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From: "gael.guennebaud at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/66472] New: -Wshadow gets confused by using statements in template classes
Date: Tue, 09 Jun 2015 11:25:00 -0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66472

            Bug ID: 66472
           Summary: -Wshadow gets confused by using statements in template
                    classes
           Product: gcc
           Version: 5.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: gael.guennebaud at gmail dot com
  Target Milestone: ---

This is a followup to bug 57709 that disabled shadow warnings between variables
and class functions. However, -Wshadow still trigger false positive when a base
member functions is imported with the "using" keyword, as in the following
example (tested with gcc 5.1):


template<typename T> struct BaseClass {
  BaseClass(int size) : m_size(size) {}
  int size() { return m_size; }
  int m_size;
};

template<typename T> struct Foo : BaseClass<T> {
  typedef BaseClass<T> Base;
  Foo(int size) : Base(size) {}
  using Base::size;
};



$ g++-mp-5 gcc_shadow.cpp -c  -Wshadow 
gcc_shadow.cpp: In constructor 'Foo<T>::Foo(int)':
gcc_shadow.cpp:9:17: warning: declaration of 'size' shadows a member of
'Foo<T>' [-Wshadow]
   Foo(int size) : Base(size) {}
                 ^
gcc_shadow.cpp:10:15: note: shadowed declaration is here
   using Base::size;



Note that clang does not warn in this case, so it should be possible to figure
out that in this case, the imported "size" symbol is a function and not a
variable.

As suggested there https://gcc.gnu.org/bugzilla/show_bug.cgi?id=57709#c16, I
tried to break at the call to warning_at to give you more input, but with no
luck, as if warning_at was not called at all. (I also tried to break at any
*warning* symbol with same result).