Remove superfluous std::string
copy operations
#11682
Merged
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Motivation
Nix uses
std::string
in many places. Often those are copied around, although this is not necessary becausestd::string_view
can be used instead.Also for most regex related code
std::string_view
is sufficent, too.Context
Nix has leftovers from code, which used C-strings in the past. Some of these leftovers are fixed.
C++20 adds the
view()
member function tostd::basic_ostringstream
. Sadly, the libc++ library shipped with clang-16 does not implement this and clang-17 would be required. Thus a workaround is implemented to get astd::string_view
fromstd::ostringstream
.The PR reduces closure size by ~50KB. When evaluating
nixpkgs
I couldn't measure a significant performance difference.Priorities and Process
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