DE165 16.05.5.4 Regular unqualified lookup of functions specified as friends P1965 LWG 3239 #163
Description
It is unclear whether friend functions declared in a class
are intended to be found via argument-dependent lookup only
(and not via regular unqualified lookup), or whether the
implementation is permitted to add declarations of that
function that would allow unqualified lookup to succeed.
For an example, see 17.11.2.2.
Proposed change:
Clarify in the vicinity of 16.5.5.4 that friend functions
are found via argument-dependent lookup only, unless a
synopsis (but not a detailed specification, 16.4.1.4)
expressly shows a namespace-scope declaration of that function.
For existing friend functions, move non-trivial definitions
from the synopses to regular descriptive elements.