335 lines
12 KiB
Rust
335 lines
12 KiB
Rust
use clippy_utils::diagnostics::{span_lint_and_help, span_lint_and_note};
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use clippy_utils::is_span_if;
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use clippy_utils::source::snippet_opt;
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use if_chain::if_chain;
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use rustc_ast::ast::{BinOpKind, Block, Expr, ExprKind, StmtKind, UnOp};
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use rustc_lint::{EarlyContext, EarlyLintPass, LintContext};
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use rustc_middle::lint::in_external_macro;
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use rustc_session::{declare_lint_pass, declare_tool_lint};
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use rustc_span::source_map::Span;
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declare_clippy_lint! {
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/// ### What it does
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/// Checks for use of the non-existent `=*`, `=!` and `=-`
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/// operators.
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///
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/// ### Why is this bad?
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/// This is either a typo of `*=`, `!=` or `-=` or
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/// confusing.
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///
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/// ### Example
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/// ```rust,ignore
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/// a =- 42; // confusing, should it be `a -= 42` or `a = -42`?
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/// ```
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#[clippy::version = "pre 1.29.0"]
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pub SUSPICIOUS_ASSIGNMENT_FORMATTING,
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suspicious,
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"suspicious formatting of `*=`, `-=` or `!=`"
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}
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declare_clippy_lint! {
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/// ### What it does
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/// Checks the formatting of a unary operator on the right hand side
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/// of a binary operator. It lints if there is no space between the binary and unary operators,
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/// but there is a space between the unary and its operand.
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///
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/// ### Why is this bad?
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/// This is either a typo in the binary operator or confusing.
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///
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/// ### Example
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/// ```rust
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/// # let foo = true;
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/// # let bar = false;
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/// // &&! looks like a different operator
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/// if foo &&! bar {}
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/// ```
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///
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/// Use instead:
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/// ```rust
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/// # let foo = true;
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/// # let bar = false;
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/// if foo && !bar {}
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/// ```
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#[clippy::version = "1.40.0"]
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pub SUSPICIOUS_UNARY_OP_FORMATTING,
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suspicious,
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"suspicious formatting of unary `-` or `!` on the RHS of a BinOp"
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}
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declare_clippy_lint! {
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/// ### What it does
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/// Checks for formatting of `else`. It lints if the `else`
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/// is followed immediately by a newline or the `else` seems to be missing.
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///
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/// ### Why is this bad?
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/// This is probably some refactoring remnant, even if the
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/// code is correct, it might look confusing.
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///
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/// ### Example
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/// ```rust,ignore
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/// if foo {
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/// } { // looks like an `else` is missing here
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/// }
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///
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/// if foo {
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/// } if bar { // looks like an `else` is missing here
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/// }
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///
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/// if foo {
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/// } else
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///
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/// { // this is the `else` block of the previous `if`, but should it be?
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/// }
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///
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/// if foo {
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/// } else
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///
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/// if bar { // this is the `else` block of the previous `if`, but should it be?
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/// }
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/// ```
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#[clippy::version = "pre 1.29.0"]
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pub SUSPICIOUS_ELSE_FORMATTING,
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suspicious,
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"suspicious formatting of `else`"
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}
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declare_clippy_lint! {
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/// ### What it does
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/// Checks for possible missing comma in an array. It lints if
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/// an array element is a binary operator expression and it lies on two lines.
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///
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/// ### Why is this bad?
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/// This could lead to unexpected results.
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///
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/// ### Example
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/// ```rust,ignore
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/// let a = &[
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/// -1, -2, -3 // <= no comma here
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/// -4, -5, -6
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/// ];
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/// ```
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#[clippy::version = "pre 1.29.0"]
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pub POSSIBLE_MISSING_COMMA,
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correctness,
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"possible missing comma in array"
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}
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declare_lint_pass!(Formatting => [
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SUSPICIOUS_ASSIGNMENT_FORMATTING,
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SUSPICIOUS_UNARY_OP_FORMATTING,
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SUSPICIOUS_ELSE_FORMATTING,
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POSSIBLE_MISSING_COMMA
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]);
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impl EarlyLintPass for Formatting {
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fn check_block(&mut self, cx: &EarlyContext<'_>, block: &Block) {
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for w in block.stmts.windows(2) {
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if let (StmtKind::Expr(first), StmtKind::Expr(second) | StmtKind::Semi(second)) = (&w[0].kind, &w[1].kind) {
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check_missing_else(cx, first, second);
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}
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}
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}
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fn check_expr(&mut self, cx: &EarlyContext<'_>, expr: &Expr) {
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check_assign(cx, expr);
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check_unop(cx, expr);
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check_else(cx, expr);
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check_array(cx, expr);
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}
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}
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/// Implementation of the `SUSPICIOUS_ASSIGNMENT_FORMATTING` lint.
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fn check_assign(cx: &EarlyContext<'_>, expr: &Expr) {
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if let ExprKind::Assign(ref lhs, ref rhs, _) = expr.kind {
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if !lhs.span.from_expansion() && !rhs.span.from_expansion() {
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let eq_span = lhs.span.between(rhs.span);
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if let ExprKind::Unary(op, ref sub_rhs) = rhs.kind {
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if let Some(eq_snippet) = snippet_opt(cx, eq_span) {
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let op = UnOp::to_string(op);
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let eqop_span = lhs.span.between(sub_rhs.span);
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if eq_snippet.ends_with('=') {
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span_lint_and_note(
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cx,
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SUSPICIOUS_ASSIGNMENT_FORMATTING,
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eqop_span,
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&format!(
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"this looks like you are trying to use `.. {op}= ..`, but you \
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really are doing `.. = ({op} ..)`"
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),
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None,
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&format!("to remove this lint, use either `{op}=` or `= {op}`"),
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);
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}
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}
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}
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}
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}
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}
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/// Implementation of the `SUSPICIOUS_UNARY_OP_FORMATTING` lint.
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fn check_unop(cx: &EarlyContext<'_>, expr: &Expr) {
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if_chain! {
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if let ExprKind::Binary(ref binop, ref lhs, ref rhs) = expr.kind;
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if !lhs.span.from_expansion() && !rhs.span.from_expansion();
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// span between BinOp LHS and RHS
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let binop_span = lhs.span.between(rhs.span);
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// if RHS is an UnOp
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if let ExprKind::Unary(op, ref un_rhs) = rhs.kind;
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// from UnOp operator to UnOp operand
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let unop_operand_span = rhs.span.until(un_rhs.span);
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if let Some(binop_snippet) = snippet_opt(cx, binop_span);
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if let Some(unop_operand_snippet) = snippet_opt(cx, unop_operand_span);
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let binop_str = BinOpKind::to_string(&binop.node);
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// no space after BinOp operator and space after UnOp operator
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if binop_snippet.ends_with(binop_str) && unop_operand_snippet.ends_with(' ');
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then {
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let unop_str = UnOp::to_string(op);
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let eqop_span = lhs.span.between(un_rhs.span);
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span_lint_and_help(
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cx,
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SUSPICIOUS_UNARY_OP_FORMATTING,
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eqop_span,
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&format!(
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"by not having a space between `{binop_str}` and `{unop_str}` it looks like \
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`{binop_str}{unop_str}` is a single operator"
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),
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None,
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&format!(
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"put a space between `{binop_str}` and `{unop_str}` and remove the space after `{unop_str}`"
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),
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);
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}
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}
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}
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/// Implementation of the `SUSPICIOUS_ELSE_FORMATTING` lint for weird `else`.
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fn check_else(cx: &EarlyContext<'_>, expr: &Expr) {
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if_chain! {
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if let ExprKind::If(_, then, Some(else_)) = &expr.kind;
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if is_block(else_) || is_if(else_);
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if !then.span.from_expansion() && !else_.span.from_expansion();
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if !in_external_macro(cx.sess(), expr.span);
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// workaround for rust-lang/rust#43081
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if expr.span.lo().0 != 0 && expr.span.hi().0 != 0;
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// this will be a span from the closing ‘}’ of the “then” block (excluding) to
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// the “if” of the “else if” block (excluding)
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let else_span = then.span.between(else_.span);
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// the snippet should look like " else \n " with maybe comments anywhere
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// it’s bad when there is a ‘\n’ after the “else”
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if let Some(else_snippet) = snippet_opt(cx, else_span);
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if let Some((pre_else, post_else)) = else_snippet.split_once("else");
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if let Some((_, post_else_post_eol)) = post_else.split_once('\n');
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then {
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// Allow allman style braces `} \n else \n {`
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if_chain! {
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if is_block(else_);
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if let Some((_, pre_else_post_eol)) = pre_else.split_once('\n');
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// Exactly one eol before and after the else
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if !pre_else_post_eol.contains('\n');
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if !post_else_post_eol.contains('\n');
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then {
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return;
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}
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}
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let else_desc = if is_if(else_) { "if" } else { "{..}" };
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span_lint_and_note(
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cx,
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SUSPICIOUS_ELSE_FORMATTING,
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else_span,
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&format!("this is an `else {else_desc}` but the formatting might hide it"),
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None,
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&format!(
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"to remove this lint, remove the `else` or remove the new line between \
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`else` and `{else_desc}`",
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),
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);
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}
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}
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}
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#[must_use]
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fn has_unary_equivalent(bin_op: BinOpKind) -> bool {
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// &, *, -
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bin_op == BinOpKind::And || bin_op == BinOpKind::Mul || bin_op == BinOpKind::Sub
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}
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fn indentation(cx: &EarlyContext<'_>, span: Span) -> usize {
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cx.sess().source_map().lookup_char_pos(span.lo()).col.0
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}
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/// Implementation of the `POSSIBLE_MISSING_COMMA` lint for array
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fn check_array(cx: &EarlyContext<'_>, expr: &Expr) {
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if let ExprKind::Array(ref array) = expr.kind {
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for element in array {
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if_chain! {
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if let ExprKind::Binary(ref op, ref lhs, _) = element.kind;
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if has_unary_equivalent(op.node) && lhs.span.ctxt() == op.span.ctxt();
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let space_span = lhs.span.between(op.span);
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if let Some(space_snippet) = snippet_opt(cx, space_span);
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let lint_span = lhs.span.with_lo(lhs.span.hi());
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if space_snippet.contains('\n');
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if indentation(cx, op.span) <= indentation(cx, lhs.span);
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then {
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span_lint_and_note(
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cx,
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POSSIBLE_MISSING_COMMA,
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lint_span,
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"possibly missing a comma here",
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None,
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"to remove this lint, add a comma or write the expr in a single line",
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);
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}
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}
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}
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}
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}
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fn check_missing_else(cx: &EarlyContext<'_>, first: &Expr, second: &Expr) {
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if_chain! {
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if !first.span.from_expansion() && !second.span.from_expansion();
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if matches!(first.kind, ExprKind::If(..));
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if is_block(second) || is_if(second);
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// Proc-macros can give weird spans. Make sure this is actually an `if`.
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if is_span_if(cx, first.span);
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// If there is a line break between the two expressions, don't lint.
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// If there is a non-whitespace character, this span came from a proc-macro.
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let else_span = first.span.between(second.span);
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if let Some(else_snippet) = snippet_opt(cx, else_span);
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if !else_snippet.chars().any(|c| c == '\n' || !c.is_whitespace());
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then {
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let (looks_like, next_thing) = if is_if(second) {
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("an `else if`", "the second `if`")
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} else {
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("an `else {..}`", "the next block")
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};
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span_lint_and_note(
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cx,
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SUSPICIOUS_ELSE_FORMATTING,
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else_span,
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&format!("this looks like {looks_like} but the `else` is missing"),
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None,
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&format!(
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"to remove this lint, add the missing `else` or add a new line before {next_thing}",
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),
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);
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}
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}
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}
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fn is_block(expr: &Expr) -> bool {
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matches!(expr.kind, ExprKind::Block(..))
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}
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/// Check if the expression is an `if` or `if let`
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fn is_if(expr: &Expr) -> bool {
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matches!(expr.kind, ExprKind::If(..))
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}
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