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limit packed copy-out to non-generic Copy structs

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This commit is contained in:
Ariel Ben-Yehuda 2017-11-19 17:04:24 +02:00 • committed by Ariel Ben-Yehuda
parent dee8a71cd5
commit 617b413e18
7 changed files with 123 additions and 15 deletions
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26
src/libsyntax_ext/deriving/generic/mod.rs
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@ -413,7 +413,24 @@ impl<'a> TraitDef<'a> {
attr::find_repr_attrs(&cx.parse_sess.span_diagnostic, attr)
.contains(&attr::ReprPacked)
});
let use_temporaries = is_packed;
let has_no_type_params = match item.node {
ast::ItemKind::Struct(_, ref generics) |
ast::ItemKind::Enum(_, ref generics) |
ast::ItemKind::Union(_, ref generics) => {
generics.ty_params.is_empty()
}
_ => {
// Non-ADT derive is an error, but it should have been
// set earlier; see
// libsyntax/ext/expand.rs:MacroExpander::expand()
return;
}
};
let is_always_copy =
attr::contains_name(&item.attrs, "rustc_copy_clone_marker") &&
has_no_type_params;
let use_temporaries = is_packed && is_always_copy;
let newitem = match item.node {
ast::ItemKind::Struct(ref struct_def, ref generics) => {
self.expand_struct_def(cx, &struct_def, item.ident, generics, from_scratch,
@ -440,12 +457,7 @@ impl<'a> TraitDef<'a> {
return;
}
}
_ => {
// Non-ADT derive is an error, but it should have been
// set earlier; see
// libsyntax/ext/expand.rs:MacroExpander::expand()
return;
}
_ => unreachable!(),
};
// Keep the lint attributes of the previous item to control how the
// generated implementations are linted