[Bug c++/97025] New: In -m32 mode the alignment of pointers returned by malloc or operator new is less than alignof(std::max_align_t)

[officesamurai at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97025

            Bug ID: 97025
           Summary: In -m32 mode the alignment of pointers returned by
                    malloc or operator new is less than
                    alignof(std::max_align_t)
           Product: gcc
           Version: 10.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: officesamurai at gmail dot com
  Target Milestone: ---

Created attachment 49210
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=49210&action=edit
The failing code

The attached code fails when compiled with -m32:
------------------------
$ g++-10.2.0 gcc_alignment_issue_in_m32_mode.cpp -o test -std=c++17 -m32 &&
./test
test: gcc_alignment_issue_in_m32_mode.cpp:23: int main(): Assertion
`UIntPtr(p2.get()) % alignof(Type) == 0' failed.
Aborted
------------------------

And if I remove the Type's default constructor, it just crashes:
------------------------
$ g++-10.2.0 gcc_alignment_issue_in_m32_mode.cpp -o test -std=c++17 -m32
-DNO_CTOR && ./test
Segmentation fault
------------------------

This happens with any version of GCC that I have in my system starting from
7.x, while 6.x works fine.
As I can see, alignof(std::max_align_t) equals 8 in 6.x and 16 in 7.x and later
versions, so this seems to be the root of the problem.

The system and compiler info:
------------------------
$ cat /etc/issue
Linux Mint 17.3 Rosa \n \l

$ g++-10.2.0 -v
Using built-in specs.
COLLECT_GCC=g++-10.2.0
COLLECT_LTO_WRAPPER=/home/brd/soft/gcc-10.2.0/libexec/gcc/x86_64-pc-linux-gnu/10.2.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ./configure --prefix=/home/brd/soft/gcc-10.2.0
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 10.2.0 (GCC) 

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