Moving an std::vector is almost always profitable.
A clang::CXXScopeSpec contains an owned
clang::NestedNameSpecifierLocBuilder which currently does not benefit
from being moved, but may structurally in the future.
A clang::MultiLevelTemplateArgumentList contains an llvm::SmalVector
which may benefit from being moved dependiong on its size.
A clang::Environment contains an llvm::ImmutableMap which itself
contains an llvm::IntrusiveRefCntPtr that benefits from being moved.
Changes suggested by performance-use-std-move from #179467
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Co-authored-by: Timm Baeder <tbaeder@redhat.com>
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