68 lines
1.8 KiB
Rust
68 lines
1.8 KiB
Rust
//! lint when items are used after statements
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use rustc::lint::*;
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use syntax::ast::*;
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use utils::{in_macro, span_lint};
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/// **What it does:** This lints checks for items declared after some statement in a block
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///
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/// **Why is this bad?** Items live for the entire scope they are declared in. But statements are
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/// processed in order. This might cause confusion as it's hard to figure out which item is meant
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/// in a statement.
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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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/// fn foo() {
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/// println!("cake");
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/// }
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/// fn main() {
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/// foo(); // prints "foo"
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/// fn foo() {
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/// println!("foo");
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/// }
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/// foo(); // prints "foo"
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/// }
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/// ```
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declare_lint! {
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pub ITEMS_AFTER_STATEMENTS,
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Allow,
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"finds blocks where an item comes after a statement"
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}
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pub struct ItemsAfterStatements;
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impl LintPass for ItemsAfterStatements {
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fn get_lints(&self) -> LintArray {
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lint_array!(ITEMS_AFTER_STATEMENTS)
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}
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}
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impl EarlyLintPass for ItemsAfterStatements {
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fn check_block(&mut self, cx: &EarlyContext, item: &Block) {
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if in_macro(cx, item.span) {
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return;
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}
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// skip initial items
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let stmts = item.stmts.iter()
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.map(|stmt| &stmt.node)
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.skip_while(|s| matches!(**s, StmtKind::Item(..)));
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// lint on all further items
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for stmt in stmts {
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if let StmtKind::Item(ref it) = *stmt {
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if in_macro(cx, it.span) {
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return;
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}
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span_lint(cx,
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ITEMS_AFTER_STATEMENTS,
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it.span,
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"adding items after statements is confusing, since items exist from the \
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start of the scope");
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}
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}
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}
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}
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