rust/clippy_lints/src/enum_glob_use.rs

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//! lint on `use`ing all variants of an enum
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use crate::utils::span_lint;
use rustc::hir::def::Def;
use rustc::hir::*;
use rustc::lint::{LateContext, LateLintPass, LintArray, LintPass};
use rustc::{declare_tool_lint, lint_array};
use syntax::ast::NodeId;
use syntax::source_map::Span;
/// **What it does:** Checks for `use Enum::*`.
///
/// **Why is this bad?** It is usually better style to use the prefixed name of
/// an enumeration variant, rather than importing variants.
///
/// **Known problems:** Old-style enumerations that prefix the variants are
/// still around.
///
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/// **Example:**
/// ```rust
/// use std::cmp::Ordering::*;
/// ```
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declare_clippy_lint! {
pub ENUM_GLOB_USE,
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pedantic,
"use items that import all variants of an enum"
}
pub struct EnumGlobUse;
impl LintPass for EnumGlobUse {
fn get_lints(&self) -> LintArray {
lint_array!(ENUM_GLOB_USE)
}
fn name(&self) -> &'static str {
"EnumGlobUse"
}
}
impl<'a, 'tcx> LateLintPass<'a, 'tcx> for EnumGlobUse {
fn check_mod(&mut self, cx: &LateContext<'a, 'tcx>, m: &'tcx Mod, _: Span, _: NodeId) {
// only check top level `use` statements
for item in &m.item_ids {
self.lint_item(cx, cx.tcx.hir().expect_item(item.id));
}
}
}
impl EnumGlobUse {
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fn lint_item(&self, cx: &LateContext<'_, '_>, item: &Item) {
if item.vis.node.is_pub() {
return; // re-exports are fine
}
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if let ItemKind::Use(ref path, UseKind::Glob) = item.node {
if let Def::Enum(_) = path.def {
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span_lint(cx, ENUM_GLOB_USE, item.span, "don't use glob imports for enum variants");
}
}
}
}