[Bug middle-end/98373] [11 Repression] Bogus error: ‘symbuf’ may be used uninitialized at -O0

[hjl.tools at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98373

H.J. Lu <hjl.tools at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|WAITING                     |NEW

--- Comment #2 from H.J. Lu <hjl.tools at gmail dot com> ---
[hjl@gnu-cfl-2 gold]$ cat /tmp/foo.cc 
template<int size>
struct Sym_data;

template<>
struct Sym_data<32>
{
  unsigned char st_info;
  unsigned char st_other;
};

template<>
struct Sym_data<64>
{
  unsigned char st_info;
  unsigned char st_other;
};

template<int size, bool big_endian>
class Sym
{
 public:
  Sym(const unsigned char* p)
    : p_(reinterpret_cast<const Sym_data<size>*>(p))
  { }

 private:
  const Sym_data<size>* p_;
};

template<int size, bool big_endian>
class Sized_relobj_incr
{
 private:
  void do_add_symbols();
  Sym<size, big_endian> *symbols_;
};

template<int size, bool big_endian>
Sym<size, big_endian> *
foo(Sym<size, big_endian> *);

template<int size, bool big_endian>
void
Sized_relobj_incr<size, big_endian>::do_add_symbols()
{
  unsigned char symbuf[100];
  Sym<size, big_endian> sym(symbuf);
  Sym<size, big_endian>* res = foo(&sym);
  this->symbols_ = res;
}

template
class Sized_relobj_incr<32, false>;
[hjl@gnu-cfl-2 gold]$ /usr/gcc-11.0.0-x32/bin/g++ -Wall -S /tmp/foo.cc
/tmp/foo.cc: In member function ‘void Sized_relobj_incr<size,
big_endian>::do_add_symbols() [with int size = 32; bool big_endian = false]’:
/tmp/foo.cc:47:25: warning: ‘symbuf’ may be used uninitialized
[-Wmaybe-uninitialized]
   47 |   Sym<size, big_endian> sym(symbuf);
      |                         ^~~
/tmp/foo.cc:22:3: note: by argument 2 of type ‘const unsigned char*’ to
‘Sym<size, big_endian>::Sym(const unsigned char*) [with int size = 32; bool
big_endian = false]’ declared here
   22 |   Sym(const unsigned char* p)
      |   ^~~
/tmp/foo.cc:46:17: note: ‘symbuf’ declared here
   46 |   unsigned char symbuf[100];
      |                 ^~~~~~
[hjl@gnu-cfl-2 gold]$