[Bug c++/66439] New: Diagnostic on failed function template lookup is missing a line

["unmobile at gmail dot com" <gcc-bugzilla@gcc.gnu.org>]

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1: Type: text/plain; charset="UTF-8", Size: 4495 bytes --]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66439

            Bug ID: 66439
           Summary: Diagnostic on failed function template lookup is
                    missing a line
           Product: gcc
           Version: 5.1.1
            Status: UNCONFIRMED
          Severity: minor
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: unmobile at gmail dot com
  Target Milestone: ---

Created attachment 35705
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=35705&action=edit
Test input

When compiling the attached code, I get a pretty messed-up diagnostic that is
both less than fully informative and suggests there's supposed to be more
output, but doesn't print any:

>    $ g++-5 -c  adltest.cpp 
>    adltest.cpp: In function ‘void g(A::B)’:
>    adltest.cpp:11:12: error: no matching function for call to ‘f(A::B&)’
>       C::f<3>(b); //ill-formed; argument dependent lookup
>                ^
>    adltest.cpp:6:26: note: candidate: template<class T> void C::f(T)
>       template<class T> void f(T t);
>                              ^
>    adltest.cpp:6:26: note:   template argument deduction/substitution failed:

(note the trailing colon ':' on the last line)

This came to light when I tried to compile the code from
http://stackoverflow.com/questions/2953684/why-doesnt-adl-find-function-templates
and saw this trailed-off report. Really, the diagnostic should report more
explicitly what's going on, that C::f isn't a valid binding because the
template parameter '3' doesn't match up with the class parameter C::f expects.
>From gcc-bugs-return-488228-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org Sat Jun 06 06:26:40 2015
Return-Path: <gcc-bugs-return-488228-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org>
Delivered-To: listarch-gcc-bugs@gcc.gnu.org
Received: (qmail 67340 invoked by alias); 6 Jun 2015 06:26:39 -0000
Mailing-List: contact gcc-bugs-help@gcc.gnu.org; run by ezmlm
Precedence: bulk
List-Id: <gcc-bugs.gcc.gnu.org>
List-Archive: <http://gcc.gnu.org/ml/gcc-bugs/>
List-Post: <mailto:gcc-bugs@gcc.gnu.org>
List-Help: <mailto:gcc-bugs-help@gcc.gnu.org>
Sender: gcc-bugs-owner@gcc.gnu.org
Delivered-To: mailing list gcc-bugs@gcc.gnu.org
Received: (qmail 66011 invoked by uid 48); 6 Jun 2015 06:26:36 -0000
From: "unmobile at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/66440] New: Diagnostic on "'foo' was not declared in this scope" offers an invalid suggestion
Date: Sat, 06 Jun 2015 06:26:00 -0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: new
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: c++
X-Bugzilla-Version: 5.1.1
X-Bugzilla-Keywords:
X-Bugzilla-Severity: minor
X-Bugzilla-Who: unmobile at gmail dot com
X-Bugzilla-Status: UNCONFIRMED
X-Bugzilla-Resolution:
X-Bugzilla-Priority: P3
X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org
X-Bugzilla-Target-Milestone: ---
X-Bugzilla-Flags:
X-Bugzilla-Changed-Fields: bug_id short_desc product version bug_status bug_severity priority component assigned_to reporter target_milestone attachments.created
Message-ID: <bug-66440-4@http.gcc.gnu.org/bugzilla/>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: 7bit
X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/
Auto-Submitted: auto-generated
MIME-Version: 1.0
X-SW-Source: 2015-06/txt/msg00560.txt.bz2
Content-length: 978

https://gcc.gnu.org/bugzilla/show_bug.cgi?idf440

            Bug ID: 66440
           Summary: Diagnostic on "'foo' was not declared in this scope"
                    offers an invalid suggestion
           Product: gcc
           Version: 5.1.1
            Status: UNCONFIRMED
          Severity: minor
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: unmobile at gmail dot com
  Target Milestone: ---

Created attachment 35706
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id5706&actioníit
Test input

When I try to compile the attached source with g++ 5.1.1, I get a suggestion to
use C::f. However, an explicit qualified call to C::f with the given template
and function arguments would be invalid, as shown in the later statement.
Perhaps the compiler should evaluate the candidates before enumerating them for
the user, and either drop them or distinguish that they wouldn't actually
match?