59 lines
2.0 KiB
Rust
59 lines
2.0 KiB
Rust
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use syntax::ptr::P;
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use syntax::ast;
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use syntax::ast::*;
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use rustc::lint::{Context, LintPass, LintArray, Lint, Level};
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use syntax::codemap::Span;
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pub struct TypePass;
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declare_lint!(CLIPPY_BOX_VEC, Warn,
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"Warn on usage of Box<Vec<T>>")
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pub fn match_ty_unwrap<'a>(ty: &'a Ty, segments: &[&str]) -> Option<&'a [P<Ty>]> {
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match ty.node {
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TyPath(Path {segments: ref seg, ..}, _, _) => {
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// So ast::Path isn't the full path, just the tokens that were provided.
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// I could muck around with the maps and find the full path
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// however the more efficient way is to simply reverse the iterators and zip them
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// which will compare them in reverse until one of them runs out of segments
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if seg.iter().rev().zip(segments.iter().rev()).all(|(a,b)| a.identifier.as_str() == *b) {
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match seg.as_slice().last() {
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Some(&PathSegment {parameters: AngleBracketedParameters(ref a), ..}) => {
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Some(a.types.as_slice())
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}
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_ => None
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}
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} else {
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None
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}
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},
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_ => None
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}
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}
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fn span_note_and_lint(cx: &Context, lint: &'static Lint, span: Span, msg: &str, note: &str) {
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cx.span_lint(lint, span, msg);
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if cx.current_level(lint) != Level::Allow {
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cx.sess().span_note(span, note);
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}
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}
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impl LintPass for TypePass {
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fn get_lints(&self) -> LintArray {
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lint_array!(CLIPPY_BOX_VEC)
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}
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fn check_ty(&mut self, cx: &Context, ty: &ast::Ty) {
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match_ty_unwrap(ty, &["std", "boxed", "Box"]).and_then(|t| t.head())
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.map(|t| match_ty_unwrap(&**t, &["std", "vec", "Vec"]))
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.map(|_| {
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span_note_and_lint(cx, CLIPPY_BOX_VEC, ty.span,
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"Detected Box<Vec<T>>. Did you mean to use Vec<T>?",
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"Vec<T> is already on the heap, Box<Vec<T>> makes an extra allocation");
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});
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}
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}
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