110 lines
4 KiB
Rust
110 lines
4 KiB
Rust
use syntax::ptr::P;
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use syntax::ast;
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use syntax::ast::*;
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use syntax::visit::{FnKind};
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use rustc::lint::{Context, LintPass, LintArray, Lint, Level};
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use rustc::middle::ty::{mod, expr_ty, ty_str, ty_ptr, ty_rptr};
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use syntax::codemap::Span;
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use types::span_note_and_lint;
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/// Handles uncategorized lints
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/// Currently handles linting of if-let-able matches
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#[allow(missing_copy_implementations)]
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pub struct MiscPass;
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declare_lint!(pub SINGLE_MATCH, Warn,
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"Warn on usage of matches with a single nontrivial arm");
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impl LintPass for MiscPass {
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fn get_lints(&self) -> LintArray {
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lint_array!(SINGLE_MATCH)
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}
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fn check_expr(&mut self, cx: &Context, expr: &Expr) {
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if let ExprMatch(ref ex, ref arms, ast::MatchSource::Normal) = expr.node {
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if arms.len() == 2 {
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if arms[0].guard.is_none() && arms[1].pats.len() == 1 {
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match arms[1].body.node {
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ExprTup(ref v) if v.len() == 0 && arms[1].guard.is_none() => (),
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ExprBlock(ref b) if b.stmts.len() == 0 && arms[1].guard.is_none() => (),
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_ => return
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}
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// In some cases, an exhaustive match is preferred to catch situations when
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// an enum is extended. So we only consider cases where a `_` wildcard is used
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if arms[1].pats[0].node == PatWild(PatWildSingle) && arms[0].pats.len() == 1 {
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let map = cx.sess().codemap();
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span_note_and_lint(cx, SINGLE_MATCH, expr.span,
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"You seem to be trying to use match for destructuring a single type. Did you mean to use `if let`?",
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format!("Try if let {} = {} {{ ... }}",
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map.span_to_snippet(arms[0].pats[0].span).unwrap_or("..".to_string()),
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map.span_to_snippet(ex.span).unwrap_or("..".to_string())).as_slice()
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);
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}
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}
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}
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}
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}
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}
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declare_lint!(pub STR_TO_STRING, Warn, "Warn when a String could use into_string() instead of to_string()");
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#[allow(missing_copy_implementations)]
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pub struct StrToStringPass;
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impl LintPass for StrToStringPass {
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fn get_lints(&self) -> LintArray {
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lint_array!(STR_TO_STRING)
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}
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fn check_expr(&mut self, cx: &Context, expr: &ast::Expr) {
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match expr.node {
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ast::ExprMethodCall(ref method, _, ref args)
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if method.node.as_str() == "to_string"
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&& is_str(cx, &*args[0]) => {
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cx.span_lint(STR_TO_STRING, expr.span, "str.into_string() is faster");
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},
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_ => ()
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}
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fn is_str(cx: &Context, expr: &ast::Expr) -> bool {
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fn walk_ty<'t>(ty: ty::Ty<'t>) -> ty::Ty<'t> {
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//println!("{}: -> {}", depth, ty);
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match ty.sty {
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ty_ptr(ref tm) | ty_rptr(_, ref tm) => walk_ty(tm.ty),
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_ => ty
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}
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}
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match walk_ty(expr_ty(cx.tcx, expr)).sty {
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ty_str => true,
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_ => false
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}
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}
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}
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}
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declare_lint!(pub TOPLEVEL_REF_ARG, Warn, "Warn about pattern matches with top-level `ref` bindings");
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#[allow(missing_copy_implementations)]
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pub struct TopLevelRefPass;
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impl LintPass for TopLevelRefPass {
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fn get_lints(&self) -> LintArray {
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lint_array!(TOPLEVEL_REF_ARG)
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}
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fn check_fn(&mut self, cx: &Context, _: FnKind, decl: &FnDecl, _: &Block, _: Span, _: NodeId) {
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for ref arg in decl.inputs.iter() {
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if let PatIdent(BindByRef(_), _, _) = arg.pat.node {
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cx.span_lint(
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TOPLEVEL_REF_ARG,
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arg.pat.span,
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"`ref` directly on a function argument is ignored. Have you considered using a reference type instead?"
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);
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}
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}
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}
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}
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