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.
40 /// if foo <- 30 { // this should be `foo < -30` but looks like a different operator
43 /// if foo &&! bar { // this should be `foo && !bar` but looks like a different operator
46 #[clippy::version = "1.40.0"]
47 pub SUSPICIOUS_UNARY_OP_FORMATTING,
49 "suspicious formatting of unary `-` or `!` on the RHS of a BinOp"
52 declare_clippy_lint! {
54 /// Checks for formatting of `else`. It lints if the `else`
55 /// is followed immediately by a newline or the `else` seems to be missing.
57 /// ### Why is this bad?
58 /// This is probably some refactoring remnant, even if the
59 /// code is correct, it might look confusing.
64 /// } { // looks like an `else` is missing here
68 /// } if bar { // looks like an `else` is missing here
74 /// { // this is the `else` block of the previous `if`, but should it be?
80 /// if bar { // this is the `else` block of the previous `if`, but should it be?
83 #[clippy::version = "pre 1.29.0"]
84 pub SUSPICIOUS_ELSE_FORMATTING,
86 "suspicious formatting of `else`"
89 declare_clippy_lint! {
91 /// Checks for possible missing comma in an array. It lints if
92 /// an array element is a binary operator expression and it lies on two lines.
94 /// ### Why is this bad?
95 /// This could lead to unexpected results.
100 /// -1, -2, -3 // <= no comma here
104 #[clippy::version = "pre 1.29.0"]
105 pub POSSIBLE_MISSING_COMMA,
107 "possible missing comma in array"
110 declare_lint_pass!(Formatting => [
111 SUSPICIOUS_ASSIGNMENT_FORMATTING,
112 SUSPICIOUS_UNARY_OP_FORMATTING,
113 SUSPICIOUS_ELSE_FORMATTING,
114 POSSIBLE_MISSING_COMMA
117 impl EarlyLintPass for Formatting {
118 fn check_block(&mut self, cx: &EarlyContext<'_>, block: &Block) {
119 for w in block.stmts.windows(2) {
120 if let (StmtKind::Expr(first), StmtKind::Expr(second) | StmtKind::Semi(second)) = (&w[0].kind, &w[1].kind) {
121 check_missing_else(cx, first, second);
126 fn check_expr(&mut self, cx: &EarlyContext<'_>, expr: &Expr) {
127 check_assign(cx, expr);
128 check_unop(cx, expr);
129 check_else(cx, expr);
130 check_array(cx, expr);
134 /// Implementation of the `SUSPICIOUS_ASSIGNMENT_FORMATTING` lint.
135 fn check_assign(cx: &EarlyContext<'_>, expr: &Expr) {
136 if let ExprKind::Assign(ref lhs, ref rhs, _) = expr.kind {
137 if !lhs.span.from_expansion() && !rhs.span.from_expansion() {
138 let eq_span = lhs.span.between(rhs.span);
139 if let ExprKind::Unary(op, ref sub_rhs) = rhs.kind {
140 if let Some(eq_snippet) = snippet_opt(cx, eq_span) {
141 let op = UnOp::to_string(op);
142 let eqop_span = lhs.span.between(sub_rhs.span);
143 if eq_snippet.ends_with('=') {
146 SUSPICIOUS_ASSIGNMENT_FORMATTING,
149 "this looks like you are trying to use `.. {op}= ..`, but you \
150 really are doing `.. = ({op} ..)`",
154 &format!("to remove this lint, use either `{op}=` or `= {op}`", op = op),
163 /// Implementation of the `SUSPICIOUS_UNARY_OP_FORMATTING` lint.
164 fn check_unop(cx: &EarlyContext<'_>, expr: &Expr) {
166 if let ExprKind::Binary(ref binop, ref lhs, ref rhs) = expr.kind;
167 if !lhs.span.from_expansion() && !rhs.span.from_expansion();
168 // span between BinOp LHS and RHS
169 let binop_span = lhs.span.between(rhs.span);
171 if let ExprKind::Unary(op, ref un_rhs) = rhs.kind;
172 // from UnOp operator to UnOp operand
173 let unop_operand_span = rhs.span.until(un_rhs.span);
174 if let Some(binop_snippet) = snippet_opt(cx, binop_span);
175 if let Some(unop_operand_snippet) = snippet_opt(cx, unop_operand_span);
176 let binop_str = BinOpKind::to_string(&binop.node);
177 // no space after BinOp operator and space after UnOp operator
178 if binop_snippet.ends_with(binop_str) && unop_operand_snippet.ends_with(' ');
180 let unop_str = UnOp::to_string(op);
181 let eqop_span = lhs.span.between(un_rhs.span);
184 SUSPICIOUS_UNARY_OP_FORMATTING,
187 "by not having a space between `{binop}` and `{unop}` it looks like \
188 `{binop}{unop}` is a single operator",
194 "put a space between `{binop}` and `{unop}` and remove the space after `{unop}`",
203 /// Implementation of the `SUSPICIOUS_ELSE_FORMATTING` lint for weird `else`.
204 fn check_else(cx: &EarlyContext<'_>, expr: &Expr) {
206 if let ExprKind::If(_, then, Some(else_)) = &expr.kind;
207 if is_block(else_) || is_if(else_);
208 if !then.span.from_expansion() && !else_.span.from_expansion();
209 if !in_external_macro(cx.sess(), expr.span);
211 // workaround for rust-lang/rust#43081
212 if expr.span.lo().0 != 0 && expr.span.hi().0 != 0;
214 // this will be a span from the closing ‘}’ of the “then” block (excluding) to
215 // the “if” of the “else if” block (excluding)
216 let else_span = then.span.between(else_.span);
218 // the snippet should look like " else \n " with maybe comments anywhere
219 // it’s bad when there is a ‘\n’ after the “else”
220 if let Some(else_snippet) = snippet_opt(cx, else_span);
221 if let Some((pre_else, post_else)) = else_snippet.split_once("else");
222 if let Some((_, post_else_post_eol)) = post_else.split_once('\n');
225 // Allow allman style braces `} \n else \n {`
228 if let Some((_, pre_else_post_eol)) = pre_else.split_once('\n');
229 // Exactly one eol before and after the else
230 if !pre_else_post_eol.contains('\n');
231 if !post_else_post_eol.contains('\n');
237 let else_desc = if is_if(else_) { "if" } else { "{..}" };
240 SUSPICIOUS_ELSE_FORMATTING,
242 &format!("this is an `else {}` but the formatting might hide it", else_desc),
245 "to remove this lint, remove the `else` or remove the new line between \
255 fn has_unary_equivalent(bin_op: BinOpKind) -> bool {
257 bin_op == BinOpKind::And || bin_op == BinOpKind::Mul || bin_op == BinOpKind::Sub
260 fn indentation(cx: &EarlyContext<'_>, span: Span) -> usize {
261 cx.sess().source_map().lookup_char_pos(span.lo()).col.0
264 /// Implementation of the `POSSIBLE_MISSING_COMMA` lint for array
265 fn check_array(cx: &EarlyContext<'_>, expr: &Expr) {
266 if let ExprKind::Array(ref array) = expr.kind {
267 for element in array {
269 if let ExprKind::Binary(ref op, ref lhs, _) = element.kind;
270 if has_unary_equivalent(op.node) && lhs.span.ctxt() == op.span.ctxt();
271 let space_span = lhs.span.between(op.span);
272 if let Some(space_snippet) = snippet_opt(cx, space_span);
273 let lint_span = lhs.span.with_lo(lhs.span.hi());
274 if space_snippet.contains('\n');
275 if indentation(cx, op.span) <= indentation(cx, lhs.span);
279 POSSIBLE_MISSING_COMMA,
281 "possibly missing a comma here",
283 "to remove this lint, add a comma or write the expr in a single line",
291 fn check_missing_else(cx: &EarlyContext<'_>, first: &Expr, second: &Expr) {
293 if !first.span.from_expansion() && !second.span.from_expansion();
294 if let ExprKind::If(cond_expr, ..) = &first.kind;
295 if is_block(second) || is_if(second);
297 // Proc-macros can give weird spans. Make sure this is actually an `if`.
298 if let Some(if_snip) = snippet_opt(cx, first.span.until(cond_expr.span));
299 if if_snip.starts_with("if");
301 // If there is a line break between the two expressions, don't lint.
302 // If there is a non-whitespace character, this span came from a proc-macro.
303 let else_span = first.span.between(second.span);
304 if let Some(else_snippet) = snippet_opt(cx, else_span);
305 if !else_snippet.chars().any(|c| c == '\n' || !c.is_whitespace());
307 let (looks_like, next_thing) = if is_if(second) {
308 ("an `else if`", "the second `if`")
310 ("an `else {..}`", "the next block")
315 SUSPICIOUS_ELSE_FORMATTING,
317 &format!("this looks like {} but the `else` is missing", looks_like),
320 "to remove this lint, add the missing `else` or add a new line before {}",
328 fn is_block(expr: &Expr) -> bool {
329 matches!(expr.kind, ExprKind::Block(..))
332 /// Check if the expression is an `if` or `if let`
333 fn is_if(expr: &Expr) -> bool {
334 matches!(expr.kind, ExprKind::If(..))