[Bug c++/84726] New: [8 regression] Unnecessary lambda capture of constant variables

[jason at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84726

            Bug ID: 84726
           Summary: [8 regression] Unnecessary lambda capture of constant
                    variables
           Product: gcc
           Version: 8.0
            Status: UNCONFIRMED
          Keywords: ABI
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: jason at gcc dot gnu.org
          Reporter: jason at gcc dot gnu.org
  Target Milestone: ---

wg21.link/p0588 changes i from not captured to captured by the lambda in this
testcase, but an implementation is allowed to optimize away that capture if it
doesn't affect the semantics of the program.  Since we didn't capture it in
previous versions of GCC, the optimization is desirable to avoid an ABI change.

int main()
{ 
  const int i = 42;
  auto l = [=]{return i;};
  if (sizeof(l) > 1)
    __builtin_abort ();
}