https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99058
Bug ID: 99058
Summary: Consider adding a note about std::optional ABI break
to the C++17 status table
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: libstdc++
Assignee: unassigned at gcc dot gnu.org
Reporter: bspencer at blackberry dot com
Target Milestone: ---
In this table
https://gcc.gnu.org/onlinedocs/libstdc++/manual/status.html#status.iso.2017
the row labelled "Library Fundamentals V1 TS Components: optional" says it's
supported since "7.1" and references Note 1, but there's no mention of the ABI
break between 7.x and 8.x.
Perhaps I was misusing this table, but I interpreted "supported since 7.1" to
mean that if I compile against 7.1 headers, my code will remain ABI compatible
against future versions of the library _and_ other code compiled against future
versions of the headers. This ABI break caught me by surprise, and even though
these versions are older now, it seems worthwhile to at least mention the break
in a note to help others.
BTW, this particular example also happens to come up as a question in Marshall
Clow's recent talk on the topic of standard library ABIs. See
https://youtu.be/7RoTDjLLXJQ?t=3191
Thanks.
