Re: RFC: [PATCH] Remove using-declarations that add std names to __gnu_cxx

[Jonathan Wakely]

On 31/05/19 11:36 +0100, Jonathan Wakely wrote:

On 29/05/19 21:00 +0100, Jonathan Wakely wrote:

These using-declarations appear to have been added for simplicity when
moving the non-standard extensions from namespace std to namespace
__gnu_cxx. Dumping all these names into namespace __gnu_cxx allows
uses like __gnu_cxx::size_t and __gnu_cxx::pair, which serve no useful
purpose, but allows creating unnecessarily unportable code.

This patch removes most of the using-declarations from namespace scope,
then either qualifies names as needed or adds using-declarations at
block scope or typedefs at class scope.

        * include/backward/hashtable.h (size_t, ptrdiff_t)
        (forward_iterator_tag, input_iterator_tag, _Construct, _Destroy)
        (distance, vector, pair, __iterator_category): Remove
        using-declarations that add these names to namespace __gnu_cxx.
        * include/ext/bitmap_allocator.h (size_t, ptrdiff_t): Likewise.
        * include/ext/debug_allocator.h (size_t): Likewise.
        * include/ext/functional (size_t, unary_function, binary_function)
        (mem_fun1_t, const_mem_fun1_t, mem_fun1_ref_t, const_mem_fun1_ref_t):
        Likewise.
        * include/ext/malloc_allocator.h (size_t, ptrdiff_t): Likewise.
        * include/ext/memory (ptrdiff_t, pair, __iterator_category): Likewise.
        * include/ext/mt_allocator.h (size_t, ptrdiff_t): Likewise.
        * include/ext/new_allocator.h (size_t, ptrdiff_t): Likewise.
        * include/ext/numeric (iota): Fix outdated comment.
        * include/ext/pool_allocator.h (size_t, ptrdiff_t): Likewise.
        * include/ext/rb_tree (_Rb_tree, allocator): Likewise.
        * include/ext/rope (size_t, ptrdiff_t, allocator, _Destroy): Likewise.
        * include/ext/ropeimpl.h (size_t, printf, basic_ostream)
        (__throw_length_error, _Destroy, std::__uninitialized_fill_n_a):
        Likewise.
        * include/ext/slist (size_t, ptrdiff_t, _Construct, _Destroy)
        (allocator, __true_type, __false_type): Likewise.

Does anybody think we should keep __gnu_cxx::size_t,
__gnu_cxx::input_iterator_tag, __gnu_cxx::vector, __gnu_cxx::pair etc.
or should I go ahead and commit this?

Committed to trunk.

And this fix is needed to fix an AIX bootstrap failure.

Committed to trunk.



commit e49b5946d09205e57a60a84d764b77a1d2d09a83
Author: Jonathan Wakely <jwak...@redhat.com>
Date:   Fri May 31 14:58:15 2019 +0100

    Fix breakage due to removing __gnu_cxx::size_t declaration
    
    Restore the using-declaration but locally in the source file, not in the
    header.
    
            * src/c++98/bitmap_allocator.cc: Add using-declaration for size_t.

diff --git a/libstdc++-v3/src/c++98/bitmap_allocator.cc b/libstdc++-v3/src/c++98/bitmap_allocator.cc
index d22bf4e118f..ffaea1cbac9 100644
--- a/libstdc++-v3/src/c++98/bitmap_allocator.cc
+++ b/libstdc++-v3/src/c++98/bitmap_allocator.cc
@@ -28,6 +28,8 @@ namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)
 {
 _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
+  using std::size_t;
+
   namespace __detail
   {
     template class __mini_vector<