Yes ([dcl.constexpr], §7.1.5/2 in the C++11 standard): “constexpr functions and constexpr constructors are implicitly inline (7.1.2).”
Note, however, that the inline
specifier really has very little (if any) effect upon whether a compiler is likely to expand a function inline or not. It does, however, affect the one definition rule, and from that perspective, the compiler is required to follow the same rules for a constexpr
function as an inline
function.
I should also add that regardless of constexpr
implying inline
, the rules for constexpr
functions in C++11 required them to be simple enough that they were often good candidates for inline expansion (the primary exception being those that are recursive). Since then, however, the rules have gotten progressively looser, so constexpr
can be applied to substantially larger, more complex functions.