},
-    {"complex_literals", "<complex>", cxx98},
+    {"complex_literals", "<complex>", cxx14},
     /* <condition_variable>. */
     {"condition_variable", "<condition_variable>", cxx11},
     {"condition_variable_any", "<condition_variable>", cxx11},
@@ -5619,7 +5619,7 @@ get_std_name_hint (const char *name)
     {"multimap", "<map>", cxx98},
     /* <memory>.  */
     {"make_shared", "<memory>", cxx11},
-    {"make_unique", "<memory>", cxx11},
+    {"make_unique", "<memory>", cxx14},
     {"shared_ptr", "<memory>", cxx11},
     {"unique_ptr", "<memory>", cxx11},
     {"weak_ptr", "<memory>", cxx11},
diff --git a/gcc/testsuite/g++.dg/lookup/missing-std-include-5.C b/gcc/testsuite/g++.dg/lookup/missing-std-include-5.C
index fe880a6263b..3ec9abd9316 100644
--- a/gcc/testsuite/g++.dg/lookup/missing-std-include-5.C
+++ b/gcc/testsuite/g++.dg/lookup/missing-std-include-5.C
@@ -1,2 +1,3 @@
+// { dg-do compile { target c++14 } }
 using namespace std::complex_literals; // { dg-error "" }
 // { dg-message "#include <complex>" "" { target *-*-* } .-1 }
diff --git a/gcc/testsuite/g++.dg/lookup/missing-std-include-6.C b/gcc/testsuite/g++.dg/lookup/missing-std-include-6.C
index d9eeb4284e8..a8f27473e6d 100644
--- a/gcc/testsuite/g++.dg/lookup/missing-std-include-6.C
+++ b/gcc/testsuite/g++.dg/lookup/missing-std-include-6.C
@@ -11,15 +11,6 @@ void test_make_shared ()
   // { dg-error "expected primary-expression before '\\)' token" "" { target *-*-* } .-3 }
 }
 
-template<class T>
-void test_make_unique ()
-{
-  auto p = std::make_unique<T>(); // { dg-error "'make_unique' is not a member of 'std'" }
-  // { dg-message "'#include <memory>'" "" { target *-*-* } .-1 }
-  // { dg-error "expected primary-expression before '>' token" "" { target *-*-* } .-2 }
-  // { dg-error "expected primary-expression before '\\)' token" "" { target *-*-* } .-3 }
-}
-
 std::shared_ptr<int> test_shared_ptr; // { dg-error "'shared_ptr' in namespace 'std' does not name a template type" }
 // { dg-message "'#include <memory>'" "" { target *-*-* } .-1 }
 

[PATCH 2/2] Add more entries to the C++ get_std_name_hint array

[Jonathan Wakely]

[-- Attachment #1: Type: text/plain, Size: 293 bytes --]

This adds some commonly-used C++11/14 names, and some new C++17/20
names. The latter aren't available when using the -std=gnu++14
default, so the fix-it suggesting to use a newer dialect is helpful.

	* name-lookup.c (get_std_name_hint): Add more entries.

Tested x86_64-linux. OK for trunk?


[-- Attachment #2: patch.txt --]
[-- Type: text/x-patch, Size: 3894 bytes --]

commit 0c12d092e5659689951b5e134b84c5b506b543d5
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Tue Aug 13 13:42:40 2019 +0100

    Add more entries to the C++ get_std_name_hint array
    
            * name-lookup.c (get_std_name_hint): Add more entries.

diff --git a/gcc/cp/name-lookup.c b/gcc/cp/name-lookup.c
index 96b2d90540d..68ebd7655c7 100644
--- a/gcc/cp/name-lookup.c
+++ b/gcc/cp/name-lookup.c
@@ -5550,9 +5550,11 @@ get_std_name_hint (const char *name)
     {"make_any", "<any>", cxx17},
     /* <array>.  */
     {"array", "<array>", cxx11},
+    {"to_array", "<array>", cxx2a},
     /* <atomic>.  */
     {"atomic", "<atomic>", cxx11},
     {"atomic_flag", "<atomic>", cxx11},
+    {"atomic_ref", "<atomic>", cxx2a},
     /* <bitset>.  */
     {"bitset", "<bitset>", cxx11},
     /* <complex>.  */
@@ -5575,9 +5577,17 @@ get_std_name_hint (const char *name)
     {"ofstream", "<fstream>", cxx98},
     /* <functional>.  */
     {"bind", "<functional>", cxx11},
+    {"bind_front", "<functional>", cxx2a},
     {"function", "<functional>", cxx11},
     {"hash", "<functional>", cxx11},
+    {"invoke", "<functional>", cxx17},
     {"mem_fn", "<functional>", cxx11},
+    {"not_fn", "<functional>", cxx17},
+    {"reference_wrapper", "<functional>", cxx11},
+    {"unwrap_reference", "<functional>", cxx2a},
+    {"unwrap_reference_t", "<functional>", cxx2a},
+    {"unwrap_ref_decay", "<functional>", cxx2a},
+    {"unwrap_ref_decay_t", "<functional>", cxx2a},
     /* <future>. */
     {"async", "<future>", cxx11},
     {"future", "<future>", cxx11},
@@ -5618,11 +5628,16 @@ get_std_name_hint (const char *name)
     {"map", "<map>", cxx98},
     {"multimap", "<map>", cxx98},
     /* <memory>.  */
+    {"allocate_shared", "<memory>", cxx11},
+    {"allocator", "<memory>", cxx98},
+    {"allocator_traits", "<memory>", cxx11},
     {"make_shared", "<memory>", cxx11},
     {"make_unique", "<memory>", cxx14},
     {"shared_ptr", "<memory>", cxx11},
     {"unique_ptr", "<memory>", cxx11},
     {"weak_ptr", "<memory>", cxx11},
+    /* <memory_resource>.  */
+    {"pmr", "<memory_resource>", cxx17},
     /* <mutex>.  */
     {"mutex", "<mutex>", cxx11},
     {"timed_mutex", "<mutex>", cxx11},
@@ -5672,14 +5687,39 @@ get_std_name_hint (const char *name)
     {"u16string", "<string>", cxx11},
     {"u32string", "<string>", cxx11},
     /* <string_view>.  */
+    {"basic_string_view", "<string_view>", cxx17},
     {"string_view", "<string_view>", cxx17},
     /* <thread>.  */
     {"thread", "<thread>", cxx11},
+    {"this_thread", "<thread>", cxx11},
     /* <tuple>.  */
+    {"apply", "<tuple>", cxx17},
+    {"forward_as_tuple", "<tuple>", cxx11},
+    {"make_from_tuple", "<tuple>", cxx17},
     {"make_tuple", "<tuple>", cxx11},
+    {"tie", "<tuple>", cxx11},
     {"tuple", "<tuple>", cxx11},
+    {"tuple_cat", "<tuple>", cxx11},
     {"tuple_element", "<tuple>", cxx11},
+    {"tuple_element_t", "<tuple>", cxx14},
     {"tuple_size", "<tuple>", cxx11},
+    {"tuple_size_v", "<tuple>", cxx17},
+    /* <type_traits>.  */
+    {"enable_if", "<type_traits>", cxx11},
+    {"enable_if_t", "<type_traits>", cxx14},
+    {"invoke_result", "<type_traits>", cxx17},
+    {"invoke_result_t", "<type_traits>", cxx17},
+    {"remove_cvref", "<type_traits>", cxx17},
+    {"remove_cvref_t", "<type_traits>", cxx17},
+    {"type_identity", "<type_traits>", cxx2a},
+    {"type_identity_t", "<type_traits>", cxx2a},
+    {"void_t", "<type_traits>", cxx17},
+    {"conjunction", "<type_traits>", cxx17},
+    {"conjunction_v", "<type_traits>", cxx17},
+    {"disjunction", "<type_traits>", cxx17},
+    {"disjunction_v", "<type_traits>", cxx17},
+    {"negation", "<type_traits>", cxx17},
+    {"negation_v", "<type_traits>", cxx17},
     /* <unordered_map>.  */
     {"unordered_map", "<unordered_map>", cxx11},
     {"unordered_multimap", "<unordered_map>", cxx11},

Re: [PATCH 1/2] PR c++/91436 fix C++ dialect for std::make_unique fix-it hint

[Jason Merrill]

On 8/13/19 9:32 AM, Jonathan Wakely wrote:
>      * g++.dg/lookup/missing-std-include-6.C: Don't check make_unique in
>      test that runs for C++11.

I'm not comfortable removing this test coverage entirely.  Doesn't it 
give a useful diagnostic in C++11 mode as well?

Jason

Re: [PATCH 2/2] Add more entries to the C++ get_std_name_hint array

[Jason Merrill]

On 8/13/19 9:36 AM, Jonathan Wakely wrote:
> This adds some commonly-used C++11/14 names, and some new C++17/20
> names. The latter aren't available when using the -std=gnu++14
> default, so the fix-it suggesting to use a newer dialect is helpful.
> 
>      * name-lookup.c (get_std_name_hint): Add more entries.
> 
> Tested x86_64-linux. OK for trunk?
> 
OK.

Jason

Re: [PATCH 2/2] Add more entries to the C++ get_std_name_hint array

[Jonathan Wakely]

On 13/08/19 16:08 -0400, Jason Merrill wrote:
>On 8/13/19 9:36 AM, Jonathan Wakely wrote:
>>This adds some commonly-used C++11/14 names, and some new C++17/20
>>names. The latter aren't available when using the -std=gnu++14
>>default, so the fix-it suggesting to use a newer dialect is helpful.
>>
>>     * name-lookup.c (get_std_name_hint): Add more entries.
>>
>>Tested x86_64-linux. OK for trunk?
>>
>OK.

I realised as I was about to commit it that cxx17 is the wrong dialect
for remove_cvref and remove_cvref_t, so I corrected them to cxx2a
before committing it.

(I've tried to use remove_cvref_t in C++17 a few times, so this
diagnostic should help me!)

Re: [PATCH 1/2] PR c++/91436 fix C++ dialect for std::make_unique fix-it hint

[Jonathan Wakely]

[-- Attachment #1: Type: text/plain, Size: 983 bytes --]

On 13/08/19 16:07 -0400, Jason Merrill wrote:
>On 8/13/19 9:32 AM, Jonathan Wakely wrote:
>>     * g++.dg/lookup/missing-std-include-6.C: Don't check make_unique in
>>     test that runs for C++11.
>
>I'm not comfortable removing this test coverage entirely.  Doesn't it 
>give a useful diagnostic in C++11 mode as well?

It does:

mu.cc:3:15: error: 'make_unique' is not a member of 'std'
    3 | auto p = std::make_unique<int>();
      |               ^~~~~~~~~~~
mu.cc:3:15: note: 'std::make_unique' is only available from C++14 onwards
mu.cc:3:27: error: expected primary-expression before 'int'
    3 | auto p = std::make_unique<int>();
      |                           ^~~

So we can add it to g++.dg/lookup/missing-std-include-8.C instead,
which runs for c++98_only and checks for the "is only available for"
cases. Here's a patch doing that.

Tested x86_64-linux.

OK for trunk?

OK for gcc-9-branch and gcc-8-branch too, since PR c++/91436 affects
those branches?


[-- Attachment #2: patch.txt --]
[-- Type: text/x-patch, Size: 4144 bytes --]

commit 5ad7b3202e4818f2d6d84e22e7e489b39a65c851
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Tue Aug 13 13:25:39 2019 +0100

    PR c++/91436 fix C++ dialect for std::make_unique fix-it hint
    
    The std::make_unique function wasn't added until C++14, and neither was
    the std::complex_literals namespace.
    
    gcc/cp:
    
            PR c++/91436
            * name-lookup.c (get_std_name_hint): Fix min_dialect field for
            complex_literals and make_unique entries.
    
    gcc/testsuite:
    
            PR c++/91436
            * g++.dg/lookup/missing-std-include-5.C: Limit test to C++14 and up.
            * g++.dg/lookup/missing-std-include-6.C: Don't check make_unique in
            test that runs for C++11.
            * g++.dg/lookup/missing-std-include-8.C: Check make_unique here.

diff --git a/gcc/cp/name-lookup.c b/gcc/cp/name-lookup.c
index d5e491e9072..16c74287bb1 100644
--- a/gcc/cp/name-lookup.c
+++ b/gcc/cp/name-lookup.c
@@ -5559,7 +5559,7 @@ get_std_name_hint (const char *name)
     {"bitset", "<bitset>", cxx11},
     /* <complex>.  */
     {"complex", "<complex>", cxx98},
-    {"complex_literals", "<complex>", cxx98},
+    {"complex_literals", "<complex>", cxx14},
     /* <condition_variable>. */
     {"condition_variable", "<condition_variable>", cxx11},
     {"condition_variable_any", "<condition_variable>", cxx11},
@@ -5632,7 +5632,7 @@ get_std_name_hint (const char *name)
     {"allocator", "<memory>", cxx98},
     {"allocator_traits", "<memory>", cxx11},
     {"make_shared", "<memory>", cxx11},
-    {"make_unique", "<memory>", cxx11},
+    {"make_unique", "<memory>", cxx14},
     {"shared_ptr", "<memory>", cxx11},
     {"unique_ptr", "<memory>", cxx11},
     {"weak_ptr", "<memory>", cxx11},
diff --git a/gcc/testsuite/g++.dg/lookup/missing-std-include-5.C b/gcc/testsuite/g++.dg/lookup/missing-std-include-5.C
index fe880a6263b..3ec9abd9316 100644
--- a/gcc/testsuite/g++.dg/lookup/missing-std-include-5.C
+++ b/gcc/testsuite/g++.dg/lookup/missing-std-include-5.C
@@ -1,2 +1,3 @@
+// { dg-do compile { target c++14 } }
 using namespace std::complex_literals; // { dg-error "" }
 // { dg-message "#include <complex>" "" { target *-*-* } .-1 }
diff --git a/gcc/testsuite/g++.dg/lookup/missing-std-include-6.C b/gcc/testsuite/g++.dg/lookup/missing-std-include-6.C
index d9eeb4284e8..a8f27473e6d 100644
--- a/gcc/testsuite/g++.dg/lookup/missing-std-include-6.C
+++ b/gcc/testsuite/g++.dg/lookup/missing-std-include-6.C
@@ -11,15 +11,6 @@ void test_make_shared ()
   // { dg-error "expected primary-expression before '\\)' token" "" { target *-*-* } .-3 }
 }
 
-template<class T>
-void test_make_unique ()
-{
-  auto p = std::make_unique<T>(); // { dg-error "'make_unique' is not a member of 'std'" }
-  // { dg-message "'#include <memory>'" "" { target *-*-* } .-1 }
-  // { dg-error "expected primary-expression before '>' token" "" { target *-*-* } .-2 }
-  // { dg-error "expected primary-expression before '\\)' token" "" { target *-*-* } .-3 }
-}
-
 std::shared_ptr<int> test_shared_ptr; // { dg-error "'shared_ptr' in namespace 'std' does not name a template type" }
 // { dg-message "'#include <memory>'" "" { target *-*-* } .-1 }
 
diff --git a/gcc/testsuite/g++.dg/lookup/missing-std-include-8.C b/gcc/testsuite/g++.dg/lookup/missing-std-include-8.C
index 68b208299f2..73532c82968 100644
--- a/gcc/testsuite/g++.dg/lookup/missing-std-include-8.C
+++ b/gcc/testsuite/g++.dg/lookup/missing-std-include-8.C
@@ -13,6 +13,15 @@ void test_make_shared ()
   // { dg-error "expected primary-expression before '\\)' token" "" { target *-*-* } .-3 }
 }
 
+template<class T>
+void test_make_unique ()
+{
+  std::make_unique<T>(); // { dg-error "'make_unique' is not a member of 'std'" }
+  // { dg-message "'std::make_unique' is only available from C\\+\\+14 onwards" "" { target *-*-* } .-1 }
+  // { dg-error "expected primary-expression before '>' token" "" { target *-*-* } .-2 }
+  // { dg-error "expected primary-expression before '\\)' token" "" { target *-*-* } .-3 }
+}
+
 void test_array ()
 {
   std::array a; // { dg-error "'array' is not a member of 'std'" }

Re: [PATCH 1/2] PR c++/91436 fix C++ dialect for std::make_unique fix-it hint

[Jason Merrill]

On Wed, Aug 14, 2019 at 7:02 AM Jonathan Wakely <jwakely@redhat.com> wrote:
>
> On 13/08/19 16:07 -0400, Jason Merrill wrote:
> >On 8/13/19 9:32 AM, Jonathan Wakely wrote:
> >>     * g++.dg/lookup/missing-std-include-6.C: Don't check make_unique in
> >>     test that runs for C++11.
> >
> >I'm not comfortable removing this test coverage entirely.  Doesn't it
> >give a useful diagnostic in C++11 mode as well?
>
> It does:
>
> mu.cc:3:15: error: 'make_unique' is not a member of 'std'
>     3 | auto p = std::make_unique<int>();
>       |               ^~~~~~~~~~~
> mu.cc:3:15: note: 'std::make_unique' is only available from C++14 onwards
> mu.cc:3:27: error: expected primary-expression before 'int'
>     3 | auto p = std::make_unique<int>();
>       |                           ^~~
>
> So we can add it to g++.dg/lookup/missing-std-include-8.C instead,
> which runs for c++98_only and checks for the "is only available for"
> cases. Here's a patch doing that.
>
> Tested x86_64-linux.
>
> OK for trunk?
>
> OK for gcc-9-branch and gcc-8-branch too, since PR c++/91436 affects
> those branches?

OK.

Jason

Re: [PATCH 1/2] PR c++/91436 fix C++ dialect for std::make_unique fix-it hint

[David Malcolm]

On Wed, 2019-08-14 at 12:02 +0100, Jonathan Wakely wrote:
> On 13/08/19 16:07 -0400, Jason Merrill wrote:
> > On 8/13/19 9:32 AM, Jonathan Wakely wrote:
> > >     * g++.dg/lookup/missing-std-include-6.C: Don't check
> > > make_unique in
> > >     test that runs for C++11.
> > 
> > I'm not comfortable removing this test coverage entirely.  Doesn't
> > it 
> > give a useful diagnostic in C++11 mode as well?
> 
> It does:
> 
> mu.cc:3:15: error: 'make_unique' is not a member of 'std'
>     3 | auto p = std::make_unique<int>();
>       |               ^~~~~~~~~~~
> mu.cc:3:15: note: 'std::make_unique' is only available from C++14
> onwards
> mu.cc:3:27: error: expected primary-expression before 'int'
>     3 | auto p = std::make_unique<int>();
>       |                           ^~~
> 
> So we can add it to g++.dg/lookup/missing-std-include-8.C instead,
> which runs for c++98_only and checks for the "is only available for"
> cases. Here's a patch doing that.

FWIW this eliminates the testing that when we do have C++14 onwards,
that including <memory> is suggested.

Maybe we need a C++14-onwards missing-std-include-* test, and to move
the existing test there?  (and to add the new test for before-C++-14)


> Tested x86_64-linux.
> 
> OK for trunk?
> 
> OK for gcc-9-branch and gcc-8-branch too, since PR c++/91436 affects
> those branches?
> 

Re: [PATCH 1/2] PR c++/91436 fix C++ dialect for std::make_unique fix-it hint

[Jason Merrill]

On 8/14/19 10:39 AM, David Malcolm wrote:
> On Wed, 2019-08-14 at 12:02 +0100, Jonathan Wakely wrote:
>> On 13/08/19 16:07 -0400, Jason Merrill wrote:
>>> On 8/13/19 9:32 AM, Jonathan Wakely wrote:
>>>>      * g++.dg/lookup/missing-std-include-6.C: Don't check
>>>> make_unique in
>>>>      test that runs for C++11.
>>>
>>> I'm not comfortable removing this test coverage entirely.  Doesn't
>>> it
>>> give a useful diagnostic in C++11 mode as well?
>>
>> It does:
>>
>> mu.cc:3:15: error: 'make_unique' is not a member of 'std'
>>      3 | auto p = std::make_unique<int>();
>>        |               ^~~~~~~~~~~
>> mu.cc:3:15: note: 'std::make_unique' is only available from C++14
>> onwards
>> mu.cc:3:27: error: expected primary-expression before 'int'
>>      3 | auto p = std::make_unique<int>();
>>        |                           ^~~
>>
>> So we can add it to g++.dg/lookup/missing-std-include-8.C instead,
>> which runs for c++98_only and checks for the "is only available for"
>> cases. Here's a patch doing that.
> 
> FWIW this eliminates the testing that when we do have C++14 onwards,
> that including <memory> is suggested.
> 
> Maybe we need a C++14-onwards missing-std-include-* test, and to move
> the existing test there?  (and to add the new test for before-C++-14)

We can also check for different messages in different std modes, i.e.

{ dg-message "one" "" { target c++11_down } .-1 }
{ dg-message "two" "" { target c++14 } .-2 }

Jason

Re: [PATCH 1/2] PR c++/91436 fix C++ dialect for std::make_unique fix-it hint

[Jonathan Wakely]

On 14/08/19 10:39 -0400, David Malcolm wrote:
>On Wed, 2019-08-14 at 12:02 +0100, Jonathan Wakely wrote:
>> On 13/08/19 16:07 -0400, Jason Merrill wrote:
>> > On 8/13/19 9:32 AM, Jonathan Wakely wrote:
>> > >     * g++.dg/lookup/missing-std-include-6.C: Don't check
>> > > make_unique in
>> > >     test that runs for C++11.
>> >
>> > I'm not comfortable removing this test coverage entirely.  Doesn't
>> > it
>> > give a useful diagnostic in C++11 mode as well?
>>
>> It does:
>>
>> mu.cc:3:15: error: 'make_unique' is not a member of 'std'
>>     3 | auto p = std::make_unique<int>();
>>       |               ^~~~~~~~~~~
>> mu.cc:3:15: note: 'std::make_unique' is only available from C++14
>> onwards
>> mu.cc:3:27: error: expected primary-expression before 'int'
>>     3 | auto p = std::make_unique<int>();
>>       |                           ^~~
>>
>> So we can add it to g++.dg/lookup/missing-std-include-8.C instead,
>> which runs for c++98_only and checks for the "is only available for"
>> cases. Here's a patch doing that.
>
>FWIW this eliminates the testing that when we do have C++14 onwards,
>that including <memory> is suggested.

Do we really care?

Are we testing that *every* entry in the array gives the right answer
for both missing-header and bad-std-option, or are we just testing a
subset of them to be sure the logic works as expected?

Because if we're testing every entry then:

1) we're missing LOTS of tests, and

2) we're just as likely to test the wrong thing and not actually catch
   bugs (as was already happening for both make_unique and
   complex_literals).

>Maybe we need a C++14-onwards missing-std-include-* test, and to move
>the existing test there?  (and to add the new test for before-C++-14)

We could, but is it worth it?

Re: [PATCH 1/2] PR c++/91436 fix C++ dialect for std::make_unique fix-it hint

[David Malcolm]

On Wed, 2019-08-14 at 16:53 +0100, Jonathan Wakely wrote:
> On 14/08/19 10:39 -0400, David Malcolm wrote:
> > On Wed, 2019-08-14 at 12:02 +0100, Jonathan Wakely wrote:
> > > On 13/08/19 16:07 -0400, Jason Merrill wrote:
> > > > On 8/13/19 9:32 AM, Jonathan Wakely wrote:
> > > > >     * g++.dg/lookup/missing-std-include-6.C: Don't check
> > > > > make_unique in
> > > > >     test that runs for C++11.
> > > > 
> > > > I'm not comfortable removing this test coverage
> > > > entirely.  Doesn't
> > > > it
> > > > give a useful diagnostic in C++11 mode as well?
> > > 
> > > It does:
> > > 
> > > mu.cc:3:15: error: 'make_unique' is not a member of 'std'
> > >     3 | auto p = std::make_unique<int>();
> > >       |               ^~~~~~~~~~~
> > > mu.cc:3:15: note: 'std::make_unique' is only available from C++14
> > > onwards
> > > mu.cc:3:27: error: expected primary-expression before 'int'
> > >     3 | auto p = std::make_unique<int>();
> > >       |                           ^~~
> > > 
> > > So we can add it to g++.dg/lookup/missing-std-include-8.C
> > > instead,
> > > which runs for c++98_only and checks for the "is only available
> > > for"
> > > cases. Here's a patch doing that.
> > 
> > FWIW this eliminates the testing that when we do have C++14
> > onwards,
> > that including <memory> is suggested.
> 
> Do we really care?
> 
> Are we testing that *every* entry in the array gives the right answer
> for both missing-header and bad-std-option, or are we just testing a
> subset of them to be sure the logic works as expected?
> 
> Because if we're testing every entry then:
> 
> 1) we're missing LOTS of tests, and
> 
> 2) we're just as likely to test the wrong thing and not actually
> catch
>    bugs (as was already happening for both make_unique and
>    complex_literals).
> 
> > Maybe we need a C++14-onwards missing-std-include-* test, and to
> > move
> > the existing test there?  (and to add the new test for before-C++-
> > 14)
> 
> We could, but is it worth it?

Fair enough.

Dave