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Merge pull request #280 from Manishearth/fx-279
Only handle ranges starting with 0 for needless_range_loop (fixes #279)
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commit
a9869e6fe4
2 changed files with 30 additions and 20 deletions
46
src/loops.rs
46
src/loops.rs
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@ -37,26 +37,32 @@ impl LintPass for LoopsPass {
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if let Some((pat, arg, body)) = recover_for_loop(expr) {
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// check for looping over a range and then indexing a sequence with it
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// -> the iteratee must be a range literal
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if let ExprRange(_, _) = arg.node {
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// the var must be a single name
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if let PatIdent(_, ref ident, _) = pat.node {
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let mut visitor = VarVisitor { cx: cx, var: ident.node.name,
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indexed: HashSet::new(), nonindex: false };
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walk_expr(&mut visitor, body);
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// linting condition: we only indexed one variable
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if visitor.indexed.len() == 1 {
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let indexed = visitor.indexed.into_iter().next().expect(
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"Len was nonzero, but no contents found");
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if visitor.nonindex {
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span_lint(cx, NEEDLESS_RANGE_LOOP, expr.span, &format!(
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"the loop variable `{}` is used to index `{}`. Consider using \
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`for ({}, item) in {}.iter().enumerate()` or similar iterators",
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ident.node.name, indexed, ident.node.name, indexed));
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} else {
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span_lint(cx, NEEDLESS_RANGE_LOOP, expr.span, &format!(
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"the loop variable `{}` is only used to index `{}`. \
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Consider using `for item in &{}` or similar iterators",
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ident.node.name, indexed, indexed));
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if let ExprRange(Some(ref l), _) = arg.node {
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// Range should start with `0`
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if let ExprLit(ref lit) = l.node {
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if let LitInt(0, _) = lit.node {
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// the var must be a single name
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if let PatIdent(_, ref ident, _) = pat.node {
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let mut visitor = VarVisitor { cx: cx, var: ident.node.name,
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indexed: HashSet::new(), nonindex: false };
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walk_expr(&mut visitor, body);
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// linting condition: we only indexed one variable
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if visitor.indexed.len() == 1 {
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let indexed = visitor.indexed.into_iter().next().expect(
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"Len was nonzero, but no contents found");
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if visitor.nonindex {
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span_lint(cx, NEEDLESS_RANGE_LOOP, expr.span, &format!(
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"the loop variable `{}` is used to index `{}`. Consider using \
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`for ({}, item) in {}.iter().enumerate()` or similar iterators",
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ident.node.name, indexed, ident.node.name, indexed));
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} else {
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span_lint(cx, NEEDLESS_RANGE_LOOP, expr.span, &format!(
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"the loop variable `{}` is only used to index `{}`. \
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Consider using `for item in &{}` or similar iterators",
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ident.node.name, indexed, indexed));
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}
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}
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}
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}
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}
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@ -30,6 +30,10 @@ fn main() {
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println!("{} {}", vec[i], vec2[i]);
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}
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for i in 5..vec.len() { // not an error, not starting with 0
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println!("{}", vec[i]);
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}
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for _v in vec.iter() { } //~ERROR it is more idiomatic to loop over `&vec`
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for _v in vec.iter_mut() { } //~ERROR it is more idiomatic to loop over `&mut vec`
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