//! This lint is **warn** by default
use if_chain::if_chain;
-use rustc::lint::{EarlyContext, EarlyLintPass, LintArray, LintPass};
-use rustc::{declare_tool_lint, lint_array};
-use syntax::ast;
+use rustc_ast::ast;
+use rustc_lint::{EarlyContext, EarlyLintPass};
+use rustc_session::{declare_lint_pass, declare_tool_lint};
use crate::utils::sugg::Sugg;
-use crate::utils::{in_macro, snippet_block, snippet_block_with_applicability, span_lint_and_sugg, span_lint_and_then};
+use crate::utils::{snippet_block, snippet_block_with_applicability, span_lint_and_sugg, span_lint_and_then};
use rustc_errors::Applicability;
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 { ... } }`)"
}
-#[derive(Copy, Clone)]
-pub struct CollapsibleIf;
-
-impl LintPass for CollapsibleIf {
- fn get_lints(&self) -> LintArray {
- lint_array!(COLLAPSIBLE_IF)
- }
-
- fn name(&self) -> &'static str {
- "CollapsibleIf"
- }
-}
+declare_lint_pass!(CollapsibleIf => [COLLAPSIBLE_IF, COLLAPSIBLE_ELSE_IF]);
impl EarlyLintPass for CollapsibleIf {
fn check_expr(&mut self, cx: &EarlyContext<'_>, expr: &ast::Expr) {
- if !in_macro(expr.span) {
+ if !expr.span.from_expansion() {
check_if(cx, expr)
}
}
}
fn check_if(cx: &EarlyContext<'_>, expr: &ast::Expr) {
- match expr.node {
- ast::ExprKind::If(ref check, ref then, ref else_) => {
- if let Some(ref else_) = *else_ {
- check_collapsible_maybe_if_let(cx, else_);
- } else {
- check_collapsible_no_if_let(cx, expr, check, then);
- }
- },
- ast::ExprKind::IfLet(_, _, _, Some(ref else_)) => {
+ if let ast::ExprKind::If(check, then, else_) = &expr.kind {
+ if let Some(else_) = else_ {
check_collapsible_maybe_if_let(cx, else_);
- },
- _ => (),
+ } else if let ast::ExprKind::Let(..) = check.kind {
+ // Prevent triggering on `if let a = b { if c { .. } }`.
+ } else {
+ check_collapsible_no_if_let(cx, expr, check, then);
+ }
}
}
fn block_starts_with_comment(cx: &EarlyContext<'_>, expr: &ast::Block) -> bool {
// We trim all opening braces and whitespaces and then check if the next string is a comment.
- let trimmed_block_text = snippet_block(cx, expr.span, "..")
+ let trimmed_block_text = snippet_block(cx, expr.span, "..", None)
.trim_start_matches(|c: char| c.is_whitespace() || c == '{')
.to_owned();
trimmed_block_text.starts_with("//") || trimmed_block_text.starts_with("/*")
fn check_collapsible_maybe_if_let(cx: &EarlyContext<'_>, else_: &ast::Expr) {
if_chain! {
- if let ast::ExprKind::Block(ref block, _) = else_.node;
+ if let ast::ExprKind::Block(ref block, _) = else_.kind;
if !block_starts_with_comment(cx, block);
if let Some(else_) = expr_block(block);
- if !in_macro(else_.span);
+ if else_.attrs.is_empty();
+ if !else_.span.from_expansion();
+ if let ast::ExprKind::If(..) = else_.kind;
then {
- match else_.node {
- ast::ExprKind::If(..) | ast::ExprKind::IfLet(..) => {
- let mut applicability = Applicability::MachineApplicable;
- span_lint_and_sugg(
- cx,
- COLLAPSIBLE_IF,
- block.span,
- "this `else { if .. }` block can be collapsed",
- "try",
- snippet_block_with_applicability(cx, else_.span, "..", &mut applicability).into_owned(),
- applicability,
- );
- }
- _ => (),
- }
+ let mut applicability = Applicability::MachineApplicable;
+ span_lint_and_sugg(
+ cx,
+ COLLAPSIBLE_ELSE_IF,
+ block.span,
+ "this `else { if .. }` block can be collapsed",
+ "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 let ast::ExprKind::If(ref check_inner, ref content, None) = inner.node;
+ 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 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),
- snippet_block(cx, content.span, ".."),
+ snippet_block(cx, content.span, "..", Some(expr.span)),
),
Applicability::MachineApplicable, // snippet
);
let mut it = block.stmts.iter();
if let (Some(stmt), None) = (it.next(), it.next()) {
- match stmt.node {
+ match stmt.kind {
ast::StmtKind::Expr(ref expr) | ast::StmtKind::Semi(ref expr) => Some(expr),
_ => None,
}