[Bug c++/106029] New: gcc doesn't report full stack trace for static_assert()

realazthat at gmail dot com gcc-bugzilla@gcc.gnu.org
Sun Jun 19 08:49:21 GMT 2022


            Bug ID: 106029
           Summary: gcc doesn't report full stack trace for
           Product: gcc
           Version: 11.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: realazthat at gmail dot com
  Target Milestone: ---

Created attachment 53165
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=53165&action=edit

When triggering a static_assert within the standard library, clang prints a
stack-trace of the instantiation that triggered the assert, but every file/line
it lists in the trace is not in user code (rather, it is within stdlib), which
makes it extraordinarily difficult to debug ( kinds of traces are very famously
difficult to read in the first place, there is no reason to make it nearly

In the code below, const std::optional<std::vector<std::optional<Thing>>> &d =
c; is invalid instantiation because Thing is not copy constructible, and this
forces the optional not to be copy constructible, yet the only possible thing
to do here is to make a copy, so it asserts.

However, the error does not point to this line, and in a large amount of code I
required creduce to pinpoint this.

### Code


#include <vector>
#include <optional>

struct Thing {
  Thing() = delete;
  Thing(const Thing&) = delete;
  Thing& operator=(const Thing&) = delete;
  Thing& operator=( Thing&&);

void b() {
  std::vector<std::optional<Thing>> c;
  // The following line instantiates the static_assert failure,
  // but it is not listed in the error.
  const std::optional<std::vector<std::optional<Thing>>> &d = c;

### Compile command

$g++-11 symbol.cxx -std=c++20

### Output
In file included from /usr/include/c++/11/vector:66,
                 from symbol.cxx:2:
/usr/include/c++/11/bits/stl_uninitialized.h: In instantiation of
‘_ForwardIterator std::uninitialized_copy(_InputIterator, _InputIterator,
_ForwardIterator) [with _InputIterator = __gnu_cxx::__normal_iterator<const
std::optional<Thing>*, std::vector<std::optional<Thing> > >; _ForwardIterator =
/usr/include/c++/11/bits/stl_uninitialized.h:333:37:   required from
‘_ForwardIterator std::__uninitialized_copy_a(_InputIterator, _InputIterator,
_ForwardIterator, std::allocator<_Tp>&) [with _InputIterator =
__gnu_cxx::__normal_iterator<const std::optional<Thing>*,
std::vector<std::optional<Thing> > >; _ForwardIterator = std::optional<Thing>*;
_Tp = std::optional<Thing>]’
/usr/include/c++/11/bits/stl_vector.h:558:31:   required from ‘std::vector<_Tp,
_Alloc>::vector(const std::vector<_Tp, _Alloc>&) [with _Tp =
std::optional<Thing>; _Alloc = std::allocator<std::optional<Thing> >]’
/usr/include/c++/11/optional:225:8:   required from ‘constexpr
false>::_Storage(std::in_place_t, _Args&& ...) [with _Args =
{std::vector<std::optional<Thing>, std::allocator<std::optional<Thing> > >&};
_Up = std::vector<std::optional<Thing> >; _Tp =
std::vector<std::optional<Thing> >]’
/usr/include/c++/11/optional:116:4:   required from ‘constexpr
_Args&& ...) [with _Args = {std::vector<std::optional<Thing>,
std::allocator<std::optional<Thing> > >&}; _Tp =
std::vector<std::optional<Thing> >]’
/usr/include/c++/11/optional:358:42:   required from here
/usr/include/c++/11/bits/stl_uninitialized.h:138:72: error: static assertion
failed: result type must be constructible from value type of input range
  138 |       static_assert(is_constructible<_ValueType2,
/usr/include/c++/11/bits/stl_uninitialized.h:138:72: note:
‘std::integral_constant<bool, false>::value’ evaluates to false

### Expected output

An additional line like this:
/path/to/symbol.cxx:16:2:   required from here

### GCC Version

$g++-11 --v
Using built-in specs.
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu
11.1.0-1ubuntu1~20.04' --with-bugurl=file:///usr/share/doc/gcc-11/README.Bugs
--enable-languages=c,ada,c++,go,brig,d,fortran,objc,obj-c++,m2 --prefix=/usr
--with-gcc-major-version-only --program-suffix=-11
--program-prefix=x86_64-linux-gnu- --enable-shared --enable-linker-build-id
--libexecdir=/usr/lib --without-included-gettext --enable-threads=posix
--libdir=/usr/lib --enable-nls --enable-bootstrap --enable-clocale=gnu
--enable-libstdcxx-debug --enable-libstdcxx-time=yes
--with-default-libstdcxx-abi=new --enable-gnu-unique-object
--disable-vtable-verify --enable-plugin --enable-default-pie --with-system-zlib
--enable-libphobos-checking=release --with-target-system-zlib=auto
--enable-objc-gc=auto --enable-multiarch --disable-werror --disable-cet
--with-arch-32=i686 --with-abi=m64 --with-multilib-list=m32,m64,mx32
--enable-multilib --with-tune=generic
--without-cuda-driver --enable-checking=release --build=x86_64-linux-gnu
--host=x86_64-linux-gnu --target=x86_64-linux-gnu
--with-build-config=bootstrap-lto-lean --enable-link-serialization=2
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 11.1.0 (Ubuntu 11.1.0-1ubuntu1~20.04)

```$ apt show g++-11
Package: g++-11
Version: 11.1.0-1ubuntu1~20.04
Priority: optional
Section: devel
Source: gcc-11
Maintainer: Ubuntu Core developers <ubuntu-devel-discuss@lists.ubuntu.com>
Original-Maintainer: Debian GCC Maintainers <debian-gcc@lists.debian.org>
Installed-Size: 29.4 MB
Provides: c++-compiler, c++abi2-dev
Depends: gcc-11-base (= 11.1.0-1ubuntu1~20.04), gcc-11 (=
11.1.0-1ubuntu1~20.04), libstdc++-11-dev (= 11.1.0-1ubuntu1~20.04), libc6 (>=
2.14), libgmp10 (>= 2:5.0.1~), libisl22 (>= 0.15), libmpc3, libmpfr6 (>=
3.1.3), libzstd1 (>= 1.3.2), zlib1g (>= 1:1.1.4)
Suggests: g++-11-multilib, gcc-11-doc (>= 11)
Download-Size: 10.5 MB
APT-Manual-Installed: yes
APT-Sources: http://ppa.launchpad.net/ubuntu-toolchain-r/test/ubuntu focal/main
amd64 Packages
Description: GNU C++ compiler
 This is the GNU C++ compiler, a fairly portable optimizing compiler for C++.

### **OS:**

Ubuntu over WSL (Windows Subsystem for Linux) 

**lsb_release -a**

$lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 20.04.4 LTS
Release:        20.04
Codename:       focal

More information about the Gcc-bugs mailing list