36 lines
1.0 KiB
Rust
36 lines
1.0 KiB
Rust
use rustc::lint::{LateContext, LateLintPass, LintArray, LintPass};
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use rustc::middle::ty::TyStruct;
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use rustc_front::hir::{Expr, ExprStruct};
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use utils::span_lint;
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declare_lint! {
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pub NEEDLESS_UPDATE,
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Warn,
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"using `{ ..base }` when there are no missing fields"
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}
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#[derive(Copy, Clone)]
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pub struct NeedlessUpdatePass;
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impl LintPass for NeedlessUpdatePass {
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fn get_lints(&self) -> LintArray {
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lint_array!(NEEDLESS_UPDATE)
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}
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}
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impl LateLintPass for NeedlessUpdatePass {
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fn check_expr(&mut self, cx: &LateContext, expr: &Expr) {
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if let ExprStruct(_, ref fields, Some(ref base)) = expr.node {
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let ty = cx.tcx.expr_ty(expr);
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if let TyStruct(def, _) = ty.sty {
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if fields.len() == def.struct_variant().fields.len() {
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span_lint(cx, NEEDLESS_UPDATE, base.span,
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"struct update has no effect, all the fields \
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in the struct have already been specified");
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}
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}
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}
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}
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}
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