Hello all,

I’d like to propose a small, local extension to the core language:

a class-head noexcept-specifier, analogous to  final  or  explicit .

Motivation

 noexcept  is currently a per-function property. For many types—especially

value types, RAII guards, and low-level utility classes—every member function

can and should be  noexcept . Today this must be repeated manually, which is

verbose, error-prone, and easily forgotten during refactoring.

A class-level specifier would make the intent clear and machine-checkable.

Semantics (intended)

The  noexcept  specifier applies only to member functions declared within the class-body.

It is non-inheriting and non-deductive.

An explicit  noexcept  on a member declaration overrides the class-level specifier.

Defaulted special members respect the class-level specifier.

The meaning is exactly as if  noexcept(true)  /  noexcept(false)  were written on each affected declaration.

The specifier does not affect:

base classes,

derived classes,

out-of-line definitions,

non-member functions,

friends.

​Relationship to existing features

Not  noexcept(auto)  (N4473): no deduction from function bodies.

Not  [[noexcept]] : this is a specifier in the grammar, not an attribute.

Similar to  final : applies locally to the class, not inherited, affects declarations within the class body.

Effect on language rules

 noexcept(expr)  sees the same result as if the specifier were written manually.

Overload resolution, function pointer type, and mangling are unchanged in semantics—only the source location of the specifier differs.

No ABI impact beyond what manual  noexcept  already implies.

gauge WG feedback on the general direction.

Thanks,

geguj geguji60@163.com