94 lines
3.6 KiB
Rust
94 lines
3.6 KiB
Rust
use crate::utils::sym;
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use crate::utils::{match_def_path, span_lint_and_sugg};
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use if_chain::if_chain;
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use lazy_static::lazy_static;
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use rustc::hir;
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use rustc::hir::def::{DefKind, Res};
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use rustc::lint::{LateContext, LateLintPass, 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::symbol::Symbol;
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declare_clippy_lint! {
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/// **What it does:** Checks for usage of `ATOMIC_X_INIT`, `ONCE_INIT`, and
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/// `uX/iX::MIN/MAX`.
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///
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/// **Why is this bad?** `const fn`s exist
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///
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/// **Known problems:** None.
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///
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/// **Example:**
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/// ```rust
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/// static FOO: AtomicIsize = ATOMIC_ISIZE_INIT;
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/// ```
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///
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/// Could be written:
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///
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/// ```rust
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/// static FOO: AtomicIsize = AtomicIsize::new(0);
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/// ```
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pub REPLACE_CONSTS,
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pedantic,
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"Lint usages of standard library `const`s that could be replaced by `const fn`s"
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}
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declare_lint_pass!(ReplaceConsts => [REPLACE_CONSTS]);
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impl<'a, 'tcx> LateLintPass<'a, 'tcx> for ReplaceConsts {
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fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx hir::Expr) {
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if_chain! {
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if let hir::ExprKind::Path(ref qp) = expr.node;
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if let Res::Def(DefKind::Const, def_id) = cx.tables.qpath_res(qp, expr.hir_id);
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then {
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for (const_path, repl_snip) in REPLACEMENTS.iter() {
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if match_def_path(cx, def_id, const_path) {
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span_lint_and_sugg(
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cx,
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REPLACE_CONSTS,
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expr.span,
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&format!("using `{}`", const_path.last().expect("empty path")),
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"try this",
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repl_snip.to_string(),
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Applicability::MachineApplicable,
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);
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return;
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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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lazy_static! {
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static ref REPLACEMENTS: [([Symbol; 3], &'static str); 25] = [
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// Once
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([*sym::core, *sym::sync, *sym::ONCE_INIT], "Once::new()"),
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// Min
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([*sym::core, *sym::isize, *sym::MIN], "isize::min_value()"),
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([*sym::core, *sym::i8, *sym::MIN], "i8::min_value()"),
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([*sym::core, *sym::i16, *sym::MIN], "i16::min_value()"),
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([*sym::core, *sym::i32, *sym::MIN], "i32::min_value()"),
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([*sym::core, *sym::i64, *sym::MIN], "i64::min_value()"),
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([*sym::core, *sym::i128, *sym::MIN], "i128::min_value()"),
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([*sym::core, *sym::usize, *sym::MIN], "usize::min_value()"),
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([*sym::core, *sym::u8, *sym::MIN], "u8::min_value()"),
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([*sym::core, *sym::u16, *sym::MIN], "u16::min_value()"),
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([*sym::core, *sym::u32, *sym::MIN], "u32::min_value()"),
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([*sym::core, *sym::u64, *sym::MIN], "u64::min_value()"),
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([*sym::core, *sym::u128, *sym::MIN], "u128::min_value()"),
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// Max
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([*sym::core, *sym::isize, *sym::MAX], "isize::max_value()"),
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([*sym::core, *sym::i8, *sym::MAX], "i8::max_value()"),
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([*sym::core, *sym::i16, *sym::MAX], "i16::max_value()"),
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([*sym::core, *sym::i32, *sym::MAX], "i32::max_value()"),
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([*sym::core, *sym::i64, *sym::MAX], "i64::max_value()"),
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([*sym::core, *sym::i128, *sym::MAX], "i128::max_value()"),
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([*sym::core, *sym::usize, *sym::MAX], "usize::max_value()"),
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([*sym::core, *sym::u8, *sym::MAX], "u8::max_value()"),
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([*sym::core, *sym::u16, *sym::MAX], "u16::max_value()"),
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([*sym::core, *sym::u32, *sym::MAX], "u32::max_value()"),
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([*sym::core, *sym::u64, *sym::MAX], "u64::max_value()"),
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([*sym::core, *sym::u128, *sym::MAX], "u128::max_value()"),
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];
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}
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