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prevent checking redundant_field_names lint on Derived code #17555

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c814fdd
add failing test for `redundant_field_names` issue
azdle Aug 13, 2026
fa40991
prevent checking `redundant_field_names` lint on `Derive`d expressions
azdle Aug 12, 2026
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3 changes: 3 additions & 0 deletions clippy_lints/src/redundant_field_names.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -49,6 +49,9 @@ impl RedundantFieldNames {

impl EarlyLintPass for RedundantFieldNames {
fn check_expr(&mut self, cx: &EarlyContext<'_>, expr: &Expr) {
if expr.span.in_external_macro(cx.sess().source_map()) {
return;
}
Comment on lines +52 to +54

@CommanderStorm CommanderStorm Aug 23, 2026

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usually, there is an is_from_proc_macro check right next to this I think.
Is it purposely ommitted?

if let ExprKind::Struct(ref se) = expr.kind
&& self.msrv.meets(msrvs::FIELD_INIT_SHORTHAND)
{
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18 changes: 18 additions & 0 deletions tests/ui/auxiliary/proc_macro_derive.rs
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Expand Up @@ -243,3 +243,21 @@ pub fn derive_double_parens(_: TokenStream) -> TokenStream {
}
}
}

// This must construct the redundant fields using the input struct's
// identifiers, so that the fields' spans are from outside this macro to be a
// reasonable approximation of real use.
#[proc_macro_derive(ConstructStructWithRedundantFields)]
pub fn derive_construct_struct_with_redundant_fields(input: TokenStream) -> TokenStream {
let syn::ItemStruct { fields, ident, .. } = syn::parse_macro_input!(input);

let field_names: Vec<_> = fields.iter().map(|f| f.ident.as_ref().expect("named field")).collect();
let field_types: Vec<_> = fields.iter().map(|f| &f.ty).collect();

quote::quote! {
pub fn construct_struct_with_redundant_fields(#(#field_names: #field_types),*) -> #ident {
#ident { #(#field_names: #field_names),* }
}
}
.into()
}
7 changes: 7 additions & 0 deletions tests/ui/redundant_field_names.fixed
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@@ -1,4 +1,5 @@
//@aux-build:proc_macros.rs
//@aux-build:proc_macro_derive.rs
#![warn(clippy::redundant_field_names)]
#![expect(clippy::no_effect)]

Expand Down Expand Up @@ -82,6 +83,12 @@ fn main() {
};
}
internal!(v);

// Derive-generated code should not be linted.
#[derive(proc_macro_derive::ConstructStructWithRedundantFields)]
struct DerivedS {
v: usize,
}
}

fn issue_3476() {
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7 changes: 7 additions & 0 deletions tests/ui/redundant_field_names.rs
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@@ -1,4 +1,5 @@
//@aux-build:proc_macros.rs
//@aux-build:proc_macro_derive.rs
#![warn(clippy::redundant_field_names)]
#![expect(clippy::no_effect)]

Expand Down Expand Up @@ -82,6 +83,12 @@ fn main() {
};
}
internal!(v);

// Derive-generated code should not be linted.
#[derive(proc_macro_derive::ConstructStructWithRedundantFields)]
struct DerivedS {
v: usize,
}
}

fn issue_3476() {
Expand Down
18 changes: 9 additions & 9 deletions tests/ui/redundant_field_names.stderr
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@@ -1,5 +1,5 @@
error: redundant field names in struct initialization
--> tests/ui/redundant_field_names.rs:33:9
--> tests/ui/redundant_field_names.rs:34:9
|
LL | gender: gender,
| ^^^^^^^^^^^^^^ help: replace it with: `gender`
Expand All @@ -8,43 +8,43 @@ LL | gender: gender,
= help: to override `-D warnings` add `#[allow(clippy::redundant_field_names)]`

error: redundant field names in struct initialization
--> tests/ui/redundant_field_names.rs:35:9
--> tests/ui/redundant_field_names.rs:36:9
|
LL | age: age,
| ^^^^^^^^ help: replace it with: `age`

error: redundant field names in struct initialization
--> tests/ui/redundant_field_names.rs:56:25
--> tests/ui/redundant_field_names.rs:57:25
|
LL | let _ = RangeFrom { start: start };
| ^^^^^^^^^^^^ help: replace it with: `start`

error: redundant field names in struct initialization
--> tests/ui/redundant_field_names.rs:58:23
--> tests/ui/redundant_field_names.rs:59:23
|
LL | let _ = RangeTo { end: end };
| ^^^^^^^^ help: replace it with: `end`

error: redundant field names in struct initialization
--> tests/ui/redundant_field_names.rs:60:21
--> tests/ui/redundant_field_names.rs:61:21
|
LL | let _ = Range { start: start, end: end };
| ^^^^^^^^^^^^ help: replace it with: `start`

error: redundant field names in struct initialization
--> tests/ui/redundant_field_names.rs:60:35
--> tests/ui/redundant_field_names.rs:61:35
|
LL | let _ = Range { start: start, end: end };
| ^^^^^^^^ help: replace it with: `end`

error: redundant field names in struct initialization
--> tests/ui/redundant_field_names.rs:64:32
--> tests/ui/redundant_field_names.rs:65:32
|
LL | let _ = RangeToInclusive { end: end };
| ^^^^^^^^ help: replace it with: `end`

error: redundant field names in struct initialization
--> tests/ui/redundant_field_names.rs:77:25
--> tests/ui/redundant_field_names.rs:78:25
|
LL | let _ = S { v: v };
| ^^^^ help: replace it with: `v`
Expand All @@ -55,7 +55,7 @@ LL | internal!(v);
= note: this error originates in the macro `internal` (in Nightly builds, run with -Z macro-backtrace for more info)

error: redundant field names in struct initialization
--> tests/ui/redundant_field_names.rs:106:25
--> tests/ui/redundant_field_names.rs:113:25
|
LL | let _ = RangeFrom { start: start };
| ^^^^^^^^^^^^ help: replace it with: `start`
Expand Down