rust/clippy_lints/src/items_after_statements.rs
Oliver Schneider b25b6b3355
Rustfmt
2017-08-14 09:43:26 +02:00

75 lines
2.0 KiB
Rust

//! lint when items are used after statements
use rustc::lint::*;
use syntax::ast::*;
use utils::{in_macro, span_lint};
/// **What it does:** Checks for items declared after some statement in a block.
///
/// **Why is this bad?** Items live for the entire scope they are declared
/// in. But statements are processed in order. This might cause confusion as
/// it's hard to figure out which item is meant in a statement.
///
/// **Known problems:** None.
///
/// **Example:**
/// ```rust
/// fn foo() {
/// println!("cake");
/// }
///
/// fn main() {
/// foo(); // prints "foo"
/// fn foo() {
/// println!("foo");
/// }
/// foo(); // prints "foo"
/// }
/// ```
declare_lint! {
pub ITEMS_AFTER_STATEMENTS,
Allow,
"blocks where an item comes after a statement"
}
pub struct ItemsAfterStatements;
impl LintPass for ItemsAfterStatements {
fn get_lints(&self) -> LintArray {
lint_array!(ITEMS_AFTER_STATEMENTS)
}
}
impl EarlyLintPass for ItemsAfterStatements {
fn check_block(&mut self, cx: &EarlyContext, item: &Block) {
if in_macro(item.span) {
return;
}
// skip initial items
let stmts = item.stmts.iter().map(|stmt| &stmt.node).skip_while(|s| {
matches!(**s, StmtKind::Item(..))
});
// lint on all further items
for stmt in stmts {
if let StmtKind::Item(ref it) = *stmt {
if in_macro(it.span) {
return;
}
if let ItemKind::MacroDef(..) = it.node {
// do not lint `macro_rules`, but continue processing further statements
continue;
}
span_lint(
cx,
ITEMS_AFTER_STATEMENTS,
it.span,
"adding items after statements is confusing, since items exist from the \
start of the scope",
);
}
}
}
}