//!
//! This lint is **warn** by default
-use rustc::lint::*;
+use if_chain::if_chain;
+use rustc::declare_lint_pass;
+use rustc::lint::{EarlyContext, EarlyLintPass, LintArray, LintPass};
+use rustc_session::declare_tool_lint;
use syntax::ast;
-use utils::{in_macro, snippet_block, span_lint_and_sugg, span_lint_and_then};
-use utils::sugg::Sugg;
+use crate::utils::sugg::Sugg;
+use crate::utils::{snippet_block, snippet_block_with_applicability, span_lint_and_sugg, span_lint_and_then};
+use rustc_errors::Applicability;
-/// **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 ...`.
-///
-/// **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 {
-/// if y {
-/// …
-/// }
-/// }
-///
-/// // or
-///
-/// if x {
-/// …
-/// } else {
-/// if y {
-/// …
-/// }
-/// }
-/// ```
-///
-/// Should be written:
-///
-/// ```rust.ignore
-/// if x && y {
-/// …
-/// }
-///
-/// // or
-///
-/// if x {
-/// …
-/// } else if y {
-/// …
-/// }
-/// ```
-declare_lint! {
+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 ...`.
+ ///
+ /// **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 {
+ /// if y {
+ /// …
+ /// }
+ /// }
+ ///
+ /// // or
+ ///
+ /// if x {
+ /// …
+ /// } else {
+ /// if y {
+ /// …
+ /// }
+ /// }
+ /// ```
+ ///
+ /// Should be written:
+ ///
+ /// ```rust.ignore
+ /// if x && y {
+ /// …
+ /// }
+ ///
+ /// // or
+ ///
+ /// if x {
+ /// …
+ /// } else if y {
+ /// …
+ /// }
+ /// ```
pub COLLAPSIBLE_IF,
- Warn,
- "`if`s that can be collapsed (e.g. `if x { if y { ... } }` and `else { if x { ... } }`)"
+ style,
+ "`if`s that can be collapsed (e.g., `if x { if y { ... } }` and `else { if x { ... } }`)"
}
-#[derive(Copy, Clone)]
-pub struct CollapsibleIf;
-
-impl LintPass for CollapsibleIf {
- fn get_lints(&self) -> LintArray {
- lint_array!(COLLAPSIBLE_IF)
- }
-}
+declare_lint_pass!(CollapsibleIf => [COLLAPSIBLE_IF]);
impl EarlyLintPass for CollapsibleIf {
- fn check_expr(&mut self, cx: &EarlyContext, expr: &ast::Expr) {
- if !in_macro(expr.span) {
+ fn check_expr(&mut self, cx: &EarlyContext<'_>, expr: &ast::Expr) {
+ 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_ {
+fn check_if(cx: &EarlyContext<'_>, expr: &ast::Expr) {
+ 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);
- },
- ast::ExprKind::IfLet(_, _, _, Some(ref else_)) => {
- check_collapsible_maybe_if_let(cx, else_);
- },
- _ => (),
+ }
}
}
-fn check_collapsible_maybe_if_let(cx: &EarlyContext, else_: &ast::Expr) {
- if_let_chain! {[
- let ast::ExprKind::Block(ref block) = else_.node,
- let Some(else_) = expr_block(block),
- !in_macro(else_.span),
- ], {
- match else_.node {
- ast::ExprKind::If(..) | ast::ExprKind::IfLet(..) => {
- span_lint_and_sugg(cx,
- COLLAPSIBLE_IF,
- block.span,
- "this `else { if .. }` block can be collapsed",
- "try",
- snippet_block(cx, else_.span, "..").into_owned());
- }
- _ => (),
+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, "..")
+ .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_.kind;
+ if !block_starts_with_comment(cx, block);
+ if let Some(else_) = expr_block(block);
+ 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,
+ block.span,
+ "this `else { if .. }` block can be collapsed",
+ "try",
+ snippet_block_with_applicability(cx, else_.span, "..", &mut applicability).into_owned(),
+ applicability,
+ );
}
- }}
+ }
}
-fn check_collapsible_no_if_let(cx: &EarlyContext, expr: &ast::Expr, check: &ast::Expr, then: &ast::Block) {
- if_let_chain! {[
- let Some(inner) = expr_block(then),
- let ast::ExprKind::If(ref check_inner, ref content, None) = inner.node,
- ], {
- if expr.span.ctxt() != inner.span.ctxt() {
- return;
+fn check_collapsible_no_if_let(cx: &EarlyContext<'_>, expr: &ast::Expr, check: &ast::Expr, then: &ast::Block) {
+ 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.kind;
+ 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| {
+ let lhs = Sugg::ast(cx, check, "..");
+ let rhs = Sugg::ast(cx, check_inner, "..");
+ db.span_suggestion(
+ expr.span,
+ "try",
+ format!(
+ "if {} {}",
+ lhs.and(&rhs),
+ snippet_block(cx, content.span, ".."),
+ ),
+ Applicability::MachineApplicable, // snippet
+ );
+ });
}
- span_lint_and_then(cx, COLLAPSIBLE_IF, expr.span, "this if statement can be collapsed", |db| {
- let lhs = Sugg::ast(cx, check, "..");
- let rhs = Sugg::ast(cx, check_inner, "..");
- db.span_suggestion(expr.span,
- "try",
- format!("if {} {}",
- lhs.and(rhs),
- snippet_block(cx, content.span, "..")));
- });
- }}
+ }
}
/// If the block contains only one expression, return it.
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,
}
projects / rust.git / blobdiff