4 use fmt_macros as parse;
6 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
7 use rustc_errors::{pluralize, Applicability, DiagnosticBuilder};
8 use rustc_expand::base::{self, *};
9 use rustc_span::symbol::{sym, Symbol};
10 use rustc_span::{MultiSpan, Span};
14 use syntax::tokenstream::TokenStream;
17 use std::collections::hash_map::Entry;
21 Placeholder(&'static str),
30 struct Context<'a, 'b> {
31 ecx: &'a mut ExtCtxt<'b>,
32 /// The macro's call site. References to unstable formatting internals must
33 /// use this span to pass the stability checker.
35 /// The span of the format string literal.
38 /// List of parsed argument expressions.
39 /// Named expressions are resolved early, and are appended to the end of
40 /// argument expressions.
42 /// Example showing the various data structures in motion:
44 /// * Original: `"{foo:o} {:o} {foo:x} {0:x} {1:o} {:x} {1:x} {0:o}"`
45 /// * Implicit argument resolution: `"{foo:o} {0:o} {foo:x} {0:x} {1:o} {1:x} {1:x} {0:o}"`
46 /// * Name resolution: `"{2:o} {0:o} {2:x} {0:x} {1:o} {1:x} {1:x} {0:o}"`
47 /// * `arg_types` (in JSON): `[[0, 1, 0], [0, 1, 1], [0, 1]]`
48 /// * `arg_unique_types` (in simplified JSON): `[["o", "x"], ["o", "x"], ["o", "x"]]`
49 /// * `names` (in JSON): `{"foo": 2}`
50 args: Vec<P<ast::Expr>>,
51 /// Placeholder slot numbers indexed by argument.
52 arg_types: Vec<Vec<usize>>,
53 /// Unique format specs seen for each argument.
54 arg_unique_types: Vec<Vec<ArgumentType>>,
55 /// Map from named arguments to their resolved indices.
56 names: FxHashMap<Symbol, usize>,
58 /// The latest consecutive literal strings, or empty if there weren't any.
61 /// Collection of the compiled `rt::Argument` structures
62 pieces: Vec<P<ast::Expr>>,
63 /// Collection of string literals
64 str_pieces: Vec<P<ast::Expr>>,
65 /// Stays `true` if all formatting parameters are default (as in "{}{}").
66 all_pieces_simple: bool,
68 /// Mapping between positional argument references and indices into the
69 /// final generated static argument array. We record the starting indices
70 /// corresponding to each positional argument, and number of references
71 /// consumed so far for each argument, to facilitate correct `Position`
72 /// mapping in `build_piece`. In effect this can be seen as a "flattened"
73 /// version of `arg_unique_types`.
75 /// Again with the example described above in docstring for `args`:
77 /// * `arg_index_map` (in JSON): `[[0, 1, 0], [2, 3, 3], [4, 5]]`
78 arg_index_map: Vec<Vec<usize>>,
80 /// Starting offset of count argument slots.
81 count_args_index_offset: usize,
83 /// Count argument slots and tracking data structures.
84 /// Count arguments are separately tracked for de-duplication in case
85 /// multiple references are made to one argument. For example, in this
88 /// * Original: `"{:.*} {:.foo$} {1:.*} {:.0$}"`
89 /// * Implicit argument resolution: `"{1:.0$} {2:.foo$} {1:.3$} {4:.0$}"`
90 /// * Name resolution: `"{1:.0$} {2:.5$} {1:.3$} {4:.0$}"`
91 /// * `count_positions` (in JSON): `{0: 0, 5: 1, 3: 2}`
92 /// * `count_args`: `vec![Exact(0), Exact(5), Exact(3)]`
93 count_args: Vec<Position>,
94 /// Relative slot numbers for count arguments.
95 count_positions: FxHashMap<usize, usize>,
96 /// Number of count slots assigned.
97 count_positions_count: usize,
99 /// Current position of the implicit positional arg pointer, as if it
100 /// still existed in this phase of processing.
101 /// Used only for `all_pieces_simple` tracking in `build_piece`.
103 /// Current piece being evaluated, used for error reporting.
105 /// Keep track of invalid references to positional arguments.
106 invalid_refs: Vec<(usize, usize)>,
107 /// Spans of all the formatting arguments, in order.
108 arg_spans: Vec<Span>,
109 /// All the formatting arguments that have formatting flags set, in order for diagnostics.
110 arg_with_formatting: Vec<parse::FormatSpec<'a>>,
111 /// Whether this formatting string is a literal or it comes from 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 if p.token.is_ident() && p.look_ahead(1, |t| *t == token::Eq) {
161 let name = if let token::Ident(name, _) = p.token.kind {
168 p.expect(&token::Eq)?;
169 let e = p.parse_expr()?;
170 if let Some(prev) = names.get(&name) {
171 ecx.struct_span_err(e.span, &format!("duplicate argument named `{}`", name))
172 .span_label(args[*prev].span, "previously here")
173 .span_label(e.span, "duplicate argument")
178 // Resolve names into slots early.
179 // Since all the positional args are already seen at this point
180 // if the input is valid, we can simply append to the positional
181 // args. And remember the names.
182 let slot = args.len();
183 names.insert(name, slot);
186 let e = p.parse_expr()?;
189 .struct_span_err(e.span, "positional arguments cannot follow named arguments");
190 err.span_label(e.span, "positional arguments must be before named arguments");
191 for (_, pos) in &names {
192 err.span_label(args[*pos].span, "named argument");
199 Ok((fmtstr, args, names))
202 impl<'a, 'b> Context<'a, 'b> {
203 fn resolve_name_inplace(&self, p: &mut parse::Piece<'_>) {
204 // NOTE: the `unwrap_or` branch is needed in case of invalid format
205 // arguments, e.g., `format_args!("{foo}")`.
206 let lookup = |s: Symbol| *self.names.get(&s).unwrap_or(&0);
209 parse::String(_) => {}
210 parse::NextArgument(ref mut arg) => {
211 if let parse::ArgumentNamed(s) = arg.position {
212 arg.position = parse::ArgumentIs(lookup(s));
214 if let parse::CountIsName(s) = arg.format.width {
215 arg.format.width = parse::CountIsParam(lookup(s));
217 if let parse::CountIsName(s) = arg.format.precision {
218 arg.format.precision = parse::CountIsParam(lookup(s));
224 /// Verifies one piece of a parse string, and remembers it if valid.
225 /// All errors are not emitted as fatal so we can continue giving errors
226 /// about this and possibly other format strings.
227 fn verify_piece(&mut self, p: &parse::Piece<'_>) {
229 parse::String(..) => {}
230 parse::NextArgument(ref arg) => {
231 // width/precision first, if they have implicit positional
232 // parameters it makes more sense to consume them first.
233 self.verify_count(arg.format.width);
234 self.verify_count(arg.format.precision);
236 // argument second, if it's an implicit positional parameter
237 // it's written second, so it should come after width/precision.
238 let pos = match arg.position {
239 parse::ArgumentIs(i) | parse::ArgumentImplicitlyIs(i) => Exact(i),
240 parse::ArgumentNamed(s) => Named(s),
243 let ty = Placeholder(match &arg.format.ty[..] {
254 let fmtsp = self.fmtsp;
255 let sp = arg.format.ty_span.map(|sp| fmtsp.from_inner(sp));
256 let mut err = self.ecx.struct_span_err(
258 &format!("unknown format trait `{}`", arg.format.ty),
261 "the only appropriate formatting traits are:\n\
262 - ``, which uses the `Display` trait\n\
263 - `?`, which uses the `Debug` trait\n\
264 - `e`, which uses the `LowerExp` trait\n\
265 - `E`, which uses the `UpperExp` trait\n\
266 - `o`, which uses the `Octal` trait\n\
267 - `p`, which uses the `Pointer` trait\n\
268 - `b`, which uses the `Binary` trait\n\
269 - `x`, which uses the `LowerHex` trait\n\
270 - `X`, which uses the `UpperHex` trait",
272 if let Some(sp) = sp {
273 for (fmt, name) in &[
284 err.tool_only_span_suggestion(
286 &format!("use the `{}` trait", name),
288 Applicability::MaybeIncorrect,
296 self.verify_arg_type(pos, ty);
302 fn verify_count(&mut self, c: parse::Count) {
304 parse::CountImplied | parse::CountIs(..) => {}
305 parse::CountIsParam(i) => {
306 self.verify_arg_type(Exact(i), Count);
308 parse::CountIsName(s) => {
309 self.verify_arg_type(Named(s), Count);
314 fn describe_num_args(&self) -> Cow<'_, str> {
315 match self.args.len() {
316 0 => "no arguments were given".into(),
317 1 => "there is 1 argument".into(),
318 x => format!("there are {} arguments", x).into(),
322 /// Handle invalid references to positional arguments. Output different
323 /// errors for the case where all arguments are positional and for when
324 /// there are named arguments or numbered positional arguments in the
326 fn report_invalid_references(&self, numbered_position_args: bool) {
328 let sp = if self.is_literal {
329 // Point at the formatting arguments.
330 MultiSpan::from_spans(self.arg_spans.clone())
332 MultiSpan::from_span(self.fmtsp)
335 self.invalid_refs.iter().map(|(r, pos)| (r.to_string(), self.arg_spans.get(*pos)));
337 let mut zero_based_note = false;
339 let count = self.pieces.len()
340 + self.arg_with_formatting.iter().filter(|fmt| fmt.precision_span.is_some()).count();
341 if self.names.is_empty() && !numbered_position_args && count != self.args.len() {
342 e = self.ecx.struct_span_err(
345 "{} positional argument{} in format string, but {}",
348 self.describe_num_args(),
351 for arg in &self.args {
352 // Point at the arguments that will be formatted.
353 e.span_label(arg.span, "");
356 let (mut refs, spans): (Vec<_>, Vec<_>) = refs.unzip();
357 // Avoid `invalid reference to positional arguments 7 and 7 (there is 1 argument)`
358 // for `println!("{7:7$}", 1);`
361 let (arg_list, mut sp) = if refs.len() == 1 {
362 let spans: Vec<_> = spans.into_iter().filter_map(|sp| sp.map(|sp| *sp)).collect();
364 format!("argument {}", refs[0]),
365 if spans.is_empty() {
366 MultiSpan::from_span(self.fmtsp)
368 MultiSpan::from_spans(spans)
372 let pos = MultiSpan::from_spans(spans.into_iter().map(|s| *s.unwrap()).collect());
373 let reg = refs.pop().unwrap();
374 (format!("arguments {head} and {tail}", head = refs.join(", "), tail = reg,), pos)
376 if !self.is_literal {
377 sp = MultiSpan::from_span(self.fmtsp);
380 e = self.ecx.struct_span_err(
383 "invalid reference to positional {} ({})",
385 self.describe_num_args()
388 zero_based_note = true;
391 for fmt in &self.arg_with_formatting {
392 if let Some(span) = fmt.precision_span {
393 let span = self.fmtsp.from_inner(span);
394 match fmt.precision {
395 parse::CountIsParam(pos) if pos > self.args.len() => {
399 "this precision flag expects an `usize` argument at position {}, \
402 self.describe_num_args(),
405 zero_based_note = true;
407 parse::CountIsParam(pos) => {
408 let count = self.pieces.len()
412 .filter(|fmt| fmt.precision_span.is_some())
414 e.span_label(span, &format!(
415 "this precision flag adds an extra required argument at position {}, \
416 which is why there {} expected",
419 "is 1 argument".to_string()
421 format!("are {} arguments", count)
424 if let Some(arg) = self.args.get(pos) {
427 "this parameter corresponds to the precision flag",
430 zero_based_note = true;
435 if let Some(span) = fmt.width_span {
436 let span = self.fmtsp.from_inner(span);
438 parse::CountIsParam(pos) if pos > self.args.len() => {
442 "this width flag expects an `usize` argument at position {}, \
445 self.describe_num_args(),
448 zero_based_note = true;
455 e.note("positional arguments are zero-based");
457 if !self.arg_with_formatting.is_empty() {
459 "for information about formatting flags, visit \
460 https://doc.rust-lang.org/std/fmt/index.html",
467 /// Actually verifies and tracks a given format placeholder
468 /// (a.k.a. argument).
469 fn verify_arg_type(&mut self, arg: Position, ty: ArgumentType) {
472 if self.args.len() <= arg {
473 self.invalid_refs.push((arg, self.curpiece));
478 // record every (position, type) combination only once
479 let ref mut seen_ty = self.arg_unique_types[arg];
480 let i = seen_ty.iter().position(|x| *x == ty).unwrap_or_else(|| {
481 let i = seen_ty.len();
485 self.arg_types[arg].push(i);
488 if let Entry::Vacant(e) = self.count_positions.entry(arg) {
489 let i = self.count_positions_count;
491 self.count_args.push(Exact(arg));
492 self.count_positions_count += 1;
499 match self.names.get(&name) {
501 // Treat as positional arg.
502 self.verify_arg_type(Exact(idx), ty)
505 let msg = format!("there is no argument named `{}`", name);
506 let sp = if self.is_literal {
507 *self.arg_spans.get(self.curpiece).unwrap_or(&self.fmtsp)
511 let mut err = self.ecx.struct_span_err(sp, &msg[..]);
519 /// Builds the mapping between format placeholders and argument objects.
520 fn build_index_map(&mut self) {
521 // NOTE: Keep the ordering the same as `into_expr`'s expansion would do!
522 let args_len = self.args.len();
523 self.arg_index_map.reserve(args_len);
525 let mut sofar = 0usize;
528 for i in 0..args_len {
529 let ref arg_types = self.arg_types[i];
530 let arg_offsets = arg_types.iter().map(|offset| sofar + *offset).collect::<Vec<_>>();
531 self.arg_index_map.push(arg_offsets);
532 sofar += self.arg_unique_types[i].len();
535 // Record starting index for counts, which appear just after arguments
536 self.count_args_index_offset = sofar;
539 fn rtpath(ecx: &ExtCtxt<'_>, s: &str) -> Vec<ast::Ident> {
540 ecx.std_path(&[sym::fmt, sym::rt, sym::v1, Symbol::intern(s)])
543 fn build_count(&self, c: parse::Count) -> P<ast::Expr> {
545 let count = |c, arg| {
546 let mut path = Context::rtpath(self.ecx, "Count");
547 path.push(self.ecx.ident_of(c, sp));
549 Some(arg) => self.ecx.expr_call_global(sp, path, vec![arg]),
550 None => self.ecx.expr_path(self.ecx.path_global(sp, path)),
554 parse::CountIs(i) => count("Is", Some(self.ecx.expr_usize(sp, i))),
555 parse::CountIsParam(i) => {
556 // This needs mapping too, as `i` is referring to a macro
557 // argument. If `i` is not found in `count_positions` then
558 // the error had already been emitted elsewhere.
559 let i = self.count_positions.get(&i).cloned().unwrap_or(0)
560 + self.count_args_index_offset;
561 count("Param", Some(self.ecx.expr_usize(sp, i)))
563 parse::CountImplied => count("Implied", None),
564 // should never be the case, names are already resolved
565 parse::CountIsName(_) => panic!("should never happen"),
569 /// Build a literal expression from the accumulated string literals
570 fn build_literal_string(&mut self) -> P<ast::Expr> {
572 let s = Symbol::intern(&self.literal);
573 self.literal.clear();
574 self.ecx.expr_str(sp, s)
577 /// Builds a static `rt::Argument` from a `parse::Piece` or append
578 /// to the `literal` string.
581 piece: &parse::Piece<'a>,
582 arg_index_consumed: &mut Vec<usize>,
583 ) -> Option<P<ast::Expr>> {
586 parse::String(s) => {
587 self.literal.push_str(s);
590 parse::NextArgument(ref arg) => {
591 // Build the position
594 let mut path = Context::rtpath(self.ecx, "Position");
595 path.push(self.ecx.ident_of(c, sp));
598 let arg = self.ecx.expr_usize(sp, i);
599 self.ecx.expr_call_global(sp, path, vec![arg])
601 None => self.ecx.expr_path(self.ecx.path_global(sp, path)),
605 parse::ArgumentIs(i) | parse::ArgumentImplicitlyIs(i) => {
606 // Map to index in final generated argument array
607 // in case of multiple types specified
608 let arg_idx = match arg_index_consumed.get_mut(i) {
609 None => 0, // error already emitted elsewhere
611 let ref idx_map = self.arg_index_map[i];
612 // unwrap_or branch: error already emitted elsewhere
613 let arg_idx = *idx_map.get(*offset).unwrap_or(&0);
618 pos("At", Some(arg_idx))
621 // should never be the case, because names are already
623 parse::ArgumentNamed(_) => panic!("should never happen"),
627 let simple_arg = parse::Argument {
629 // We don't have ArgumentNext any more, so we have to
630 // track the current argument ourselves.
635 format: parse::FormatSpec {
636 fill: arg.format.fill,
637 align: parse::AlignUnknown,
639 precision: parse::CountImplied,
640 precision_span: None,
641 width: parse::CountImplied,
644 ty_span: arg.format.ty_span,
648 let fill = arg.format.fill.unwrap_or(' ');
650 let pos_simple = arg.position.index() == simple_arg.position.index();
652 if arg.format.precision_span.is_some() || arg.format.width_span.is_some() {
653 self.arg_with_formatting.push(arg.format);
655 if !pos_simple || arg.format != simple_arg.format || fill != ' ' {
656 self.all_pieces_simple = false;
660 let fill = self.ecx.expr_lit(sp, ast::LitKind::Char(fill));
662 let mut p = Context::rtpath(self.ecx, "Alignment");
663 p.push(self.ecx.ident_of(name, sp));
664 self.ecx.path_global(sp, p)
666 let align = match arg.format.align {
667 parse::AlignLeft => align("Left"),
668 parse::AlignRight => align("Right"),
669 parse::AlignCenter => align("Center"),
670 parse::AlignUnknown => align("Unknown"),
672 let align = self.ecx.expr_path(align);
673 let flags = self.ecx.expr_u32(sp, arg.format.flags);
674 let prec = self.build_count(arg.format.precision);
675 let width = self.build_count(arg.format.width);
676 let path = self.ecx.path_global(sp, Context::rtpath(self.ecx, "FormatSpec"));
677 let fmt = self.ecx.expr_struct(
681 self.ecx.field_imm(sp, self.ecx.ident_of("fill", sp), fill),
682 self.ecx.field_imm(sp, self.ecx.ident_of("align", sp), align),
683 self.ecx.field_imm(sp, self.ecx.ident_of("flags", sp), flags),
684 self.ecx.field_imm(sp, self.ecx.ident_of("precision", sp), prec),
685 self.ecx.field_imm(sp, self.ecx.ident_of("width", sp), width),
689 let path = self.ecx.path_global(sp, Context::rtpath(self.ecx, "Argument"));
690 Some(self.ecx.expr_struct(
694 self.ecx.field_imm(sp, self.ecx.ident_of("position", sp), pos),
695 self.ecx.field_imm(sp, self.ecx.ident_of("format", sp), fmt),
702 /// Actually builds the expression which the format_args! block will be
704 fn into_expr(self) -> P<ast::Expr> {
706 Vec::with_capacity((0..self.args.len()).map(|i| self.arg_unique_types[i].len()).sum());
707 let mut counts = Vec::with_capacity(self.count_args.len());
708 let mut pats = Vec::with_capacity(self.args.len());
709 let mut heads = Vec::with_capacity(self.args.len());
711 let names_pos: Vec<_> = (0..self.args.len())
712 .map(|i| self.ecx.ident_of(&format!("arg{}", i), self.macsp))
715 // First, build up the static array which will become our precompiled
717 let pieces = self.ecx.expr_vec_slice(self.fmtsp, self.str_pieces);
719 // Before consuming the expressions, we have to remember spans for
720 // count arguments as they are now generated separate from other
721 // arguments, hence have no access to the `P<ast::Expr>`'s.
722 let spans_pos: Vec<_> = self.args.iter().map(|e| e.span.clone()).collect();
724 // Right now there is a bug such that for the expression:
726 // the lifetime of `1` doesn't outlast the call to `bar`, so it's not
727 // valid for the call to `foo`. To work around this all arguments to the
728 // format! string are shoved into locals. Furthermore, we shove the address
729 // of each variable because we don't want to move out of the arguments
730 // passed to this function.
731 for (i, e) in self.args.into_iter().enumerate() {
732 let name = names_pos[i];
733 let span = self.ecx.with_def_site_ctxt(e.span);
734 pats.push(self.ecx.pat_ident(span, name));
735 for ref arg_ty in self.arg_unique_types[i].iter() {
736 locals.push(Context::format_arg(self.ecx, self.macsp, e.span, arg_ty, name));
738 heads.push(self.ecx.expr_addr_of(e.span, e));
740 for pos in self.count_args {
741 let index = match pos {
743 _ => panic!("should never happen"),
745 let name = names_pos[index];
746 let span = spans_pos[index];
747 counts.push(Context::format_arg(self.ecx, self.macsp, span, &Count, name));
750 // Now create a vector containing all the arguments
751 let args = locals.into_iter().chain(counts.into_iter());
753 let args_array = self.ecx.expr_vec(self.macsp, args.collect());
755 // Constructs an AST equivalent to:
757 // match (&arg0, &arg1) {
758 // (tmp0, tmp1) => args_array
767 // Because of #11585 the new temporary lifetime rule, the enclosing
768 // statements for these temporaries become the let's themselves.
769 // If one or more of them are RefCell's, RefCell borrow() will also
770 // end there; they don't last long enough for args_array to use them.
771 // The match expression solves the scope problem.
773 // Note, it may also very well be transformed to:
778 // ref tmp1 => args_array } } }
780 // But the nested match expression is proved to perform not as well
781 // as series of let's; the first approach does.
782 let pat = self.ecx.pat_tuple(self.macsp, pats);
783 let arm = self.ecx.arm(self.macsp, pat, args_array);
784 let head = self.ecx.expr(self.macsp, ast::ExprKind::Tup(heads));
785 let result = self.ecx.expr_match(self.macsp, head, vec![arm]);
787 let args_slice = self.ecx.expr_addr_of(self.macsp, result);
789 // Now create the fmt::Arguments struct with all our locals we created.
790 let (fn_name, fn_args) = if self.all_pieces_simple {
791 ("new_v1", vec![pieces, args_slice])
793 // Build up the static array which will store our precompiled
794 // nonstandard placeholders, if there are any.
795 let fmt = self.ecx.expr_vec_slice(self.macsp, self.pieces);
797 ("new_v1_formatted", vec![pieces, args_slice, fmt])
800 let path = self.ecx.std_path(&[sym::fmt, sym::Arguments, Symbol::intern(fn_name)]);
801 self.ecx.expr_call_global(self.macsp, path, fn_args)
811 sp = ecx.with_def_site_ctxt(sp);
812 let arg = ecx.expr_ident(sp, arg);
813 let trait_ = match *ty {
814 Placeholder(trait_) if trait_ == "<invalid>" => return DummyResult::raw_expr(sp, true),
815 Placeholder(trait_) => trait_,
817 let path = ecx.std_path(&[sym::fmt, sym::ArgumentV1, sym::from_usize]);
818 return ecx.expr_call_global(macsp, path, vec![arg]);
822 let path = ecx.std_path(&[sym::fmt, Symbol::intern(trait_), sym::fmt]);
823 let format_fn = ecx.path_global(sp, path);
824 let path = ecx.std_path(&[sym::fmt, sym::ArgumentV1, sym::new]);
825 ecx.expr_call_global(macsp, path, vec![arg, ecx.expr_path(format_fn)])
829 fn expand_format_args_impl<'cx>(
830 ecx: &'cx mut ExtCtxt<'_>,
834 ) -> Box<dyn base::MacResult + 'cx> {
835 sp = ecx.with_def_site_ctxt(sp);
836 match parse_args(ecx, sp, tts) {
837 Ok((efmt, args, names)) => {
838 MacEager::expr(expand_preparsed_format_args(ecx, sp, efmt, args, names, nl))
847 pub fn expand_format_args<'cx>(
848 ecx: &'cx mut ExtCtxt<'_>,
851 ) -> Box<dyn base::MacResult + 'cx> {
852 expand_format_args_impl(ecx, sp, tts, false)
855 pub fn expand_format_args_nl<'cx>(
856 ecx: &'cx mut ExtCtxt<'_>,
859 ) -> Box<dyn base::MacResult + 'cx> {
860 expand_format_args_impl(ecx, sp, tts, true)
863 /// Take the various parts of `format_args!(efmt, args..., name=names...)`
864 /// and construct the appropriate formatting expression.
865 pub fn expand_preparsed_format_args(
866 ecx: &mut ExtCtxt<'_>,
869 args: Vec<P<ast::Expr>>,
870 names: FxHashMap<Symbol, usize>,
871 append_newline: bool,
873 // NOTE: this verbose way of initializing `Vec<Vec<ArgumentType>>` is because
874 // `ArgumentType` does not derive `Clone`.
875 let arg_types: Vec<_> = (0..args.len()).map(|_| Vec::new()).collect();
876 let arg_unique_types: Vec<_> = (0..args.len()).map(|_| Vec::new()).collect();
878 let mut macsp = ecx.call_site();
879 macsp = ecx.with_def_site_ctxt(macsp);
881 let msg = "format argument must be a string literal";
882 let fmt_sp = efmt.span;
883 let (fmt_str, fmt_style, fmt_span) = match expr_to_spanned_string(ecx, efmt, msg) {
884 Ok(mut fmt) if append_newline => {
885 fmt.0 = Symbol::intern(&format!("{}\n", fmt.0));
890 if let Some(mut err) = err {
891 let sugg_fmt = match args.len() {
892 0 => "{}".to_string(),
893 _ => format!("{}{{}}", "{} ".repeat(args.len())),
896 fmt_sp.shrink_to_lo(),
897 "you might be missing a string literal to format with",
898 format!("\"{}\", ", sugg_fmt),
899 Applicability::MaybeIncorrect,
903 return DummyResult::raw_expr(sp, true);
907 let (is_literal, fmt_snippet) = match ecx.source_map().span_to_snippet(fmt_sp) {
908 Ok(s) => (s.starts_with("\"") || s.starts_with("r#"), Some(s)),
912 let str_style = match fmt_style {
913 ast::StrStyle::Cooked => None,
914 ast::StrStyle::Raw(raw) => Some(raw as usize),
917 /// Finds the indices of all characters that have been processed and differ between the actual
918 /// written code (code snippet) and the `InternedString` that get's processed in the `Parser`
919 /// in order to properly synthethise the intra-string `Span`s for error diagnostics.
920 fn find_skips(snippet: &str, is_raw: bool) -> Vec<usize> {
921 let mut eat_ws = false;
922 let mut s = snippet.chars().enumerate().peekable();
923 let mut skips = vec![];
924 while let Some((pos, c)) = s.next() {
925 match (c, s.peek()) {
926 // skip whitespace and empty lines ending in '\\'
927 ('\\', Some((next_pos, '\n'))) if !is_raw => {
930 skips.push(*next_pos);
933 ('\\', Some((next_pos, '\n')))
934 | ('\\', Some((next_pos, 'n')))
935 | ('\\', Some((next_pos, 't')))
939 skips.push(*next_pos);
942 (' ', _) | ('\n', _) | ('\t', _) if eat_ws => {
945 ('\\', Some((next_pos, 'n')))
946 | ('\\', Some((next_pos, 't')))
947 | ('\\', Some((next_pos, '0')))
948 | ('\\', Some((next_pos, '\\')))
949 | ('\\', Some((next_pos, '\'')))
950 | ('\\', Some((next_pos, '\"'))) => {
951 skips.push(*next_pos);
954 ('\\', Some((_, 'x'))) if !is_raw => {
956 // consume `\xAB` literal
957 if let Some((pos, _)) = s.next() {
964 ('\\', Some((_, 'u'))) if !is_raw => {
965 if let Some((pos, _)) = s.next() {
968 if let Some((next_pos, next_c)) = s.next() {
970 skips.push(next_pos);
971 let mut i = 0; // consume up to 6 hexanumeric chars + closing `}`
972 while let (Some((next_pos, c)), true) = (s.next(), i < 7) {
974 skips.push(next_pos);
976 skips.push(next_pos);
983 } else if next_c.is_digit(16) {
984 skips.push(next_pos);
985 // We suggest adding `{` and `}` when appropriate, accept it here as if
987 let mut i = 0; // consume up to 6 hexanumeric chars
988 while let (Some((next_pos, c)), _) = (s.next(), i < 6) {
990 skips.push(next_pos);
1000 // `take_while(|c| c.is_whitespace())`
1009 let skips = if let (true, Some(ref snippet)) = (is_literal, fmt_snippet.as_ref()) {
1010 let r_start = str_style.map(|r| r + 1).unwrap_or(0);
1011 let r_end = str_style.map(|r| r).unwrap_or(0);
1012 let s = &snippet[r_start + 1..snippet.len() - r_end - 1];
1013 find_skips(s, str_style.is_some())
1018 let fmt_str = &fmt_str.as_str(); // for the suggestions below
1019 let mut parser = parse::Parser::new(fmt_str, str_style, skips, append_newline);
1021 let mut unverified_pieces = Vec::new();
1022 while let Some(piece) = parser.next() {
1023 if !parser.errors.is_empty() {
1026 unverified_pieces.push(piece);
1030 if !parser.errors.is_empty() {
1031 let err = parser.errors.remove(0);
1032 let sp = fmt_span.from_inner(err.span);
1033 let mut e = ecx.struct_span_err(sp, &format!("invalid format string: {}", err.description));
1034 e.span_label(sp, err.label + " in format string");
1035 if let Some(note) = err.note {
1038 if let Some((label, span)) = err.secondary_label {
1039 let sp = fmt_span.from_inner(span);
1040 e.span_label(sp, label);
1043 return DummyResult::raw_expr(sp, true);
1046 let arg_spans = parser.arg_places.iter().map(|span| fmt_span.from_inner(*span)).collect();
1048 let named_pos: FxHashSet<usize> = names.values().cloned().collect();
1050 let mut cx = Context {
1058 arg_index_map: Vec::new(),
1059 count_args: Vec::new(),
1060 count_positions: FxHashMap::default(),
1061 count_positions_count: 0,
1062 count_args_index_offset: 0,
1063 literal: String::new(),
1064 pieces: Vec::with_capacity(unverified_pieces.len()),
1065 str_pieces: Vec::with_capacity(unverified_pieces.len()),
1066 all_pieces_simple: true,
1069 invalid_refs: Vec::new(),
1071 arg_with_formatting: Vec::new(),
1075 // This needs to happen *after* the Parser has consumed all pieces to create all the spans
1076 let pieces = unverified_pieces
1079 cx.verify_piece(&piece);
1080 cx.resolve_name_inplace(&mut piece);
1083 .collect::<Vec<_>>();
1085 let numbered_position_args = pieces.iter().any(|arg: &parse::Piece<'_>| match *arg {
1086 parse::String(_) => false,
1087 parse::NextArgument(arg) => match arg.position {
1088 parse::Position::ArgumentIs(_) => true,
1093 cx.build_index_map();
1095 let mut arg_index_consumed = vec![0usize; cx.arg_index_map.len()];
1097 for piece in pieces {
1098 if let Some(piece) = cx.build_piece(&piece, &mut arg_index_consumed) {
1099 let s = cx.build_literal_string();
1100 cx.str_pieces.push(s);
1101 cx.pieces.push(piece);
1105 if !cx.literal.is_empty() {
1106 let s = cx.build_literal_string();
1107 cx.str_pieces.push(s);
1110 if cx.invalid_refs.len() >= 1 {
1111 cx.report_invalid_references(numbered_position_args);
1114 // Make sure that all arguments were used and all arguments have types.
1119 .filter(|(i, ty)| ty.is_empty() && !cx.count_positions.contains_key(&i))
1121 let msg = if named_pos.contains(&i) {
1123 "named argument never used"
1125 // positional argument
1126 "argument never used"
1128 (cx.args[i].span, msg)
1130 .collect::<Vec<_>>();
1132 let errs_len = errs.len();
1133 if !errs.is_empty() {
1134 let args_used = cx.arg_types.len() - errs_len;
1135 let args_unused = errs_len;
1139 let (sp, msg) = errs.into_iter().next().unwrap();
1140 let mut diag = cx.ecx.struct_span_err(sp, msg);
1141 diag.span_label(sp, msg);
1144 let mut diag = cx.ecx.struct_span_err(
1145 errs.iter().map(|&(sp, _)| sp).collect::<Vec<Span>>(),
1146 "multiple unused formatting arguments",
1148 diag.span_label(cx.fmtsp, "multiple missing formatting specifiers");
1149 for (sp, msg) in errs {
1150 diag.span_label(sp, msg);
1156 // Used to ensure we only report translations for *one* kind of foreign format.
1157 let mut found_foreign = false;
1158 // Decide if we want to look for foreign formatting directives.
1159 if args_used < args_unused {
1160 use super::format_foreign as foreign;
1162 // The set of foreign substitutions we've explained. This prevents spamming the user
1163 // with `%d should be written as {}` over and over again.
1164 let mut explained = FxHashSet::default();
1166 macro_rules! check_foreign {
1168 let mut show_doc_note = false;
1170 let mut suggestions = vec![];
1171 // account for `"` and account for raw strings `r#`
1172 let padding = str_style.map(|i| i + 2).unwrap_or(1);
1173 for sub in foreign::$kind::iter_subs(fmt_str, padding) {
1174 let trn = match sub.translate() {
1177 // If it has no translation, don't call it out specifically.
1181 let pos = sub.position();
1182 let sub = String::from(sub.as_str());
1183 if explained.contains(&sub) {
1186 explained.insert(sub.clone());
1189 found_foreign = true;
1190 show_doc_note = true;
1193 if let Some(inner_sp) = pos {
1194 let sp = fmt_sp.from_inner(inner_sp);
1195 suggestions.push((sp, trn));
1197 diag.help(&format!("`{}` should be written as `{}`", sub, trn));
1204 " formatting not supported; see the documentation for `std::fmt`",
1207 if suggestions.len() > 0 {
1208 diag.multipart_suggestion(
1209 "format specifiers use curly braces",
1211 Applicability::MachineApplicable,
1217 check_foreign!(printf);
1219 check_foreign!(shell);
1222 if !found_foreign && errs_len == 1 {
1223 diag.span_label(cx.fmtsp, "formatting specifier missing");