[Bug c++/52869] New: "this" not being allowed in noexcept clauses

[Bug c++/52869] New: "this" not being allowed in noexcept clauses

[dave at boostpro dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52869

             Bug #: 52869
           Summary: "this" not being allowed in noexcept clauses
    Classification: Unclassified
           Product: gcc
           Version: 4.7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: dave@boostpro.com


Given the following, GCC says: "error: invalid use of 'this' at top level"
However, according to [expr.prim.general]/3 'this'
should be valid in the exception-specification as it comes after the
member function's optional cv-qualifier-seq.

  #define RETURNS(...) noexcept(noexcept(__VA_ARGS__)) -> decltype(__VA_ARGS__)
 { return (__VA_ARGS__); } 

  struct mul_ {
      int operator()() const { return 1; }

      template <typename A>
      A operator()(A const & a) const noexcept(A(std::move(a))) { return a; }

      template <typename A, typename B, typename... C>
      auto operator()(A const & a, B const & b, C const &... c) const
          RETURNS((*this)(a * b, c...))
  };

[Bug c++/52869] [DR 1207] "this" not being allowed in noexcept clauses

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52869

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2013-09-18
            Summary|"this" not being allowed in |[DR 1207] "this" not being
                   |noexcept clauses            |allowed in noexcept clauses
     Ever confirmed|0                           |1

[Bug c++/52869] [DR 1207] "this" not being allowed in noexcept clauses

[lz96 at foxmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=52869

--- Comment #1 from htfy96 <lz96 at foxmail dot com> ---
#include <iostream>
using namespace std;
class A
{
    public:
    void g() noexcept(false)  {}
    void f() noexcept( noexcept( g() )) {};
};

A a;
int main()
{
    cout<<noexcept(a.f())<<endl;
    return 0;
}

This is another testcase.

[Bug c++/52869] [DR 1207] "this" not being allowed in noexcept clauses

[spam+gcc at alt dot ee]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=52869

Sven Suursoho <spam+gcc at alt dot ee> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |spam+gcc at alt dot ee

--- Comment #20 from Sven Suursoho <spam+gcc at alt dot ee> ---
Seems some variant of this bug has returned with g++-11 (but not in g++-10)

$ cat s.cpp
struct S
{
    void f() noexcept {}
    S &g() noexcept(noexcept(f())) { f(); return *this; }
};

$ g++-11 -Wall -Werror -std=c++2a -c s.cpp
s.cpp:4:31: error: cannot call member function 'void S::f()' without object
    4 |     S &g() noexcept(noexcept(f())) { f(); return *this; }
      |                              ~^~


$ cat s.cpp
struct S
{
    void f() noexcept {}
    S &g() noexcept(noexcept(this->f())) { f(); return *this; }
};

$ g++-11 -Wall -Werror -std=c++2a -c s.cpp
s.cpp:4:30: error: invalid use of 'this' at top level
    4 |     S &g() noexcept(noexcept(this->f())) { f(); return *this; }
      |                              ^~~~


$ cat workaround.cpp
struct S
{
    void f() noexcept {}
    auto g() noexcept(noexcept(this->f())) -> S& { f(); return *this; }
};

$ g++-11 -Wall -Werror -std=c++2a -c workaround.cpp


$ g++-11 -v
Using built-in specs.
COLLECT_GCC=g++-11
COLLECT_LTO_WRAPPER=/usr/local/Cellar/gcc/11.1.0/libexec/gcc/x86_64-apple-darwin19/11.1.0/lto-wrapper
Target: x86_64-apple-darwin19
Configured with: ../configure --prefix=/usr/local/Cellar/gcc/11.1.0
--libdir=/usr/local/Cellar/gcc/11.1.0/lib/gcc/11 --disable-nls
--enable-checking=release --enable-languages=c,c++,objc,obj-c++,fortran,d
--program-suffix=-11 --with-gmp=/usr/local/opt/gmp
--with-mpfr=/usr/local/opt/mpfr --with-mpc=/usr/local/opt/libmpc
--with-isl=/usr/local/opt/isl --with-pkgversion='Homebrew GCC 11.1.0'
--with-bugurl=https://github.com/Homebrew/homebrew-core/issues
--enable-libphobos --build=x86_64-apple-darwin19 --with-system-zlib
--disable-multilib --with-native-system-header-dir=/usr/include
--with-sysroot=/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 11.1.0 (Homebrew GCC 11.1.0)


~ $ uname -a
Darwin home.local 19.6.0 Darwin Kernel Version 19.6.0: Mon Apr 12 20:57:45 PDT
2021; root:xnu-6153.141.28.1~1/RELEASE_X86_64 x86_64

[Bug c++/52869] [DR 1207] "this" not being allowed in noexcept clauses

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=52869

--- Comment #21 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Oh dear. It started to fail with r11-289. I've created Bug 100752.