use crate::utils::{differing_macro_contexts, in_macro_or_desugar, snippet_opt, span_note_and_lint}; use if_chain::if_chain; use rustc::lint::{in_external_macro, EarlyContext, EarlyLintPass, LintArray, LintPass}; use rustc::{declare_lint_pass, declare_tool_lint}; use syntax::ast; use syntax::ptr::P; declare_clippy_lint! { /// **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`? /// ``` pub SUSPICIOUS_ASSIGNMENT_FORMATTING, style, "suspicious formatting of `*=`, `-=` or `!=`" } declare_clippy_lint! { /// **What it does:** Checks for formatting of `else`. It lints if the `else` /// is followed immediately by a newline 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 { /// } { // looks like an `else` is missing here /// } /// /// if foo { /// } if bar { // looks like an `else` is missing here /// } /// /// if foo { /// } else /// /// { // this is the `else` block of the previous `if`, but should it be? /// } /// /// if foo { /// } else /// /// if bar { // this is the `else` block of the previous `if`, but should it be? /// } /// ``` pub SUSPICIOUS_ELSE_FORMATTING, style, "suspicious formatting of `else`" } declare_clippy_lint! { /// **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 /// ]; /// ``` pub POSSIBLE_MISSING_COMMA, correctness, "possible missing comma in array" } declare_lint_pass!(Formatting => [ 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_missing_else(cx, first, second); }, _ => (), } } } fn check_expr(&mut self, cx: &EarlyContext<'_>, expr: &ast::Expr) { check_assign(cx, expr); check_else(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_or_desugar(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`. fn check_else(cx: &EarlyContext<'_>, expr: &ast::Expr) { if_chain! { if let Some((then, &Some(ref else_))) = unsugar_if(expr); if is_block(else_) || unsugar_if(else_).is_some(); if !differing_macro_contexts(then.span, else_.span); if !in_macro_or_desugar(then.span) && !in_external_macro(cx.sess, expr.span); // workaround for rust-lang/rust#43081 if expr.span.lo().0 != 0 && expr.span.hi().0 != 0; // 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); if let Some(else_pos) = else_snippet.find("else"); if else_snippet[else_pos..].contains('\n'); let else_desc = if unsugar_if(else_).is_some() { "if" } else { "{..}" }; then { span_note_and_lint( cx, SUSPICIOUS_ELSE_FORMATTING, else_span, &format!("this is an `else {}` but the formatting might hide it", else_desc), else_span, &format!( "to remove this lint, remove the `else` or remove the new line between \ `else` and `{}`", else_desc, ), ); } } } fn has_unary_equivalent(bin_op: ast::BinOpKind) -> bool { // &, *, - 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", ); } } } } } } } fn check_missing_else(cx: &EarlyContext<'_>, first: &ast::Expr, second: &ast::Expr) { if !differing_macro_contexts(first.span, second.span) && !in_macro_or_desugar(first.span) && unsugar_if(first).is_some() && (is_block(second) || 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') { let (looks_like, next_thing) = if unsugar_if(second).is_some() { ("an `else if`", "the second `if`") } else { ("an `else {..}`", "the next block") }; span_note_and_lint( cx, SUSPICIOUS_ELSE_FORMATTING, else_span, &format!("this looks like {} but the `else` is missing", looks_like), else_span, &format!( "to remove this lint, add the missing `else` or add a new line before {}", next_thing, ), ); } } } } fn is_block(expr: &ast::Expr) -> bool { if let ast::ExprKind::Block(..) = expr.node { true } else { false } } /// 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, } }