rust-clippy/clippy_lints/src/items_after_statements.rs

78 lines
2.1 KiB
Rust
Raw Normal View History

2016-01-24 09:16:56 +00:00
//! lint when items are used after statements
2018-07-19 07:24:19 +00:00
use matches::matches;
2018-08-28 11:13:42 +00:00
use rustc::lint::{EarlyContext, EarlyLintPass, LintArray, LintPass};
2018-07-29 09:04:40 +00:00
use rustc::{declare_tool_lint, lint_array};
2016-01-24 09:16:56 +00:00
use syntax::ast::*;
2018-05-30 08:15:50 +00:00
use crate::utils::{in_macro, span_lint};
2016-01-24 09:16:56 +00:00
/// **What it does:** Checks for items declared after some statement in a block.
2016-01-24 09:16:56 +00:00
///
/// **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.
2016-01-24 09:16:56 +00:00
///
/// **Known problems:** None.
2016-01-24 09:16:56 +00:00
///
/// **Example:**
/// ```rust
/// fn foo() {
/// println!("cake");
/// }
2016-07-15 22:25:44 +00:00
///
2016-01-24 09:16:56 +00:00
/// fn main() {
/// foo(); // prints "foo"
/// fn foo() {
/// println!("foo");
/// }
/// foo(); // prints "foo"
/// }
/// ```
2018-03-28 13:24:26 +00:00
declare_clippy_lint! {
pub ITEMS_AFTER_STATEMENTS,
2018-03-28 13:24:26 +00:00
pedantic,
"blocks where an item comes after a statement"
}
2016-01-24 09:16:56 +00:00
pub struct ItemsAfterStatements;
2016-01-24 09:16:56 +00:00
impl LintPass for ItemsAfterStatements {
2016-01-24 09:16:56 +00:00
fn get_lints(&self) -> LintArray {
lint_array!(ITEMS_AFTER_STATEMENTS)
}
}
impl EarlyLintPass for ItemsAfterStatements {
2018-07-23 11:01:12 +00:00
fn check_block(&mut self, cx: &EarlyContext<'_>, item: &Block) {
if in_macro(item.span) {
2016-01-24 09:16:56 +00:00
return;
}
2016-01-24 09:16:56 +00:00
// skip initial items
2017-09-05 09:33:04 +00:00
let stmts = item.stmts
.iter()
.map(|stmt| &stmt.node)
.skip_while(|s| matches!(**s, StmtKind::Item(..)));
2016-01-24 09:16:56 +00:00
// lint on all further items
for stmt in stmts {
if let StmtKind::Item(ref it) = *stmt {
if in_macro(it.span) {
return;
2016-01-24 09:16:56 +00:00
}
if let ItemKind::MacroDef(..) = it.node {
// do not lint `macro_rules`, but continue processing further statements
continue;
}
2017-08-09 07:30:56 +00:00
span_lint(
cx,
ITEMS_AFTER_STATEMENTS,
it.span,
"adding items after statements is confusing, since items exist from the \
2017-09-05 09:33:04 +00:00
start of the scope",
2017-08-09 07:30:56 +00:00
);
2016-01-24 09:16:56 +00:00
}
}
}
}