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Auto merge of #536 - serde-rs:mutempty, r=oli-obk

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Fix "variable does not need to be mutable" warning

Fixes #534.

cc @EliDupree
This commit is contained in:
Homu
2016-09-06 01:10:43 +09:00
parent bf779ea343 e03dedabe4
commit 1ff2053262
2 changed files with 45 additions and 6 deletions
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serde_codegen/src/ser.rs
+35 -6
View File
@@ -4,6 +4,7 @@ use syntax::ast::{self, Ident, MetaItem};
use syntax::codemap::Span;
use syntax::ext::base::{Annotatable, ExtCtxt};
use syntax::ptr::P;
use syntax::tokenstream::TokenTree;
use bound;
use span;
@@ -226,9 +227,10 @@ fn serialize_tuple_struct(
let type_name = name_expr(builder, item_attrs.name());
let len = serialize_stmts.len();
let let_mut = mut_if(cx, len > 0);
quote_block!(cx, {
let mut state = try!(_serializer.serialize_tuple_struct($type_name, $len));
let $let_mut state = try!(_serializer.serialize_tuple_struct($type_name, $len));
$serialize_stmts
_serializer.serialize_tuple_struct_end(state)
}).unwrap()
@@ -253,8 +255,14 @@ fn serialize_struct(
);
let type_name = name_expr(builder, item_attrs.name());
let len = fields.iter()
let mut serialized_fields = fields.iter()
.filter(|&field| !field.attrs.skip_serializing())
.peekable();
let let_mut = mut_if(cx, serialized_fields.peek().is_some());
let len = serialized_fields
.map(|field| {
let ident = field.ident.expect("struct has unnamed fields");
let field_expr = quote_expr!(cx, &self.$ident);
@@ -267,7 +275,7 @@ fn serialize_struct(
.fold(quote_expr!(cx, 0), |sum, expr| quote_expr!(cx, $sum + $expr));
quote_block!(cx, {
let mut state = try!(_serializer.serialize_struct($type_name, $len));
let $let_mut state = try!(_serializer.serialize_struct($type_name, $len));
$serialize_fields
_serializer.serialize_struct_end(state)
}).unwrap()
@@ -458,9 +466,10 @@ fn serialize_tuple_variant(
);
let len = serialize_stmts.len();
let let_mut = mut_if(cx, len > 0);
quote_block!(cx, {
let mut state = try!(_serializer.serialize_tuple_variant($type_name, $variant_index, $variant_name, $len));
let $let_mut state = try!(_serializer.serialize_tuple_variant($type_name, $variant_index, $variant_name, $len));
$serialize_stmts
_serializer.serialize_tuple_variant_end(state)
}).unwrap()
@@ -488,8 +497,14 @@ fn serialize_struct_variant(
);
let item_name = name_expr(builder, item_attrs.name());
let len = fields.iter()
let mut serialized_fields = fields.iter()
.filter(|&field| !field.attrs.skip_serializing())
.peekable();
let let_mut = mut_if(cx, serialized_fields.peek().is_some());
let len = serialized_fields
.map(|field| {
let ident = field.ident.expect("struct has unnamed fields");
let field_expr = quote_expr!(cx, $ident);
@@ -502,7 +517,7 @@ fn serialize_struct_variant(
.fold(quote_expr!(cx, 0), |sum, expr| quote_expr!(cx, $sum + $expr));
quote_block!(cx, {
let mut state = try!(_serializer.serialize_struct_variant(
let $let_mut state = try!(_serializer.serialize_struct_variant(
$item_name,
$variant_index,
$variant_name,
@@ -641,3 +656,17 @@ fn name_expr(
) -> P<ast::Expr> {
builder.expr().str(name.serialize_name())
}
// Serialization of an empty struct results in code like:
//
// let mut state = try!(serializer.serialize_struct("S", 0));
// serializer.serialize_struct_end(state)
//
// where we want to omit the `mut` to avoid a warning.
fn mut_if(cx: &ExtCtxt, is_mut: bool) -> Vec<TokenTree> {
if is_mut {
quote_tokens!(cx, mut)
} else {
Vec::new()
}
}