+// Copyright 2014-2018 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
//! Checks for if expressions that contain only an if expression.
//!
//! For example, the lint would catch:
//!
//! This lint is **warn** by default
-use rustc::lint::*;
+use if_chain::if_chain;
+use rustc::lint::{EarlyContext, EarlyLintPass, LintArray, LintPass};
+use rustc::{declare_tool_lint, lint_array};
use syntax::ast;
-use utils::{in_macro, snippet_block, span_lint_and_then};
-use utils::sugg::Sugg;
+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 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
+/// 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
/// …
/// }
/// ```
-declare_lint! {
+declare_clippy_lint! {
pub COLLAPSIBLE_IF,
- Warn,
+ style,
"`if`s that can be collapsed (e.g. `if x { if y { ... } }` and `else { if x { ... } }`)"
}
-#[derive(Copy,Clone)]
+#[derive(Copy, Clone)]
pub struct CollapsibleIf;
impl LintPass for CollapsibleIf {
}
impl EarlyLintPass for CollapsibleIf {
- fn check_expr(&mut self, cx: &EarlyContext, expr: &ast::Expr) {
- if !in_macro(cx, expr.span) {
+ fn check_expr(&mut self, cx: &EarlyContext<'_>, expr: &ast::Expr) {
+ if !in_macro(expr.span) {
check_if(cx, expr)
}
}
}
-fn check_if(cx: &EarlyContext, expr: &ast::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_collapsible_maybe_if_let(cx: &EarlyContext, else_: &ast::Expr) {
- if_let_chain! {[
- let ast::ExprKind::Block(ref block) = else_.node,
- let Some(ref else_) = expr_block(block),
- !in_macro(cx, else_.span),
- ], {
- match else_.node {
- ast::ExprKind::If(..) | ast::ExprKind::IfLet(..) => {
- span_lint_and_then(cx,
- COLLAPSIBLE_IF,
- block.span,
- "this `else { if .. }` block can be collapsed", |db| {
- db.span_suggestion(block.span, "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_.node;
+ if !block_starts_with_comment(cx, block);
+ if let Some(else_) = expr_block(block);
+ if !in_macro(else_.span);
+ 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,
+ );
+ }
+ _ => (),
}
- _ => (),
}
- }}
+ }
}
-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.expn_id != inner.span.expn_id {
- 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.node;
+ 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| {
+ let lhs = Sugg::ast(cx, check, "..");
+ let rhs = Sugg::ast(cx, check_inner, "..");
+ db.span_suggestion_with_applicability(
+ 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.
if let (Some(stmt), None) = (it.next(), it.next()) {
match stmt.node {
- ast::StmtKind::Expr(ref expr) |
- ast::StmtKind::Semi(ref expr) => Some(expr),
+ ast::StmtKind::Expr(ref expr) | ast::StmtKind::Semi(ref expr) => Some(expr),
_ => None,
}
} else {
projects / rust.git / blobdiff