https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112421
Bug ID: 112421
Summary: GCC emits warning potential null dereference
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: jlame646 at gmail dot com
Target Milestone: ---
GCC emits a false positive with the following code.
https://godbolt.org/z/KojKWT4WK
```
std::ifstream t("file.txt");
std::string str((std::istreambuf_iterator<char>(t)),
std::istreambuf_iterator<char>());
```
It says:
```
In file included from
/opt/compiler-explorer/gcc-13.2.0/include/c++/13.2.0/ios:45,
from
/opt/compiler-explorer/gcc-13.2.0/include/c++/13.2.0/ostream:40,
from
/opt/compiler-explorer/gcc-13.2.0/include/c++/13.2.0/iostream:41,
from <source>:1:
In member function 'std::basic_streambuf<_CharT, _Traits>::char_type*
std::basic_streambuf<_CharT, _Traits>::egptr() const [with _CharT = char;
_Traits = std::char_traits<char>]',
inlined from 'std::basic_streambuf<_CharT, _Traits>::int_type
std::basic_streambuf<_CharT, _Traits>::sbumpc() [with _CharT = char; _Traits =
std::char_traits<char>]' at
/opt/compiler-explorer/gcc-13.2.0/include/c++/13.2.0/streambuf:326:49,
inlined from 'std::istreambuf_iterator<_CharT, _Traits>&
std::istreambuf_iterator<_CharT, _Traits>::operator++() [with _CharT = char;
_Traits = std::char_traits<char>]' at
/opt/compiler-explorer/gcc-13.2.0/include/c++/13.2.0/bits/streambuf_iterator.h:173:17,
inlined from 'void std::__cxx11::basic_string<_CharT, _Traits,
_Alloc>::_M_construct(_InIterator, _InIterator, std::input_iterator_tag) [with
_InIterator = std::istreambuf_iterator<char, std::char_traits<char> >; _CharT =
char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]' at
/opt/compiler-explorer/gcc-13.2.0/include/c++/13.2.0/bits/basic_string.tcc:178:6,
inlined from 'std::__cxx11::basic_string<_CharT, _Traits,
_Alloc>::basic_string(_InputIterator, _InputIterator, const _Alloc&) [with
_InputIterator = std::istreambuf_iterator<char, std::char_traits<char> >;
<template-parameter-2-2> = void; _CharT = char; _Traits =
std::char_traits<char>; _Alloc = std::allocator<char>]' at
/opt/compiler-explorer/gcc-13.2.0/include/c++/13.2.0/bits/basic_string.h:753:16,
inlined from 'int main()' at <source>:18:53:
/opt/compiler-explorer/gcc-13.2.0/include/c++/13.2.0/streambuf:495:30: warning:
potential null pointer dereference [-Wnull-dereference]
495 | egptr() const { return _M_in_end; }
```
