src/tools/clippy/clippy_lints/src/formatting.rs - toolchain/rustc - Git at Google

 use clippy_utils::diagnostics::{span_lint_and_help, span_lint_and_note};
 use clippy_utils::is_span_if;
 use clippy_utils::source::snippet_opt;
 use if_chain::if_chain;
 use rustc_ast::ast::{BinOpKind, Block, Expr, ExprKind, StmtKind, UnOp};
 use rustc_lint::{EarlyContext, EarlyLintPass, LintContext};
 use rustc_middle::lint::in_external_macro;
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 use rustc_span::Span;

 declare_clippy_lint! {
     /// ### What it does
     /// Checks for usage of the non-existent `=*`, `=!` and `=-`
     /// operators.
     ///
     /// ### Why is this bad?
     /// This is either a typo of `*=`, `!=` or `-=` or
     /// confusing.
     ///
     /// ### Example
     /// ```rust,ignore
     /// a =- 42; // confusing, should it be `a -= 42` or `a = -42`?
     /// ```
     #[clippy::version = "pre 1.29.0"]
     pub SUSPICIOUS_ASSIGNMENT_FORMATTING,
     suspicious,
     "suspicious formatting of `*=`, `-=` or `!=`"
 }

 declare_clippy_lint! {
     /// ### What it does
     /// Checks the formatting of a unary operator on the right hand side
     /// of a binary operator. It lints if there is no space between the binary and unary operators,
     /// but there is a space between the unary and its operand.
     ///
     /// ### Why is this bad?
     /// This is either a typo in the binary operator or confusing.
     ///
     /// ### Example
     /// ```no_run
     /// # let foo = true;
     /// # let bar = false;
     /// // &&! looks like a different operator
     /// if foo &&! bar {}
     /// ```
     ///
     /// Use instead:
     /// ```no_run
     /// # let foo = true;
     /// # let bar = false;
     /// if foo && !bar {}
     /// ```
     #[clippy::version = "1.40.0"]
     pub SUSPICIOUS_UNARY_OP_FORMATTING,
     suspicious,
     "suspicious formatting of unary `-` or `!` on the RHS of a BinOp"
 }

 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.
     ///
     /// ### 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?
     /// }
     /// ```
     #[clippy::version = "pre 1.29.0"]
     pub SUSPICIOUS_ELSE_FORMATTING,
     suspicious,
     "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.
     ///
     /// ### Example
     /// ```rust,ignore
     /// let a = &[
     ///     -1, -2, -3 // <= no comma here
     ///     -4, -5, -6
     /// ];
     /// ```
     #[clippy::version = "pre 1.29.0"]
     pub POSSIBLE_MISSING_COMMA,
     correctness,
     "possible missing comma in array"
 }

 declare_lint_pass!(Formatting => [
     SUSPICIOUS_ASSIGNMENT_FORMATTING,
     SUSPICIOUS_UNARY_OP_FORMATTING,
     SUSPICIOUS_ELSE_FORMATTING,
     POSSIBLE_MISSING_COMMA
 ]);

 impl EarlyLintPass for Formatting {
     fn check_block(&mut self, cx: &EarlyContext<'_>, block: &Block) {
         for w in block.stmts.windows(2) {
             if let (StmtKind::Expr(first), StmtKind::Expr(second) | StmtKind::Semi(second)) = (&w[0].kind, &w[1].kind) {
                 check_missing_else(cx, first, second);
             }
         }
     }

     fn check_expr(&mut self, cx: &EarlyContext<'_>, expr: &Expr) {
         check_assign(cx, expr);
         check_unop(cx, expr);
         check_else(cx, expr);
         check_array(cx, expr);
     }
 }

 /// Implementation of the `SUSPICIOUS_ASSIGNMENT_FORMATTING` lint.
 fn check_assign(cx: &EarlyContext<'_>, expr: &Expr) {
     if let ExprKind::Assign(ref lhs, ref rhs, _) = expr.kind {
         if !lhs.span.from_expansion() && !rhs.span.from_expansion() {
             let eq_span = lhs.span.between(rhs.span);
             if let ExprKind::Unary(op, ref sub_rhs) = rhs.kind {
                 if let Some(eq_snippet) = snippet_opt(cx, eq_span) {
                     let op = UnOp::to_string(op);
                     let eqop_span = lhs.span.between(sub_rhs.span);
                     if eq_snippet.ends_with('=') {
                         span_lint_and_note(
                             cx,
                             SUSPICIOUS_ASSIGNMENT_FORMATTING,
                             eqop_span,
                             &format!(
                                 "this looks like you are trying to use `.. {op}= ..`, but you \
                                  really are doing `.. = ({op} ..)`"
                             ),
                             None,
                             &format!("to remove this lint, use either `{op}=` or `= {op}`"),
                         );
                     }
                 }
             }
         }
     }
 }

 /// Implementation of the `SUSPICIOUS_UNARY_OP_FORMATTING` lint.
 fn check_unop(cx: &EarlyContext<'_>, expr: &Expr) {
     if_chain! {
         if let ExprKind::Binary(ref binop, ref lhs, ref rhs) = expr.kind;
         if !lhs.span.from_expansion() && !rhs.span.from_expansion();
         // span between BinOp LHS and RHS
         let binop_span = lhs.span.between(rhs.span);
         // if RHS is an UnOp
         if let ExprKind::Unary(op, ref un_rhs) = rhs.kind;
         // from UnOp operator to UnOp operand
         let unop_operand_span = rhs.span.until(un_rhs.span);
         if let Some(binop_snippet) = snippet_opt(cx, binop_span);
         if let Some(unop_operand_snippet) = snippet_opt(cx, unop_operand_span);
         let binop_str = BinOpKind::to_string(&binop.node);
         // no space after BinOp operator and space after UnOp operator
         if binop_snippet.ends_with(binop_str) && unop_operand_snippet.ends_with(' ');
         then {
             let unop_str = UnOp::to_string(op);
             let eqop_span = lhs.span.between(un_rhs.span);
             span_lint_and_help(
                 cx,
                 SUSPICIOUS_UNARY_OP_FORMATTING,
                 eqop_span,
                 &format!(
                     "by not having a space between `{binop_str}` and `{unop_str}` it looks like \
                      `{binop_str}{unop_str}` is a single operator"
                 ),
                 None,
                 &format!(
                     "put a space between `{binop_str}` and `{unop_str}` and remove the space after `{unop_str}`"
                 ),
             );
         }
     }
 }

 /// Implementation of the `SUSPICIOUS_ELSE_FORMATTING` lint for weird `else`.
 fn check_else(cx: &EarlyContext<'_>, expr: &Expr) {
     if_chain! {
         if let ExprKind::If(_, then, Some(else_)) = &expr.kind;
         if is_block(else_) || is_if(else_);
         if !then.span.from_expansion() && !else_.span.from_expansion();
         if !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((pre_else, post_else)) = else_snippet.split_once("else");
         if let Some((_, post_else_post_eol)) = post_else.split_once('\n');

         then {
             // Allow allman style braces `} \n else \n {`
             if_chain! {
                 if is_block(else_);
                 if let Some((_, pre_else_post_eol)) = pre_else.split_once('\n');
                 // Exactly one eol before and after the else
                 if !pre_else_post_eol.contains('\n');
                 if !post_else_post_eol.contains('\n');
                 then {
                     return;
                 }
             }

             // Don't warn if the only thing inside post_else_post_eol is a comment block.
             let trimmed_post_else_post_eol = post_else_post_eol.trim();
             if trimmed_post_else_post_eol.starts_with("/*") && trimmed_post_else_post_eol.ends_with("*/") {
                 return
             }

             let else_desc = if is_if(else_) { "if" } else { "{..}" };
             span_lint_and_note(
                 cx,
                 SUSPICIOUS_ELSE_FORMATTING,
                 else_span,
                 &format!("this is an `else {else_desc}` but the formatting might hide it"),
                 None,
                 &format!(
                     "to remove this lint, remove the `else` or remove the new line between \
                      `else` and `{else_desc}`",
                 ),
             );
         }
     }
 }

 #[must_use]
 fn has_unary_equivalent(bin_op: BinOpKind) -> bool {
     // &, *, -
     bin_op == BinOpKind::And || bin_op == BinOpKind::Mul || bin_op == BinOpKind::Sub
 }

 fn indentation(cx: &EarlyContext<'_>, span: Span) -> usize {
     cx.sess().source_map().lookup_char_pos(span.lo()).col.0
 }

 /// Implementation of the `POSSIBLE_MISSING_COMMA` lint for array
 fn check_array(cx: &EarlyContext<'_>, expr: &Expr) {
     if let ExprKind::Array(ref array) = expr.kind {
         for element in array {
             if_chain! {
                 if let ExprKind::Binary(ref op, ref lhs, _) = element.kind;
                 if has_unary_equivalent(op.node) && lhs.span.eq_ctxt(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');
                 if indentation(cx, op.span) <= indentation(cx, lhs.span);
                 then {
                     span_lint_and_note(
                         cx,
                         POSSIBLE_MISSING_COMMA,
                         lint_span,
                         "possibly missing a comma here",
                         None,
                         "to remove this lint, add a comma or write the expr in a single line",
                     );
                 }
             }
         }
     }
 }

 fn check_missing_else(cx: &EarlyContext<'_>, first: &Expr, second: &Expr) {
     if_chain! {
         if !first.span.from_expansion() && !second.span.from_expansion();
         if matches!(first.kind, ExprKind::If(..));
         if is_block(second) || is_if(second);

         // Proc-macros can give weird spans. Make sure this is actually an `if`.
         if is_span_if(cx, first.span);

         // If there is a line break between the two expressions, don't lint.
         // If there is a non-whitespace character, this span came from a proc-macro.
         let else_span = first.span.between(second.span);
         if let Some(else_snippet) = snippet_opt(cx, else_span);
         if !else_snippet.chars().any(|c| c == '\n' || !c.is_whitespace());
         then {
             let (looks_like, next_thing) = if is_if(second) {
                 ("an `else if`", "the second `if`")
             } else {
                 ("an `else {..}`", "the next block")
             };

             span_lint_and_note(
                 cx,
                 SUSPICIOUS_ELSE_FORMATTING,
                 else_span,
                 &format!("this looks like {looks_like} but the `else` is missing"),
                 None,
                 &format!(
                     "to remove this lint, add the missing `else` or add a new line before {next_thing}",
                 ),
             );
         }
     }
 }

 fn is_block(expr: &Expr) -> bool {
     matches!(expr.kind, ExprKind::Block(..))
 }

 /// Check if the expression is an `if` or `if let`
 fn is_if(expr: &Expr) -> bool {
     matches!(expr.kind, ExprKind::If(..))
 }
	use clippy_utils::diagnostics::{span_lint_and_help, span_lint_and_note};
	use clippy_utils::is_span_if;
	use clippy_utils::source::snippet_opt;
	use if_chain::if_chain;
	use rustc_ast::ast::{BinOpKind, Block, Expr, ExprKind, StmtKind, UnOp};
	use rustc_lint::{EarlyContext, EarlyLintPass, LintContext};
	use rustc_middle::lint::in_external_macro;
	use rustc_session::{declare_lint_pass, declare_tool_lint};
	use rustc_span::Span;

	declare_clippy_lint! {
	/// ### What it does
	/// Checks for usage of the non-existent `=*`, `=!` and `=-`
	/// operators.
	///
	/// ### Why is this bad?
	/// This is either a typo of `*=`, `!=` or `-=` or
	/// confusing.
	///
	/// ### Example
	/// ```rust,ignore
	/// a =- 42; // confusing, should it be `a -= 42` or `a = -42`?
	/// ```
	#[clippy::version = "pre 1.29.0"]
	pub SUSPICIOUS_ASSIGNMENT_FORMATTING,
	suspicious,
	"suspicious formatting of `*=`, `-=` or `!=`"
	}

	declare_clippy_lint! {
	/// ### What it does
	/// Checks the formatting of a unary operator on the right hand side
	/// of a binary operator. It lints if there is no space between the binary and unary operators,
	/// but there is a space between the unary and its operand.
	///
	/// ### Why is this bad?
	/// This is either a typo in the binary operator or confusing.
	///
	/// ### Example
	/// ```no_run
	/// # let foo = true;
	/// # let bar = false;
	/// // &&! looks like a different operator
	/// if foo &&! bar {}
	/// ```
	///
	/// Use instead:
	/// ```no_run
	/// # let foo = true;
	/// # let bar = false;
	/// if foo && !bar {}
	/// ```
	#[clippy::version = "1.40.0"]
	pub SUSPICIOUS_UNARY_OP_FORMATTING,
	suspicious,
	"suspicious formatting of unary `-` or `!` on the RHS of a BinOp"
	}

	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.
	///
	/// ### 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?
	/// }
	/// ```
	#[clippy::version = "pre 1.29.0"]
	pub SUSPICIOUS_ELSE_FORMATTING,
	suspicious,
	"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.
	///
	/// ### Example
	/// ```rust,ignore
	/// let a = &[
	/// -1, -2, -3 // <= no comma here
	/// -4, -5, -6
	/// ];
	/// ```
	#[clippy::version = "pre 1.29.0"]
	pub POSSIBLE_MISSING_COMMA,
	correctness,
	"possible missing comma in array"
	}

	declare_lint_pass!(Formatting => [
	SUSPICIOUS_ASSIGNMENT_FORMATTING,
	SUSPICIOUS_UNARY_OP_FORMATTING,
	SUSPICIOUS_ELSE_FORMATTING,
	POSSIBLE_MISSING_COMMA
	]);

	impl EarlyLintPass for Formatting {
	fn check_block(&mut self, cx: &EarlyContext<'_>, block: &Block) {
	for w in block.stmts.windows(2) {
	if let (StmtKind::Expr(first), StmtKind::Expr(second) \| StmtKind::Semi(second)) = (&w[0].kind, &w[1].kind) {
	check_missing_else(cx, first, second);
	}
	}
	}

	fn check_expr(&mut self, cx: &EarlyContext<'_>, expr: &Expr) {
	check_assign(cx, expr);
	check_unop(cx, expr);
	check_else(cx, expr);
	check_array(cx, expr);
	}
	}

	/// Implementation of the `SUSPICIOUS_ASSIGNMENT_FORMATTING` lint.
	fn check_assign(cx: &EarlyContext<'_>, expr: &Expr) {
	if let ExprKind::Assign(ref lhs, ref rhs, _) = expr.kind {
	if !lhs.span.from_expansion() && !rhs.span.from_expansion() {
	let eq_span = lhs.span.between(rhs.span);
	if let ExprKind::Unary(op, ref sub_rhs) = rhs.kind {
	if let Some(eq_snippet) = snippet_opt(cx, eq_span) {
	let op = UnOp::to_string(op);
	let eqop_span = lhs.span.between(sub_rhs.span);
	if eq_snippet.ends_with('=') {
	span_lint_and_note(
	cx,
	SUSPICIOUS_ASSIGNMENT_FORMATTING,
	eqop_span,
	&format!(
	"this looks like you are trying to use `.. {op}= ..`, but you \
	really are doing `.. = ({op} ..)`"
	),
	None,
	&format!("to remove this lint, use either `{op}=` or `= {op}`"),
	);
	}
	}
	}
	}
	}
	}

	/// Implementation of the `SUSPICIOUS_UNARY_OP_FORMATTING` lint.
	fn check_unop(cx: &EarlyContext<'_>, expr: &Expr) {
	if_chain! {
	if let ExprKind::Binary(ref binop, ref lhs, ref rhs) = expr.kind;
	if !lhs.span.from_expansion() && !rhs.span.from_expansion();
	// span between BinOp LHS and RHS
	let binop_span = lhs.span.between(rhs.span);
	// if RHS is an UnOp
	if let ExprKind::Unary(op, ref un_rhs) = rhs.kind;
	// from UnOp operator to UnOp operand
	let unop_operand_span = rhs.span.until(un_rhs.span);
	if let Some(binop_snippet) = snippet_opt(cx, binop_span);
	if let Some(unop_operand_snippet) = snippet_opt(cx, unop_operand_span);
	let binop_str = BinOpKind::to_string(&binop.node);
	// no space after BinOp operator and space after UnOp operator
	if binop_snippet.ends_with(binop_str) && unop_operand_snippet.ends_with(' ');
	then {
	let unop_str = UnOp::to_string(op);
	let eqop_span = lhs.span.between(un_rhs.span);
	span_lint_and_help(
	cx,
	SUSPICIOUS_UNARY_OP_FORMATTING,
	eqop_span,
	&format!(
	"by not having a space between `{binop_str}` and `{unop_str}` it looks like \
	`{binop_str}{unop_str}` is a single operator"
	),
	None,
	&format!(
	"put a space between `{binop_str}` and `{unop_str}` and remove the space after `{unop_str}`"
	),
	);
	}
	}
	}

	/// Implementation of the `SUSPICIOUS_ELSE_FORMATTING` lint for weird `else`.
	fn check_else(cx: &EarlyContext<'_>, expr: &Expr) {
	if_chain! {
	if let ExprKind::If(_, then, Some(else_)) = &expr.kind;
	if is_block(else_) \|\| is_if(else_);
	if !then.span.from_expansion() && !else_.span.from_expansion();
	if !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((pre_else, post_else)) = else_snippet.split_once("else");
	if let Some((_, post_else_post_eol)) = post_else.split_once('\n');

	then {
	// Allow allman style braces `} \n else \n {`
	if_chain! {
	if is_block(else_);
	if let Some((_, pre_else_post_eol)) = pre_else.split_once('\n');
	// Exactly one eol before and after the else
	if !pre_else_post_eol.contains('\n');
	if !post_else_post_eol.contains('\n');
	then {
	return;
	}
	}

	// Don't warn if the only thing inside post_else_post_eol is a comment block.
	let trimmed_post_else_post_eol = post_else_post_eol.trim();
	if trimmed_post_else_post_eol.starts_with("/") && trimmed_post_else_post_eol.ends_with("/") {
	return
	}

	let else_desc = if is_if(else_) { "if" } else { "{..}" };
	span_lint_and_note(
	cx,
	SUSPICIOUS_ELSE_FORMATTING,
	else_span,
	&format!("this is an `else {else_desc}` but the formatting might hide it"),
	None,
	&format!(
	"to remove this lint, remove the `else` or remove the new line between \
	`else` and `{else_desc}`",
	),
	);
	}
	}
	}

	#[must_use]
	fn has_unary_equivalent(bin_op: BinOpKind) -> bool {
	// &, *, -
	bin_op == BinOpKind::And \|\| bin_op == BinOpKind::Mul \|\| bin_op == BinOpKind::Sub
	}

	fn indentation(cx: &EarlyContext<'_>, span: Span) -> usize {
	cx.sess().source_map().lookup_char_pos(span.lo()).col.0
	}

	/// Implementation of the `POSSIBLE_MISSING_COMMA` lint for array
	fn check_array(cx: &EarlyContext<'_>, expr: &Expr) {
	if let ExprKind::Array(ref array) = expr.kind {
	for element in array {
	if_chain! {
	if let ExprKind::Binary(ref op, ref lhs, _) = element.kind;
	if has_unary_equivalent(op.node) && lhs.span.eq_ctxt(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');
	if indentation(cx, op.span) <= indentation(cx, lhs.span);
	then {
	span_lint_and_note(
	cx,
	POSSIBLE_MISSING_COMMA,
	lint_span,
	"possibly missing a comma here",
	None,
	"to remove this lint, add a comma or write the expr in a single line",
	);
	}
	}
	}
	}
	}

	fn check_missing_else(cx: &EarlyContext<'_>, first: &Expr, second: &Expr) {
	if_chain! {
	if !first.span.from_expansion() && !second.span.from_expansion();
	if matches!(first.kind, ExprKind::If(..));
	if is_block(second) \|\| is_if(second);

	// Proc-macros can give weird spans. Make sure this is actually an `if`.
	if is_span_if(cx, first.span);

	// If there is a line break between the two expressions, don't lint.
	// If there is a non-whitespace character, this span came from a proc-macro.
	let else_span = first.span.between(second.span);
	if let Some(else_snippet) = snippet_opt(cx, else_span);
	if !else_snippet.chars().any(\|c\| c == '\n' \|\| !c.is_whitespace());
	then {
	let (looks_like, next_thing) = if is_if(second) {
	("an `else if`", "the second `if`")
	} else {
	("an `else {..}`", "the next block")
	};

	span_lint_and_note(
	cx,
	SUSPICIOUS_ELSE_FORMATTING,
	else_span,
	&format!("this looks like {looks_like} but the `else` is missing"),
	None,
	&format!(
	"to remove this lint, add the missing `else` or add a new line before {next_thing}",
	),
	);
	}
	}
	}

	fn is_block(expr: &Expr) -> bool {
	matches!(expr.kind, ExprKind::Block(..))
	}

	/// Check if the expression is an `if` or `if let`
	fn is_if(expr: &Expr) -> bool {
	matches!(expr.kind, ExprKind::If(..))
	}