6 use rustc_ast::tokenstream::TokenStream;
7 use rustc_ast::{token, BlockCheckMode, UnsafeSource};
8 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
9 use rustc_errors::{pluralize, Applicability, DiagnosticBuilder};
10 use rustc_expand::base::{self, *};
11 use rustc_parse_format as parse;
12 use rustc_span::symbol::{sym, Ident, Symbol};
13 use rustc_span::{MultiSpan, Span};
16 use std::collections::hash_map::Entry;
20 Placeholder(&'static str),
29 struct Context<'a, 'b> {
30 ecx: &'a mut ExtCtxt<'b>,
31 /// The macro's call site. References to unstable formatting internals must
32 /// use this span to pass the stability checker.
34 /// The span of the format string literal.
37 /// List of parsed argument expressions.
38 /// Named expressions are resolved early, and are appended to the end of
39 /// argument expressions.
41 /// Example showing the various data structures in motion:
43 /// * Original: `"{foo:o} {:o} {foo:x} {0:x} {1:o} {:x} {1:x} {0:o}"`
44 /// * Implicit argument resolution: `"{foo:o} {0:o} {foo:x} {0:x} {1:o} {1:x} {1:x} {0:o}"`
45 /// * Name resolution: `"{2:o} {0:o} {2:x} {0:x} {1:o} {1:x} {1:x} {0:o}"`
46 /// * `arg_types` (in JSON): `[[0, 1, 0], [0, 1, 1], [0, 1]]`
47 /// * `arg_unique_types` (in simplified JSON): `[["o", "x"], ["o", "x"], ["o", "x"]]`
48 /// * `names` (in JSON): `{"foo": 2}`
49 args: Vec<P<ast::Expr>>,
50 /// Placeholder slot numbers indexed by argument.
51 arg_types: Vec<Vec<usize>>,
52 /// Unique format specs seen for each argument.
53 arg_unique_types: Vec<Vec<ArgumentType>>,
54 /// Map from named arguments to their resolved indices.
55 names: FxHashMap<Symbol, usize>,
57 /// The latest consecutive literal strings, or empty if there weren't any.
60 /// Collection of the compiled `rt::Argument` structures
61 pieces: Vec<P<ast::Expr>>,
62 /// Collection of string literals
63 str_pieces: Vec<P<ast::Expr>>,
64 /// Stays `true` if all formatting parameters are default (as in "{}{}").
65 all_pieces_simple: bool,
67 /// Mapping between positional argument references and indices into the
68 /// final generated static argument array. We record the starting indices
69 /// corresponding to each positional argument, and number of references
70 /// consumed so far for each argument, to facilitate correct `Position`
71 /// mapping in `build_piece`. In effect this can be seen as a "flattened"
72 /// version of `arg_unique_types`.
74 /// Again with the example described above in docstring for `args`:
76 /// * `arg_index_map` (in JSON): `[[0, 1, 0], [2, 3, 3], [4, 5]]`
77 arg_index_map: Vec<Vec<usize>>,
79 /// Starting offset of count argument slots.
80 count_args_index_offset: usize,
82 /// Count argument slots and tracking data structures.
83 /// Count arguments are separately tracked for de-duplication in case
84 /// multiple references are made to one argument. For example, in this
87 /// * Original: `"{:.*} {:.foo$} {1:.*} {:.0$}"`
88 /// * Implicit argument resolution: `"{1:.0$} {2:.foo$} {1:.3$} {4:.0$}"`
89 /// * Name resolution: `"{1:.0$} {2:.5$} {1:.3$} {4:.0$}"`
90 /// * `count_positions` (in JSON): `{0: 0, 5: 1, 3: 2}`
91 /// * `count_args`: `vec![Exact(0), Exact(5), Exact(3)]`
92 count_args: Vec<Position>,
93 /// Relative slot numbers for count arguments.
94 count_positions: FxHashMap<usize, usize>,
95 /// Number of count slots assigned.
96 count_positions_count: usize,
98 /// Current position of the implicit positional arg pointer, as if it
99 /// still existed in this phase of processing.
100 /// Used only for `all_pieces_simple` tracking in `build_piece`.
102 /// Current piece being evaluated, used for error reporting.
104 /// Keep track of invalid references to positional arguments.
105 invalid_refs: Vec<(usize, usize)>,
106 /// Spans of all the formatting arguments, in order.
107 arg_spans: Vec<Span>,
108 /// All the formatting arguments that have formatting flags set, in order for diagnostics.
109 arg_with_formatting: Vec<parse::FormatSpec<'a>>,
111 /// Whether this format string came from a string literal, as opposed to a macro.
115 /// Parses the arguments from the given list of tokens, returning the diagnostic
116 /// if there's a parse error so we can continue parsing other format!
119 /// If parsing succeeds, the return value is:
122 /// Some((fmtstr, parsed arguments, index map for named arguments))
125 ecx: &mut ExtCtxt<'a>,
128 ) -> Result<(P<ast::Expr>, Vec<P<ast::Expr>>, FxHashMap<Symbol, usize>), DiagnosticBuilder<'a>> {
129 let mut args = Vec::<P<ast::Expr>>::new();
130 let mut names = FxHashMap::<Symbol, usize>::default();
132 let mut p = ecx.new_parser_from_tts(tts);
134 if p.token == token::Eof {
135 return Err(ecx.struct_span_err(sp, "requires at least a format string argument"));
138 let first_token = &p.token;
139 let fmtstr = match first_token.kind {
140 token::TokenKind::Literal(token::Lit {
141 kind: token::LitKind::Str | token::LitKind::StrRaw(_),
144 // If the first token is a string literal, then a format expression
145 // is constructed from it.
147 // This allows us to properly handle cases when the first comma
148 // after the format string is mistakenly replaced with any operator,
149 // which cause the expression parser to eat too much tokens.
150 p.parse_literal_maybe_minus()?
153 // Otherwise, we fall back to the expression parser.
158 let mut first = true;
159 let mut named = false;
161 while p.token != token::Eof {
162 if !p.eat(&token::Comma) {
164 p.clear_expected_tokens();
167 match p.expect(&token::Comma) {
169 match token::TokenKind::Comma.similar_tokens() {
170 Some(tks) if tks.contains(&p.token.kind) => {
171 // If a similar token is found, then it may be a typo. We
172 // consider it as a comma, and continue parsing.
176 // Otherwise stop the parsing and return the error.
177 _ => return Err(err),
186 if p.token == token::Eof {
188 } // accept trailing commas
189 match p.token.ident() {
190 Some((ident, _)) if p.look_ahead(1, |t| *t == token::Eq) => {
193 p.expect(&token::Eq)?;
194 let e = p.parse_expr()?;
195 if let Some(prev) = names.get(&ident.name) {
196 ecx.struct_span_err(e.span, &format!("duplicate argument named `{}`", ident))
197 .span_label(args[*prev].span, "previously here")
198 .span_label(e.span, "duplicate argument")
203 // Resolve names into slots early.
204 // Since all the positional args are already seen at this point
205 // if the input is valid, we can simply append to the positional
206 // args. And remember the names.
207 let slot = args.len();
208 names.insert(ident.name, slot);
212 let e = p.parse_expr()?;
214 let mut err = ecx.struct_span_err(
216 "positional arguments cannot follow named arguments",
218 err.span_label(e.span, "positional arguments must be before named arguments");
219 for pos in names.values() {
220 err.span_label(args[*pos].span, "named argument");
228 Ok((fmtstr, args, names))
231 impl<'a, 'b> Context<'a, 'b> {
232 fn resolve_name_inplace(&self, p: &mut parse::Piece<'_>) {
233 // NOTE: the `unwrap_or` branch is needed in case of invalid format
234 // arguments, e.g., `format_args!("{foo}")`.
235 let lookup = |s: Symbol| *self.names.get(&s).unwrap_or(&0);
238 parse::String(_) => {}
239 parse::NextArgument(ref mut arg) => {
240 if let parse::ArgumentNamed(s) = arg.position {
241 arg.position = parse::ArgumentIs(lookup(s));
243 if let parse::CountIsName(s) = arg.format.width {
244 arg.format.width = parse::CountIsParam(lookup(s));
246 if let parse::CountIsName(s) = arg.format.precision {
247 arg.format.precision = parse::CountIsParam(lookup(s));
253 /// Verifies one piece of a parse string, and remembers it if valid.
254 /// All errors are not emitted as fatal so we can continue giving errors
255 /// about this and possibly other format strings.
256 fn verify_piece(&mut self, p: &parse::Piece<'_>) {
258 parse::String(..) => {}
259 parse::NextArgument(ref arg) => {
260 // width/precision first, if they have implicit positional
261 // parameters it makes more sense to consume them first.
262 self.verify_count(arg.format.width);
263 self.verify_count(arg.format.precision);
265 // argument second, if it's an implicit positional parameter
266 // it's written second, so it should come after width/precision.
267 let pos = match arg.position {
268 parse::ArgumentIs(i) | parse::ArgumentImplicitlyIs(i) => Exact(i),
269 parse::ArgumentNamed(s) => Named(s),
272 let ty = Placeholder(match arg.format.ty {
283 let fmtsp = self.fmtsp;
284 let sp = arg.format.ty_span.map(|sp| fmtsp.from_inner(sp));
285 let mut err = self.ecx.struct_span_err(
287 &format!("unknown format trait `{}`", arg.format.ty),
290 "the only appropriate formatting traits are:\n\
291 - ``, which uses the `Display` trait\n\
292 - `?`, which uses the `Debug` trait\n\
293 - `e`, which uses the `LowerExp` trait\n\
294 - `E`, which uses the `UpperExp` trait\n\
295 - `o`, which uses the `Octal` trait\n\
296 - `p`, which uses the `Pointer` trait\n\
297 - `b`, which uses the `Binary` trait\n\
298 - `x`, which uses the `LowerHex` trait\n\
299 - `X`, which uses the `UpperHex` trait",
301 if let Some(sp) = sp {
302 for (fmt, name) in &[
313 // FIXME: rustfix (`run-rustfix`) fails to apply suggestions.
314 // > "Cannot replace slice of data that was already replaced"
315 err.tool_only_span_suggestion(
317 &format!("use the `{}` trait", name),
319 Applicability::MaybeIncorrect,
327 self.verify_arg_type(pos, ty);
333 fn verify_count(&mut self, c: parse::Count) {
335 parse::CountImplied | parse::CountIs(..) => {}
336 parse::CountIsParam(i) => {
337 self.verify_arg_type(Exact(i), Count);
339 parse::CountIsName(s) => {
340 self.verify_arg_type(Named(s), Count);
345 fn describe_num_args(&self) -> Cow<'_, str> {
346 match self.args.len() {
347 0 => "no arguments were given".into(),
348 1 => "there is 1 argument".into(),
349 x => format!("there are {} arguments", x).into(),
353 /// Handle invalid references to positional arguments. Output different
354 /// errors for the case where all arguments are positional and for when
355 /// there are named arguments or numbered positional arguments in the
357 fn report_invalid_references(&self, numbered_position_args: bool) {
359 let sp = if !self.arg_spans.is_empty() {
360 // Point at the formatting arguments.
361 MultiSpan::from_spans(self.arg_spans.clone())
363 MultiSpan::from_span(self.fmtsp)
366 self.invalid_refs.iter().map(|(r, pos)| (r.to_string(), self.arg_spans.get(*pos)));
368 let mut zero_based_note = false;
370 let count = self.pieces.len()
371 + self.arg_with_formatting.iter().filter(|fmt| fmt.precision_span.is_some()).count();
372 if self.names.is_empty() && !numbered_position_args && count != self.args.len() {
373 e = self.ecx.struct_span_err(
376 "{} positional argument{} in format string, but {}",
379 self.describe_num_args(),
382 for arg in &self.args {
383 // Point at the arguments that will be formatted.
384 e.span_label(arg.span, "");
387 let (mut refs, spans): (Vec<_>, Vec<_>) = refs.unzip();
388 // Avoid `invalid reference to positional arguments 7 and 7 (there is 1 argument)`
389 // for `println!("{7:7$}", 1);`
392 let spans: Vec<_> = spans.into_iter().filter_map(|sp| sp.copied()).collect();
393 let sp = if self.arg_spans.is_empty() || spans.is_empty() {
394 MultiSpan::from_span(self.fmtsp)
396 MultiSpan::from_spans(spans)
398 let arg_list = if refs.len() == 1 {
399 format!("argument {}", refs[0])
401 let reg = refs.pop().unwrap();
402 format!("arguments {head} and {tail}", head = refs.join(", "), tail = reg)
405 e = self.ecx.struct_span_err(
408 "invalid reference to positional {} ({})",
410 self.describe_num_args()
413 zero_based_note = true;
416 for fmt in &self.arg_with_formatting {
417 if let Some(span) = fmt.precision_span {
418 let span = self.fmtsp.from_inner(span);
419 match fmt.precision {
420 parse::CountIsParam(pos) if pos > self.args.len() => {
424 "this precision flag expects an `usize` argument at position {}, \
427 self.describe_num_args(),
430 zero_based_note = true;
432 parse::CountIsParam(pos) => {
433 let count = self.pieces.len()
437 .filter(|fmt| fmt.precision_span.is_some())
439 e.span_label(span, &format!(
440 "this precision flag adds an extra required argument at position {}, \
441 which is why there {} expected",
444 "is 1 argument".to_string()
446 format!("are {} arguments", count)
449 if let Some(arg) = self.args.get(pos) {
452 "this parameter corresponds to the precision flag",
455 zero_based_note = true;
460 if let Some(span) = fmt.width_span {
461 let span = self.fmtsp.from_inner(span);
463 parse::CountIsParam(pos) if pos > self.args.len() => {
467 "this width flag expects an `usize` argument at position {}, \
470 self.describe_num_args(),
473 zero_based_note = true;
480 e.note("positional arguments are zero-based");
482 if !self.arg_with_formatting.is_empty() {
484 "for information about formatting flags, visit \
485 https://doc.rust-lang.org/std/fmt/index.html",
492 /// Actually verifies and tracks a given format placeholder
493 /// (a.k.a. argument).
494 fn verify_arg_type(&mut self, arg: Position, ty: ArgumentType) {
497 if self.args.len() <= arg {
498 self.invalid_refs.push((arg, self.curpiece));
503 // record every (position, type) combination only once
504 let seen_ty = &mut self.arg_unique_types[arg];
505 let i = seen_ty.iter().position(|x| *x == ty).unwrap_or_else(|| {
506 let i = seen_ty.len();
510 self.arg_types[arg].push(i);
513 if let Entry::Vacant(e) = self.count_positions.entry(arg) {
514 let i = self.count_positions_count;
516 self.count_args.push(Exact(arg));
517 self.count_positions_count += 1;
524 match self.names.get(&name) {
526 // Treat as positional arg.
527 self.verify_arg_type(Exact(idx), ty)
530 // For the moment capturing variables from format strings expanded from macros is
531 // disabled (see RFC #2795)
533 // Treat this name as a variable to capture from the surrounding scope
534 let idx = self.args.len();
535 self.arg_types.push(Vec::new());
536 self.arg_unique_types.push(Vec::new());
537 let span = if self.is_literal {
538 *self.arg_spans.get(self.curpiece).unwrap_or(&self.fmtsp)
542 self.args.push(self.ecx.expr_ident(span, Ident::new(name, span)));
543 self.names.insert(name, idx);
544 self.verify_arg_type(Exact(idx), ty)
546 let msg = format!("there is no argument named `{}`", name);
547 let sp = if self.is_literal {
548 *self.arg_spans.get(self.curpiece).unwrap_or(&self.fmtsp)
552 let mut err = self.ecx.struct_span_err(sp, &msg[..]);
555 "did you intend to capture a variable `{}` from \
556 the surrounding scope?",
560 "to avoid ambiguity, `format_args!` cannot capture variables \
561 when the format string is expanded from a macro",
572 /// Builds the mapping between format placeholders and argument objects.
573 fn build_index_map(&mut self) {
574 // NOTE: Keep the ordering the same as `into_expr`'s expansion would do!
575 let args_len = self.args.len();
576 self.arg_index_map.reserve(args_len);
578 let mut sofar = 0usize;
581 for i in 0..args_len {
582 let arg_types = &self.arg_types[i];
583 let arg_offsets = arg_types.iter().map(|offset| sofar + *offset).collect::<Vec<_>>();
584 self.arg_index_map.push(arg_offsets);
585 sofar += self.arg_unique_types[i].len();
588 // Record starting index for counts, which appear just after arguments
589 self.count_args_index_offset = sofar;
592 fn rtpath(ecx: &ExtCtxt<'_>, s: Symbol) -> Vec<Ident> {
593 ecx.std_path(&[sym::fmt, sym::rt, sym::v1, s])
596 fn build_count(&self, c: parse::Count) -> P<ast::Expr> {
598 let count = |c, arg| {
599 let mut path = Context::rtpath(self.ecx, sym::Count);
600 path.push(Ident::new(c, sp));
602 Some(arg) => self.ecx.expr_call_global(sp, path, vec![arg]),
603 None => self.ecx.expr_path(self.ecx.path_global(sp, path)),
607 parse::CountIs(i) => count(sym::Is, Some(self.ecx.expr_usize(sp, i))),
608 parse::CountIsParam(i) => {
609 // This needs mapping too, as `i` is referring to a macro
610 // argument. If `i` is not found in `count_positions` then
611 // the error had already been emitted elsewhere.
612 let i = self.count_positions.get(&i).cloned().unwrap_or(0)
613 + self.count_args_index_offset;
614 count(sym::Param, Some(self.ecx.expr_usize(sp, i)))
616 parse::CountImplied => count(sym::Implied, None),
617 // should never be the case, names are already resolved
618 parse::CountIsName(_) => panic!("should never happen"),
622 /// Build a literal expression from the accumulated string literals
623 fn build_literal_string(&mut self) -> P<ast::Expr> {
625 let s = Symbol::intern(&self.literal);
626 self.literal.clear();
627 self.ecx.expr_str(sp, s)
630 /// Builds a static `rt::Argument` from a `parse::Piece` or append
631 /// to the `literal` string.
634 piece: &parse::Piece<'a>,
635 arg_index_consumed: &mut Vec<usize>,
636 ) -> Option<P<ast::Expr>> {
639 parse::String(s) => {
640 self.literal.push_str(s);
643 parse::NextArgument(ref arg) => {
644 // Build the position
647 parse::ArgumentIs(i) | parse::ArgumentImplicitlyIs(i) => {
648 // Map to index in final generated argument array
649 // in case of multiple types specified
650 let arg_idx = match arg_index_consumed.get_mut(i) {
651 None => 0, // error already emitted elsewhere
653 let idx_map = &self.arg_index_map[i];
654 // unwrap_or branch: error already emitted elsewhere
655 let arg_idx = *idx_map.get(*offset).unwrap_or(&0);
660 self.ecx.expr_usize(sp, arg_idx)
663 // should never be the case, because names are already
665 parse::ArgumentNamed(_) => panic!("should never happen"),
669 let simple_arg = parse::Argument {
671 // We don't have ArgumentNext any more, so we have to
672 // track the current argument ourselves.
677 format: parse::FormatSpec {
678 fill: arg.format.fill,
679 align: parse::AlignUnknown,
681 precision: parse::CountImplied,
682 precision_span: None,
683 width: parse::CountImplied,
686 ty_span: arg.format.ty_span,
690 let fill = arg.format.fill.unwrap_or(' ');
692 let pos_simple = arg.position.index() == simple_arg.position.index();
694 if arg.format.precision_span.is_some() || arg.format.width_span.is_some() {
695 self.arg_with_formatting.push(arg.format);
697 if !pos_simple || arg.format != simple_arg.format || fill != ' ' {
698 self.all_pieces_simple = false;
702 let fill = self.ecx.expr_lit(sp, ast::LitKind::Char(fill));
704 let mut p = Context::rtpath(self.ecx, sym::Alignment);
705 p.push(Ident::new(name, sp));
706 self.ecx.path_global(sp, p)
708 let align = match arg.format.align {
709 parse::AlignLeft => align(sym::Left),
710 parse::AlignRight => align(sym::Right),
711 parse::AlignCenter => align(sym::Center),
712 parse::AlignUnknown => align(sym::Unknown),
714 let align = self.ecx.expr_path(align);
715 let flags = self.ecx.expr_u32(sp, arg.format.flags);
716 let prec = self.build_count(arg.format.precision);
717 let width = self.build_count(arg.format.width);
718 let path = self.ecx.path_global(sp, Context::rtpath(self.ecx, sym::FormatSpec));
719 let fmt = self.ecx.expr_struct(
723 self.ecx.field_imm(sp, Ident::new(sym::fill, sp), fill),
724 self.ecx.field_imm(sp, Ident::new(sym::align, sp), align),
725 self.ecx.field_imm(sp, Ident::new(sym::flags, sp), flags),
726 self.ecx.field_imm(sp, Ident::new(sym::precision, sp), prec),
727 self.ecx.field_imm(sp, Ident::new(sym::width, sp), width),
731 let path = self.ecx.path_global(sp, Context::rtpath(self.ecx, sym::Argument));
732 Some(self.ecx.expr_struct(
736 self.ecx.field_imm(sp, Ident::new(sym::position, sp), pos),
737 self.ecx.field_imm(sp, Ident::new(sym::format, sp), fmt),
744 /// Actually builds the expression which the format_args! block will be
746 fn into_expr(self) -> P<ast::Expr> {
747 let mut args = Vec::with_capacity(
748 self.arg_unique_types.iter().map(|v| v.len()).sum::<usize>() + self.count_args.len(),
750 let mut heads = Vec::with_capacity(self.args.len());
752 // First, build up the static array which will become our precompiled
754 let pieces = self.ecx.expr_vec_slice(self.fmtsp, self.str_pieces);
756 // Before consuming the expressions, we have to remember spans for
757 // count arguments as they are now generated separate from other
758 // arguments, hence have no access to the `P<ast::Expr>`'s.
759 let spans_pos: Vec<_> = self.args.iter().map(|e| e.span).collect();
761 // Right now there is a bug such that for the expression:
763 // the lifetime of `1` doesn't outlast the call to `bar`, so it's not
764 // valid for the call to `foo`. To work around this all arguments to the
765 // format! string are shoved into locals. Furthermore, we shove the address
766 // of each variable because we don't want to move out of the arguments
767 // passed to this function.
768 for (i, e) in self.args.into_iter().enumerate() {
769 for arg_ty in self.arg_unique_types[i].iter() {
770 args.push(Context::format_arg(self.ecx, self.macsp, e.span, arg_ty, i));
772 heads.push(self.ecx.expr_addr_of(e.span, e));
774 for pos in self.count_args {
775 let index = match pos {
777 _ => panic!("should never happen"),
779 let span = spans_pos[index];
780 args.push(Context::format_arg(self.ecx, self.macsp, span, &Count, index));
783 let args_array = self.ecx.expr_vec(self.macsp, args);
785 // Constructs an AST equivalent to:
787 // match (&arg0, &arg1) {
788 // (tmp0, tmp1) => args_array
797 // Because of #11585 the new temporary lifetime rule, the enclosing
798 // statements for these temporaries become the let's themselves.
799 // If one or more of them are RefCell's, RefCell borrow() will also
800 // end there; they don't last long enough for args_array to use them.
801 // The match expression solves the scope problem.
803 // Note, it may also very well be transformed to:
808 // ref tmp1 => args_array } } }
810 // But the nested match expression is proved to perform not as well
811 // as series of let's; the first approach does.
813 let pat = self.ecx.pat_ident(self.macsp, Ident::new(sym::_args, self.macsp));
814 let arm = self.ecx.arm(self.macsp, pat, args_array);
815 let head = self.ecx.expr(self.macsp, ast::ExprKind::Tup(heads));
816 self.ecx.expr_match(self.macsp, head, vec![arm])
819 let args_slice = self.ecx.expr_addr_of(self.macsp, args_match);
821 // Now create the fmt::Arguments struct with all our locals we created.
822 let (fn_name, fn_args) = if self.all_pieces_simple {
823 ("new_v1", vec![pieces, args_slice])
825 // Build up the static array which will store our precompiled
826 // nonstandard placeholders, if there are any.
827 let fmt = self.ecx.expr_vec_slice(self.macsp, self.pieces);
829 let path = self.ecx.std_path(&[sym::fmt, sym::UnsafeArg, sym::new]);
830 let unsafe_arg = self.ecx.expr_call_global(self.macsp, path, Vec::new());
831 let unsafe_expr = self.ecx.expr_block(P(ast::Block {
832 stmts: vec![self.ecx.stmt_expr(unsafe_arg)],
833 id: ast::DUMMY_NODE_ID,
834 rules: BlockCheckMode::Unsafe(UnsafeSource::CompilerGenerated),
837 could_be_bare_literal: false,
840 ("new_v1_formatted", vec![pieces, args_slice, fmt, unsafe_expr])
843 let path = self.ecx.std_path(&[sym::fmt, sym::Arguments, Symbol::intern(fn_name)]);
844 self.ecx.expr_call_global(self.macsp, path, fn_args)
854 sp = ecx.with_def_site_ctxt(sp);
855 let arg = ecx.expr_ident(sp, Ident::new(sym::_args, sp));
856 let arg = ecx.expr(sp, ast::ExprKind::Field(arg, Ident::new(sym::integer(arg_index), sp)));
857 let trait_ = match *ty {
858 Placeholder(trait_) if trait_ == "<invalid>" => return DummyResult::raw_expr(sp, true),
859 Placeholder(trait_) => trait_,
861 let path = ecx.std_path(&[sym::fmt, sym::ArgumentV1, sym::from_usize]);
862 return ecx.expr_call_global(macsp, path, vec![arg]);
866 let path = ecx.std_path(&[sym::fmt, Symbol::intern(trait_), sym::fmt]);
867 let format_fn = ecx.path_global(sp, path);
868 let path = ecx.std_path(&[sym::fmt, sym::ArgumentV1, sym::new]);
869 ecx.expr_call_global(macsp, path, vec![arg, ecx.expr_path(format_fn)])
873 fn expand_format_args_impl<'cx>(
874 ecx: &'cx mut ExtCtxt<'_>,
878 ) -> Box<dyn base::MacResult + 'cx> {
879 sp = ecx.with_def_site_ctxt(sp);
880 match parse_args(ecx, sp, tts) {
881 Ok((efmt, args, names)) => {
882 MacEager::expr(expand_preparsed_format_args(ecx, sp, efmt, args, names, nl))
891 pub fn expand_format_args<'cx>(
892 ecx: &'cx mut ExtCtxt<'_>,
895 ) -> Box<dyn base::MacResult + 'cx> {
896 expand_format_args_impl(ecx, sp, tts, false)
899 pub fn expand_format_args_nl<'cx>(
900 ecx: &'cx mut ExtCtxt<'_>,
903 ) -> Box<dyn base::MacResult + 'cx> {
904 expand_format_args_impl(ecx, sp, tts, true)
907 /// Take the various parts of `format_args!(efmt, args..., name=names...)`
908 /// and construct the appropriate formatting expression.
909 pub fn expand_preparsed_format_args(
910 ecx: &mut ExtCtxt<'_>,
913 args: Vec<P<ast::Expr>>,
914 names: FxHashMap<Symbol, usize>,
915 append_newline: bool,
917 // NOTE: this verbose way of initializing `Vec<Vec<ArgumentType>>` is because
918 // `ArgumentType` does not derive `Clone`.
919 let arg_types: Vec<_> = (0..args.len()).map(|_| Vec::new()).collect();
920 let arg_unique_types: Vec<_> = (0..args.len()).map(|_| Vec::new()).collect();
922 let mut macsp = ecx.call_site();
923 macsp = ecx.with_def_site_ctxt(macsp);
925 let msg = "format argument must be a string literal";
926 let fmt_sp = efmt.span;
927 let efmt_kind_is_lit: bool = matches!(efmt.kind, ast::ExprKind::Lit(_));
928 let (fmt_str, fmt_style, fmt_span) = match expr_to_spanned_string(ecx, efmt, msg) {
929 Ok(mut fmt) if append_newline => {
930 fmt.0 = Symbol::intern(&format!("{}\n", fmt.0));
935 if let Some((mut err, suggested)) = err {
936 let sugg_fmt = match args.len() {
937 0 => "{}".to_string(),
938 _ => format!("{}{{}}", "{} ".repeat(args.len())),
942 fmt_sp.shrink_to_lo(),
943 "you might be missing a string literal to format with",
944 format!("\"{}\", ", sugg_fmt),
945 Applicability::MaybeIncorrect,
950 return DummyResult::raw_expr(sp, true);
954 let str_style = match fmt_style {
955 ast::StrStyle::Cooked => None,
956 ast::StrStyle::Raw(raw) => Some(raw as usize),
959 let fmt_str = &fmt_str.as_str(); // for the suggestions below
960 let fmt_snippet = ecx.source_map().span_to_snippet(fmt_sp).ok();
961 let mut parser = parse::Parser::new(
966 parse::ParseMode::Format,
969 let mut unverified_pieces = Vec::new();
970 while let Some(piece) = parser.next() {
971 if !parser.errors.is_empty() {
974 unverified_pieces.push(piece);
978 if !parser.errors.is_empty() {
979 let err = parser.errors.remove(0);
980 let sp = if efmt_kind_is_lit {
981 fmt_span.from_inner(err.span)
983 // The format string could be another macro invocation, e.g.:
984 // format!(concat!("abc", "{}"), 4);
985 // However, `err.span` is an inner span relative to the *result* of
986 // the macro invocation, which is why we would get a nonsensical
987 // result calling `fmt_span.from_inner(err.span)` as above, and
988 // might even end up inside a multibyte character (issue #86085).
989 // Therefore, we conservatively report the error for the entire
990 // argument span here.
993 let mut e = ecx.struct_span_err(sp, &format!("invalid format string: {}", err.description));
994 e.span_label(sp, err.label + " in format string");
995 if let Some(note) = err.note {
998 if let Some((label, span)) = err.secondary_label {
999 let sp = fmt_span.from_inner(span);
1000 e.span_label(sp, label);
1003 return DummyResult::raw_expr(sp, true);
1006 let arg_spans = parser.arg_places.iter().map(|span| fmt_span.from_inner(*span)).collect();
1008 let named_pos: FxHashSet<usize> = names.values().cloned().collect();
1010 let mut cx = Context {
1018 arg_index_map: Vec::new(),
1019 count_args: Vec::new(),
1020 count_positions: FxHashMap::default(),
1021 count_positions_count: 0,
1022 count_args_index_offset: 0,
1023 literal: String::new(),
1024 pieces: Vec::with_capacity(unverified_pieces.len()),
1025 str_pieces: Vec::with_capacity(unverified_pieces.len()),
1026 all_pieces_simple: true,
1029 invalid_refs: Vec::new(),
1031 arg_with_formatting: Vec::new(),
1032 is_literal: parser.is_literal,
1035 // This needs to happen *after* the Parser has consumed all pieces to create all the spans
1036 let pieces = unverified_pieces
1039 cx.verify_piece(&piece);
1040 cx.resolve_name_inplace(&mut piece);
1043 .collect::<Vec<_>>();
1045 let numbered_position_args = pieces.iter().any(|arg: &parse::Piece<'_>| match *arg {
1046 parse::String(_) => false,
1047 parse::NextArgument(arg) => matches!(arg.position, parse::Position::ArgumentIs(_)),
1050 cx.build_index_map();
1052 let mut arg_index_consumed = vec![0usize; cx.arg_index_map.len()];
1054 for piece in pieces {
1055 if let Some(piece) = cx.build_piece(&piece, &mut arg_index_consumed) {
1056 let s = cx.build_literal_string();
1057 cx.str_pieces.push(s);
1058 cx.pieces.push(piece);
1062 if !cx.literal.is_empty() {
1063 let s = cx.build_literal_string();
1064 cx.str_pieces.push(s);
1067 if !cx.invalid_refs.is_empty() {
1068 cx.report_invalid_references(numbered_position_args);
1071 // Make sure that all arguments were used and all arguments have types.
1076 .filter(|(i, ty)| ty.is_empty() && !cx.count_positions.contains_key(&i))
1078 let msg = if named_pos.contains(&i) {
1080 "named argument never used"
1082 // positional argument
1083 "argument never used"
1085 (cx.args[i].span, msg)
1087 .collect::<Vec<_>>();
1089 let errs_len = errs.len();
1090 if !errs.is_empty() {
1091 let args_used = cx.arg_types.len() - errs_len;
1092 let args_unused = errs_len;
1095 if let [(sp, msg)] = &errs[..] {
1096 let mut diag = cx.ecx.struct_span_err(*sp, *msg);
1097 diag.span_label(*sp, *msg);
1100 let mut diag = cx.ecx.struct_span_err(
1101 errs.iter().map(|&(sp, _)| sp).collect::<Vec<Span>>(),
1102 "multiple unused formatting arguments",
1104 diag.span_label(cx.fmtsp, "multiple missing formatting specifiers");
1105 for (sp, msg) in errs {
1106 diag.span_label(sp, msg);
1112 // Used to ensure we only report translations for *one* kind of foreign format.
1113 let mut found_foreign = false;
1114 // Decide if we want to look for foreign formatting directives.
1115 if args_used < args_unused {
1116 use super::format_foreign as foreign;
1118 // The set of foreign substitutions we've explained. This prevents spamming the user
1119 // with `%d should be written as {}` over and over again.
1120 let mut explained = FxHashSet::default();
1122 macro_rules! check_foreign {
1124 let mut show_doc_note = false;
1126 let mut suggestions = vec![];
1127 // account for `"` and account for raw strings `r#`
1128 let padding = str_style.map(|i| i + 2).unwrap_or(1);
1129 for sub in foreign::$kind::iter_subs(fmt_str, padding) {
1130 let (trn, success) = match sub.translate() {
1131 Ok(trn) => (trn, true),
1132 Err(Some(msg)) => (msg, false),
1134 // If it has no translation, don't call it out specifically.
1138 let pos = sub.position();
1139 let sub = String::from(sub.as_str());
1140 if explained.contains(&sub) {
1143 explained.insert(sub.clone());
1146 found_foreign = true;
1147 show_doc_note = true;
1150 if let Some(inner_sp) = pos {
1151 let sp = fmt_sp.from_inner(inner_sp);
1154 suggestions.push((sp, trn));
1158 &format!("format specifiers use curly braces, and {}", trn),
1163 diag.help(&format!("`{}` should be written as `{}`", sub, trn));
1166 "`{}` should use curly braces, and {}",
1176 " formatting not supported; see the documentation for `std::fmt`",
1179 if suggestions.len() > 0 {
1180 diag.multipart_suggestion(
1181 "format specifiers use curly braces",
1183 Applicability::MachineApplicable,
1189 check_foreign!(printf);
1191 check_foreign!(shell);
1194 if !found_foreign && errs_len == 1 {
1195 diag.span_label(cx.fmtsp, "formatting specifier missing");