rustfmt_nightly/
macros.rs

1// Format list-like macro invocations. These are invocations whose token trees
2// can be interpreted as expressions and separated by commas.
3// Note that these token trees do not actually have to be interpreted as
4// expressions by the compiler. An example of an invocation we would reformat is
5// foo!( x, y, z ). The token x may represent an identifier in the code, but we
6// interpreted as an expression.
7// Macro uses which are not-list like, such as bar!(key => val), will not be
8// reformatted.
9// List-like invocations with parentheses will be formatted as function calls,
10// and those with brackets will be formatted as array literals.
11
12use std::collections::HashMap;
13use std::panic::{AssertUnwindSafe, catch_unwind};
14
15use rustc_ast::token::{Delimiter, Token, TokenKind};
16use rustc_ast::tokenstream::{TokenStream, TokenStreamIter, TokenTree};
17use rustc_ast::{ast, ptr};
18use rustc_ast_pretty::pprust;
19use rustc_span::{
20    BytePos, DUMMY_SP, Span, Symbol,
21    symbol::{self, kw},
22};
23use tracing::debug;
24
25use crate::comment::{
26    CharClasses, FindUncommented, FullCodeCharKind, LineClasses, contains_comment,
27};
28use crate::config::StyleEdition;
29use crate::config::lists::*;
30use crate::expr::{RhsAssignKind, rewrite_array, rewrite_assign_rhs};
31use crate::lists::{ListFormatting, itemize_list, write_list};
32use crate::overflow;
33use crate::parse::macros::lazy_static::parse_lazy_static;
34use crate::parse::macros::{ParsedMacroArgs, parse_expr, parse_macro_args};
35use crate::rewrite::{
36    MacroErrorKind, Rewrite, RewriteContext, RewriteError, RewriteErrorExt, RewriteResult,
37};
38use crate::shape::{Indent, Shape};
39use crate::source_map::SpanUtils;
40use crate::spanned::Spanned;
41use crate::utils::{
42    NodeIdExt, filtered_str_fits, format_visibility, indent_next_line, is_empty_line, mk_sp,
43    remove_trailing_white_spaces, rewrite_ident, trim_left_preserve_layout,
44};
45use crate::visitor::FmtVisitor;
46
47const FORCED_BRACKET_MACROS: &[&str] = &["vec!"];
48
49#[derive(Debug, Clone, Copy, PartialEq, Eq)]
50pub(crate) enum MacroPosition {
51    Item,
52    Statement,
53    Expression,
54    Pat,
55}
56
57#[derive(Debug)]
58pub(crate) enum MacroArg {
59    Expr(ptr::P<ast::Expr>),
60    Ty(ptr::P<ast::Ty>),
61    Pat(ptr::P<ast::Pat>),
62    Item(ptr::P<ast::Item>),
63    Keyword(symbol::Ident, Span),
64}
65
66impl MacroArg {
67    pub(crate) fn is_item(&self) -> bool {
68        match self {
69            MacroArg::Item(..) => true,
70            _ => false,
71        }
72    }
73}
74
75impl Rewrite for ast::Item {
76    fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> {
77        self.rewrite_result(context, shape).ok()
78    }
79
80    fn rewrite_result(&self, context: &RewriteContext<'_>, shape: Shape) -> RewriteResult {
81        let mut visitor = crate::visitor::FmtVisitor::from_context(context);
82        visitor.block_indent = shape.indent;
83        visitor.last_pos = self.span().lo();
84        visitor.visit_item(self);
85        Ok(visitor.buffer.to_owned())
86    }
87}
88
89impl Rewrite for MacroArg {
90    fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> {
91        self.rewrite_result(context, shape).ok()
92    }
93
94    fn rewrite_result(&self, context: &RewriteContext<'_>, shape: Shape) -> RewriteResult {
95        match *self {
96            MacroArg::Expr(ref expr) => expr.rewrite_result(context, shape),
97            MacroArg::Ty(ref ty) => ty.rewrite_result(context, shape),
98            MacroArg::Pat(ref pat) => pat.rewrite_result(context, shape),
99            MacroArg::Item(ref item) => item.rewrite_result(context, shape),
100            MacroArg::Keyword(ident, _) => Ok(ident.name.to_string()),
101        }
102    }
103}
104
105/// Rewrite macro name without using pretty-printer if possible.
106fn rewrite_macro_name(
107    context: &RewriteContext<'_>,
108    path: &ast::Path,
109    extra_ident: Option<symbol::Ident>,
110) -> String {
111    let name = if path.segments.len() == 1 {
112        // Avoid using pretty-printer in the common case.
113        format!("{}!", rewrite_ident(context, path.segments[0].ident))
114    } else {
115        format!("{}!", pprust::path_to_string(path))
116    };
117    match extra_ident {
118        Some(ident) if ident.name != kw::Empty => format!("{name} {ident}"),
119        _ => name,
120    }
121}
122
123// Use this on failing to format the macro call.
124// TODO(ding-young) We should also report macro parse failure to tell users why given snippet
125// is left unformatted. One possible improvement is appending formatting error to context.report
126fn return_macro_parse_failure_fallback(
127    context: &RewriteContext<'_>,
128    indent: Indent,
129    position: MacroPosition,
130    span: Span,
131) -> RewriteResult {
132    // Mark this as a failure however we format it
133    context.macro_rewrite_failure.replace(true);
134
135    // Heuristically determine whether the last line of the macro uses "Block" style
136    // rather than using "Visual" style, or another indentation style.
137    let is_like_block_indent_style = context
138        .snippet(span)
139        .lines()
140        .last()
141        .map(|closing_line| {
142            closing_line
143                .trim()
144                .chars()
145                .all(|ch| matches!(ch, '}' | ')' | ']'))
146        })
147        .unwrap_or(false);
148    if is_like_block_indent_style {
149        return trim_left_preserve_layout(context.snippet(span), indent, context.config)
150            .macro_error(MacroErrorKind::Unknown, span);
151    }
152
153    context.skipped_range.borrow_mut().push((
154        context.psess.line_of_byte_pos(span.lo()),
155        context.psess.line_of_byte_pos(span.hi()),
156    ));
157
158    // Return the snippet unmodified if the macro is not block-like
159    let mut snippet = context.snippet(span).to_owned();
160    if position == MacroPosition::Item {
161        snippet.push(';');
162    }
163    Ok(snippet)
164}
165
166pub(crate) fn rewrite_macro(
167    mac: &ast::MacCall,
168    extra_ident: Option<symbol::Ident>,
169    context: &RewriteContext<'_>,
170    shape: Shape,
171    position: MacroPosition,
172) -> RewriteResult {
173    let should_skip = context
174        .skip_context
175        .macros
176        .skip(context.snippet(mac.path.span));
177    if should_skip {
178        Err(RewriteError::SkipFormatting)
179    } else {
180        let guard = context.enter_macro();
181        let result = catch_unwind(AssertUnwindSafe(|| {
182            rewrite_macro_inner(
183                mac,
184                extra_ident,
185                context,
186                shape,
187                position,
188                guard.is_nested(),
189            )
190        }));
191        match result {
192            Err(..) => {
193                context.macro_rewrite_failure.replace(true);
194                Err(RewriteError::MacroFailure {
195                    kind: MacroErrorKind::Unknown,
196                    span: mac.span(),
197                })
198            }
199            Ok(Err(e)) => {
200                context.macro_rewrite_failure.replace(true);
201                Err(e)
202            }
203            Ok(rw) => rw,
204        }
205    }
206}
207
208fn rewrite_macro_inner(
209    mac: &ast::MacCall,
210    extra_ident: Option<symbol::Ident>,
211    context: &RewriteContext<'_>,
212    shape: Shape,
213    position: MacroPosition,
214    is_nested_macro: bool,
215) -> RewriteResult {
216    if context.config.use_try_shorthand() {
217        if let Some(expr) = convert_try_mac(mac, context) {
218            context.leave_macro();
219            return expr.rewrite_result(context, shape);
220        }
221    }
222
223    let original_style = macro_style(mac, context);
224
225    let macro_name = rewrite_macro_name(context, &mac.path, extra_ident);
226    let is_forced_bracket = FORCED_BRACKET_MACROS.contains(&&macro_name[..]);
227
228    let style = if is_forced_bracket && !is_nested_macro {
229        Delimiter::Bracket
230    } else {
231        original_style
232    };
233
234    let ts = mac.args.tokens.clone();
235    let has_comment = contains_comment(context.snippet(mac.span()));
236    if ts.is_empty() && !has_comment {
237        return match style {
238            Delimiter::Parenthesis if position == MacroPosition::Item => {
239                Ok(format!("{macro_name}();"))
240            }
241            Delimiter::Bracket if position == MacroPosition::Item => Ok(format!("{macro_name}[];")),
242            Delimiter::Parenthesis => Ok(format!("{macro_name}()")),
243            Delimiter::Bracket => Ok(format!("{macro_name}[]")),
244            Delimiter::Brace => Ok(format!("{macro_name} {{}}")),
245            _ => unreachable!(),
246        };
247    }
248    // Format well-known macros which cannot be parsed as a valid AST.
249    if macro_name == "lazy_static!" && !has_comment {
250        match format_lazy_static(context, shape, ts.clone(), mac.span()) {
251            Ok(rw) => return Ok(rw),
252            Err(err) => match err {
253                // We will move on to parsing macro args just like other macros
254                // if we could not parse lazy_static! with known syntax
255                RewriteError::MacroFailure { kind, span: _ }
256                    if kind == MacroErrorKind::ParseFailure => {}
257                // If formatting fails even though parsing succeeds, return the err early
258                _ => return Err(err),
259            },
260        }
261    }
262
263    let ParsedMacroArgs {
264        args: arg_vec,
265        vec_with_semi,
266        trailing_comma,
267    } = match parse_macro_args(context, ts, style, is_forced_bracket) {
268        Some(args) => args,
269        None => {
270            return return_macro_parse_failure_fallback(
271                context,
272                shape.indent,
273                position,
274                mac.span(),
275            );
276        }
277    };
278
279    if !arg_vec.is_empty() && arg_vec.iter().all(MacroArg::is_item) {
280        return rewrite_macro_with_items(
281            context,
282            &arg_vec,
283            &macro_name,
284            shape,
285            style,
286            original_style,
287            position,
288            mac.span(),
289        );
290    }
291
292    match style {
293        Delimiter::Parenthesis => {
294            // Handle special case: `vec!(expr; expr)`
295            if vec_with_semi {
296                handle_vec_semi(context, shape, arg_vec, macro_name, style, mac.span())
297            } else {
298                // Format macro invocation as function call, preserve the trailing
299                // comma because not all macros support them.
300                overflow::rewrite_with_parens(
301                    context,
302                    &macro_name,
303                    arg_vec.iter(),
304                    shape,
305                    mac.span(),
306                    context.config.fn_call_width(),
307                    if trailing_comma {
308                        Some(SeparatorTactic::Always)
309                    } else {
310                        Some(SeparatorTactic::Never)
311                    },
312                )
313                .map(|rw| match position {
314                    MacroPosition::Item => format!("{};", rw),
315                    _ => rw,
316                })
317            }
318        }
319        Delimiter::Bracket => {
320            // Handle special case: `vec![expr; expr]`
321            if vec_with_semi {
322                handle_vec_semi(context, shape, arg_vec, macro_name, style, mac.span())
323            } else {
324                // If we are rewriting `vec!` macro or other special macros,
325                // then we can rewrite this as a usual array literal.
326                // Otherwise, we must preserve the original existence of trailing comma.
327                let mut force_trailing_comma = if trailing_comma {
328                    Some(SeparatorTactic::Always)
329                } else {
330                    Some(SeparatorTactic::Never)
331                };
332                if is_forced_bracket && !is_nested_macro {
333                    context.leave_macro();
334                    if context.use_block_indent() {
335                        force_trailing_comma = Some(SeparatorTactic::Vertical);
336                    };
337                }
338                let rewrite = rewrite_array(
339                    &macro_name,
340                    arg_vec.iter(),
341                    mac.span(),
342                    context,
343                    shape,
344                    force_trailing_comma,
345                    Some(original_style),
346                )?;
347                let comma = match position {
348                    MacroPosition::Item => ";",
349                    _ => "",
350                };
351
352                Ok(format!("{rewrite}{comma}"))
353            }
354        }
355        Delimiter::Brace => {
356            // For macro invocations with braces, always put a space between
357            // the `macro_name!` and `{ /* macro_body */ }` but skip modifying
358            // anything in between the braces (for now).
359            let snippet = context.snippet(mac.span()).trim_start_matches(|c| c != '{');
360            match trim_left_preserve_layout(snippet, shape.indent, context.config) {
361                Some(macro_body) => Ok(format!("{macro_name} {macro_body}")),
362                None => Ok(format!("{macro_name} {snippet}")),
363            }
364        }
365        _ => unreachable!(),
366    }
367}
368
369fn handle_vec_semi(
370    context: &RewriteContext<'_>,
371    shape: Shape,
372    arg_vec: Vec<MacroArg>,
373    macro_name: String,
374    delim_token: Delimiter,
375    span: Span,
376) -> RewriteResult {
377    let (left, right) = match delim_token {
378        Delimiter::Parenthesis => ("(", ")"),
379        Delimiter::Bracket => ("[", "]"),
380        _ => unreachable!(),
381    };
382
383    // Should we return MaxWidthError, Or Macro failure
384    let mac_shape = shape
385        .offset_left(macro_name.len())
386        .max_width_error(shape.width, span)?;
387    // 8 = `vec![]` + `; ` or `vec!()` + `; `
388    let total_overhead = 8;
389    let nested_shape = mac_shape.block_indent(context.config.tab_spaces());
390    let lhs = arg_vec[0].rewrite_result(context, nested_shape)?;
391    let rhs = arg_vec[1].rewrite_result(context, nested_shape)?;
392    if !lhs.contains('\n')
393        && !rhs.contains('\n')
394        && lhs.len() + rhs.len() + total_overhead <= shape.width
395    {
396        // macro_name(lhs; rhs) or macro_name[lhs; rhs]
397        Ok(format!("{macro_name}{left}{lhs}; {rhs}{right}"))
398    } else {
399        // macro_name(\nlhs;\nrhs\n) or macro_name[\nlhs;\nrhs\n]
400        Ok(format!(
401            "{}{}{}{};{}{}{}{}",
402            macro_name,
403            left,
404            nested_shape.indent.to_string_with_newline(context.config),
405            lhs,
406            nested_shape.indent.to_string_with_newline(context.config),
407            rhs,
408            shape.indent.to_string_with_newline(context.config),
409            right
410        ))
411    }
412}
413
414fn rewrite_empty_macro_def_body(
415    context: &RewriteContext<'_>,
416    span: Span,
417    shape: Shape,
418) -> RewriteResult {
419    // Create an empty, dummy `ast::Block` representing an empty macro body
420    let block = ast::Block {
421        stmts: vec![].into(),
422        id: rustc_ast::node_id::DUMMY_NODE_ID,
423        rules: ast::BlockCheckMode::Default,
424        span,
425        tokens: None,
426    };
427    block.rewrite_result(context, shape)
428}
429
430pub(crate) fn rewrite_macro_def(
431    context: &RewriteContext<'_>,
432    shape: Shape,
433    indent: Indent,
434    def: &ast::MacroDef,
435    ident: symbol::Ident,
436    vis: &ast::Visibility,
437    span: Span,
438) -> RewriteResult {
439    let snippet = Ok(remove_trailing_white_spaces(context.snippet(span)));
440    if snippet.as_ref().map_or(true, |s| s.ends_with(';')) {
441        return snippet;
442    }
443
444    let ts = def.body.tokens.clone();
445    let mut parser = MacroParser::new(ts.iter());
446    let parsed_def = match parser.parse() {
447        Some(def) => def,
448        None => return snippet,
449    };
450
451    let mut result = if def.macro_rules {
452        String::from("macro_rules!")
453    } else {
454        format!("{}macro", format_visibility(context, vis))
455    };
456
457    result += " ";
458    result += rewrite_ident(context, ident);
459
460    let multi_branch_style = def.macro_rules || parsed_def.branches.len() != 1;
461
462    let arm_shape = if multi_branch_style {
463        shape
464            .block_indent(context.config.tab_spaces())
465            .with_max_width(context.config)
466    } else {
467        shape
468    };
469
470    if parsed_def.branches.len() == 0 {
471        let lo = context.snippet_provider.span_before(span, "{");
472        result += " ";
473        result += &rewrite_empty_macro_def_body(context, span.with_lo(lo), shape)?;
474        return Ok(result);
475    }
476
477    let branch_items = itemize_list(
478        context.snippet_provider,
479        parsed_def.branches.iter(),
480        "}",
481        ";",
482        |branch| branch.span.lo(),
483        |branch| branch.span.hi(),
484        |branch| match branch.rewrite(context, arm_shape, multi_branch_style) {
485            Ok(v) => Ok(v),
486            // if the rewrite returned None because a macro could not be rewritten, then return the
487            // original body
488            // TODO(ding-young) report rewrite error even if we return Ok with original snippet
489            Err(_) if context.macro_rewrite_failure.get() => {
490                Ok(context.snippet(branch.body).trim().to_string())
491            }
492            Err(e) => Err(e),
493        },
494        context.snippet_provider.span_after(span, "{"),
495        span.hi(),
496        false,
497    )
498    .collect::<Vec<_>>();
499
500    let fmt = ListFormatting::new(arm_shape, context.config)
501        .separator(if def.macro_rules { ";" } else { "" })
502        .trailing_separator(SeparatorTactic::Always)
503        .preserve_newline(true);
504
505    if multi_branch_style {
506        result += " {";
507        result += &arm_shape.indent.to_string_with_newline(context.config);
508    }
509
510    match write_list(&branch_items, &fmt) {
511        Ok(ref s) => result += s,
512        Err(_) => return snippet,
513    }
514
515    if multi_branch_style {
516        result += &indent.to_string_with_newline(context.config);
517        result += "}";
518    }
519
520    Ok(result)
521}
522
523fn register_metavariable(
524    map: &mut HashMap<String, String>,
525    result: &mut String,
526    name: &str,
527    dollar_count: usize,
528) {
529    let mut new_name = "$".repeat(dollar_count - 1);
530    let mut old_name = "$".repeat(dollar_count);
531
532    new_name.push('z');
533    new_name.push_str(name);
534    old_name.push_str(name);
535
536    result.push_str(&new_name);
537    map.insert(old_name, new_name);
538}
539
540// Replaces `$foo` with `zfoo`. We must check for name overlap to ensure we
541// aren't causing problems.
542// This should also work for escaped `$` variables, where we leave earlier `$`s.
543fn replace_names(input: &str) -> Option<(String, HashMap<String, String>)> {
544    // Each substitution will require five or six extra bytes.
545    let mut result = String::with_capacity(input.len() + 64);
546    let mut substs = HashMap::new();
547    let mut dollar_count = 0;
548    let mut cur_name = String::new();
549
550    for (kind, c) in CharClasses::new(input.chars()) {
551        if kind != FullCodeCharKind::Normal {
552            result.push(c);
553        } else if c == '$' {
554            dollar_count += 1;
555        } else if dollar_count == 0 {
556            result.push(c);
557        } else if !c.is_alphanumeric() && !cur_name.is_empty() {
558            // Terminates a name following one or more dollars.
559            register_metavariable(&mut substs, &mut result, &cur_name, dollar_count);
560
561            result.push(c);
562            dollar_count = 0;
563            cur_name.clear();
564        } else if c == '(' && cur_name.is_empty() {
565            // FIXME: Support macro def with repeat.
566            return None;
567        } else if c.is_alphanumeric() || c == '_' {
568            cur_name.push(c);
569        }
570    }
571
572    if !cur_name.is_empty() {
573        register_metavariable(&mut substs, &mut result, &cur_name, dollar_count);
574    }
575
576    debug!("replace_names `{}` {:?}", result, substs);
577
578    Some((result, substs))
579}
580
581#[derive(Debug, Clone)]
582enum MacroArgKind {
583    /// e.g., `$x: expr`.
584    MetaVariable(Symbol, String),
585    /// e.g., `$($foo: expr),*`
586    Repeat(
587        /// `()`, `[]` or `{}`.
588        Delimiter,
589        /// Inner arguments inside delimiters.
590        Vec<ParsedMacroArg>,
591        /// Something after the closing delimiter and the repeat token, if available.
592        Option<Box<ParsedMacroArg>>,
593        /// The repeat token. This could be one of `*`, `+` or `?`.
594        Token,
595    ),
596    /// e.g., `[derive(Debug)]`
597    Delimited(Delimiter, Vec<ParsedMacroArg>),
598    /// A possible separator. e.g., `,` or `;`.
599    Separator(String, String),
600    /// Other random stuff that does not fit to other kinds.
601    /// e.g., `== foo` in `($x: expr == foo)`.
602    Other(String, String),
603}
604
605fn delim_token_to_str(
606    context: &RewriteContext<'_>,
607    delim_token: Delimiter,
608    shape: Shape,
609    use_multiple_lines: bool,
610    inner_is_empty: bool,
611) -> (String, String) {
612    let (lhs, rhs) = match delim_token {
613        Delimiter::Parenthesis => ("(", ")"),
614        Delimiter::Bracket => ("[", "]"),
615        Delimiter::Brace => {
616            if inner_is_empty || use_multiple_lines {
617                ("{", "}")
618            } else {
619                ("{ ", " }")
620            }
621        }
622        Delimiter::Invisible(_) => unreachable!(),
623    };
624    if use_multiple_lines {
625        let indent_str = shape.indent.to_string_with_newline(context.config);
626        let nested_indent_str = shape
627            .indent
628            .block_indent(context.config)
629            .to_string_with_newline(context.config);
630        (
631            format!("{lhs}{nested_indent_str}"),
632            format!("{indent_str}{rhs}"),
633        )
634    } else {
635        (lhs.to_owned(), rhs.to_owned())
636    }
637}
638
639impl MacroArgKind {
640    fn starts_with_brace(&self) -> bool {
641        matches!(
642            *self,
643            MacroArgKind::Repeat(Delimiter::Brace, _, _, _)
644                | MacroArgKind::Delimited(Delimiter::Brace, _)
645        )
646    }
647
648    fn starts_with_dollar(&self) -> bool {
649        matches!(
650            *self,
651            MacroArgKind::Repeat(..) | MacroArgKind::MetaVariable(..)
652        )
653    }
654
655    fn ends_with_space(&self) -> bool {
656        matches!(*self, MacroArgKind::Separator(..))
657    }
658
659    fn has_meta_var(&self) -> bool {
660        match *self {
661            MacroArgKind::MetaVariable(..) => true,
662            MacroArgKind::Repeat(_, ref args, _, _) => args.iter().any(|a| a.kind.has_meta_var()),
663            _ => false,
664        }
665    }
666
667    fn rewrite(
668        &self,
669        context: &RewriteContext<'_>,
670        shape: Shape,
671        use_multiple_lines: bool,
672    ) -> RewriteResult {
673        type DelimitedArgsRewrite = Result<(String, String, String), RewriteError>;
674        let rewrite_delimited_inner = |delim_tok, args| -> DelimitedArgsRewrite {
675            let inner = wrap_macro_args(context, args, shape)?;
676            let (lhs, rhs) = delim_token_to_str(context, delim_tok, shape, false, inner.is_empty());
677            if lhs.len() + inner.len() + rhs.len() <= shape.width {
678                return Ok((lhs, inner, rhs));
679            }
680
681            let (lhs, rhs) = delim_token_to_str(context, delim_tok, shape, true, false);
682            let nested_shape = shape
683                .block_indent(context.config.tab_spaces())
684                .with_max_width(context.config);
685            let inner = wrap_macro_args(context, args, nested_shape)?;
686            Ok((lhs, inner, rhs))
687        };
688
689        match *self {
690            MacroArgKind::MetaVariable(ty, ref name) => Ok(format!("${name}:{ty}")),
691            MacroArgKind::Repeat(delim_tok, ref args, ref another, ref tok) => {
692                let (lhs, inner, rhs) = rewrite_delimited_inner(delim_tok, args)?;
693                let another = another
694                    .as_ref()
695                    .and_then(|a| a.rewrite(context, shape, use_multiple_lines).ok())
696                    .unwrap_or_else(|| "".to_owned());
697                let repeat_tok = pprust::token_to_string(tok);
698
699                Ok(format!("${lhs}{inner}{rhs}{another}{repeat_tok}"))
700            }
701            MacroArgKind::Delimited(delim_tok, ref args) => {
702                rewrite_delimited_inner(delim_tok, args)
703                    .map(|(lhs, inner, rhs)| format!("{}{}{}", lhs, inner, rhs))
704            }
705            MacroArgKind::Separator(ref sep, ref prefix) => Ok(format!("{prefix}{sep} ")),
706            MacroArgKind::Other(ref inner, ref prefix) => Ok(format!("{prefix}{inner}")),
707        }
708    }
709}
710
711#[derive(Debug, Clone)]
712struct ParsedMacroArg {
713    kind: MacroArgKind,
714}
715
716impl ParsedMacroArg {
717    fn rewrite(
718        &self,
719        context: &RewriteContext<'_>,
720        shape: Shape,
721        use_multiple_lines: bool,
722    ) -> RewriteResult {
723        self.kind.rewrite(context, shape, use_multiple_lines)
724    }
725}
726
727/// Parses macro arguments on macro def.
728struct MacroArgParser {
729    /// Either a name of the next metavariable, a separator, or junk.
730    buf: String,
731    /// The first token of the current buffer.
732    start_tok: Token,
733    /// `true` if we are parsing a metavariable or a repeat.
734    is_meta_var: bool,
735    /// The last token parsed.
736    last_tok: Token,
737    /// Holds the parsed arguments.
738    result: Vec<ParsedMacroArg>,
739}
740
741fn last_tok(tt: &TokenTree) -> Token {
742    match *tt {
743        TokenTree::Token(ref t, _) => t.clone(),
744        TokenTree::Delimited(delim_span, _, delim, _) => Token {
745            kind: TokenKind::CloseDelim(delim),
746            span: delim_span.close,
747        },
748    }
749}
750
751impl MacroArgParser {
752    fn new() -> MacroArgParser {
753        MacroArgParser {
754            buf: String::new(),
755            is_meta_var: false,
756            last_tok: Token {
757                kind: TokenKind::Eof,
758                span: DUMMY_SP,
759            },
760            start_tok: Token {
761                kind: TokenKind::Eof,
762                span: DUMMY_SP,
763            },
764            result: vec![],
765        }
766    }
767
768    fn set_last_tok(&mut self, tok: &TokenTree) {
769        self.last_tok = last_tok(tok);
770    }
771
772    fn add_separator(&mut self) {
773        let prefix = if self.need_space_prefix() {
774            " ".to_owned()
775        } else {
776            "".to_owned()
777        };
778        self.result.push(ParsedMacroArg {
779            kind: MacroArgKind::Separator(self.buf.clone(), prefix),
780        });
781        self.buf.clear();
782    }
783
784    fn add_other(&mut self) {
785        let prefix = if self.need_space_prefix() {
786            " ".to_owned()
787        } else {
788            "".to_owned()
789        };
790        self.result.push(ParsedMacroArg {
791            kind: MacroArgKind::Other(self.buf.clone(), prefix),
792        });
793        self.buf.clear();
794    }
795
796    fn add_meta_variable(&mut self, iter: &mut TokenStreamIter<'_>) -> Option<()> {
797        match iter.next() {
798            Some(&TokenTree::Token(
799                Token {
800                    kind: TokenKind::Ident(name, _),
801                    ..
802                },
803                _,
804            )) => {
805                self.result.push(ParsedMacroArg {
806                    kind: MacroArgKind::MetaVariable(name, self.buf.clone()),
807                });
808
809                self.buf.clear();
810                self.is_meta_var = false;
811                Some(())
812            }
813            _ => None,
814        }
815    }
816
817    fn add_delimited(&mut self, inner: Vec<ParsedMacroArg>, delim: Delimiter) {
818        self.result.push(ParsedMacroArg {
819            kind: MacroArgKind::Delimited(delim, inner),
820        });
821    }
822
823    // $($foo: expr),?
824    fn add_repeat(
825        &mut self,
826        inner: Vec<ParsedMacroArg>,
827        delim: Delimiter,
828        iter: &mut TokenStreamIter<'_>,
829    ) -> Option<()> {
830        let mut buffer = String::new();
831        let mut first = true;
832
833        // Parse '*', '+' or '?.
834        for tok in iter {
835            self.set_last_tok(&tok);
836            if first {
837                first = false;
838            }
839
840            match tok {
841                TokenTree::Token(
842                    Token {
843                        kind: TokenKind::Plus,
844                        ..
845                    },
846                    _,
847                )
848                | TokenTree::Token(
849                    Token {
850                        kind: TokenKind::Question,
851                        ..
852                    },
853                    _,
854                )
855                | TokenTree::Token(
856                    Token {
857                        kind: TokenKind::Star,
858                        ..
859                    },
860                    _,
861                ) => {
862                    break;
863                }
864                TokenTree::Token(ref t, _) => {
865                    buffer.push_str(&pprust::token_to_string(t));
866                }
867                _ => return None,
868            }
869        }
870
871        // There could be some random stuff between ')' and '*', '+' or '?'.
872        let another = if buffer.trim().is_empty() {
873            None
874        } else {
875            Some(Box::new(ParsedMacroArg {
876                kind: MacroArgKind::Other(buffer, "".to_owned()),
877            }))
878        };
879
880        self.result.push(ParsedMacroArg {
881            kind: MacroArgKind::Repeat(delim, inner, another, self.last_tok.clone()),
882        });
883        Some(())
884    }
885
886    fn update_buffer(&mut self, t: &Token) {
887        if self.buf.is_empty() {
888            self.start_tok = t.clone();
889        } else {
890            let needs_space = match next_space(&self.last_tok.kind) {
891                SpaceState::Ident => ident_like(t),
892                SpaceState::Punctuation => !ident_like(t),
893                SpaceState::Always => true,
894                SpaceState::Never => false,
895            };
896            if force_space_before(&t.kind) || needs_space {
897                self.buf.push(' ');
898            }
899        }
900
901        self.buf.push_str(&pprust::token_to_string(t));
902    }
903
904    fn need_space_prefix(&self) -> bool {
905        if self.result.is_empty() {
906            return false;
907        }
908
909        let last_arg = self.result.last().unwrap();
910        if let MacroArgKind::MetaVariable(..) = last_arg.kind {
911            if ident_like(&self.start_tok) {
912                return true;
913            }
914            if self.start_tok.kind == TokenKind::Colon {
915                return true;
916            }
917        }
918
919        if force_space_before(&self.start_tok.kind) {
920            return true;
921        }
922
923        false
924    }
925
926    /// Returns a collection of parsed macro def's arguments.
927    fn parse(mut self, tokens: TokenStream) -> Option<Vec<ParsedMacroArg>> {
928        let mut iter = tokens.iter();
929
930        while let Some(tok) = iter.next() {
931            match tok {
932                &TokenTree::Token(
933                    Token {
934                        kind: TokenKind::Dollar,
935                        span,
936                    },
937                    _,
938                ) => {
939                    // We always want to add a separator before meta variables.
940                    if !self.buf.is_empty() {
941                        self.add_separator();
942                    }
943
944                    // Start keeping the name of this metavariable in the buffer.
945                    self.is_meta_var = true;
946                    self.start_tok = Token {
947                        kind: TokenKind::Dollar,
948                        span,
949                    };
950                }
951                TokenTree::Token(
952                    Token {
953                        kind: TokenKind::Colon,
954                        ..
955                    },
956                    _,
957                ) if self.is_meta_var => {
958                    self.add_meta_variable(&mut iter)?;
959                }
960                TokenTree::Token(ref t, _) => self.update_buffer(t),
961                &TokenTree::Delimited(_dspan, _spacing, delimited, ref tts) => {
962                    if !self.buf.is_empty() {
963                        if next_space(&self.last_tok.kind) == SpaceState::Always {
964                            self.add_separator();
965                        } else {
966                            self.add_other();
967                        }
968                    }
969
970                    // Parse the stuff inside delimiters.
971                    let parser = MacroArgParser::new();
972                    let delimited_arg = parser.parse(tts.clone())?;
973
974                    if self.is_meta_var {
975                        self.add_repeat(delimited_arg, delimited, &mut iter)?;
976                        self.is_meta_var = false;
977                    } else {
978                        self.add_delimited(delimited_arg, delimited);
979                    }
980                }
981            }
982
983            self.set_last_tok(&tok);
984        }
985
986        // We are left with some stuff in the buffer. Since there is nothing
987        // left to separate, add this as `Other`.
988        if !self.buf.is_empty() {
989            self.add_other();
990        }
991
992        Some(self.result)
993    }
994}
995
996fn wrap_macro_args(
997    context: &RewriteContext<'_>,
998    args: &[ParsedMacroArg],
999    shape: Shape,
1000) -> RewriteResult {
1001    wrap_macro_args_inner(context, args, shape, false)
1002        .or_else(|_| wrap_macro_args_inner(context, args, shape, true))
1003}
1004
1005fn wrap_macro_args_inner(
1006    context: &RewriteContext<'_>,
1007    args: &[ParsedMacroArg],
1008    shape: Shape,
1009    use_multiple_lines: bool,
1010) -> RewriteResult {
1011    let mut result = String::with_capacity(128);
1012    let mut iter = args.iter().peekable();
1013    let indent_str = shape.indent.to_string_with_newline(context.config);
1014
1015    while let Some(arg) = iter.next() {
1016        result.push_str(&arg.rewrite(context, shape, use_multiple_lines)?);
1017
1018        if use_multiple_lines
1019            && (arg.kind.ends_with_space() || iter.peek().map_or(false, |a| a.kind.has_meta_var()))
1020        {
1021            if arg.kind.ends_with_space() {
1022                result.pop();
1023            }
1024            result.push_str(&indent_str);
1025        } else if let Some(next_arg) = iter.peek() {
1026            let space_before_dollar =
1027                !arg.kind.ends_with_space() && next_arg.kind.starts_with_dollar();
1028            let space_before_brace = next_arg.kind.starts_with_brace();
1029            if space_before_dollar || space_before_brace {
1030                result.push(' ');
1031            }
1032        }
1033    }
1034
1035    if !use_multiple_lines && result.len() >= shape.width {
1036        Err(RewriteError::Unknown)
1037    } else {
1038        Ok(result)
1039    }
1040}
1041
1042// This is a bit sketchy. The token rules probably need tweaking, but it works
1043// for some common cases. I hope the basic logic is sufficient. Note that the
1044// meaning of some tokens is a bit different here from usual Rust, e.g., `*`
1045// and `(`/`)` have special meaning.
1046fn format_macro_args(
1047    context: &RewriteContext<'_>,
1048    token_stream: TokenStream,
1049    shape: Shape,
1050) -> RewriteResult {
1051    let span = span_for_token_stream(&token_stream);
1052    if !context.config.format_macro_matchers() {
1053        return Ok(match span {
1054            Some(span) => context.snippet(span).to_owned(),
1055            None => String::new(),
1056        });
1057    }
1058    let parsed_args = MacroArgParser::new()
1059        .parse(token_stream)
1060        .macro_error(MacroErrorKind::ParseFailure, span.unwrap())?;
1061    wrap_macro_args(context, &parsed_args, shape)
1062}
1063
1064fn span_for_token_stream(token_stream: &TokenStream) -> Option<Span> {
1065    token_stream.iter().next().map(|tt| tt.span())
1066}
1067
1068// We should insert a space if the next token is a:
1069#[derive(Copy, Clone, PartialEq)]
1070enum SpaceState {
1071    Never,
1072    Punctuation,
1073    Ident, // Or ident/literal-like thing.
1074    Always,
1075}
1076
1077fn force_space_before(tok: &TokenKind) -> bool {
1078    debug!("tok: force_space_before {:?}", tok);
1079
1080    match tok {
1081        TokenKind::Eq
1082        | TokenKind::Lt
1083        | TokenKind::Le
1084        | TokenKind::EqEq
1085        | TokenKind::Ne
1086        | TokenKind::Ge
1087        | TokenKind::Gt
1088        | TokenKind::AndAnd
1089        | TokenKind::OrOr
1090        | TokenKind::Bang
1091        | TokenKind::Tilde
1092        | TokenKind::PlusEq
1093        | TokenKind::MinusEq
1094        | TokenKind::StarEq
1095        | TokenKind::SlashEq
1096        | TokenKind::PercentEq
1097        | TokenKind::CaretEq
1098        | TokenKind::AndEq
1099        | TokenKind::OrEq
1100        | TokenKind::ShlEq
1101        | TokenKind::ShrEq
1102        | TokenKind::At
1103        | TokenKind::RArrow
1104        | TokenKind::LArrow
1105        | TokenKind::FatArrow
1106        | TokenKind::Plus
1107        | TokenKind::Minus
1108        | TokenKind::Star
1109        | TokenKind::Slash
1110        | TokenKind::Percent
1111        | TokenKind::Caret
1112        | TokenKind::And
1113        | TokenKind::Or
1114        | TokenKind::Shl
1115        | TokenKind::Shr
1116        | TokenKind::Pound
1117        | TokenKind::Dollar => true,
1118        _ => false,
1119    }
1120}
1121
1122fn ident_like(tok: &Token) -> bool {
1123    matches!(
1124        tok.kind,
1125        TokenKind::Ident(..) | TokenKind::Literal(..) | TokenKind::Lifetime(..)
1126    )
1127}
1128
1129fn next_space(tok: &TokenKind) -> SpaceState {
1130    debug!("next_space: {:?}", tok);
1131
1132    match tok {
1133        TokenKind::Bang
1134        | TokenKind::And
1135        | TokenKind::Tilde
1136        | TokenKind::At
1137        | TokenKind::Comma
1138        | TokenKind::Dot
1139        | TokenKind::DotDot
1140        | TokenKind::DotDotDot
1141        | TokenKind::DotDotEq
1142        | TokenKind::Question => SpaceState::Punctuation,
1143
1144        TokenKind::PathSep
1145        | TokenKind::Pound
1146        | TokenKind::Dollar
1147        | TokenKind::OpenDelim(_)
1148        | TokenKind::CloseDelim(_) => SpaceState::Never,
1149
1150        TokenKind::Literal(..) | TokenKind::Ident(..) | TokenKind::Lifetime(..) => {
1151            SpaceState::Ident
1152        }
1153
1154        _ => SpaceState::Always,
1155    }
1156}
1157
1158/// Tries to convert a macro use into a short hand try expression. Returns `None`
1159/// when the macro is not an instance of `try!` (or parsing the inner expression
1160/// failed).
1161pub(crate) fn convert_try_mac(
1162    mac: &ast::MacCall,
1163    context: &RewriteContext<'_>,
1164) -> Option<ast::Expr> {
1165    let path = &pprust::path_to_string(&mac.path);
1166    if path == "try" || path == "r#try" {
1167        let ts = mac.args.tokens.clone();
1168
1169        Some(ast::Expr {
1170            id: ast::NodeId::root(), // dummy value
1171            kind: ast::ExprKind::Try(parse_expr(context, ts)?),
1172            span: mac.span(), // incorrect span, but shouldn't matter too much
1173            attrs: ast::AttrVec::new(),
1174            tokens: None,
1175        })
1176    } else {
1177        None
1178    }
1179}
1180
1181pub(crate) fn macro_style(mac: &ast::MacCall, context: &RewriteContext<'_>) -> Delimiter {
1182    let snippet = context.snippet(mac.span());
1183    let paren_pos = snippet.find_uncommented("(").unwrap_or(usize::MAX);
1184    let bracket_pos = snippet.find_uncommented("[").unwrap_or(usize::MAX);
1185    let brace_pos = snippet.find_uncommented("{").unwrap_or(usize::MAX);
1186
1187    if paren_pos < bracket_pos && paren_pos < brace_pos {
1188        Delimiter::Parenthesis
1189    } else if bracket_pos < brace_pos {
1190        Delimiter::Bracket
1191    } else {
1192        Delimiter::Brace
1193    }
1194}
1195
1196// A very simple parser that just parses a macros 2.0 definition into its branches.
1197// Currently we do not attempt to parse any further than that.
1198struct MacroParser<'a> {
1199    iter: TokenStreamIter<'a>,
1200}
1201
1202impl<'a> MacroParser<'a> {
1203    const fn new(iter: TokenStreamIter<'a>) -> Self {
1204        Self { iter }
1205    }
1206
1207    // (`(` ... `)` `=>` `{` ... `}`)*
1208    fn parse(&mut self) -> Option<Macro> {
1209        let mut branches = vec![];
1210        while self.iter.peek().is_some() {
1211            branches.push(self.parse_branch()?);
1212        }
1213
1214        Some(Macro { branches })
1215    }
1216
1217    // `(` ... `)` `=>` `{` ... `}`
1218    fn parse_branch(&mut self) -> Option<MacroBranch> {
1219        let tok = self.iter.next()?;
1220        let (lo, args_paren_kind) = match tok {
1221            TokenTree::Token(..) => return None,
1222            &TokenTree::Delimited(delimited_span, _, d, _) => (delimited_span.open.lo(), d),
1223        };
1224        let args = TokenStream::new(vec![tok.clone()]);
1225        match self.iter.next()? {
1226            TokenTree::Token(
1227                Token {
1228                    kind: TokenKind::FatArrow,
1229                    ..
1230                },
1231                _,
1232            ) => {}
1233            _ => return None,
1234        }
1235        let (mut hi, body, whole_body) = match self.iter.next()? {
1236            TokenTree::Token(..) => return None,
1237            TokenTree::Delimited(delimited_span, ..) => {
1238                let data = delimited_span.entire().data();
1239                (
1240                    data.hi,
1241                    Span::new(
1242                        data.lo + BytePos(1),
1243                        data.hi - BytePos(1),
1244                        data.ctxt,
1245                        data.parent,
1246                    ),
1247                    delimited_span.entire(),
1248                )
1249            }
1250        };
1251        if let Some(TokenTree::Token(
1252            Token {
1253                kind: TokenKind::Semi,
1254                span,
1255            },
1256            _,
1257        )) = self.iter.peek()
1258        {
1259            hi = span.hi();
1260            self.iter.next();
1261        }
1262        Some(MacroBranch {
1263            span: mk_sp(lo, hi),
1264            args_paren_kind,
1265            args,
1266            body,
1267            whole_body,
1268        })
1269    }
1270}
1271
1272// A parsed macros 2.0 macro definition.
1273struct Macro {
1274    branches: Vec<MacroBranch>,
1275}
1276
1277// FIXME: it would be more efficient to use references to the token streams
1278// rather than clone them, if we can make the borrowing work out.
1279struct MacroBranch {
1280    span: Span,
1281    args_paren_kind: Delimiter,
1282    args: TokenStream,
1283    body: Span,
1284    whole_body: Span,
1285}
1286
1287impl MacroBranch {
1288    fn rewrite(
1289        &self,
1290        context: &RewriteContext<'_>,
1291        shape: Shape,
1292        multi_branch_style: bool,
1293    ) -> RewriteResult {
1294        // Only attempt to format function-like macros.
1295        if self.args_paren_kind != Delimiter::Parenthesis {
1296            // FIXME(#1539): implement for non-sugared macros.
1297            return Err(RewriteError::MacroFailure {
1298                kind: MacroErrorKind::Unknown,
1299                span: self.span,
1300            });
1301        }
1302
1303        let old_body = context.snippet(self.body).trim();
1304        let has_block_body = old_body.starts_with('{');
1305        let mut prefix_width = 5; // 5 = " => {"
1306        if context.config.style_edition() >= StyleEdition::Edition2024 {
1307            if has_block_body {
1308                prefix_width = 6; // 6 = " => {{"
1309            }
1310        }
1311        let mut result = format_macro_args(
1312            context,
1313            self.args.clone(),
1314            shape
1315                .sub_width(prefix_width)
1316                .max_width_error(shape.width, self.span)?,
1317        )?;
1318
1319        if multi_branch_style {
1320            result += " =>";
1321        }
1322
1323        if !context.config.format_macro_bodies() {
1324            result += " ";
1325            result += context.snippet(self.whole_body);
1326            return Ok(result);
1327        }
1328
1329        // The macro body is the most interesting part. It might end up as various
1330        // AST nodes, but also has special variables (e.g, `$foo`) which can't be
1331        // parsed as regular Rust code (and note that these can be escaped using
1332        // `$$`). We'll try and format like an AST node, but we'll substitute
1333        // variables for new names with the same length first.
1334
1335        let (body_str, substs) =
1336            replace_names(old_body).macro_error(MacroErrorKind::ReplaceMacroVariable, self.span)?;
1337
1338        let mut config = context.config.clone();
1339        config.set().show_parse_errors(false);
1340
1341        result += " {";
1342
1343        let body_indent = if has_block_body {
1344            shape.indent
1345        } else {
1346            shape.indent.block_indent(&config)
1347        };
1348        let new_width = config.max_width() - body_indent.width();
1349        config.set().max_width(new_width);
1350
1351        // First try to format as items, then as statements.
1352        let new_body_snippet = match crate::format_snippet(&body_str, &config, true) {
1353            Some(new_body) => new_body,
1354            None => {
1355                let new_width = new_width + config.tab_spaces();
1356                config.set().max_width(new_width);
1357                match crate::format_code_block(&body_str, &config, true) {
1358                    Some(new_body) => new_body,
1359                    None => {
1360                        return Err(RewriteError::MacroFailure {
1361                            kind: MacroErrorKind::Unknown,
1362                            span: self.span,
1363                        });
1364                    }
1365                }
1366            }
1367        };
1368
1369        if !filtered_str_fits(&new_body_snippet.snippet, config.max_width(), shape) {
1370            return Err(RewriteError::ExceedsMaxWidth {
1371                configured_width: shape.width,
1372                span: self.span,
1373            });
1374        }
1375
1376        // Indent the body since it is in a block.
1377        let indent_str = body_indent.to_string(&config);
1378        let mut new_body = LineClasses::new(new_body_snippet.snippet.trim_end())
1379            .enumerate()
1380            .fold(
1381                (String::new(), true),
1382                |(mut s, need_indent), (i, (kind, ref l))| {
1383                    if !is_empty_line(l)
1384                        && need_indent
1385                        && !new_body_snippet.is_line_non_formatted(i + 1)
1386                    {
1387                        s += &indent_str;
1388                    }
1389                    (s + l + "\n", indent_next_line(kind, l, &config))
1390                },
1391            )
1392            .0;
1393
1394        // Undo our replacement of macro variables.
1395        // FIXME: this could be *much* more efficient.
1396        for (old, new) in &substs {
1397            if old_body.contains(new) {
1398                debug!("rewrite_macro_def: bailing matching variable: `{}`", new);
1399                return Err(RewriteError::MacroFailure {
1400                    kind: MacroErrorKind::ReplaceMacroVariable,
1401                    span: self.span,
1402                });
1403            }
1404            new_body = new_body.replace(new, old);
1405        }
1406
1407        if has_block_body {
1408            result += new_body.trim();
1409        } else if !new_body.is_empty() {
1410            result += "\n";
1411            result += &new_body;
1412            result += &shape.indent.to_string(&config);
1413        }
1414
1415        result += "}";
1416
1417        Ok(result)
1418    }
1419}
1420
1421/// Format `lazy_static!` from <https://crates.io/crates/lazy_static>.
1422///
1423/// # Expected syntax
1424///
1425/// ```text
1426/// lazy_static! {
1427///     [pub] static ref NAME_1: TYPE_1 = EXPR_1;
1428///     [pub] static ref NAME_2: TYPE_2 = EXPR_2;
1429///     ...
1430///     [pub] static ref NAME_N: TYPE_N = EXPR_N;
1431/// }
1432/// ```
1433fn format_lazy_static(
1434    context: &RewriteContext<'_>,
1435    shape: Shape,
1436    ts: TokenStream,
1437    span: Span,
1438) -> RewriteResult {
1439    let mut result = String::with_capacity(1024);
1440    let nested_shape = shape
1441        .block_indent(context.config.tab_spaces())
1442        .with_max_width(context.config);
1443
1444    result.push_str("lazy_static! {");
1445    result.push_str(&nested_shape.indent.to_string_with_newline(context.config));
1446
1447    let parsed_elems =
1448        parse_lazy_static(context, ts).macro_error(MacroErrorKind::ParseFailure, span)?;
1449    let last = parsed_elems.len() - 1;
1450    for (i, (vis, id, ty, expr)) in parsed_elems.iter().enumerate() {
1451        // Rewrite as a static item.
1452        let vis = crate::utils::format_visibility(context, vis);
1453        let mut stmt = String::with_capacity(128);
1454        stmt.push_str(&format!(
1455            "{}static ref {}: {} =",
1456            vis,
1457            id,
1458            ty.rewrite_result(context, nested_shape)?
1459        ));
1460        result.push_str(&rewrite_assign_rhs(
1461            context,
1462            stmt,
1463            &*expr,
1464            &RhsAssignKind::Expr(&expr.kind, expr.span),
1465            nested_shape
1466                .sub_width(1)
1467                .max_width_error(nested_shape.width, expr.span)?,
1468        )?);
1469        result.push(';');
1470        if i != last {
1471            result.push_str(&nested_shape.indent.to_string_with_newline(context.config));
1472        }
1473    }
1474
1475    result.push_str(&shape.indent.to_string_with_newline(context.config));
1476    result.push('}');
1477
1478    Ok(result)
1479}
1480
1481fn rewrite_macro_with_items(
1482    context: &RewriteContext<'_>,
1483    items: &[MacroArg],
1484    macro_name: &str,
1485    shape: Shape,
1486    style: Delimiter,
1487    original_style: Delimiter,
1488    position: MacroPosition,
1489    span: Span,
1490) -> RewriteResult {
1491    let style_to_delims = |style| match style {
1492        Delimiter::Parenthesis => Ok(("(", ")")),
1493        Delimiter::Bracket => Ok(("[", "]")),
1494        Delimiter::Brace => Ok((" {", "}")),
1495        _ => Err(RewriteError::Unknown),
1496    };
1497
1498    let (opener, closer) = style_to_delims(style)?;
1499    let (original_opener, _) = style_to_delims(original_style)?;
1500    let trailing_semicolon = match style {
1501        Delimiter::Parenthesis | Delimiter::Bracket if position == MacroPosition::Item => ";",
1502        _ => "",
1503    };
1504
1505    let mut visitor = FmtVisitor::from_context(context);
1506    visitor.block_indent = shape.indent.block_indent(context.config);
1507
1508    // The current opener may be different from the original opener. This can happen
1509    // if our macro is a forced bracket macro originally written with non-bracket
1510    // delimiters. We need to use the original opener to locate the span after it.
1511    visitor.last_pos = context
1512        .snippet_provider
1513        .span_after(span, original_opener.trim());
1514    for item in items {
1515        let item = match item {
1516            MacroArg::Item(item) => item,
1517            _ => return Err(RewriteError::Unknown),
1518        };
1519        visitor.visit_item(item);
1520    }
1521
1522    let mut result = String::with_capacity(256);
1523    result.push_str(macro_name);
1524    result.push_str(opener);
1525    result.push_str(&visitor.block_indent.to_string_with_newline(context.config));
1526    result.push_str(visitor.buffer.trim());
1527    result.push_str(&shape.indent.to_string_with_newline(context.config));
1528    result.push_str(closer);
1529    result.push_str(trailing_semicolon);
1530    Ok(result)
1531}