1 use clippy_utils::diagnostics::{span_lint_and_help, span_lint_and_note};
2 use clippy_utils::source::snippet_opt;
3 use if_chain::if_chain;
4 use rustc_ast::ast::{BinOpKind, Block, Expr, ExprKind, StmtKind, UnOp};
5 use rustc_lint::{EarlyContext, EarlyLintPass, LintContext};
6 use rustc_middle::lint::in_external_macro;
7 use rustc_session::{declare_lint_pass, declare_tool_lint};
8 use rustc_span::source_map::Span;
10 declare_clippy_lint! {
12 /// Checks for use of the non-existent `=*`, `=!` and `=-`
15 /// ### Why is this bad?
16 /// This is either a typo of `*=`, `!=` or `-=` or
21 /// a =- 42; // confusing, should it be `a -= 42` or `a = -42`?
23 #[clippy::version = "pre 1.29.0"]
24 pub SUSPICIOUS_ASSIGNMENT_FORMATTING,
26 "suspicious formatting of `*=`, `-=` or `!=`"
29 declare_clippy_lint! {
31 /// Checks the formatting of a unary operator on the right hand side
32 /// of a binary operator. It lints if there is no space between the binary and unary operators,
33 /// but there is a space between the unary and its operand.
35 /// ### Why is this bad?
36 /// This is either a typo in the binary operator or confusing.
41 /// # let bar = false;
42 /// // &&! looks like a different operator
49 /// # let bar = false;
52 #[clippy::version = "1.40.0"]
53 pub SUSPICIOUS_UNARY_OP_FORMATTING,
55 "suspicious formatting of unary `-` or `!` on the RHS of a BinOp"
58 declare_clippy_lint! {
60 /// Checks for formatting of `else`. It lints if the `else`
61 /// is followed immediately by a newline or the `else` seems to be missing.
63 /// ### Why is this bad?
64 /// This is probably some refactoring remnant, even if the
65 /// code is correct, it might look confusing.
70 /// } { // looks like an `else` is missing here
74 /// } if bar { // looks like an `else` is missing here
80 /// { // this is the `else` block of the previous `if`, but should it be?
86 /// if bar { // this is the `else` block of the previous `if`, but should it be?
89 #[clippy::version = "pre 1.29.0"]
90 pub SUSPICIOUS_ELSE_FORMATTING,
92 "suspicious formatting of `else`"
95 declare_clippy_lint! {
97 /// Checks for possible missing comma in an array. It lints if
98 /// an array element is a binary operator expression and it lies on two lines.
100 /// ### Why is this bad?
101 /// This could lead to unexpected results.
106 /// -1, -2, -3 // <= no comma here
110 #[clippy::version = "pre 1.29.0"]
111 pub POSSIBLE_MISSING_COMMA,
113 "possible missing comma in array"
116 declare_lint_pass!(Formatting => [
117 SUSPICIOUS_ASSIGNMENT_FORMATTING,
118 SUSPICIOUS_UNARY_OP_FORMATTING,
119 SUSPICIOUS_ELSE_FORMATTING,
120 POSSIBLE_MISSING_COMMA
123 impl EarlyLintPass for Formatting {
124 fn check_block(&mut self, cx: &EarlyContext<'_>, block: &Block) {
125 for w in block.stmts.windows(2) {
126 if let (StmtKind::Expr(first), StmtKind::Expr(second) | StmtKind::Semi(second)) = (&w[0].kind, &w[1].kind) {
127 check_missing_else(cx, first, second);
132 fn check_expr(&mut self, cx: &EarlyContext<'_>, expr: &Expr) {
133 check_assign(cx, expr);
134 check_unop(cx, expr);
135 check_else(cx, expr);
136 check_array(cx, expr);
140 /// Implementation of the `SUSPICIOUS_ASSIGNMENT_FORMATTING` lint.
141 fn check_assign(cx: &EarlyContext<'_>, expr: &Expr) {
142 if let ExprKind::Assign(ref lhs, ref rhs, _) = expr.kind {
143 if !lhs.span.from_expansion() && !rhs.span.from_expansion() {
144 let eq_span = lhs.span.between(rhs.span);
145 if let ExprKind::Unary(op, ref sub_rhs) = rhs.kind {
146 if let Some(eq_snippet) = snippet_opt(cx, eq_span) {
147 let op = UnOp::to_string(op);
148 let eqop_span = lhs.span.between(sub_rhs.span);
149 if eq_snippet.ends_with('=') {
152 SUSPICIOUS_ASSIGNMENT_FORMATTING,
155 "this looks like you are trying to use `.. {op}= ..`, but you \
156 really are doing `.. = ({op} ..)`",
160 &format!("to remove this lint, use either `{op}=` or `= {op}`", op = op),
169 /// Implementation of the `SUSPICIOUS_UNARY_OP_FORMATTING` lint.
170 fn check_unop(cx: &EarlyContext<'_>, expr: &Expr) {
172 if let ExprKind::Binary(ref binop, ref lhs, ref rhs) = expr.kind;
173 if !lhs.span.from_expansion() && !rhs.span.from_expansion();
174 // span between BinOp LHS and RHS
175 let binop_span = lhs.span.between(rhs.span);
177 if let ExprKind::Unary(op, ref un_rhs) = rhs.kind;
178 // from UnOp operator to UnOp operand
179 let unop_operand_span = rhs.span.until(un_rhs.span);
180 if let Some(binop_snippet) = snippet_opt(cx, binop_span);
181 if let Some(unop_operand_snippet) = snippet_opt(cx, unop_operand_span);
182 let binop_str = BinOpKind::to_string(&binop.node);
183 // no space after BinOp operator and space after UnOp operator
184 if binop_snippet.ends_with(binop_str) && unop_operand_snippet.ends_with(' ');
186 let unop_str = UnOp::to_string(op);
187 let eqop_span = lhs.span.between(un_rhs.span);
190 SUSPICIOUS_UNARY_OP_FORMATTING,
193 "by not having a space between `{binop}` and `{unop}` it looks like \
194 `{binop}{unop}` is a single operator",
200 "put a space between `{binop}` and `{unop}` and remove the space after `{unop}`",
209 /// Implementation of the `SUSPICIOUS_ELSE_FORMATTING` lint for weird `else`.
210 fn check_else(cx: &EarlyContext<'_>, expr: &Expr) {
212 if let ExprKind::If(_, then, Some(else_)) = &expr.kind;
213 if is_block(else_) || is_if(else_);
214 if !then.span.from_expansion() && !else_.span.from_expansion();
215 if !in_external_macro(cx.sess(), expr.span);
217 // workaround for rust-lang/rust#43081
218 if expr.span.lo().0 != 0 && expr.span.hi().0 != 0;
220 // this will be a span from the closing ‘}’ of the “then” block (excluding) to
221 // the “if” of the “else if” block (excluding)
222 let else_span = then.span.between(else_.span);
224 // the snippet should look like " else \n " with maybe comments anywhere
225 // it’s bad when there is a ‘\n’ after the “else”
226 if let Some(else_snippet) = snippet_opt(cx, else_span);
227 if let Some((pre_else, post_else)) = else_snippet.split_once("else");
228 if let Some((_, post_else_post_eol)) = post_else.split_once('\n');
231 // Allow allman style braces `} \n else \n {`
234 if let Some((_, pre_else_post_eol)) = pre_else.split_once('\n');
235 // Exactly one eol before and after the else
236 if !pre_else_post_eol.contains('\n');
237 if !post_else_post_eol.contains('\n');
243 let else_desc = if is_if(else_) { "if" } else { "{..}" };
246 SUSPICIOUS_ELSE_FORMATTING,
248 &format!("this is an `else {}` but the formatting might hide it", else_desc),
251 "to remove this lint, remove the `else` or remove the new line between \
261 fn has_unary_equivalent(bin_op: BinOpKind) -> bool {
263 bin_op == BinOpKind::And || bin_op == BinOpKind::Mul || bin_op == BinOpKind::Sub
266 fn indentation(cx: &EarlyContext<'_>, span: Span) -> usize {
267 cx.sess().source_map().lookup_char_pos(span.lo()).col.0
270 /// Implementation of the `POSSIBLE_MISSING_COMMA` lint for array
271 fn check_array(cx: &EarlyContext<'_>, expr: &Expr) {
272 if let ExprKind::Array(ref array) = expr.kind {
273 for element in array {
275 if let ExprKind::Binary(ref op, ref lhs, _) = element.kind;
276 if has_unary_equivalent(op.node) && lhs.span.ctxt() == op.span.ctxt();
277 let space_span = lhs.span.between(op.span);
278 if let Some(space_snippet) = snippet_opt(cx, space_span);
279 let lint_span = lhs.span.with_lo(lhs.span.hi());
280 if space_snippet.contains('\n');
281 if indentation(cx, op.span) <= indentation(cx, lhs.span);
285 POSSIBLE_MISSING_COMMA,
287 "possibly missing a comma here",
289 "to remove this lint, add a comma or write the expr in a single line",
297 fn check_missing_else(cx: &EarlyContext<'_>, first: &Expr, second: &Expr) {
299 if !first.span.from_expansion() && !second.span.from_expansion();
300 if let ExprKind::If(cond_expr, ..) = &first.kind;
301 if is_block(second) || is_if(second);
303 // Proc-macros can give weird spans. Make sure this is actually an `if`.
304 if let Some(if_snip) = snippet_opt(cx, first.span.until(cond_expr.span));
305 if if_snip.starts_with("if");
307 // If there is a line break between the two expressions, don't lint.
308 // If there is a non-whitespace character, this span came from a proc-macro.
309 let else_span = first.span.between(second.span);
310 if let Some(else_snippet) = snippet_opt(cx, else_span);
311 if !else_snippet.chars().any(|c| c == '\n' || !c.is_whitespace());
313 let (looks_like, next_thing) = if is_if(second) {
314 ("an `else if`", "the second `if`")
316 ("an `else {..}`", "the next block")
321 SUSPICIOUS_ELSE_FORMATTING,
323 &format!("this looks like {} but the `else` is missing", looks_like),
326 "to remove this lint, add the missing `else` or add a new line before {}",
334 fn is_block(expr: &Expr) -> bool {
335 matches!(expr.kind, ExprKind::Block(..))
338 /// Check if the expression is an `if` or `if let`
339 fn is_if(expr: &Expr) -> bool {
340 matches!(expr.kind, ExprKind::If(..))