[Bug c++/93618] New: [10 Regression] : unknown array size in delete when using C++20 standard

[laurent.stacul at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93618

            Bug ID: 93618
           Summary: [10 Regression] : unknown array size in delete when
                    using C++20 standard
           Product: gcc
           Version: 10.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: laurent.stacul at gmail dot com
  Target Milestone: ---

Hello,

I tried to compile Re2 (https://github.com/google/re2) with a close to HEAD
gcc:

g++ (GCC) 10.0.1 20200124 (experimental)

And I got the error described here: https://github.com/google/re2/issues/102.

This one was fixed several years ago for gcc 6.1 & 6,2 through
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71147.

Now with gcc 10 it works fine except when I add the flag -std=gnu++2a as you
can see below:

$ make CXXFLAGS="-std=gnu++2a" -j8 
...
g++ -c -o obj/re2/dfa.o  -std=c++11 -pthread -Wall -Wextra
-Wno-unused-parameter -Wno-missing-field-initializers -I.   -std=gnu++2a
-DNDEBUG re2/dfa.cc

re2/dfa.cc: In constructor ‘constexpr re2::DFA::State::State()’:
re2/dfa.cc:120:10: error: unknown array size in delete
  120 |   struct State {
      |          ^~~~~
re2/dfa.cc: In member function ‘re2::DFA::State* re2::DFA::CachedState(int*,
int, uint32_t)’:
re2/dfa.cc:753:9: note: synthesized method ‘constexpr re2::DFA::State::State()’
first required here
  753 |   State state;
      |         ^~~~~

Thanks in advance for you help,

Stac