-use rustc::lint::{LateContext, LateLintPass, LintArray, LintPass};
-use rustc::hir::{Expr, ExprAssign, ExprField, ExprStruct, ExprTup, ExprTupField};
-use utils::is_adjusted;
-use utils::span_lint;
+use clippy_utils::diagnostics::span_lint;
+use clippy_utils::is_adjusted;
+use rustc_hir::{Expr, ExprKind};
+use rustc_lint::{LateContext, LateLintPass};
+use rustc_session::{declare_lint_pass, declare_tool_lint};
-/// **What it does:** Checks for construction of a structure or tuple just to
-/// assign a value in it.
-///
-/// **Why is this bad?** Readability. If the structure is only created to be
-/// updated, why not write the structure you want in the first place?
-///
-/// **Known problems:** None.
-///
-/// **Example:**
-/// ```rust
-/// (0, 0).0 = 1
-/// ```
-declare_lint! {
+declare_clippy_lint! {
+ /// **What it does:** Checks for construction of a structure or tuple just to
+ /// assign a value in it.
+ ///
+ /// **Why is this bad?** Readability. If the structure is only created to be
+ /// updated, why not write the structure you want in the first place?
+ ///
+ /// **Known problems:** None.
+ ///
+ /// **Example:**
+ /// ```rust
+ /// (0, 0).0 = 1
+ /// ```
pub TEMPORARY_ASSIGNMENT,
- Warn,
+ complexity,
"assignments to temporaries"
}
-fn is_temporary(expr: &Expr) -> bool {
- match expr.node {
- ExprStruct(..) | ExprTup(..) => true,
- _ => false,
- }
+fn is_temporary(expr: &Expr<'_>) -> bool {
+ matches!(&expr.kind, ExprKind::Struct(..) | ExprKind::Tup(..))
}
-#[derive(Copy, Clone)]
-pub struct Pass;
+declare_lint_pass!(TemporaryAssignment => [TEMPORARY_ASSIGNMENT]);
-impl LintPass for Pass {
- fn get_lints(&self) -> LintArray {
- lint_array!(TEMPORARY_ASSIGNMENT)
- }
-}
-
-impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass {
- fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) {
- if let ExprAssign(ref target, _) = expr.node {
- match target.node {
- ExprField(ref base, _) |
- ExprTupField(ref base, _) => {
- if is_temporary(base) && !is_adjusted(cx, base) {
- span_lint(cx, TEMPORARY_ASSIGNMENT, expr.span, "assignment to temporary");
- }
- }
- _ => (),
+impl<'tcx> LateLintPass<'tcx> for TemporaryAssignment {
+ fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
+ if let ExprKind::Assign(target, ..) = &expr.kind {
+ let mut base = target;
+ while let ExprKind::Field(f, _) | ExprKind::Index(f, _) = &base.kind {
+ base = f;
+ }
+ if is_temporary(base) && !is_adjusted(cx, base) {
+ span_lint(cx, TEMPORARY_ASSIGNMENT, expr.span, "assignment to temporary");
}
}
}