63 lines
1.9 KiB
Rust
63 lines
1.9 KiB
Rust
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//! lint when items are used after statements
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use rustc::lint::*;
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use syntax::attr::*;
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use syntax::ast::*;
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use utils::in_macro;
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/// **What it does:** It `Warn`s on blocks where there are items that are declared in the middle of or after the statements
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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 processed in order. This might cause confusion as it's hard to figure out which item is meant 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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declare_lint! { pub ITEMS_AFTER_STATEMENTS, Warn, "finds blocks where an item comes after a statement" }
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pub struct ItemsAfterStatemets;
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impl LintPass for ItemsAfterStatemets {
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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 ItemsAfterStatemets {
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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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let mut stmts = item.stmts.iter().map(|stmt| &stmt.node);
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// skip initial items
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while let Some(&StmtDecl(ref decl, _)) = stmts.next() {
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if let DeclLocal(_) = decl.node {
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break;
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}
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}
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// lint on all further items
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for stmt in stmts {
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if let StmtDecl(ref decl, _) = *stmt {
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if let DeclItem(ref it) = decl.node {
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if in_macro(cx, it.span) {
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return;
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}
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cx.struct_span_lint(ITEMS_AFTER_STATEMENTS, it.span,
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"adding items after statements is confusing, since items exist from the start of the scope")
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.emit();
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}
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}
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}
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}
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}
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