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Add lint for statics with explicit static lifetime.
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‎CHANGELOG.md

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@@ -1087,6 +1087,7 @@ All notable changes to this project will be documented in this file.
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[`single_match`]: https://rust-lang.github.io/rust-clippy/master/index.html#single_match
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[`single_match_else`]: https://rust-lang.github.io/rust-clippy/master/index.html#single_match_else
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[`slow_vector_initialization`]: https://rust-lang.github.io/rust-clippy/master/index.html#slow_vector_initialization
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[`static_static_lifetime`]: https://rust-lang.github.io/rust-clippy/master/index.html#static_static_lifetime
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[`str_to_string`]: https://rust-lang.github.io/rust-clippy/master/index.html#str_to_string
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[`string_add`]: https://rust-lang.github.io/rust-clippy/master/index.html#string_add
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[`string_add_assign`]: https://rust-lang.github.io/rust-clippy/master/index.html#string_add_assign

‎README.md

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@@ -7,7 +7,7 @@
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A collection of lints to catch common mistakes and improve your [Rust](https://github.com/rust-lang/rust) code.
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[There are 304 lints included in this crate!](https://rust-lang.github.io/rust-clippy/master/index.html)
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[There are 305 lints included in this crate!](https://rust-lang.github.io/rust-clippy/master/index.html)
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We have a bunch of lint categories to allow you to choose how much Clippy is supposed to ~~annoy~~ help you:
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‎clippy_lints/src/lib.rs

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@@ -255,6 +255,7 @@ pub mod returns;
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pub mod serde_api;
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pub mod shadow;
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pub mod slow_vector_initialization;
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pub mod static_static_lifetime;
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pub mod strings;
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pub mod suspicious_trait_impl;
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pub mod swap;
@@ -553,6 +554,7 @@ pub fn register_plugins(reg: &mut rustc_plugin::Registry<'_>, conf: &Conf) {
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reg.register_late_lint_pass(box identity_conversion::IdentityConversion::default());
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reg.register_late_lint_pass(box types::ImplicitHasher);
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reg.register_early_lint_pass(box const_static_lifetime::StaticConst);
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reg.register_early_lint_pass(box static_static_lifetime::StaticStatic);
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reg.register_late_lint_pass(box fallible_impl_from::FallibleImplFrom);
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reg.register_late_lint_pass(box replace_consts::ReplaceConsts);
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reg.register_late_lint_pass(box types::UnitArg);
@@ -841,6 +843,7 @@ pub fn register_plugins(reg: &mut rustc_plugin::Registry<'_>, conf: &Conf) {
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returns::UNUSED_UNIT,
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serde_api::SERDE_API_MISUSE,
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slow_vector_initialization::SLOW_VECTOR_INITIALIZATION,
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static_static_lifetime::STATIC_STATIC_LIFETIME,
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strings::STRING_LIT_AS_BYTES,
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suspicious_trait_impl::SUSPICIOUS_ARITHMETIC_IMPL,
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suspicious_trait_impl::SUSPICIOUS_OP_ASSIGN_IMPL,
@@ -959,6 +962,7 @@ pub fn register_plugins(reg: &mut rustc_plugin::Registry<'_>, conf: &Conf) {
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returns::LET_AND_RETURN,
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returns::NEEDLESS_RETURN,
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returns::UNUSED_UNIT,
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static_static_lifetime::STATIC_STATIC_LIFETIME,
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strings::STRING_LIT_AS_BYTES,
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types::FN_TO_NUMERIC_CAST,
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types::FN_TO_NUMERIC_CAST_WITH_TRUNCATION,

‎clippy_lints/src/static_static_lifetime.rs

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use crate::utils::{in_macro_or_desugar, snippet, span_lint_and_then};
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use rustc::lint::{EarlyContext, EarlyLintPass, LintArray, LintPass};
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use rustc::{declare_lint_pass, declare_tool_lint};
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use rustc_errors::Applicability;
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use syntax::ast::*;
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declare_clippy_lint! {
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/// **What it does:** Checks for statics with an explicit `'static` lifetime.
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///
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/// **Why is this bad?** Adding `'static` to every reference can create very
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/// complicated types.
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///
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/// **Known problems:** None.
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///
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/// **Example:**
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/// ```ignore
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/// static FOO: &'static [(&'static str, &'static str, fn(&Bar) -> bool)] =
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/// &[...]
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/// ```
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/// This code can be rewritten as
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/// ```ignore
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/// static FOO: &[(&str, &str, fn(&Bar) -> bool)] = &[...]
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/// ```
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pub STATIC_STATIC_LIFETIME,
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style,
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"Using explicit `'static` lifetime for statics when elision rules would allow omitting them."
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}
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declare_lint_pass!(StaticStatic => [STATIC_STATIC_LIFETIME]);
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impl StaticStatic {
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// Recursively visit types
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fn visit_type(&mut self, ty: &Ty, cx: &EarlyContext<'_>) {
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match ty.node {
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// Be careful of nested structures (arrays and tuples)
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TyKind::Array(ref ty, _) => {
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self.visit_type(&*ty, cx);
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},
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TyKind::Tup(ref tup) => {
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for tup_ty in tup {
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self.visit_type(&*tup_ty, cx);
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}
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},
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// This is what we are looking for !
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TyKind::Rptr(ref optional_lifetime, ref borrow_type) => {
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// Match the 'static lifetime
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if let Some(lifetime) = *optional_lifetime {
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match borrow_type.ty.node {
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TyKind::Path(..) | TyKind::Slice(..) | TyKind::Array(..) | TyKind::Tup(..) => {
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if lifetime.ident.name == syntax::symbol::kw::StaticLifetime {
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let snip = snippet(cx, borrow_type.ty.span, "<type>");
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let sugg = format!("&{}", snip);
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span_lint_and_then(
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cx,
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STATIC_STATIC_LIFETIME,
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lifetime.ident.span,
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"Statics have by default a `'static` lifetime",
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|db| {
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db.span_suggestion(
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ty.span,
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"consider removing `'static`",
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sugg,
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Applicability::MachineApplicable, //snippet
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);
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},
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);
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}
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},
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_ => {},
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}
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}
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self.visit_type(&*borrow_type.ty, cx);
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},
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TyKind::Slice(ref ty) => {
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self.visit_type(ty, cx);
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},
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_ => {},
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}
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}
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}
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impl EarlyLintPass for StaticStatic {
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fn check_item(&mut self, cx: &EarlyContext<'_>, item: &Item) {
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if !in_macro_or_desugar(item.span) {
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// Match only statics...
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if let ItemKind::Static(ref var_type, _, _) = item.node {
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self.visit_type(var_type, cx);
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}
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}
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}
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// Don't check associated consts because `'static` cannot be elided on those (issue #2438)
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}

‎tests/ui/static_static_lifetime.rs

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#[derive(Debug)]
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struct Foo {}
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static VAR_ONE: &'static str = "Test static #1"; // ERROR Consider removing 'static.
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static VAR_TWO: &str = "Test static #2"; // This line should not raise a warning.
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static VAR_THREE: &[&'static str] = &["one", "two"]; // ERROR Consider removing 'static
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static VAR_FOUR: (&str, (&str, &'static str), &'static str) = ("on", ("th", "th"), "on"); // ERROR Consider removing 'static
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static VAR_FIVE: &'static [&[&'static str]] = &[&["test"], &["other one"]]; // ERROR Consider removing 'static
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static VAR_SIX: &'static u8 = &5;
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static VAR_SEVEN: &[&(&str, &'static [&'static str])] = &[&("one", &["other one"])];
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static VAR_HEIGHT: &'static Foo = &Foo {};
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static VAR_SLICE: &'static [u8] = b"Test static #3"; // ERROR Consider removing 'static.
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static VAR_TUPLE: &'static (u8, u8) = &(1, 2); // ERROR Consider removing 'static.
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static VAR_ARRAY: &'static [u8; 1] = b"T"; // ERROR Consider removing 'static.
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fn main() {
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let false_positive: &'static str = "test";
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println!("{}", VAR_ONE);
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println!("{}", VAR_TWO);
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println!("{:?}", VAR_THREE);
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println!("{:?}", VAR_FOUR);
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println!("{:?}", VAR_FIVE);
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println!("{:?}", VAR_SIX);
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println!("{:?}", VAR_SEVEN);
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println!("{:?}", VAR_HEIGHT);
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println!("{}", false_positive);
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}
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// trait Bar {
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// static TRAIT_VAR: &'static str;
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// }
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// impl Foo {
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// static IMPL_VAR: &'static str = "var";
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// }
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// impl Bar for Foo {
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// static TRAIT_VAR: &'static str = "foo";
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// }

‎tests/ui/static_static_lifetime.stderr

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error: Statics have by default a `'static` lifetime
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--> $DIR/static_static_lifetime.rs:4:18
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|
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LL | static VAR_ONE: &'static str = "Test static #1"; // ERROR Consider removing 'static.
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| -^^^^^^^---- help: consider removing `'static`: `&str`
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|
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= note: `-D clippy::static-static-lifetime` implied by `-D warnings`
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error: Statics have by default a `'static` lifetime
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--> $DIR/static_static_lifetime.rs:8:22
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|
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LL | static VAR_THREE: &[&'static str] = &["one", "two"]; // ERROR Consider removing 'static
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| -^^^^^^^---- help: consider removing `'static`: `&str`
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error: Statics have by default a `'static` lifetime
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--> $DIR/static_static_lifetime.rs:10:33
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|
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LL | static VAR_FOUR: (&str, (&str, &'static str), &'static str) = ("on", ("th", "th"), "on"); // ERROR Consider removing 'static
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| -^^^^^^^---- help: consider removing `'static`: `&str`
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error: Statics have by default a `'static` lifetime
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--> $DIR/static_static_lifetime.rs:10:48
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|
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LL | static VAR_FOUR: (&str, (&str, &'static str), &'static str) = ("on", ("th", "th"), "on"); // ERROR Consider removing 'static
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| -^^^^^^^---- help: consider removing `'static`: `&str`
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error: Statics have by default a `'static` lifetime
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--> $DIR/static_static_lifetime.rs:12:19
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|
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LL | static VAR_FIVE: &'static [&[&'static str]] = &[&["test"], &["other one"]]; // ERROR Consider removing 'static
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| -^^^^^^^------------------ help: consider removing `'static`: `&[&[&'static str]]`
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error: Statics have by default a `'static` lifetime
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--> $DIR/static_static_lifetime.rs:12:31
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|
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LL | static VAR_FIVE: &'static [&[&'static str]] = &[&["test"], &["other one"]]; // ERROR Consider removing 'static
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| -^^^^^^^---- help: consider removing `'static`: `&str`
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error: Statics have by default a `'static` lifetime
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--> $DIR/static_static_lifetime.rs:14:18
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|
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LL | static VAR_SIX: &'static u8 = &5;
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| -^^^^^^^--- help: consider removing `'static`: `&u8`
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error: Statics have by default a `'static` lifetime
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--> $DIR/static_static_lifetime.rs:16:30
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|
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LL | static VAR_SEVEN: &[&(&str, &'static [&'static str])] = &[&("one", &["other one"])];
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| -^^^^^^^--------------- help: consider removing `'static`: `&[&'static str]`
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error: Statics have by default a `'static` lifetime
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--> $DIR/static_static_lifetime.rs:16:40
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|
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LL | static VAR_SEVEN: &[&(&str, &'static [&'static str])] = &[&("one", &["other one"])];
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| -^^^^^^^---- help: consider removing `'static`: `&str`
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error: Statics have by default a `'static` lifetime
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--> $DIR/static_static_lifetime.rs:18:21
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|
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LL | static VAR_HEIGHT: &'static Foo = &Foo {};
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| -^^^^^^^---- help: consider removing `'static`: `&Foo`
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error: Statics have by default a `'static` lifetime
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--> $DIR/static_static_lifetime.rs:20:20
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|
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LL | static VAR_SLICE: &'static [u8] = b"Test static #3"; // ERROR Consider removing 'static.
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| -^^^^^^^----- help: consider removing `'static`: `&[u8]`
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error: Statics have by default a `'static` lifetime
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--> $DIR/static_static_lifetime.rs:22:20
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|
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LL | static VAR_TUPLE: &'static (u8, u8) = &(1, 2); // ERROR Consider removing 'static.
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| -^^^^^^^--------- help: consider removing `'static`: `&(u8, u8)`
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error: Statics have by default a `'static` lifetime
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--> $DIR/static_static_lifetime.rs:24:20
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|
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LL | static VAR_ARRAY: &'static [u8; 1] = b"T"; // ERROR Consider removing 'static.
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| -^^^^^^^-------- help: consider removing `'static`: `&[u8; 1]`
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error: aborting due to 13 previous errors
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