[diff.cpp17.temp]

# Annex C (informative) Compatibility [[diff]](./#diff)

## C.3 C++ and ISO C++ 2017 [[diff.cpp17]](diff.cpp17#temp)

### C.3.8 [[temp]](temp "13 Templates"): templates [diff.cpp17.temp]

[1](#1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/compatibility.tex#L1275)

**Affected subclause:** [[temp.names]](temp.names)  


**Change:** An [*unqualified-id*](expr.prim.id.unqual#nt:unqualified-id "7.5.5.2 Unqualified names [expr.prim.id.unqual]") that is followed by a < and for which name lookup
finds nothing or finds a function
will be treated as a [*template-name*](temp.names#nt:template-name "13.3 Names of template specializations [temp.names]") in order to potentially cause argument-dependent lookup to be performed[.](#1.sentence-1)

  


**Rationale:** It was problematic to call a function template
with an explicit template argument list
via argument-dependent lookup
because of the need to have a template with the same name
visible via normal lookup[.](#1.sentence-2)

  


**Effect on original feature:** Previously valid code that uses a function name
as the left operand of a < operator
would become ill-formed[.](#1.sentence-3)

[*Example [1](#example-1)*: struct A {};bool operator<(void (*fp)(), A);void f() {}int main() { A a;
 f < a; // ill-formed; previously well-formed(f) < a; // still well-formed} — *end example*]