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Introduce REDUNDANT_IMPORTS lint
1 parent 19d0226 commit ddb8dda

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+323
-55
lines changed

‎compiler/rustc_lint_defs/src/builtin.rs‎

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@@ -79,6 +79,7 @@ declare_lint_pass! {
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PROC_MACRO_BACK_COMPAT,
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PROC_MACRO_DERIVE_RESOLUTION_FALLBACK,
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PUB_USE_OF_PRIVATE_EXTERN_CRATE,
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REDUNDANT_IMPORTS,
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REDUNDANT_LIFETIMES,
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REFINING_IMPL_TRAIT_INTERNAL,
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REFINING_IMPL_TRAIT_REACHABLE,
@@ -419,6 +420,29 @@ declare_lint! {
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"imports that are never used"
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}
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declare_lint! {
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/// The `unused_imports` lint detects imports that are redundant due to being
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/// imported already; either through a previous import, or being present in
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/// the prelude.
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///
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/// ### Example
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///
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/// ```rust
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/// use std::option::Option::None;
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/// ```
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///
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/// {{produces}}
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///
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/// ### Explanation
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///
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/// Redundant imports are unnecessary and can be removed to simplify code.
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/// If you intended to re-export the item to make it available outside of the
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/// module, add a visibility modifier like `pub`.
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pub REDUNDANT_IMPORTS,
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Allow,
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"imports that are redundant due to being imported already"
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}
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declare_lint! {
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/// The `must_not_suspend` lint guards against values that shouldn't be held across suspend points
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/// (`.await`)

‎compiler/rustc_resolve/src/imports.rs‎

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@@ -26,7 +26,7 @@ use rustc_middle::span_bug;
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use rustc_middle::ty;
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use rustc_session::lint::builtin::{
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AMBIGUOUS_GLOB_REEXPORTS, HIDDEN_GLOB_REEXPORTS, PUB_USE_OF_PRIVATE_EXTERN_CRATE,
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UNUSED_IMPORTS,
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REDUNDANT_IMPORTS, UNUSED_IMPORTS,
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};
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use rustc_session::lint::BuiltinLintDiag;
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use rustc_span::edit_distance::find_best_match_for_name;
@@ -1391,15 +1391,13 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
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let mut redundant_spans: Vec<_> = redundant_span.present_items().collect();
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redundant_spans.sort();
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redundant_spans.dedup();
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/* FIXME(unused_imports): Add this back as a new lint
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self.lint_buffer.buffer_lint_with_diagnostic(
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UNUSED_IMPORTS,
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REDUNDANT_IMPORTS,
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id,
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import.span,
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format!("the item `{source}` is imported redundantly"),
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BuiltinLintDiag::RedundantImport(redundant_spans, source),
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);
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*/
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return true;
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}
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‎tests/ui/imports/redundant-import-extern-prelude.rs‎

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Original file line numberDiff line numberDiff line change
@@ -1,16 +1,17 @@
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//@ check-pass
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// Check that we detect imports that are redundant due to the extern prelude
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// and that we emit a reasonable diagnostic.
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// issue: rust-lang/rust#121915
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//~^^^ NOTE the item `aux_issue_121915` is already defined by the extern prelude
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// See also the discussion in <https://github.com/rust-lang/rust/pull/122954>.
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//@ compile-flags: --extern aux_issue_121915 --edition 2018
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//@ aux-build: aux-issue-121915.rs
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#[deny(unused_imports)]
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#[deny(redundant_imports)]
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//~^ NOTE the lint level is defined here
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fn main() {
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use aux_issue_121915;
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//FIXME(unused_imports): ~^ ERROR the item `aux_issue_121915` is imported redundantly
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//~^ ERROR the item `aux_issue_121915` is imported redundantly
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aux_issue_121915::item();
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}

‎tests/ui/imports/redundant-import-extern-prelude.stderr‎

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@@ -0,0 +1,14 @@
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error: the item `aux_issue_121915` is imported redundantly
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--> $DIR/redundant-import-extern-prelude.rs:14:9
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|
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LL | use aux_issue_121915;
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| ^^^^^^^^^^^^^^^^ the item `aux_issue_121915` is already defined by the extern prelude
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|
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note: the lint level is defined here
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--> $DIR/redundant-import-extern-prelude.rs:11:8
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|
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LL | #[deny(redundant_imports)]
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| ^^^^^^^^^^^^^^^^^
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error: aborting due to 1 previous error
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‎tests/ui/imports/redundant-import-issue-121915-2015.rs‎

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@@ -1,12 +1,11 @@
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//@ check-pass
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//@ compile-flags: --extern aux_issue_121915 --edition 2015
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//@ aux-build: aux-issue-121915.rs
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extern crate aux_issue_121915;
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7-
#[deny(unused_imports)]
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#[deny(redundant_imports)]
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fn main() {
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use aux_issue_121915;
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//FIXME(unused_imports): ~^ ERROR the item `aux_issue_121915` is imported redundantly
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//~^ ERROR the item `aux_issue_121915` is imported redundantly
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aux_issue_121915::item();
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}

‎tests/ui/imports/redundant-import-issue-121915-2015.stderr‎

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@@ -0,0 +1,17 @@
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error: the item `aux_issue_121915` is imported redundantly
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--> $DIR/redundant-import-issue-121915-2015.rs:8:9
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|
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LL | extern crate aux_issue_121915;
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| ------------------------------ the item `aux_issue_121915` is already imported here
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...
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LL | use aux_issue_121915;
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| ^^^^^^^^^^^^^^^^
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|
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note: the lint level is defined here
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--> $DIR/redundant-import-issue-121915-2015.rs:6:8
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|
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LL | #[deny(redundant_imports)]
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| ^^^^^^^^^^^^^^^^^
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error: aborting due to 1 previous error
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‎tests/ui/imports/redundant-import-lang-prelude-attr.rs‎

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@@ -1,6 +1,6 @@
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//@ check-pass
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// Check that we detect imports (of built-in attributes) that are redundant due to
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// the language prelude and that we emit a reasonable diagnostic.
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//~^^ NOTE the item `allow` is already defined by the extern prelude
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// Note that we use the term "extern prelude" in the label even though "language prelude"
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// would be more correct. However, it's not worth special-casing this.
@@ -9,9 +9,10 @@
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//@ edition: 2018
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#![deny(unused_imports)]
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#![deny(redundant_imports)]
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//~^ NOTE the lint level is defined here
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14-
use allow; //FIXME(unused_imports): ~ ERROR the item `allow` is imported redundantly
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use allow; //~ ERROR the item `allow` is imported redundantly
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#[allow(unused)]
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fn main() {}

‎tests/ui/imports/redundant-import-lang-prelude-attr.stderr‎

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@@ -0,0 +1,14 @@
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error: the item `allow` is imported redundantly
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--> $DIR/redundant-import-lang-prelude-attr.rs:15:5
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|
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LL | use allow;
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| ^^^^^ the item `allow` is already defined by the extern prelude
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|
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note: the lint level is defined here
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--> $DIR/redundant-import-lang-prelude-attr.rs:12:9
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|
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LL | #![deny(redundant_imports)]
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| ^^^^^^^^^^^^^^^^^
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error: aborting due to 1 previous error
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‎tests/ui/imports/redundant-import-lang-prelude.rs‎

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@@ -1,16 +1,17 @@
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//@ check-pass
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// Check that we detect imports that are redundant due to the language prelude
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// and that we emit a reasonable diagnostic.
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//~^^ NOTE the item `u8` is already defined by the extern prelude
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// Note that we use the term "extern prelude" in the label even though "language prelude"
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// would be more correct. However, it's not worth special-casing this.
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// See also the discussion in <https://github.com/rust-lang/rust/pull/122954>.
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10-
#![deny(unused_imports)]
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#![deny(redundant_imports)]
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//~^ NOTE the lint level is defined here
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1213
use std::primitive::u8;
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//FIXME(unused_imports): ~^ ERROR the item `u8` is imported redundantly
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//~^ ERROR the item `u8` is imported redundantly
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const _: u8 = 0;
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‎tests/ui/imports/redundant-import-lang-prelude.stderr‎

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@@ -0,0 +1,14 @@
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error: the item `u8` is imported redundantly
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--> $DIR/redundant-import-lang-prelude.rs:13:5
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|
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LL | use std::primitive::u8;
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| ^^^^^^^^^^^^^^^^^^ the item `u8` is already defined by the extern prelude
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|
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note: the lint level is defined here
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--> $DIR/redundant-import-lang-prelude.rs:10:9
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|
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LL | #![deny(redundant_imports)]
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| ^^^^^^^^^^^^^^^^^
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error: aborting due to 1 previous error
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