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</pre><pre class="rust"><code><span class="kw">use </span>proc_macro2::TokenStream;
<span class="kw">use </span>quote::format_ident;
<span class="kw">use </span>internals::ast::{Container, Data, Field, Style, Variant};
<span class="comment">// Suppress dead_code warnings that would otherwise appear when using a remote
// derive. Other than this pretend code, a struct annotated with remote derive
// never has its fields referenced and an enum annotated with remote derive
// never has its variants constructed.
//
// warning: field is never used: `i`
// --&gt; src/main.rs:4:20
// |
// 4 | struct StructDef { i: i32 }
// | ^^^^^^
//
// warning: variant is never constructed: `V`
// --&gt; src/main.rs:8:16
// |
// 8 | enum EnumDef { V }
// | ^
//
</span><span class="kw">pub fn </span>pretend_used(cont: <span class="kw-2">&amp;</span>Container, is_packed: bool) -&gt; TokenStream {
<span class="kw">let </span>pretend_fields = pretend_fields_used(cont, is_packed);
<span class="kw">let </span>pretend_variants = pretend_variants_used(cont);
<span class="macro">quote! </span>{
#pretend_fields
#pretend_variants
}
}
<span class="comment">// For structs with named fields, expands to:
//
// match None::&lt;&amp;T&gt; {
// Some(T { a: __v0, b: __v1 }) =&gt; {}
// _ =&gt; {}
// }
//
// For packed structs on sufficiently new rustc, expands to:
//
// match None::&lt;&amp;T&gt; {
// Some(__v @ T { a: _, b: _ }) =&gt; {
// let _ = addr_of!(__v.a);
// let _ = addr_of!(__v.b);
// }
// _ =&gt; {}
// }
//
// For packed structs on older rustc, we assume Sized and !Drop, and expand to:
//
// match None::&lt;T&gt; {
// Some(T { a: __v0, b: __v1 }) =&gt; {}
// _ =&gt; {}
// }
//
// For enums, expands to the following but only including struct variants:
//
// match None::&lt;&amp;T&gt; {
// Some(T::A { a: __v0 }) =&gt; {}
// Some(T::B { b: __v0 }) =&gt; {}
// _ =&gt; {}
// }
//
</span><span class="kw">fn </span>pretend_fields_used(cont: <span class="kw-2">&amp;</span>Container, is_packed: bool) -&gt; TokenStream {
<span class="kw">match </span><span class="kw-2">&amp;</span>cont.data {
Data::Enum(variants) =&gt; pretend_fields_used_enum(cont, variants),
Data::Struct(Style::Struct, fields) =&gt; {
<span class="kw">if </span>is_packed {
pretend_fields_used_struct_packed(cont, fields)
} <span class="kw">else </span>{
pretend_fields_used_struct(cont, fields)
}
}
Data::Struct(<span class="kw">_</span>, <span class="kw">_</span>) =&gt; <span class="macro">quote!</span>(),
}
}
<span class="kw">fn </span>pretend_fields_used_struct(cont: <span class="kw-2">&amp;</span>Container, fields: <span class="kw-2">&amp;</span>[Field]) -&gt; TokenStream {
<span class="kw">let </span>type_ident = <span class="kw-2">&amp;</span>cont.ident;
<span class="kw">let </span>(<span class="kw">_</span>, ty_generics, <span class="kw">_</span>) = cont.generics.split_for_impl();
<span class="kw">let </span>members = fields.iter().map(|field| <span class="kw-2">&amp;</span>field.member);
<span class="kw">let </span>placeholders = (<span class="number">0usize</span>..).map(|i| <span class="macro">format_ident!</span>(<span class="string">&quot;__v{}&quot;</span>, i));
<span class="macro">quote! </span>{
<span class="kw">match </span>_serde::__private::None::&lt;<span class="kw-2">&amp;</span>#type_ident #ty_generics&gt; {
_serde::__private::Some(#type_ident { #(#members: #placeholders),* }) =&gt; {}
<span class="kw">_ </span>=&gt; {}
}
}
}
<span class="kw">fn </span>pretend_fields_used_struct_packed(cont: <span class="kw-2">&amp;</span>Container, fields: <span class="kw-2">&amp;</span>[Field]) -&gt; TokenStream {
<span class="kw">let </span>type_ident = <span class="kw-2">&amp;</span>cont.ident;
<span class="kw">let </span>(<span class="kw">_</span>, ty_generics, <span class="kw">_</span>) = cont.generics.split_for_impl();
<span class="kw">let </span>members = fields.iter().map(|field| <span class="kw-2">&amp;</span>field.member).collect::&lt;Vec&lt;<span class="kw">_</span>&gt;&gt;();
<span class="macro">quote! </span>{
<span class="kw">match </span>_serde::__private::None::&lt;<span class="kw-2">&amp;</span>#type_ident #ty_generics&gt; {
_serde::__private::Some(__v @ #type_ident { #(#members: <span class="kw">_</span>),* }) =&gt; {
#(
<span class="kw">let _ </span>= <span class="macro">_serde::__private::ptr::addr_of!</span>(__v.#members);
)*
}
<span class="kw">_ </span>=&gt; {}
}
}
}
<span class="kw">fn </span>pretend_fields_used_enum(cont: <span class="kw-2">&amp;</span>Container, variants: <span class="kw-2">&amp;</span>[Variant]) -&gt; TokenStream {
<span class="kw">let </span>type_ident = <span class="kw-2">&amp;</span>cont.ident;
<span class="kw">let </span>(<span class="kw">_</span>, ty_generics, <span class="kw">_</span>) = cont.generics.split_for_impl();
<span class="kw">let </span>patterns = variants
.iter()
.filter_map(|variant| <span class="kw">match </span>variant.style {
Style::Struct =&gt; {
<span class="kw">let </span>variant_ident = <span class="kw-2">&amp;</span>variant.ident;
<span class="kw">let </span>members = variant.fields.iter().map(|field| <span class="kw-2">&amp;</span>field.member);
<span class="kw">let </span>placeholders = (<span class="number">0usize</span>..).map(|i| <span class="macro">format_ident!</span>(<span class="string">&quot;__v{}&quot;</span>, i));
<span class="prelude-val">Some</span>(<span class="macro">quote!</span>(#type_ident::#variant_ident { #(#members: #placeholders),* }))
}
<span class="kw">_ </span>=&gt; <span class="prelude-val">None</span>,
})
.collect::&lt;Vec&lt;<span class="kw">_</span>&gt;&gt;();
<span class="macro">quote! </span>{
<span class="kw">match </span>_serde::__private::None::&lt;<span class="kw-2">&amp;</span>#type_ident #ty_generics&gt; {
#(
_serde::__private::Some(#patterns) =&gt; {}
)*
<span class="kw">_ </span>=&gt; {}
}
}
}
<span class="comment">// Expands to one of these per enum variant:
//
// match None {
// Some((__v0, __v1,)) =&gt; {
// let _ = E::V { a: __v0, b: __v1 };
// }
// _ =&gt; {}
// }
//
</span><span class="kw">fn </span>pretend_variants_used(cont: <span class="kw-2">&amp;</span>Container) -&gt; TokenStream {
<span class="kw">let </span>variants = <span class="kw">match </span><span class="kw-2">&amp;</span>cont.data {
Data::Enum(variants) =&gt; variants,
Data::Struct(<span class="kw">_</span>, <span class="kw">_</span>) =&gt; {
<span class="kw">return </span><span class="macro">quote!</span>();
}
};
<span class="kw">let </span>type_ident = <span class="kw-2">&amp;</span>cont.ident;
<span class="kw">let </span>(<span class="kw">_</span>, ty_generics, <span class="kw">_</span>) = cont.generics.split_for_impl();
<span class="kw">let </span>turbofish = ty_generics.as_turbofish();
<span class="kw">let </span>cases = variants.iter().map(|variant| {
<span class="kw">let </span>variant_ident = <span class="kw-2">&amp;</span>variant.ident;
<span class="kw">let </span>placeholders = <span class="kw-2">&amp;</span>(<span class="number">0</span>..variant.fields.len())
.map(|i| <span class="macro">format_ident!</span>(<span class="string">&quot;__v{}&quot;</span>, i))
.collect::&lt;Vec&lt;<span class="kw">_</span>&gt;&gt;();
<span class="kw">let </span>pat = <span class="kw">match </span>variant.style {
Style::Struct =&gt; {
<span class="kw">let </span>members = variant.fields.iter().map(|field| <span class="kw-2">&amp;</span>field.member);
<span class="macro">quote!</span>({ #(#members: #placeholders),* })
}
Style::Tuple | Style::Newtype =&gt; <span class="macro">quote!</span>(( #(#placeholders),* )),
Style::Unit =&gt; <span class="macro">quote!</span>(),
};
<span class="macro">quote! </span>{
<span class="kw">match </span>_serde::__private::None {
_serde::__private::Some((#(#placeholders,)<span class="kw-2">*</span>)) =&gt; {
<span class="kw">let _ </span>= #type_ident::#variant_ident #turbofish #pat;
}
<span class="kw">_ </span>=&gt; {}
}
}
});
<span class="macro">quote!</span>(#(#cases)<span class="kw-2">*</span>)
}
</code></pre></div>
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