bjoernager/rust
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Don't generate unecessary &&self.field in deriving Debug

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This commit is contained in:
clubby789 2023-02-02 15:39:00 +00:00
parent a9985cf172
commit d8651aae22
2 changed files with 27 additions and 12 deletions
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25
compiler/rustc_builtin_macros/src/deriving/debug.rs
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@ -76,6 +76,21 @@ fn show_substructure(cx: &mut ExtCtxt<'_>, span: Span, substr: &Substructure<'_>
// The number of fields that can be handled without an array.
const CUTOFF: usize = 5;
fn expr_for_field(
cx: &ExtCtxt<'_>,
field: &FieldInfo,
index: usize,
len: usize,
) -> ast::ptr::P<ast::Expr> {
if index < len - 1 {
field.self_expr.clone()
} else {
// Unsized types need an extra indirection, but only the last field
// may be unsized.
cx.expr_addr_of(field.span, field.self_expr.clone())
}
}
if fields.is_empty() {
// Special case for no fields.
let fn_path_write_str = cx.std_path(&[sym::fmt, sym::Formatter, sym::write_str]);
@ -98,8 +113,8 @@ fn show_substructure(cx: &mut ExtCtxt<'_>, span: Span, substr: &Substructure<'_>
let name = cx.expr_str(field.span, field.name.unwrap().name);
args.push(name);
}
// Use an extra indirection to make sure this works for unsized types.
let field = cx.expr_addr_of(field.span, field.self_expr.clone());
let field = expr_for_field(cx, field, i, fields.len());
args.push(field);
}
let expr = cx.expr_call_global(span, fn_path_debug, args);
@ -109,13 +124,13 @@ fn show_substructure(cx: &mut ExtCtxt<'_>, span: Span, substr: &Substructure<'_>
let mut name_exprs = Vec::with_capacity(fields.len());
let mut value_exprs = Vec::with_capacity(fields.len());
for field in fields {
for i in 0..fields.len() {
let field = &fields[i];
if is_struct {
name_exprs.push(cx.expr_str(field.span, field.name.unwrap().name));
}
// Use an extra indirection to make sure this works for unsized types.
let field = cx.expr_addr_of(field.span, field.self_expr.clone());
let field = expr_for_field(cx, field, i, fields.len());
value_exprs.push(field);
}