[Bug libstdc++/111685] Segfault while sorting on array element address

[knoepfel at fnal dot gov via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111685

Kyle Knoepfel  changed:

   What|Removed |Added

 Resolution|--- |INVALID
 Status|UNCONFIRMED |RESOLVED

--- Comment #11 from Kyle Knoepfel  ---
@Xi Ruoyao's comment above re. strict weak ordering of values and not object
addresses is persuasive.  Thank you for your time and for clarifying my
misconceptions.

[Bug libstdc++/111685] Segfault while sorting on array element address

[knoepfel at fnal dot gov via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111685

Kyle Knoepfel  changed:

   What|Removed |Added

 Status|RESOLVED|UNCONFIRMED
 Resolution|INVALID |---

--- Comment #4 from Kyle Knoepfel  ---
@Andrew Pinski described what has happened, but not whether that is the
expected behavior of the standard.  See comment #3.

[Bug libstdc++/111685] Segfault while sorting on array element address

[knoepfel at fnal dot gov via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111685

--- Comment #3 from Kyle Knoepfel  ---
@Andrew Pinski, yes I surmised as much.  My difficulty, though, is in
understanding if this is the correct behavior according to the standard's
specification of std::sort, which presumably is reasonably summarized in the
type requirements listed at https://en.cppreference.com/w/cpp/algorithm/sort. 
Which formal requirements/preconditions are being violated by cmp?

[Bug c++/111685] New: Segfault while sorting on array element address

[knoepfel at fnal dot gov via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111685

Bug ID: 111685
   Summary: Segfault while sorting on array element address
   Product: gcc
   Version: 13.2.0
Status: UNCONFIRMED
  Severity: normal
  Priority: P3
 Component: c++
  Assignee: unassigned at gcc dot gnu.org
  Reporter: knoepfel at fnal dot gov
  Target Milestone: ---

The following file (`sort-bug.cpp`) results in a segmentation violation:

```
#include 
#include 
#include 
#include 

int main()
{
  std::vector vnums{1, 5, 4};
  std::array anums{1, 5, 4};
  int nums[] = {1, 5, 4};

  auto cmp = [](auto&& a, auto&& b) { return  <  };

  std::sort(vnums.begin(), vnums.end(), cmp);
  std::sort(anums.begin(), anums.end(), cmp); // segfault
  std::sort(nums, nums + 3, cmp); // segfault
}
```

*Expected result*: the `vnums`, `anums`, and `nums` variables remain unaltered
after the invocation to `std::sort`.

*Compiler info*:

- Target: x86_64-pc-linux-gnu
- Configured with:
/scratch/workspace/art-build-base/v13_02_00-e28/SLF7/build/gcc/v13_1_0/src/gcc-13.1.0/configure
--enable-__cxa_atexit --enable-checking=release
--enable-compressed-debug-sections=all
--enable-languages=c,c++,fortran,go,objc,obj-c++ --enable-libstdcxx-time=rt
--enable-plugin --enable-stage1-checking=all --enable-threads=posix
--prefix=/scratch/workspace/art-build-base/v13_02_00-e28/SLF7/build/gcc/v13_1_0/Linux64bit+3.10-2.17
--with-system-zlib --enable-lto --with-zstd --enable-link-serialization=15
- Thread model: posix
- Supported LTO compression algorithms: zlib zstd
- gcc version 13.1.0 (GCC) 

*Compiler/runtime command*: `g++ sort-bug.cpp -o sort-bug -std=c++20 -pedantic
-Werror -Wall; ./sort-bug`