declare_clippy_lint! {
/// **What it does:** Checks for nested `if` statements which can be collapsed
- /// by `&&`-combining their conditions and for `else { if ... }` expressions
- /// that
- /// can be collapsed to `else if ...`.
+ /// by `&&`-combining their conditions.
///
/// **Why is this bad?** Each `if`-statement adds one level of nesting, which
/// makes code look more complex than it really is.
/// }
/// }
///
- /// // or
+ /// ```
+ ///
+ /// Should be written:
+ ///
+ /// ```rust.ignore
+ /// if x && y {
+ /// …
+ /// }
+ /// ```
+ pub COLLAPSIBLE_IF,
+ style,
+ "nested `if`s that can be collapsed (e.g., `if x { if y { ... } }`"
+}
+
+declare_clippy_lint! {
+ /// **What it does:** Checks for collapsible `else { if ... }` expressions
+ /// that can be collapsed to `else if ...`.
+ ///
+ /// **Why is this bad?** Each `if`-statement adds one level of nesting, which
+ /// makes code look more complex than it really is.
+ ///
+ /// **Known problems:** None.
+ ///
+ /// **Example:**
+ /// ```rust,ignore
///
/// if x {
/// …
/// Should be written:
///
/// ```rust.ignore
- /// if x && y {
- /// …
- /// }
- ///
- /// // or
- ///
/// if x {
/// …
/// } else if y {
/// …
/// }
/// ```
- pub COLLAPSIBLE_IF,
+ pub COLLAPSIBLE_ELSE_IF,
style,
- "`if`s that can be collapsed (e.g., `if x { if y { ... } }` and `else { if x { ... } }`)"
+ "nested `else`-`if` expressions that can be collapsed (e.g., `else { if x { ... } }`)"
}
-declare_lint_pass!(CollapsibleIf => [COLLAPSIBLE_IF]);
+declare_lint_pass!(CollapsibleIf => [COLLAPSIBLE_IF, COLLAPSIBLE_ELSE_IF]);
impl EarlyLintPass for CollapsibleIf {
fn check_expr(&mut self, cx: &EarlyContext<'_>, expr: &ast::Expr) {
if let ast::ExprKind::Block(ref block, _) = else_.kind;
if !block_starts_with_comment(cx, block);
if let Some(else_) = expr_block(block);
+ if else_.attrs.is_empty();
if !else_.span.from_expansion();
if let ast::ExprKind::If(..) = else_.kind;
then {
let mut applicability = Applicability::MachineApplicable;
span_lint_and_sugg(
cx,
- COLLAPSIBLE_IF,
+ COLLAPSIBLE_ELSE_IF,
block.span,
"this `else { if .. }` block can be collapsed",
- "try",
+ "collapse nested if block",
snippet_block_with_applicability(cx, else_.span, "..", Some(block.span), &mut applicability).into_owned(),
applicability,
);
if_chain! {
if !block_starts_with_comment(cx, then);
if let Some(inner) = expr_block(then);
+ if inner.attrs.is_empty();
if let ast::ExprKind::If(ref check_inner, ref content, None) = inner.kind;
+ // Prevent triggering on `if c { if let a = b { .. } }`.
+ if !matches!(check_inner.kind, ast::ExprKind::Let(..));
+ if expr.span.ctxt() == inner.span.ctxt();
then {
- if let ast::ExprKind::Let(..) = check_inner.kind {
- // Prevent triggering on `if c { if let a = b { .. } }`.
- return;
- }
-
- if expr.span.ctxt() != inner.span.ctxt() {
- return;
- }
- span_lint_and_then(cx, COLLAPSIBLE_IF, expr.span, "this `if` statement can be collapsed", |db| {
+ span_lint_and_then(cx, COLLAPSIBLE_IF, expr.span, "this `if` statement can be collapsed", |diag| {
let lhs = Sugg::ast(cx, check, "..");
let rhs = Sugg::ast(cx, check_inner, "..");
- db.span_suggestion(
+ diag.span_suggestion(
expr.span,
- "try",
+ "collapse nested if block",
format!(
"if {} {}",
lhs.and(&rhs),