rust-clippy/clippy_lints/src/items_after_statements.rs
Konrad Borowski 3f62fc3a7e Remove crate:: prefixes from crate paths
This is somewhat misleading, as those are actually external crates,
and don't need a crate:: prefix.
2018-12-29 16:05:49 +01:00

87 lines
2.6 KiB
Rust

// Copyright 2014-2018 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
//! lint when items are used after statements
use crate::utils::{in_macro, span_lint};
use matches::matches;
use rustc::lint::{EarlyContext, EarlyLintPass, LintArray, LintPass};
use rustc::{declare_tool_lint, lint_array};
use syntax::ast::*;
/// **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_clippy_lint! {
pub ITEMS_AFTER_STATEMENTS,
pedantic,
"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",
);
}
}
}
}