[Bug libstdc++/93672] New: std::basic_istream::ignore hangs if delim MSB is set

[erenon2 at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93672

Bug ID: 93672
   Summary: std::basic_istream::ignore hangs if delim MSB is set
   Product: gcc
   Version: 9.1.0
   URL: https://stackoverflow.com/questions/60140947/stdbasic-
istreamignore-hangs-if-delim-msb-is-set
Status: UNCONFIRMED
  Severity: normal
  Priority: P3
 Component: libstdc++
  Assignee: unassigned at gcc dot gnu.org
  Reporter: erenon2 at gmail dot com
  Target Milestone: ---

The following program hangs:

#include 
#include 

int main()
{
  std::stringstream str;
  str.put('a');   // 1
  str.put('\x80');// 2
  str.put('a');   // 3

  str.ignore(32, '\x80'); // hangs
  std::cout << str.tellg() << "\n";
}

Removing any of the numbered lines (1,2,3) makes the problem go away.
Using std::basic_stringstream does not exhibit the issue.
Passing unsigned delim (that does not get sign extended) also fixes it.
ASAN or UBSAN is silent. `-D_GLIBCXX_DEBUG` does not make a difference.
GCC 5.4, 6.3, 8.2, 9.2 are affected.

[Bug c++/41091] Using section attribute in c and c++ function causes section type conflict

[erenon2 at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=41091

Benedek  changed:

   What|Removed |Added

 CC||erenon2 at gmail dot com

--- Comment #6 from Benedek  ---
The following code reproduces this, or a very similar issue:

#define STORE(SECTION, STRING) \
  __attribute__((section(SECTION), used)) \
  static constexpr const char* s[] = { STRING }

void f()
{
  STORE(".custom", "normal_foobar");
}

inline void g()
{
  STORE(".custom", "inline_foobar");
}

template 
void h()
{
  STORE(".custom", "template_foobar");
}

int main()
{
  f(); g(); h();
  return 0;
}

$ g++ -std=c++11 section.cpp
section.cpp: error: 's' causes a section type conflict with 's'

GCC 4.8, 5.2, 7.2, and trunk are affected (x86-64, checked on godbolt).
Depending on the compiler version, either the normal and the inline, or the
normal and the function template clashes.

I suppose because of how comdat is handled, they might have slightly different
needs, but it would be really nice to make it easier for the user.

(Clang compiles it fine)

[Bug c++/97544] New: -Wtype-limits triggered for comparison to template argument

[erenon2 at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97544

Bug ID: 97544
   Summary: -Wtype-limits triggered for comparison to template
argument
   Product: gcc
   Version: 10.2.0
Status: UNCONFIRMED
  Keywords: diagnostic
  Severity: normal
  Priority: P3
 Component: c++
  Assignee: unassigned at gcc dot gnu.org
  Reporter: erenon2 at gmail dot com
  Target Milestone: ---

The following code triggers -Wtype-limits:

template 
constexpr int f(unsigned i)
{
  return (i < N) ? 0 : 1;
}

int main()
{
  return f<0>(1);
}

On GCC 10.2 and trunk, it produces this warning:

: In instantiation of 'constexpr int f(unsigned int) [with unsigned int
N = 0]':
:4:13: warning: comparison of unsigned expression in '< 0' is always
false [-Wtype-limits]

4 |   return (i < N) ? 0 : 1;

  |  ~~~^~~~

On GCC 10.1, there's no warning.
godbolt: https://gcc.godbolt.org/z/cqzq8P

[Bug c++/97544] -Wtype-limits triggered for comparison to template argument

[erenon2 at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97544

--- Comment #4 from Benedek Thaler  ---
FTR, Using (N != 0 && i < N) does not silence the warning.
https://gcc.godbolt.org/z/WqaT3G