89 lines
3.1 KiB
Rust
89 lines
3.1 KiB
Rust
use rustc::lint::*;
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use rustc_front::hir::*;
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use rustc::middle::ty;
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use utils::{snippet, span_lint};
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#[allow(missing_copy_implementations)]
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pub struct EtaPass;
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declare_lint!(pub REDUNDANT_CLOSURE, Warn,
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"using redundant closures, i.e. `|a| foo(a)` (which can be written as just `foo`)");
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impl LintPass for EtaPass {
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fn get_lints(&self) -> LintArray {
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lint_array!(REDUNDANT_CLOSURE)
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}
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}
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impl LateLintPass for EtaPass {
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fn check_expr(&mut self, cx: &LateContext, expr: &Expr) {
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match expr.node {
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ExprCall(_, ref args) |
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ExprMethodCall(_, _, ref args) => {
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for arg in args {
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check_closure(cx, arg)
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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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fn is_adjusted(cx: &LateContext, e: &Expr) -> bool {
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cx.tcx.tables.borrow().adjustments.get(&e.id).is_some()
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}
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fn check_closure(cx: &LateContext, expr: &Expr) {
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if let ExprClosure(_, ref decl, ref blk) = expr.node {
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if !blk.stmts.is_empty() {
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// || {foo(); bar()}; can't be reduced here
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return;
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}
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if let Some(ref ex) = blk.expr {
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if let ExprCall(ref caller, ref args) = ex.node {
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if args.len() != decl.inputs.len() {
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// Not the same number of arguments, there
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// is no way the closure is the same as the function
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return;
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}
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if args.iter().any(|arg| is_adjusted(cx, arg)) {
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// Are the arguments type-adjusted? Then we need the closure
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return;
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}
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let fn_ty = cx.tcx.expr_ty(caller);
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if let ty::TyBareFn(_, fn_ty) = fn_ty.sty {
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// Is it an unsafe function? They don't implement the closure traits
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if fn_ty.unsafety == Unsafety::Unsafe {
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return;
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}
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}
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for (ref a1, ref a2) in decl.inputs.iter().zip(args) {
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if let PatIdent(_, ident, _) = a1.pat.node {
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// XXXManishearth Should I be checking the binding mode here?
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if let ExprPath(None, ref p) = a2.node {
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if p.segments.len() != 1 {
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// If it's a proper path, it can't be a local variable
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return;
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}
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if p.segments[0].identifier != ident.node {
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// The two idents should be the same
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return
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}
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} else {
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return
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}
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} else {
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return
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}
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}
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span_lint(cx, REDUNDANT_CLOSURE, expr.span, &format!(
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"redundant closure found. Consider using `{}` in its place",
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snippet(cx, caller.span, "..")));
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}
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}
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}
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}
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