[Bug c++/88528] [7 Regression] ICE with templated operator bool() in gcc 7

[proski at gnu dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88528

--- Comment #4 from Pavel Roskin <proski at gnu dot org> ---
The trivial backport of PR c++/85032 fixes both my testcase and the original
issue with my code. Please include the fix in gcc 7.5.