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std::visit by reference

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I had started the trend of doing `std::visit` by value (because a type
error once mislead me into thinking that was the only form that
existed). While the optomizer in principle should be able to deal with
extra coppying or extra indirection once the lambdas inlined, sticking
with by reference is the conventional default. I hope this might even
improve performance.
This commit is contained in:
John Ericson 2021-09-30 21:31:21 +00:00
parent 6a8d6246f6
commit 242f9bf3dc
19 changed files with 88 additions and 88 deletions
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4
src/libstore/path-with-outputs.cc
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@ -31,14 +31,14 @@ std::vector<DerivedPath> toDerivedPaths(const std::vector<StorePathWithOutputs>
std::variant<StorePathWithOutputs, StorePath> StorePathWithOutputs::tryFromDerivedPath(const DerivedPath & p)
{
return std::visit(overloaded {
[&](DerivedPath::Opaque bo) -> std::variant<StorePathWithOutputs, StorePath> {
[&](const DerivedPath::Opaque & bo) -> std::variant<StorePathWithOutputs, StorePath> {
if (bo.path.isDerivation()) {
// drv path gets interpreted as "build", not "get drv file itself"
return bo.path;
}
return StorePathWithOutputs { bo.path };
},
[&](DerivedPath::Built bfd) -> std::variant<StorePathWithOutputs, StorePath> {
[&](const DerivedPath::Built & bfd) -> std::variant<StorePathWithOutputs, StorePath> {
return StorePathWithOutputs { bfd.drvPath, bfd.outputs };
},
}, p.raw());