https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88572
--- Comment #1 from Will Wray <wjwray at gmail dot com> ---
This bug is straightforward to confirm.
Compile this snippet (-std=c++11 / 14 / 17 / 2a):
struct S { int i; };
S s{{0}};
Gives error: braces around scalar initializer for type 'int'
Should be a warning
(Or, follow the provided compiler explorer link to the test code
which includes two more failing cases - array and array member.)
The standard is clear that scalar brace init should be accepted:
C++14 [dcl.init.aggr]/2 says:
"Each member is copy-initialized from the corresponding initializer-clause.
[...] [ Note: If an initializer-clause is itself an initializer list, the
member is list-initialized, which will result in a recursive application of the
rules in this section if the member is an aggregate. — end note ]"
C++14 [dcl.init.list]/3.5:
"Otherwise, if the initializer list has a single element of type E and
either T is not a reference type or its referenced type is reference-related to
E, the object or reference is initialized from that element;"
Some historical links leading up to the wording fixes:
DR 155. Brace initializer for scalar
Explains it was a C/C++ incompatibility pre-11 and points to:
DR 632. Brace-enclosed initializer for scalar member of aggregate
http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_defects.html#632
"The initializer-list proposal will resolve this issue..."
As stated, it was resolved in C++11 by Initializer Lists:
http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2008/n2672.htm
1501. Nested braces in list-initialization
http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_closed.html#1501
DR1467 List-initialization of aggregate from same-type object
http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_defects.html#1467
Submitter: Jason Merrill Date: 2012-02-06
[Moved to DR at the November, 2014 meeting.]
Please CONFIRM this bug.
