Re: C++/24314

[Paolo Carlini <paolo dot carlini at oracle dot com>]

Hi,

On 09/07/2012 11:36 PM, Jason Merrill wrote:
> On 09/07/2012 05:07 PM, Paolo Carlini wrote:
> > the regression of template/crash83.C because of excess errors. The 
> > latter happens because we have code in cp_parser_class_head which 
> > tries to improve error recovery for cases of missing 'template <>' in 
> > explicit specializations, and, for that rather broken testcase, it 
> > confuses the code I'm tentatively adding, resulting in the additional 
> > error message below:
> >
> > crash83.C:5:27: error: an explicit specialization must be preceded by 
> > âtemplate <>â
> >  template<typename = class A<0>: > struct B {}; // { dg-error 
> > "explicit specialization|expected" }
> >                            ^
> > crash83.C:5:27: error: too many template-parameter-lists for A<0> 
> > (should be 1)
>
> So we're adding a second irrelevant diagnostic to go with the first 
> one.  The error in this testcase is a simple stray ':' causing a 
> syntax error, it has nothing to do with explicit specialization.  It 
> would be nice to improve this, but given that we're already not giving 
> the right error, adding a second wrong error doesn't seem like a big 
> problem.
Yeah. I wasn't particularly worried by that regression.
> > More importantly, I'm having troubles removing the early
> > cp_parser_check_template_parameters check in cp_parser_class_head: one
> > issue is that it also checks for too few template-parameter-lists not
> > just too many, and thus catches rather broken testcases like, eg,
> > template/error7.C or template/class2.C:
> >
> > template <class T>
> > struct A {
> >    struct B;
> >    struct A::B { }; // { dg-error "" }
> > };
>
> This testcase is indeed ill-formed, but its ill-formedness has nothing 
> to do with too few template-parameter-lists.  The problem is that 
> clause 9 says
>
> If a class-head-name contains a nested-name-specifier, the 
> class-specifier shall refer to a class that was previously declared 
> directly in the class or namespace to which the nested-name-specifier 
> refers, ... and the class-specifier shall appear in a namespace 
> enclosing the previous declaration.
>
> The definition of A::B does not appear at namespace scope, so it is 
> ill-formed.  Removing the incorrect error is an improvement, but then 
> we need to add the correct error rather than accept the testcase.
>
> > but there are definitely more problems with just checking
> > template_header_count < wanted too in
> > maybe_process_partial_specialization and removing the early check, I'm
> > seeing many, many fails if I just try to extend "p4" like that...
>
> Like what?
Like a nightmare ;) If I run the testsuite with the attached "p5" a lot 
is broken, with template templates, variadic templates, we have all sort 
of problems. The below is just the beginning, template/pr39425.C times 
out. I think we need something radically different / radically more complex.

Paolo.

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

FAIL: g++.dg/abi/mangle34.C -std=c++98 (test for excess errors)
FAIL: g++.dg/abi/mangle34.C -std=c++11 (test for excess errors)
FAIL: g++.dg/cpp0x/initlist48.C (test for excess errors)
FAIL: g++.dg/cpp0x/lambda/lambda-pass.C (test for excess errors)
WARNING: g++.dg/cpp0x/lambda/lambda-pass.C compilation failed to produce 
executable
FAIL: g++.dg/cpp0x/lambda/lambda-recursive.C (test for excess errors)
WARNING: g++.dg/cpp0x/lambda/lambda-recursive.C compilation failed to 
produce executable
FAIL: g++.dg/cpp0x/lambda/lambda-std-function.C (test for excess errors)
WARNING: g++.dg/cpp0x/lambda/lambda-std-function.C compilation failed to 
produce executable
FAIL: g++.dg/cpp0x/pr31993.C (test for excess errors)
FAIL: g++.dg/cpp0x/pr38646.C (test for excess errors)
FAIL: g++.dg/cpp0x/pr47416.C (test for excess errors)
FAIL: g++.dg/cpp0x/variadic-104.C (test for excess errors)
FAIL: g++.dg/cpp0x/variadic-crash1.C (test for excess errors)
FAIL: g++.dg/cpp0x/variadic-lambda.C (test for excess errors)
FAIL: g++.dg/cpp0x/variadic129.C -std=c++11 (test for excess errors)
FAIL: g++.dg/cpp0x/variadic132.C -std=c++11 (test for excess errors)
FAIL: g++.dg/cpp0x/variadic19.C (test for excess errors)
FAIL: g++.dg/cpp0x/variadic20.C  (test for errors, line 16)
FAIL: g++.dg/cpp0x/variadic20.C  (test for errors, line 27)
FAIL: g++.dg/cpp0x/variadic20.C  (test for errors, line 34)
FAIL: g++.dg/cpp0x/variadic20.C bound (test for errors, line 40)
FAIL: g++.dg/cpp0x/variadic20.C bound (test for errors, line 42)
FAIL: g++.dg/cpp0x/variadic20.C incomplete (test for errors, line 40)
FAIL: g++.dg/cpp0x/variadic20.C incomplete (test for errors, line 42)
FAIL: g++.dg/cpp0x/variadic20.C (test for excess errors)
FAIL: g++.dg/cpp0x/variadic26.C (test for excess errors)
FAIL: g++.dg/cpp0x/variadic84.C (test for excess errors)
FAIL: g++.dg/cpp0x/variadic85.C (test for excess errors)
FAIL: g++.dg/cpp0x/variadic86.C (test for excess errors)
FAIL: g++.dg/cpp0x/variadic87.C (test for excess errors)
FAIL: g++.dg/cpp0x/variadic89.C (test for excess errors)
FAIL: g++.dg/ext/attrib9.C -std=c++98 (test for excess errors)
FAIL: g++.dg/ext/attrib9.C -std=c++11 (test for excess errors)
FAIL: g++.dg/ext/complex4.C -std=c++11 (test for excess errors)
FAIL: g++.dg/init/new18.C -std=gnu++11 (test for excess errors)
FAIL: g++.dg/opt/pr30965.C -std=gnu++98 (test for excess errors)
FAIL: g++.dg/opt/pr30965.C -std=gnu++11 (test for excess errors)
FAIL: g++.dg/opt/pr47615.C -std=gnu++98 (test for excess errors)
FAIL: g++.dg/opt/pr47615.C -std=gnu++11 (test for excess errors)
FAIL: g++.dg/other/crash-10.C -std=c++98 (test for excess errors)
FAIL: g++.dg/other/crash-10.C -std=c++11 (test for excess errors)
FAIL: g++.dg/other/crash-11.C -std=c++98 (test for excess errors)
FAIL: g++.dg/other/crash-11.C -std=c++11 (test for excess errors)
FAIL: g++.dg/template/class2.C -std=c++98  (test for errors, line 6)
FAIL: g++.dg/template/class2.C -std=c++11  (test for errors, line 6)
FAIL: g++.dg/template/crash104.C -std=c++98  (test for errors, line 25)
FAIL: g++.dg/template/crash104.C -std=c++98 (test for excess errors)
FAIL: g++.dg/template/crash104.C -std=c++11  (test for errors, line 25)
FAIL: g++.dg/template/crash104.C -std=c++11 (test for excess errors)
FAIL: g++.dg/template/crash83.C -std=c++98 (test for excess errors)
FAIL: g++.dg/template/crash83.C -std=c++11 (test for excess errors)
FAIL: g++.dg/template/crash95.C -std=c++98  (test for errors, line 11)
FAIL: g++.dg/template/crash95.C -std=c++98 (test for excess errors)
FAIL: g++.dg/template/crash95.C -std=c++11  (test for errors, line 11)
FAIL: g++.dg/template/crash95.C -std=c++11 (test for excess errors)
FAIL: g++.dg/template/ctor4.C -std=c++98 (test for excess errors)
FAIL: g++.dg/template/ctor4.C -std=c++11 (test for excess errors)
FAIL: g++.dg/template/defarg11.C -std=c++98 (test for excess errors)
FAIL: g++.dg/template/defarg11.C -std=c++11 (test for excess errors)
FAIL: g++.dg/template/error7.C -std=gnu++98 (internal compiler error)
FAIL: g++.dg/template/error7.C -std=gnu++98  (test for errors, line 5)
FAIL: g++.dg/template/error7.C -std=gnu++98  (test for errors, line 6)
FAIL: g++.dg/template/error7.C -std=gnu++98 (test for excess errors)
FAIL: g++.dg/template/error7.C -std=gnu++11 (internal compiler error)
FAIL: g++.dg/template/error7.C -std=gnu++11  (test for errors, line 5)
FAIL: g++.dg/template/error7.C -std=gnu++11  (test for errors, line 6)
FAIL: g++.dg/template/error7.C -std=gnu++11 (test for excess errors)
FAIL: g++.dg/template/mem-partial1.C -std=c++98 (test for excess errors)
FAIL: g++.dg/template/mem-partial1.C -std=c++11 (test for excess errors)
FAIL: g++.dg/template/mem-partial2.C -std=c++98 (test for excess errors)
WARNING: g++.dg/template/mem-partial2.C -std=c++98 compilation failed to 
produce executable
FAIL: g++.dg/template/mem-partial2.C -std=c++11 (test for excess errors)
WARNING: g++.dg/template/mem-partial2.C -std=c++11 compilation failed to 
produce executable
FAIL: g++.dg/template/mem-partial3.C -std=c++98 (test for excess errors)
FAIL: g++.dg/template/mem-partial3.C -std=c++11 (test for excess errors)
FAIL: g++.dg/template/partial13.C -std=c++98 (test for excess errors)
FAIL: g++.dg/template/partial13.C -std=c++11 (test for excess errors)
FAIL: g++.dg/template/partial2.C -std=c++98 (test for excess errors)
FAIL: g++.dg/template/partial2.C -std=c++11 (test for excess errors)
FAIL: g++.dg/template/partial4.C -std=c++98 (test for excess errors)
FAIL: g++.dg/template/partial4.C -std=c++11 (test for excess errors)
WARNING: program timed out.
FAIL: g++.dg/template/pr39425.C -std=c++98  (test for errors, line 18)
FAIL: g++.dg/template/pr39425.C -std=c++98 (test for excess errors)

Attachment: p5
Description: Text document