// 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 or the MIT license // , at your // option. This file may not be copied, modified, or distributed // except according to those terms. use crate::rustc::lint::{EarlyContext, EarlyLintPass, LintArray, LintPass}; use crate::rustc::{declare_tool_lint, lint_array}; use crate::syntax::ast; use crate::utils::{differing_macro_contexts, in_macro, snippet_opt, span_note_and_lint}; use crate::syntax::ptr::P; /// **What it does:** Checks for use of the non-existent `=*`, `=!` and `=-` /// operators. /// /// **Why is this bad?** This is either a typo of `*=`, `!=` or `-=` or /// confusing. /// /// **Known problems:** None. /// /// **Example:** /// ```rust,ignore /// a =- 42; // confusing, should it be `a -= 42` or `a = -42`? /// ``` declare_clippy_lint! { pub SUSPICIOUS_ASSIGNMENT_FORMATTING, style, "suspicious formatting of `*=`, `-=` or `!=`" } /// **What it does:** Checks for formatting of `else if`. It lints if the `else` /// and `if` are not on the same line or the `else` seems to be missing. /// /// **Why is this bad?** This is probably some refactoring remnant, even if the /// code is correct, it might look confusing. /// /// **Known problems:** None. /// /// **Example:** /// ```rust,ignore /// if foo { /// } if bar { // looks like an `else` is missing here /// } /// /// if foo { /// } else /// /// if bar { // this is the `else` block of the previous `if`, but should it be? /// } /// ``` declare_clippy_lint! { pub SUSPICIOUS_ELSE_FORMATTING, style, "suspicious formatting of `else if`" } /// **What it does:** Checks for possible missing comma in an array. It lints if /// an array element is a binary operator expression and it lies on two lines. /// /// **Why is this bad?** This could lead to unexpected results. /// /// **Known problems:** None. /// /// **Example:** /// ```rust,ignore /// let a = &[ /// -1, -2, -3 // <= no comma here /// -4, -5, -6 /// ]; /// ``` declare_clippy_lint! { pub POSSIBLE_MISSING_COMMA, correctness, "possible missing comma in array" } #[derive(Copy, Clone)] pub struct Formatting; impl LintPass for Formatting { fn get_lints(&self) -> LintArray { lint_array!( SUSPICIOUS_ASSIGNMENT_FORMATTING, SUSPICIOUS_ELSE_FORMATTING, POSSIBLE_MISSING_COMMA ) } } impl EarlyLintPass for Formatting { fn check_block(&mut self, cx: &EarlyContext<'_>, block: &ast::Block) { for w in block.stmts.windows(2) { match (&w[0].node, &w[1].node) { (&ast::StmtKind::Expr(ref first), &ast::StmtKind::Expr(ref second)) | (&ast::StmtKind::Expr(ref first), &ast::StmtKind::Semi(ref second)) => { check_consecutive_ifs(cx, first, second); }, _ => (), } } } fn check_expr(&mut self, cx: &EarlyContext<'_>, expr: &ast::Expr) { check_assign(cx, expr); check_else_if(cx, expr); check_array(cx, expr); } } /// Implementation of the `SUSPICIOUS_ASSIGNMENT_FORMATTING` lint. fn check_assign(cx: &EarlyContext<'_>, expr: &ast::Expr) { if let ast::ExprKind::Assign(ref lhs, ref rhs) = expr.node { if !differing_macro_contexts(lhs.span, rhs.span) && !in_macro(lhs.span) { let eq_span = lhs.span.between(rhs.span); if let ast::ExprKind::Unary(op, ref sub_rhs) = rhs.node { if let Some(eq_snippet) = snippet_opt(cx, eq_span) { let op = ast::UnOp::to_string(op); let eqop_span = lhs.span.between(sub_rhs.span); if eq_snippet.ends_with('=') { span_note_and_lint( cx, SUSPICIOUS_ASSIGNMENT_FORMATTING, eqop_span, &format!( "this looks like you are trying to use `.. {op}= ..`, but you \ really are doing `.. = ({op} ..)`", op = op ), eqop_span, &format!("to remove this lint, use either `{op}=` or `= {op}`", op = op), ); } } } } } } /// Implementation of the `SUSPICIOUS_ELSE_FORMATTING` lint for weird `else if`. fn check_else_if(cx: &EarlyContext<'_>, expr: &ast::Expr) { if let Some((then, &Some(ref else_))) = unsugar_if(expr) { if unsugar_if(else_).is_some() && !differing_macro_contexts(then.span, else_.span) && !in_macro(then.span) { // this will be a span from the closing ‘}’ of the “then” block (excluding) to // the // “if” of the “else if” block (excluding) let else_span = then.span.between(else_.span); // the snippet should look like " else \n " with maybe comments anywhere // it’s bad when there is a ‘\n’ after the “else” if let Some(else_snippet) = snippet_opt(cx, else_span) { let else_pos = else_snippet .find("else") .expect("there must be a `else` here"); if else_snippet[else_pos..].contains('\n') { span_note_and_lint( cx, SUSPICIOUS_ELSE_FORMATTING, else_span, "this is an `else if` but the formatting might hide it", else_span, "to remove this lint, remove the `else` or remove the new line between `else` \ and `if`", ); } } } } } fn has_unary_equivalent(bin_op: ast::BinOpKind) -> bool { //+, &, *, - bin_op == ast::BinOpKind::Add || bin_op == ast::BinOpKind::And || bin_op == ast::BinOpKind::Mul || bin_op == ast::BinOpKind::Sub } /// Implementation of the `POSSIBLE_MISSING_COMMA` lint for array fn check_array(cx: &EarlyContext<'_>, expr: &ast::Expr) { if let ast::ExprKind::Array(ref array) = expr.node { for element in array { if let ast::ExprKind::Binary(ref op, ref lhs, _) = element.node { if has_unary_equivalent(op.node) && !differing_macro_contexts(lhs.span, op.span) { let space_span = lhs.span.between(op.span); if let Some(space_snippet) = snippet_opt(cx, space_span) { let lint_span = lhs.span.with_lo(lhs.span.hi()); if space_snippet.contains('\n') { span_note_and_lint( cx, POSSIBLE_MISSING_COMMA, lint_span, "possibly missing a comma here", lint_span, "to remove this lint, add a comma or write the expr in a single line", ); } } } } } } } /// Implementation of the `SUSPICIOUS_ELSE_FORMATTING` lint for consecutive ifs. fn check_consecutive_ifs(cx: &EarlyContext<'_>, first: &ast::Expr, second: &ast::Expr) { if !differing_macro_contexts(first.span, second.span) && !in_macro(first.span) && unsugar_if(first).is_some() && unsugar_if(second).is_some() { // where the else would be let else_span = first.span.between(second.span); if let Some(else_snippet) = snippet_opt(cx, else_span) { if !else_snippet.contains('\n') { span_note_and_lint( cx, SUSPICIOUS_ELSE_FORMATTING, else_span, "this looks like an `else if` but the `else` is missing", else_span, "to remove this lint, add the missing `else` or add a new line before the second \ `if`", ); } } } } /// Match `if` or `if let` expressions and return the `then` and `else` block. fn unsugar_if(expr: &ast::Expr) -> Option<(&P, &Option>)> { match expr.node { ast::ExprKind::If(_, ref then, ref else_) | ast::ExprKind::IfLet(_, _, ref then, ref else_) => { Some((then, else_)) }, _ => None, } }