7 use rustc_ast::tokenstream::TokenStream;
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 fmtstr = p.parse_expr()?;
139 let mut first = true;
140 let mut named = false;
142 while p.token != token::Eof {
143 if !p.eat(&token::Comma) {
145 // After `format!(""` we always expect *only* a comma...
146 let mut err = ecx.struct_span_err(p.token.span, "expected token: `,`");
147 err.span_label(p.token.span, "expected `,`");
148 p.maybe_annotate_with_ascription(&mut err, false);
151 // ...after that delegate to `expect` to also include the other expected tokens.
152 return Err(p.expect(&token::Comma).err().unwrap());
156 if p.token == token::Eof {
158 } // accept trailing commas
159 match p.token.ident() {
160 Some((ident, _)) if p.look_ahead(1, |t| *t == token::Eq) => {
163 p.expect(&token::Eq)?;
164 let e = p.parse_expr()?;
165 if let Some(prev) = names.get(&ident.name) {
166 ecx.struct_span_err(e.span, &format!("duplicate argument named `{}`", ident))
167 .span_label(args[*prev].span, "previously here")
168 .span_label(e.span, "duplicate argument")
173 // Resolve names into slots early.
174 // Since all the positional args are already seen at this point
175 // if the input is valid, we can simply append to the positional
176 // args. And remember the names.
177 let slot = args.len();
178 names.insert(ident.name, slot);
182 let e = p.parse_expr()?;
184 let mut err = ecx.struct_span_err(
186 "positional arguments cannot follow named arguments",
188 err.span_label(e.span, "positional arguments must be before named arguments");
189 for pos in names.values() {
190 err.span_label(args[*pos].span, "named argument");
198 Ok((fmtstr, args, names))
201 impl<'a, 'b> Context<'a, 'b> {
202 fn resolve_name_inplace(&self, p: &mut parse::Piece<'_>) {
203 // NOTE: the `unwrap_or` branch is needed in case of invalid format
204 // arguments, e.g., `format_args!("{foo}")`.
205 let lookup = |s: Symbol| *self.names.get(&s).unwrap_or(&0);
208 parse::String(_) => {}
209 parse::NextArgument(ref mut arg) => {
210 if let parse::ArgumentNamed(s) = arg.position {
211 arg.position = parse::ArgumentIs(lookup(s));
213 if let parse::CountIsName(s) = arg.format.width {
214 arg.format.width = parse::CountIsParam(lookup(s));
216 if let parse::CountIsName(s) = arg.format.precision {
217 arg.format.precision = parse::CountIsParam(lookup(s));
223 /// Verifies one piece of a parse string, and remembers it if valid.
224 /// All errors are not emitted as fatal so we can continue giving errors
225 /// about this and possibly other format strings.
226 fn verify_piece(&mut self, p: &parse::Piece<'_>) {
228 parse::String(..) => {}
229 parse::NextArgument(ref arg) => {
230 // width/precision first, if they have implicit positional
231 // parameters it makes more sense to consume them first.
232 self.verify_count(arg.format.width);
233 self.verify_count(arg.format.precision);
235 // argument second, if it's an implicit positional parameter
236 // it's written second, so it should come after width/precision.
237 let pos = match arg.position {
238 parse::ArgumentIs(i) | parse::ArgumentImplicitlyIs(i) => Exact(i),
239 parse::ArgumentNamed(s) => Named(s),
242 let ty = Placeholder(match &arg.format.ty[..] {
253 let fmtsp = self.fmtsp;
254 let sp = arg.format.ty_span.map(|sp| fmtsp.from_inner(sp));
255 let mut err = self.ecx.struct_span_err(
257 &format!("unknown format trait `{}`", arg.format.ty),
260 "the only appropriate formatting traits are:\n\
261 - ``, which uses the `Display` trait\n\
262 - `?`, which uses the `Debug` trait\n\
263 - `e`, which uses the `LowerExp` trait\n\
264 - `E`, which uses the `UpperExp` trait\n\
265 - `o`, which uses the `Octal` trait\n\
266 - `p`, which uses the `Pointer` trait\n\
267 - `b`, which uses the `Binary` trait\n\
268 - `x`, which uses the `LowerHex` trait\n\
269 - `X`, which uses the `UpperHex` trait",
271 if let Some(sp) = sp {
272 for (fmt, name) in &[
283 err.tool_only_span_suggestion(
285 &format!("use the `{}` trait", name),
287 Applicability::MaybeIncorrect,
295 self.verify_arg_type(pos, ty);
301 fn verify_count(&mut self, c: parse::Count) {
303 parse::CountImplied | parse::CountIs(..) => {}
304 parse::CountIsParam(i) => {
305 self.verify_arg_type(Exact(i), Count);
307 parse::CountIsName(s) => {
308 self.verify_arg_type(Named(s), Count);
313 fn describe_num_args(&self) -> Cow<'_, str> {
314 match self.args.len() {
315 0 => "no arguments were given".into(),
316 1 => "there is 1 argument".into(),
317 x => format!("there are {} arguments", x).into(),
321 /// Handle invalid references to positional arguments. Output different
322 /// errors for the case where all arguments are positional and for when
323 /// there are named arguments or numbered positional arguments in the
325 fn report_invalid_references(&self, numbered_position_args: bool) {
327 let sp = if !self.arg_spans.is_empty() {
328 // Point at the formatting arguments.
329 MultiSpan::from_spans(self.arg_spans.clone())
331 MultiSpan::from_span(self.fmtsp)
334 self.invalid_refs.iter().map(|(r, pos)| (r.to_string(), self.arg_spans.get(*pos)));
336 let mut zero_based_note = false;
338 let count = self.pieces.len()
339 + self.arg_with_formatting.iter().filter(|fmt| fmt.precision_span.is_some()).count();
340 if self.names.is_empty() && !numbered_position_args && count != self.args.len() {
341 e = self.ecx.struct_span_err(
344 "{} positional argument{} in format string, but {}",
347 self.describe_num_args(),
350 for arg in &self.args {
351 // Point at the arguments that will be formatted.
352 e.span_label(arg.span, "");
355 let (mut refs, spans): (Vec<_>, Vec<_>) = refs.unzip();
356 // Avoid `invalid reference to positional arguments 7 and 7 (there is 1 argument)`
357 // for `println!("{7:7$}", 1);`
360 let (arg_list, mut sp) = if refs.len() == 1 {
361 let spans: Vec<_> = spans.into_iter().filter_map(|sp| sp.copied()).collect();
363 format!("argument {}", refs[0]),
364 if spans.is_empty() {
365 MultiSpan::from_span(self.fmtsp)
367 MultiSpan::from_spans(spans)
371 let pos = MultiSpan::from_spans(spans.into_iter().map(|s| *s.unwrap()).collect());
372 let reg = refs.pop().unwrap();
373 (format!("arguments {head} and {tail}", head = refs.join(", "), tail = reg,), pos)
375 if self.arg_spans.is_empty() {
376 sp = MultiSpan::from_span(self.fmtsp);
379 e = self.ecx.struct_span_err(
382 "invalid reference to positional {} ({})",
384 self.describe_num_args()
387 zero_based_note = true;
390 for fmt in &self.arg_with_formatting {
391 if let Some(span) = fmt.precision_span {
392 let span = self.fmtsp.from_inner(span);
393 match fmt.precision {
394 parse::CountIsParam(pos) if pos > self.args.len() => {
398 "this precision flag expects an `usize` argument at position {}, \
401 self.describe_num_args(),
404 zero_based_note = true;
406 parse::CountIsParam(pos) => {
407 let count = self.pieces.len()
411 .filter(|fmt| fmt.precision_span.is_some())
413 e.span_label(span, &format!(
414 "this precision flag adds an extra required argument at position {}, \
415 which is why there {} expected",
418 "is 1 argument".to_string()
420 format!("are {} arguments", count)
423 if let Some(arg) = self.args.get(pos) {
426 "this parameter corresponds to the precision flag",
429 zero_based_note = true;
434 if let Some(span) = fmt.width_span {
435 let span = self.fmtsp.from_inner(span);
437 parse::CountIsParam(pos) if pos > self.args.len() => {
441 "this width flag expects an `usize` argument at position {}, \
444 self.describe_num_args(),
447 zero_based_note = true;
454 e.note("positional arguments are zero-based");
456 if !self.arg_with_formatting.is_empty() {
458 "for information about formatting flags, visit \
459 https://doc.rust-lang.org/std/fmt/index.html",
466 /// Actually verifies and tracks a given format placeholder
467 /// (a.k.a. argument).
468 fn verify_arg_type(&mut self, arg: Position, ty: ArgumentType) {
471 if self.args.len() <= arg {
472 self.invalid_refs.push((arg, self.curpiece));
477 // record every (position, type) combination only once
478 let seen_ty = &mut self.arg_unique_types[arg];
479 let i = seen_ty.iter().position(|x| *x == ty).unwrap_or_else(|| {
480 let i = seen_ty.len();
484 self.arg_types[arg].push(i);
487 if let Entry::Vacant(e) = self.count_positions.entry(arg) {
488 let i = self.count_positions_count;
490 self.count_args.push(Exact(arg));
491 self.count_positions_count += 1;
498 match self.names.get(&name) {
500 // Treat as positional arg.
501 self.verify_arg_type(Exact(idx), ty)
504 let capture_feature_enabled = self
508 .map_or(false, |features| features.format_args_capture);
510 // For the moment capturing variables from format strings expanded from macros is
511 // disabled (see RFC #2795)
512 let can_capture = capture_feature_enabled && self.is_literal;
515 // Treat this name as a variable to capture from the surrounding scope
516 let idx = self.args.len();
517 self.arg_types.push(Vec::new());
518 self.arg_unique_types.push(Vec::new());
520 self.ecx.expr_ident(self.fmtsp, Ident::new(name, self.fmtsp)),
522 self.names.insert(name, idx);
523 self.verify_arg_type(Exact(idx), ty)
525 let msg = format!("there is no argument named `{}`", name);
526 let sp = if self.is_literal {
527 *self.arg_spans.get(self.curpiece).unwrap_or(&self.fmtsp)
531 let mut err = self.ecx.struct_span_err(sp, &msg[..]);
533 if capture_feature_enabled && !self.is_literal {
535 "did you intend to capture a variable `{}` from \
536 the surrounding scope?",
540 "to avoid ambiguity, `format_args!` cannot capture variables \
541 when the format string is expanded from a macro",
543 } else if self.ecx.parse_sess().unstable_features.is_nightly_build() {
545 "if you intended to capture `{}` from the surrounding scope, add \
546 `#![feature(format_args_capture)]` to the crate attributes",
559 /// Builds the mapping between format placeholders and argument objects.
560 fn build_index_map(&mut self) {
561 // NOTE: Keep the ordering the same as `into_expr`'s expansion would do!
562 let args_len = self.args.len();
563 self.arg_index_map.reserve(args_len);
565 let mut sofar = 0usize;
568 for i in 0..args_len {
569 let arg_types = &self.arg_types[i];
570 let arg_offsets = arg_types.iter().map(|offset| sofar + *offset).collect::<Vec<_>>();
571 self.arg_index_map.push(arg_offsets);
572 sofar += self.arg_unique_types[i].len();
575 // Record starting index for counts, which appear just after arguments
576 self.count_args_index_offset = sofar;
579 fn rtpath(ecx: &ExtCtxt<'_>, s: &str) -> Vec<Ident> {
580 ecx.std_path(&[sym::fmt, sym::rt, sym::v1, Symbol::intern(s)])
583 fn build_count(&self, c: parse::Count) -> P<ast::Expr> {
585 let count = |c, arg| {
586 let mut path = Context::rtpath(self.ecx, "Count");
587 path.push(self.ecx.ident_of(c, sp));
589 Some(arg) => self.ecx.expr_call_global(sp, path, vec![arg]),
590 None => self.ecx.expr_path(self.ecx.path_global(sp, path)),
594 parse::CountIs(i) => count("Is", Some(self.ecx.expr_usize(sp, i))),
595 parse::CountIsParam(i) => {
596 // This needs mapping too, as `i` is referring to a macro
597 // argument. If `i` is not found in `count_positions` then
598 // the error had already been emitted elsewhere.
599 let i = self.count_positions.get(&i).cloned().unwrap_or(0)
600 + self.count_args_index_offset;
601 count("Param", Some(self.ecx.expr_usize(sp, i)))
603 parse::CountImplied => count("Implied", None),
604 // should never be the case, names are already resolved
605 parse::CountIsName(_) => panic!("should never happen"),
609 /// Build a literal expression from the accumulated string literals
610 fn build_literal_string(&mut self) -> P<ast::Expr> {
612 let s = Symbol::intern(&self.literal);
613 self.literal.clear();
614 self.ecx.expr_str(sp, s)
617 /// Builds a static `rt::Argument` from a `parse::Piece` or append
618 /// to the `literal` string.
621 piece: &parse::Piece<'a>,
622 arg_index_consumed: &mut Vec<usize>,
623 ) -> Option<P<ast::Expr>> {
626 parse::String(s) => {
627 self.literal.push_str(s);
630 parse::NextArgument(ref arg) => {
631 // Build the position
634 parse::ArgumentIs(i) | parse::ArgumentImplicitlyIs(i) => {
635 // Map to index in final generated argument array
636 // in case of multiple types specified
637 let arg_idx = match arg_index_consumed.get_mut(i) {
638 None => 0, // error already emitted elsewhere
640 let idx_map = &self.arg_index_map[i];
641 // unwrap_or branch: error already emitted elsewhere
642 let arg_idx = *idx_map.get(*offset).unwrap_or(&0);
647 self.ecx.expr_usize(sp, arg_idx)
650 // should never be the case, because names are already
652 parse::ArgumentNamed(_) => panic!("should never happen"),
656 let simple_arg = parse::Argument {
658 // We don't have ArgumentNext any more, so we have to
659 // track the current argument ourselves.
664 format: parse::FormatSpec {
665 fill: arg.format.fill,
666 align: parse::AlignUnknown,
668 precision: parse::CountImplied,
669 precision_span: None,
670 width: parse::CountImplied,
673 ty_span: arg.format.ty_span,
677 let fill = arg.format.fill.unwrap_or(' ');
679 let pos_simple = arg.position.index() == simple_arg.position.index();
681 if arg.format.precision_span.is_some() || arg.format.width_span.is_some() {
682 self.arg_with_formatting.push(arg.format);
684 if !pos_simple || arg.format != simple_arg.format || fill != ' ' {
685 self.all_pieces_simple = false;
689 let fill = self.ecx.expr_lit(sp, ast::LitKind::Char(fill));
691 let mut p = Context::rtpath(self.ecx, "Alignment");
692 p.push(self.ecx.ident_of(name, sp));
693 self.ecx.path_global(sp, p)
695 let align = match arg.format.align {
696 parse::AlignLeft => align("Left"),
697 parse::AlignRight => align("Right"),
698 parse::AlignCenter => align("Center"),
699 parse::AlignUnknown => align("Unknown"),
701 let align = self.ecx.expr_path(align);
702 let flags = self.ecx.expr_u32(sp, arg.format.flags);
703 let prec = self.build_count(arg.format.precision);
704 let width = self.build_count(arg.format.width);
705 let path = self.ecx.path_global(sp, Context::rtpath(self.ecx, "FormatSpec"));
706 let fmt = self.ecx.expr_struct(
710 self.ecx.field_imm(sp, self.ecx.ident_of("fill", sp), fill),
711 self.ecx.field_imm(sp, self.ecx.ident_of("align", sp), align),
712 self.ecx.field_imm(sp, self.ecx.ident_of("flags", sp), flags),
713 self.ecx.field_imm(sp, self.ecx.ident_of("precision", sp), prec),
714 self.ecx.field_imm(sp, self.ecx.ident_of("width", sp), width),
718 let path = self.ecx.path_global(sp, Context::rtpath(self.ecx, "Argument"));
719 Some(self.ecx.expr_struct(
723 self.ecx.field_imm(sp, self.ecx.ident_of("position", sp), pos),
724 self.ecx.field_imm(sp, self.ecx.ident_of("format", sp), fmt),
731 /// Actually builds the expression which the format_args! block will be
733 fn into_expr(self) -> P<ast::Expr> {
735 Vec::with_capacity((0..self.args.len()).map(|i| self.arg_unique_types[i].len()).sum());
736 let mut counts = Vec::with_capacity(self.count_args.len());
737 let mut pats = Vec::with_capacity(self.args.len());
738 let mut heads = Vec::with_capacity(self.args.len());
740 let names_pos: Vec<_> = (0..self.args.len())
741 .map(|i| self.ecx.ident_of(&format!("arg{}", i), self.macsp))
744 // First, build up the static array which will become our precompiled
746 let pieces = self.ecx.expr_vec_slice(self.fmtsp, self.str_pieces);
748 // Before consuming the expressions, we have to remember spans for
749 // count arguments as they are now generated separate from other
750 // arguments, hence have no access to the `P<ast::Expr>`'s.
751 let spans_pos: Vec<_> = self.args.iter().map(|e| e.span).collect();
753 // Right now there is a bug such that for the expression:
755 // the lifetime of `1` doesn't outlast the call to `bar`, so it's not
756 // valid for the call to `foo`. To work around this all arguments to the
757 // format! string are shoved into locals. Furthermore, we shove the address
758 // of each variable because we don't want to move out of the arguments
759 // passed to this function.
760 for (i, e) in self.args.into_iter().enumerate() {
761 let name = names_pos[i];
762 let span = self.ecx.with_def_site_ctxt(e.span);
763 pats.push(self.ecx.pat_ident(span, name));
764 for arg_ty in self.arg_unique_types[i].iter() {
765 locals.push(Context::format_arg(self.ecx, self.macsp, e.span, arg_ty, name));
767 heads.push(self.ecx.expr_addr_of(e.span, e));
769 for pos in self.count_args {
770 let index = match pos {
772 _ => panic!("should never happen"),
774 let name = names_pos[index];
775 let span = spans_pos[index];
776 counts.push(Context::format_arg(self.ecx, self.macsp, span, &Count, name));
779 // Now create a vector containing all the arguments
780 let args = locals.into_iter().chain(counts.into_iter());
782 let args_array = self.ecx.expr_vec(self.macsp, args.collect());
784 // Constructs an AST equivalent to:
786 // match (&arg0, &arg1) {
787 // (tmp0, tmp1) => args_array
796 // Because of #11585 the new temporary lifetime rule, the enclosing
797 // statements for these temporaries become the let's themselves.
798 // If one or more of them are RefCell's, RefCell borrow() will also
799 // end there; they don't last long enough for args_array to use them.
800 // The match expression solves the scope problem.
802 // Note, it may also very well be transformed to:
807 // ref tmp1 => args_array } } }
809 // But the nested match expression is proved to perform not as well
810 // as series of let's; the first approach does.
811 let pat = self.ecx.pat_tuple(self.macsp, pats);
812 let arm = self.ecx.arm(self.macsp, pat, args_array);
813 let head = self.ecx.expr(self.macsp, ast::ExprKind::Tup(heads));
814 let result = self.ecx.expr_match(self.macsp, head, vec![arm]);
816 let args_slice = self.ecx.expr_addr_of(self.macsp, result);
818 // Now create the fmt::Arguments struct with all our locals we created.
819 let (fn_name, fn_args) = if self.all_pieces_simple {
820 ("new_v1", vec![pieces, args_slice])
822 // Build up the static array which will store our precompiled
823 // nonstandard placeholders, if there are any.
824 let fmt = self.ecx.expr_vec_slice(self.macsp, self.pieces);
826 ("new_v1_formatted", vec![pieces, args_slice, fmt])
829 let path = self.ecx.std_path(&[sym::fmt, sym::Arguments, Symbol::intern(fn_name)]);
830 self.ecx.expr_call_global(self.macsp, path, fn_args)
840 sp = ecx.with_def_site_ctxt(sp);
841 let arg = ecx.expr_ident(sp, arg);
842 let trait_ = match *ty {
843 Placeholder(trait_) if trait_ == "<invalid>" => return DummyResult::raw_expr(sp, true),
844 Placeholder(trait_) => trait_,
846 let path = ecx.std_path(&[sym::fmt, sym::ArgumentV1, sym::from_usize]);
847 return ecx.expr_call_global(macsp, path, vec![arg]);
851 let path = ecx.std_path(&[sym::fmt, Symbol::intern(trait_), sym::fmt]);
852 let format_fn = ecx.path_global(sp, path);
853 let path = ecx.std_path(&[sym::fmt, sym::ArgumentV1, sym::new]);
854 ecx.expr_call_global(macsp, path, vec![arg, ecx.expr_path(format_fn)])
858 fn expand_format_args_impl<'cx>(
859 ecx: &'cx mut ExtCtxt<'_>,
863 ) -> Box<dyn base::MacResult + 'cx> {
864 sp = ecx.with_def_site_ctxt(sp);
865 match parse_args(ecx, sp, tts) {
866 Ok((efmt, args, names)) => {
867 MacEager::expr(expand_preparsed_format_args(ecx, sp, efmt, args, names, nl))
876 pub fn expand_format_args<'cx>(
877 ecx: &'cx mut ExtCtxt<'_>,
880 ) -> Box<dyn base::MacResult + 'cx> {
881 expand_format_args_impl(ecx, sp, tts, false)
884 pub fn expand_format_args_nl<'cx>(
885 ecx: &'cx mut ExtCtxt<'_>,
888 ) -> Box<dyn base::MacResult + 'cx> {
889 expand_format_args_impl(ecx, sp, tts, true)
892 /// Take the various parts of `format_args!(efmt, args..., name=names...)`
893 /// and construct the appropriate formatting expression.
894 pub fn expand_preparsed_format_args(
895 ecx: &mut ExtCtxt<'_>,
898 args: Vec<P<ast::Expr>>,
899 names: FxHashMap<Symbol, usize>,
900 append_newline: bool,
902 // NOTE: this verbose way of initializing `Vec<Vec<ArgumentType>>` is because
903 // `ArgumentType` does not derive `Clone`.
904 let arg_types: Vec<_> = (0..args.len()).map(|_| Vec::new()).collect();
905 let arg_unique_types: Vec<_> = (0..args.len()).map(|_| Vec::new()).collect();
907 let mut macsp = ecx.call_site();
908 macsp = ecx.with_def_site_ctxt(macsp);
910 let msg = "format argument must be a string literal";
911 let fmt_sp = efmt.span;
912 let (fmt_str, fmt_style, fmt_span) = match expr_to_spanned_string(ecx, efmt, msg) {
913 Ok(mut fmt) if append_newline => {
914 fmt.0 = Symbol::intern(&format!("{}\n", fmt.0));
919 if let Some(mut err) = err {
920 let sugg_fmt = match args.len() {
921 0 => "{}".to_string(),
922 _ => format!("{}{{}}", "{} ".repeat(args.len())),
925 fmt_sp.shrink_to_lo(),
926 "you might be missing a string literal to format with",
927 format!("\"{}\", ", sugg_fmt),
928 Applicability::MaybeIncorrect,
932 return DummyResult::raw_expr(sp, true);
936 let str_style = match fmt_style {
937 ast::StrStyle::Cooked => None,
938 ast::StrStyle::Raw(raw) => Some(raw as usize),
941 let fmt_str = &fmt_str.as_str(); // for the suggestions below
942 let fmt_snippet = ecx.source_map().span_to_snippet(fmt_sp).ok();
943 let mut parser = parse::Parser::new(
948 parse::ParseMode::Format,
951 let mut unverified_pieces = Vec::new();
952 while let Some(piece) = parser.next() {
953 if !parser.errors.is_empty() {
956 unverified_pieces.push(piece);
960 if !parser.errors.is_empty() {
961 let err = parser.errors.remove(0);
962 let sp = fmt_span.from_inner(err.span);
963 let mut e = ecx.struct_span_err(sp, &format!("invalid format string: {}", err.description));
964 e.span_label(sp, err.label + " in format string");
965 if let Some(note) = err.note {
968 if let Some((label, span)) = err.secondary_label {
969 let sp = fmt_span.from_inner(span);
970 e.span_label(sp, label);
973 return DummyResult::raw_expr(sp, true);
976 let arg_spans = parser.arg_places.iter().map(|span| fmt_span.from_inner(*span)).collect();
978 let named_pos: FxHashSet<usize> = names.values().cloned().collect();
980 let mut cx = Context {
988 arg_index_map: Vec::new(),
989 count_args: Vec::new(),
990 count_positions: FxHashMap::default(),
991 count_positions_count: 0,
992 count_args_index_offset: 0,
993 literal: String::new(),
994 pieces: Vec::with_capacity(unverified_pieces.len()),
995 str_pieces: Vec::with_capacity(unverified_pieces.len()),
996 all_pieces_simple: true,
999 invalid_refs: Vec::new(),
1001 arg_with_formatting: Vec::new(),
1002 is_literal: parser.is_literal,
1005 // This needs to happen *after* the Parser has consumed all pieces to create all the spans
1006 let pieces = unverified_pieces
1009 cx.verify_piece(&piece);
1010 cx.resolve_name_inplace(&mut piece);
1013 .collect::<Vec<_>>();
1015 let numbered_position_args = pieces.iter().any(|arg: &parse::Piece<'_>| match *arg {
1016 parse::String(_) => false,
1017 parse::NextArgument(arg) => match arg.position {
1018 parse::Position::ArgumentIs(_) => true,
1023 cx.build_index_map();
1025 let mut arg_index_consumed = vec![0usize; cx.arg_index_map.len()];
1027 for piece in pieces {
1028 if let Some(piece) = cx.build_piece(&piece, &mut arg_index_consumed) {
1029 let s = cx.build_literal_string();
1030 cx.str_pieces.push(s);
1031 cx.pieces.push(piece);
1035 if !cx.literal.is_empty() {
1036 let s = cx.build_literal_string();
1037 cx.str_pieces.push(s);
1040 if !cx.invalid_refs.is_empty() {
1041 cx.report_invalid_references(numbered_position_args);
1044 // Make sure that all arguments were used and all arguments have types.
1049 .filter(|(i, ty)| ty.is_empty() && !cx.count_positions.contains_key(&i))
1051 let msg = if named_pos.contains(&i) {
1053 "named argument never used"
1055 // positional argument
1056 "argument never used"
1058 (cx.args[i].span, msg)
1060 .collect::<Vec<_>>();
1062 let errs_len = errs.len();
1063 if !errs.is_empty() {
1064 let args_used = cx.arg_types.len() - errs_len;
1065 let args_unused = errs_len;
1069 let (sp, msg) = errs.into_iter().next().unwrap();
1070 let mut diag = cx.ecx.struct_span_err(sp, msg);
1071 diag.span_label(sp, msg);
1074 let mut diag = cx.ecx.struct_span_err(
1075 errs.iter().map(|&(sp, _)| sp).collect::<Vec<Span>>(),
1076 "multiple unused formatting arguments",
1078 diag.span_label(cx.fmtsp, "multiple missing formatting specifiers");
1079 for (sp, msg) in errs {
1080 diag.span_label(sp, msg);
1086 // Used to ensure we only report translations for *one* kind of foreign format.
1087 let mut found_foreign = false;
1088 // Decide if we want to look for foreign formatting directives.
1089 if args_used < args_unused {
1090 use super::format_foreign as foreign;
1092 // The set of foreign substitutions we've explained. This prevents spamming the user
1093 // with `%d should be written as {}` over and over again.
1094 let mut explained = FxHashSet::default();
1096 macro_rules! check_foreign {
1098 let mut show_doc_note = false;
1100 let mut suggestions = vec![];
1101 // account for `"` and account for raw strings `r#`
1102 let padding = str_style.map(|i| i + 2).unwrap_or(1);
1103 for sub in foreign::$kind::iter_subs(fmt_str, padding) {
1104 let trn = match sub.translate() {
1107 // If it has no translation, don't call it out specifically.
1111 let pos = sub.position();
1112 let sub = String::from(sub.as_str());
1113 if explained.contains(&sub) {
1116 explained.insert(sub.clone());
1119 found_foreign = true;
1120 show_doc_note = true;
1123 if let Some(inner_sp) = pos {
1124 let sp = fmt_sp.from_inner(inner_sp);
1125 suggestions.push((sp, trn));
1127 diag.help(&format!("`{}` should be written as `{}`", sub, trn));
1134 " formatting not supported; see the documentation for `std::fmt`",
1137 if suggestions.len() > 0 {
1138 diag.multipart_suggestion(
1139 "format specifiers use curly braces",
1141 Applicability::MachineApplicable,
1147 check_foreign!(printf);
1149 check_foreign!(shell);
1152 if !found_foreign && errs_len == 1 {
1153 diag.span_label(cx.fmtsp, "formatting specifier missing");