4 use fmt_macros as parse;
7 use errors::Applicability;
8 use errors::DiagnosticBuilder;
12 use syntax::symbol::{sym, Symbol};
14 use syntax::tokenstream::TokenStream;
15 use syntax_expand::base::{self, *};
16 use syntax_pos::{MultiSpan, Span};
18 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
20 use std::collections::hash_map::Entry;
24 Placeholder(&'static str),
33 struct Context<'a, 'b> {
34 ecx: &'a mut ExtCtxt<'b>,
35 /// The macro's call site. References to unstable formatting internals must
36 /// use this span to pass the stability checker.
38 /// The span of the format string literal.
41 /// List of parsed argument expressions.
42 /// Named expressions are resolved early, and are appended to the end of
43 /// argument expressions.
45 /// Example showing the various data structures in motion:
47 /// * Original: `"{foo:o} {:o} {foo:x} {0:x} {1:o} {:x} {1:x} {0:o}"`
48 /// * Implicit argument resolution: `"{foo:o} {0:o} {foo:x} {0:x} {1:o} {1:x} {1:x} {0:o}"`
49 /// * Name resolution: `"{2:o} {0:o} {2:x} {0:x} {1:o} {1:x} {1:x} {0:o}"`
50 /// * `arg_types` (in JSON): `[[0, 1, 0], [0, 1, 1], [0, 1]]`
51 /// * `arg_unique_types` (in simplified JSON): `[["o", "x"], ["o", "x"], ["o", "x"]]`
52 /// * `names` (in JSON): `{"foo": 2}`
53 args: Vec<P<ast::Expr>>,
54 /// Placeholder slot numbers indexed by argument.
55 arg_types: Vec<Vec<usize>>,
56 /// Unique format specs seen for each argument.
57 arg_unique_types: Vec<Vec<ArgumentType>>,
58 /// Map from named arguments to their resolved indices.
59 names: FxHashMap<Symbol, usize>,
61 /// The latest consecutive literal strings, or empty if there weren't any.
64 /// Collection of the compiled `rt::Argument` structures
65 pieces: Vec<P<ast::Expr>>,
66 /// Collection of string literals
67 str_pieces: Vec<P<ast::Expr>>,
68 /// Stays `true` if all formatting parameters are default (as in "{}{}").
69 all_pieces_simple: bool,
71 /// Mapping between positional argument references and indices into the
72 /// final generated static argument array. We record the starting indices
73 /// corresponding to each positional argument, and number of references
74 /// consumed so far for each argument, to facilitate correct `Position`
75 /// mapping in `build_piece`. In effect this can be seen as a "flattened"
76 /// version of `arg_unique_types`.
78 /// Again with the example described above in docstring for `args`:
80 /// * `arg_index_map` (in JSON): `[[0, 1, 0], [2, 3, 3], [4, 5]]`
81 arg_index_map: Vec<Vec<usize>>,
83 /// Starting offset of count argument slots.
84 count_args_index_offset: usize,
86 /// Count argument slots and tracking data structures.
87 /// Count arguments are separately tracked for de-duplication in case
88 /// multiple references are made to one argument. For example, in this
91 /// * Original: `"{:.*} {:.foo$} {1:.*} {:.0$}"`
92 /// * Implicit argument resolution: `"{1:.0$} {2:.foo$} {1:.3$} {4:.0$}"`
93 /// * Name resolution: `"{1:.0$} {2:.5$} {1:.3$} {4:.0$}"`
94 /// * `count_positions` (in JSON): `{0: 0, 5: 1, 3: 2}`
95 /// * `count_args`: `vec![Exact(0), Exact(5), Exact(3)]`
96 count_args: Vec<Position>,
97 /// Relative slot numbers for count arguments.
98 count_positions: FxHashMap<usize, usize>,
99 /// Number of count slots assigned.
100 count_positions_count: usize,
102 /// Current position of the implicit positional arg pointer, as if it
103 /// still existed in this phase of processing.
104 /// Used only for `all_pieces_simple` tracking in `build_piece`.
106 /// Current piece being evaluated, used for error reporting.
108 /// Keep track of invalid references to positional arguments.
109 invalid_refs: Vec<(usize, usize)>,
110 /// Spans of all the formatting arguments, in order.
111 arg_spans: Vec<Span>,
112 /// All the formatting arguments that have formatting flags set, in order for diagnostics.
113 arg_with_formatting: Vec<parse::FormatSpec<'a>>,
114 /// Whether this formatting string is a literal or it comes from a macro.
118 /// Parses the arguments from the given list of tokens, returning the diagnostic
119 /// if there's a parse error so we can continue parsing other format!
122 /// If parsing succeeds, the return value is:
125 /// Some((fmtstr, parsed arguments, index map for named arguments))
128 ecx: &mut ExtCtxt<'a>,
131 ) -> Result<(P<ast::Expr>, Vec<P<ast::Expr>>, FxHashMap<Symbol, usize>), DiagnosticBuilder<'a>> {
132 let mut args = Vec::<P<ast::Expr>>::new();
133 let mut names = FxHashMap::<Symbol, usize>::default();
135 let mut p = ecx.new_parser_from_tts(tts);
137 if p.token == token::Eof {
138 return Err(ecx.struct_span_err(sp, "requires at least a format string argument"));
141 let fmtstr = p.parse_expr()?;
142 let mut first = true;
143 let mut named = false;
145 while p.token != token::Eof {
146 if !p.eat(&token::Comma) {
148 // After `format!(""` we always expect *only* a comma...
149 let mut err = ecx.struct_span_err(p.token.span, "expected token: `,`");
150 err.span_label(p.token.span, "expected `,`");
151 p.maybe_annotate_with_ascription(&mut err, false);
154 // ...after that delegate to `expect` to also include the other expected tokens.
155 return Err(p.expect(&token::Comma).err().unwrap());
159 if p.token == token::Eof {
161 } // accept trailing commas
162 if p.token.is_ident() && p.look_ahead(1, |t| *t == token::Eq) {
164 let name = if let token::Ident(name, _) = p.token.kind {
171 p.expect(&token::Eq)?;
172 let e = p.parse_expr()?;
173 if let Some(prev) = names.get(&name) {
174 ecx.struct_span_err(e.span, &format!("duplicate argument named `{}`", name))
175 .span_label(args[*prev].span, "previously here")
176 .span_label(e.span, "duplicate argument")
181 // Resolve names into slots early.
182 // Since all the positional args are already seen at this point
183 // if the input is valid, we can simply append to the positional
184 // args. And remember the names.
185 let slot = args.len();
186 names.insert(name, slot);
189 let e = p.parse_expr()?;
192 .struct_span_err(e.span, "positional arguments cannot follow named arguments");
193 err.span_label(e.span, "positional arguments must be before named arguments");
194 for (_, pos) in &names {
195 err.span_label(args[*pos].span, "named argument");
202 Ok((fmtstr, args, names))
205 impl<'a, 'b> Context<'a, 'b> {
206 fn resolve_name_inplace(&self, p: &mut parse::Piece<'_>) {
207 // NOTE: the `unwrap_or` branch is needed in case of invalid format
208 // arguments, e.g., `format_args!("{foo}")`.
209 let lookup = |s: Symbol| *self.names.get(&s).unwrap_or(&0);
212 parse::String(_) => {}
213 parse::NextArgument(ref mut arg) => {
214 if let parse::ArgumentNamed(s) = arg.position {
215 arg.position = parse::ArgumentIs(lookup(s));
217 if let parse::CountIsName(s) = arg.format.width {
218 arg.format.width = parse::CountIsParam(lookup(s));
220 if let parse::CountIsName(s) = arg.format.precision {
221 arg.format.precision = parse::CountIsParam(lookup(s));
227 /// Verifies one piece of a parse string, and remembers it if valid.
228 /// All errors are not emitted as fatal so we can continue giving errors
229 /// about this and possibly other format strings.
230 fn verify_piece(&mut self, p: &parse::Piece<'_>) {
232 parse::String(..) => {}
233 parse::NextArgument(ref arg) => {
234 // width/precision first, if they have implicit positional
235 // parameters it makes more sense to consume them first.
236 self.verify_count(arg.format.width);
237 self.verify_count(arg.format.precision);
239 // argument second, if it's an implicit positional parameter
240 // it's written second, so it should come after width/precision.
241 let pos = match arg.position {
242 parse::ArgumentIs(i) | parse::ArgumentImplicitlyIs(i) => Exact(i),
243 parse::ArgumentNamed(s) => Named(s),
246 let ty = Placeholder(match &arg.format.ty[..] {
257 let fmtsp = self.fmtsp;
258 let sp = arg.format.ty_span.map(|sp| fmtsp.from_inner(sp));
259 let mut err = self.ecx.struct_span_err(
261 &format!("unknown format trait `{}`", arg.format.ty),
264 "the only appropriate formatting traits are:\n\
265 - ``, which uses the `Display` trait\n\
266 - `?`, which uses the `Debug` trait\n\
267 - `e`, which uses the `LowerExp` trait\n\
268 - `E`, which uses the `UpperExp` trait\n\
269 - `o`, which uses the `Octal` trait\n\
270 - `p`, which uses the `Pointer` trait\n\
271 - `b`, which uses the `Binary` trait\n\
272 - `x`, which uses the `LowerHex` trait\n\
273 - `X`, which uses the `UpperHex` trait",
275 if let Some(sp) = sp {
276 for (fmt, name) in &[
287 err.tool_only_span_suggestion(
289 &format!("use the `{}` trait", name),
291 Applicability::MaybeIncorrect,
299 self.verify_arg_type(pos, ty);
305 fn verify_count(&mut self, c: parse::Count) {
307 parse::CountImplied | parse::CountIs(..) => {}
308 parse::CountIsParam(i) => {
309 self.verify_arg_type(Exact(i), Count);
311 parse::CountIsName(s) => {
312 self.verify_arg_type(Named(s), Count);
317 fn describe_num_args(&self) -> Cow<'_, str> {
318 match self.args.len() {
319 0 => "no arguments were given".into(),
320 1 => "there is 1 argument".into(),
321 x => format!("there are {} arguments", x).into(),
325 /// Handle invalid references to positional arguments. Output different
326 /// errors for the case where all arguments are positional and for when
327 /// there are named arguments or numbered positional arguments in the
329 fn report_invalid_references(&self, numbered_position_args: bool) {
331 let sp = if self.is_literal {
332 // Point at the formatting arguments.
333 MultiSpan::from_spans(self.arg_spans.clone())
335 MultiSpan::from_span(self.fmtsp)
338 self.invalid_refs.iter().map(|(r, pos)| (r.to_string(), self.arg_spans.get(*pos)));
340 let mut zero_based_note = false;
342 let count = self.pieces.len()
343 + self.arg_with_formatting.iter().filter(|fmt| fmt.precision_span.is_some()).count();
344 if self.names.is_empty() && !numbered_position_args && count != self.args.len() {
345 e = self.ecx.struct_span_err(
348 "{} positional argument{} in format string, but {}",
351 self.describe_num_args(),
354 for arg in &self.args {
355 // Point at the arguments that will be formatted.
356 e.span_label(arg.span, "");
359 let (mut refs, spans): (Vec<_>, Vec<_>) = refs.unzip();
360 // Avoid `invalid reference to positional arguments 7 and 7 (there is 1 argument)`
361 // for `println!("{7:7$}", 1);`
364 let (arg_list, mut sp) = if refs.len() == 1 {
365 let spans: Vec<_> = spans.into_iter().filter_map(|sp| sp.map(|sp| *sp)).collect();
367 format!("argument {}", refs[0]),
368 if spans.is_empty() {
369 MultiSpan::from_span(self.fmtsp)
371 MultiSpan::from_spans(spans)
375 let pos = MultiSpan::from_spans(spans.into_iter().map(|s| *s.unwrap()).collect());
376 let reg = refs.pop().unwrap();
377 (format!("arguments {head} and {tail}", head = refs.join(", "), tail = reg,), pos)
379 if !self.is_literal {
380 sp = MultiSpan::from_span(self.fmtsp);
383 e = self.ecx.struct_span_err(
386 "invalid reference to positional {} ({})",
388 self.describe_num_args()
391 zero_based_note = true;
394 for fmt in &self.arg_with_formatting {
395 if let Some(span) = fmt.precision_span {
396 let span = self.fmtsp.from_inner(span);
397 match fmt.precision {
398 parse::CountIsParam(pos) if pos > self.args.len() => {
402 "this precision flag expects an `usize` argument at position {}, \
405 self.describe_num_args(),
408 zero_based_note = true;
410 parse::CountIsParam(pos) => {
411 let count = self.pieces.len()
415 .filter(|fmt| fmt.precision_span.is_some())
417 e.span_label(span, &format!(
418 "this precision flag adds an extra required argument at position {}, \
419 which is why there {} expected",
422 "is 1 argument".to_string()
424 format!("are {} arguments", count)
427 if let Some(arg) = self.args.get(pos) {
430 "this parameter corresponds to the precision flag",
433 zero_based_note = true;
438 if let Some(span) = fmt.width_span {
439 let span = self.fmtsp.from_inner(span);
441 parse::CountIsParam(pos) if pos > self.args.len() => {
445 "this width flag expects an `usize` argument at position {}, \
448 self.describe_num_args(),
451 zero_based_note = true;
458 e.note("positional arguments are zero-based");
460 if !self.arg_with_formatting.is_empty() {
462 "for information about formatting flags, visit \
463 https://doc.rust-lang.org/std/fmt/index.html",
470 /// Actually verifies and tracks a given format placeholder
471 /// (a.k.a. argument).
472 fn verify_arg_type(&mut self, arg: Position, ty: ArgumentType) {
475 if self.args.len() <= arg {
476 self.invalid_refs.push((arg, self.curpiece));
481 // record every (position, type) combination only once
482 let ref mut seen_ty = self.arg_unique_types[arg];
483 let i = seen_ty.iter().position(|x| *x == ty).unwrap_or_else(|| {
484 let i = seen_ty.len();
488 self.arg_types[arg].push(i);
491 if let Entry::Vacant(e) = self.count_positions.entry(arg) {
492 let i = self.count_positions_count;
494 self.count_args.push(Exact(arg));
495 self.count_positions_count += 1;
502 match self.names.get(&name) {
504 // Treat as positional arg.
505 self.verify_arg_type(Exact(idx), ty)
508 let msg = format!("there is no argument named `{}`", name);
509 let sp = if self.is_literal {
510 *self.arg_spans.get(self.curpiece).unwrap_or(&self.fmtsp)
514 let mut err = self.ecx.struct_span_err(sp, &msg[..]);
522 /// Builds the mapping between format placeholders and argument objects.
523 fn build_index_map(&mut self) {
524 // NOTE: Keep the ordering the same as `into_expr`'s expansion would do!
525 let args_len = self.args.len();
526 self.arg_index_map.reserve(args_len);
528 let mut sofar = 0usize;
531 for i in 0..args_len {
532 let ref arg_types = self.arg_types[i];
533 let arg_offsets = arg_types.iter().map(|offset| sofar + *offset).collect::<Vec<_>>();
534 self.arg_index_map.push(arg_offsets);
535 sofar += self.arg_unique_types[i].len();
538 // Record starting index for counts, which appear just after arguments
539 self.count_args_index_offset = sofar;
542 fn rtpath(ecx: &ExtCtxt<'_>, s: &str) -> Vec<ast::Ident> {
543 ecx.std_path(&[sym::fmt, sym::rt, sym::v1, Symbol::intern(s)])
546 fn build_count(&self, c: parse::Count) -> P<ast::Expr> {
548 let count = |c, arg| {
549 let mut path = Context::rtpath(self.ecx, "Count");
550 path.push(self.ecx.ident_of(c, sp));
552 Some(arg) => self.ecx.expr_call_global(sp, path, vec![arg]),
553 None => self.ecx.expr_path(self.ecx.path_global(sp, path)),
557 parse::CountIs(i) => count("Is", Some(self.ecx.expr_usize(sp, i))),
558 parse::CountIsParam(i) => {
559 // This needs mapping too, as `i` is referring to a macro
560 // argument. If `i` is not found in `count_positions` then
561 // the error had already been emitted elsewhere.
562 let i = self.count_positions.get(&i).cloned().unwrap_or(0)
563 + self.count_args_index_offset;
564 count("Param", Some(self.ecx.expr_usize(sp, i)))
566 parse::CountImplied => count("Implied", None),
567 // should never be the case, names are already resolved
568 parse::CountIsName(_) => panic!("should never happen"),
572 /// Build a literal expression from the accumulated string literals
573 fn build_literal_string(&mut self) -> P<ast::Expr> {
575 let s = Symbol::intern(&self.literal);
576 self.literal.clear();
577 self.ecx.expr_str(sp, s)
580 /// Builds a static `rt::Argument` from a `parse::Piece` or append
581 /// to the `literal` string.
584 piece: &parse::Piece<'a>,
585 arg_index_consumed: &mut Vec<usize>,
586 ) -> Option<P<ast::Expr>> {
589 parse::String(s) => {
590 self.literal.push_str(s);
593 parse::NextArgument(ref arg) => {
594 // Build the position
597 let mut path = Context::rtpath(self.ecx, "Position");
598 path.push(self.ecx.ident_of(c, sp));
601 let arg = self.ecx.expr_usize(sp, i);
602 self.ecx.expr_call_global(sp, path, vec![arg])
604 None => self.ecx.expr_path(self.ecx.path_global(sp, path)),
608 parse::ArgumentIs(i) | parse::ArgumentImplicitlyIs(i) => {
609 // Map to index in final generated argument array
610 // in case of multiple types specified
611 let arg_idx = match arg_index_consumed.get_mut(i) {
612 None => 0, // error already emitted elsewhere
614 let ref idx_map = self.arg_index_map[i];
615 // unwrap_or branch: error already emitted elsewhere
616 let arg_idx = *idx_map.get(*offset).unwrap_or(&0);
621 pos("At", Some(arg_idx))
624 // should never be the case, because names are already
626 parse::ArgumentNamed(_) => panic!("should never happen"),
630 let simple_arg = parse::Argument {
632 // We don't have ArgumentNext any more, so we have to
633 // track the current argument ourselves.
638 format: parse::FormatSpec {
639 fill: arg.format.fill,
640 align: parse::AlignUnknown,
642 precision: parse::CountImplied,
643 precision_span: None,
644 width: parse::CountImplied,
647 ty_span: arg.format.ty_span,
651 let fill = arg.format.fill.unwrap_or(' ');
653 let pos_simple = arg.position.index() == simple_arg.position.index();
655 if arg.format.precision_span.is_some() || arg.format.width_span.is_some() {
656 self.arg_with_formatting.push(arg.format);
658 if !pos_simple || arg.format != simple_arg.format || fill != ' ' {
659 self.all_pieces_simple = false;
663 let fill = self.ecx.expr_lit(sp, ast::LitKind::Char(fill));
665 let mut p = Context::rtpath(self.ecx, "Alignment");
666 p.push(self.ecx.ident_of(name, sp));
667 self.ecx.path_global(sp, p)
669 let align = match arg.format.align {
670 parse::AlignLeft => align("Left"),
671 parse::AlignRight => align("Right"),
672 parse::AlignCenter => align("Center"),
673 parse::AlignUnknown => align("Unknown"),
675 let align = self.ecx.expr_path(align);
676 let flags = self.ecx.expr_u32(sp, arg.format.flags);
677 let prec = self.build_count(arg.format.precision);
678 let width = self.build_count(arg.format.width);
679 let path = self.ecx.path_global(sp, Context::rtpath(self.ecx, "FormatSpec"));
680 let fmt = self.ecx.expr_struct(
684 self.ecx.field_imm(sp, self.ecx.ident_of("fill", sp), fill),
685 self.ecx.field_imm(sp, self.ecx.ident_of("align", sp), align),
686 self.ecx.field_imm(sp, self.ecx.ident_of("flags", sp), flags),
687 self.ecx.field_imm(sp, self.ecx.ident_of("precision", sp), prec),
688 self.ecx.field_imm(sp, self.ecx.ident_of("width", sp), width),
692 let path = self.ecx.path_global(sp, Context::rtpath(self.ecx, "Argument"));
693 Some(self.ecx.expr_struct(
697 self.ecx.field_imm(sp, self.ecx.ident_of("position", sp), pos),
698 self.ecx.field_imm(sp, self.ecx.ident_of("format", sp), fmt),
705 /// Actually builds the expression which the format_args! block will be
707 fn into_expr(self) -> P<ast::Expr> {
709 Vec::with_capacity((0..self.args.len()).map(|i| self.arg_unique_types[i].len()).sum());
710 let mut counts = Vec::with_capacity(self.count_args.len());
711 let mut pats = Vec::with_capacity(self.args.len());
712 let mut heads = Vec::with_capacity(self.args.len());
714 let names_pos: Vec<_> = (0..self.args.len())
715 .map(|i| self.ecx.ident_of(&format!("arg{}", i), self.macsp))
718 // First, build up the static array which will become our precompiled
720 let pieces = self.ecx.expr_vec_slice(self.fmtsp, self.str_pieces);
722 // Before consuming the expressions, we have to remember spans for
723 // count arguments as they are now generated separate from other
724 // arguments, hence have no access to the `P<ast::Expr>`'s.
725 let spans_pos: Vec<_> = self.args.iter().map(|e| e.span.clone()).collect();
727 // Right now there is a bug such that for the expression:
729 // the lifetime of `1` doesn't outlast the call to `bar`, so it's not
730 // valid for the call to `foo`. To work around this all arguments to the
731 // format! string are shoved into locals. Furthermore, we shove the address
732 // of each variable because we don't want to move out of the arguments
733 // passed to this function.
734 for (i, e) in self.args.into_iter().enumerate() {
735 let name = names_pos[i];
736 let span = self.ecx.with_def_site_ctxt(e.span);
737 pats.push(self.ecx.pat_ident(span, name));
738 for ref arg_ty in self.arg_unique_types[i].iter() {
739 locals.push(Context::format_arg(self.ecx, self.macsp, e.span, arg_ty, name));
741 heads.push(self.ecx.expr_addr_of(e.span, e));
743 for pos in self.count_args {
744 let index = match pos {
746 _ => panic!("should never happen"),
748 let name = names_pos[index];
749 let span = spans_pos[index];
750 counts.push(Context::format_arg(self.ecx, self.macsp, span, &Count, name));
753 // Now create a vector containing all the arguments
754 let args = locals.into_iter().chain(counts.into_iter());
756 let args_array = self.ecx.expr_vec(self.macsp, args.collect());
758 // Constructs an AST equivalent to:
760 // match (&arg0, &arg1) {
761 // (tmp0, tmp1) => args_array
770 // Because of #11585 the new temporary lifetime rule, the enclosing
771 // statements for these temporaries become the let's themselves.
772 // If one or more of them are RefCell's, RefCell borrow() will also
773 // end there; they don't last long enough for args_array to use them.
774 // The match expression solves the scope problem.
776 // Note, it may also very well be transformed to:
781 // ref tmp1 => args_array } } }
783 // But the nested match expression is proved to perform not as well
784 // as series of let's; the first approach does.
785 let pat = self.ecx.pat_tuple(self.macsp, pats);
786 let arm = self.ecx.arm(self.macsp, pat, args_array);
787 let head = self.ecx.expr(self.macsp, ast::ExprKind::Tup(heads));
788 let result = self.ecx.expr_match(self.macsp, head, vec![arm]);
790 let args_slice = self.ecx.expr_addr_of(self.macsp, result);
792 // Now create the fmt::Arguments struct with all our locals we created.
793 let (fn_name, fn_args) = if self.all_pieces_simple {
794 ("new_v1", vec![pieces, args_slice])
796 // Build up the static array which will store our precompiled
797 // nonstandard placeholders, if there are any.
798 let fmt = self.ecx.expr_vec_slice(self.macsp, self.pieces);
800 ("new_v1_formatted", vec![pieces, args_slice, fmt])
803 let path = self.ecx.std_path(&[sym::fmt, sym::Arguments, Symbol::intern(fn_name)]);
804 self.ecx.expr_call_global(self.macsp, path, fn_args)
814 sp = ecx.with_def_site_ctxt(sp);
815 let arg = ecx.expr_ident(sp, arg);
816 let trait_ = match *ty {
817 Placeholder(trait_) if trait_ == "<invalid>" => return DummyResult::raw_expr(sp, true),
818 Placeholder(trait_) => trait_,
820 let path = ecx.std_path(&[sym::fmt, sym::ArgumentV1, sym::from_usize]);
821 return ecx.expr_call_global(macsp, path, vec![arg]);
825 let path = ecx.std_path(&[sym::fmt, Symbol::intern(trait_), sym::fmt]);
826 let format_fn = ecx.path_global(sp, path);
827 let path = ecx.std_path(&[sym::fmt, sym::ArgumentV1, sym::new]);
828 ecx.expr_call_global(macsp, path, vec![arg, ecx.expr_path(format_fn)])
832 fn expand_format_args_impl<'cx>(
833 ecx: &'cx mut ExtCtxt<'_>,
837 ) -> Box<dyn base::MacResult + 'cx> {
838 sp = ecx.with_def_site_ctxt(sp);
839 match parse_args(ecx, sp, tts) {
840 Ok((efmt, args, names)) => {
841 MacEager::expr(expand_preparsed_format_args(ecx, sp, efmt, args, names, nl))
850 pub fn expand_format_args<'cx>(
851 ecx: &'cx mut ExtCtxt<'_>,
854 ) -> Box<dyn base::MacResult + 'cx> {
855 expand_format_args_impl(ecx, sp, tts, false)
858 pub fn expand_format_args_nl<'cx>(
859 ecx: &'cx mut ExtCtxt<'_>,
862 ) -> Box<dyn base::MacResult + 'cx> {
863 expand_format_args_impl(ecx, sp, tts, true)
866 /// Take the various parts of `format_args!(efmt, args..., name=names...)`
867 /// and construct the appropriate formatting expression.
868 pub fn expand_preparsed_format_args(
869 ecx: &mut ExtCtxt<'_>,
872 args: Vec<P<ast::Expr>>,
873 names: FxHashMap<Symbol, usize>,
874 append_newline: bool,
876 // NOTE: this verbose way of initializing `Vec<Vec<ArgumentType>>` is because
877 // `ArgumentType` does not derive `Clone`.
878 let arg_types: Vec<_> = (0..args.len()).map(|_| Vec::new()).collect();
879 let arg_unique_types: Vec<_> = (0..args.len()).map(|_| Vec::new()).collect();
881 let mut macsp = ecx.call_site();
882 macsp = ecx.with_def_site_ctxt(macsp);
884 let msg = "format argument must be a string literal";
885 let fmt_sp = efmt.span;
886 let (fmt_str, fmt_style, fmt_span) = match expr_to_spanned_string(ecx, efmt, msg) {
887 Ok(mut fmt) if append_newline => {
888 fmt.0 = Symbol::intern(&format!("{}\n", fmt.0));
893 if let Some(mut err) = err {
894 let sugg_fmt = match args.len() {
895 0 => "{}".to_string(),
896 _ => format!("{}{{}}", "{} ".repeat(args.len())),
899 fmt_sp.shrink_to_lo(),
900 "you might be missing a string literal to format with",
901 format!("\"{}\", ", sugg_fmt),
902 Applicability::MaybeIncorrect,
906 return DummyResult::raw_expr(sp, true);
910 let (is_literal, fmt_snippet) = match ecx.source_map().span_to_snippet(fmt_sp) {
911 Ok(s) => (s.starts_with("\"") || s.starts_with("r#"), Some(s)),
915 let str_style = match fmt_style {
916 ast::StrStyle::Cooked => None,
917 ast::StrStyle::Raw(raw) => Some(raw as usize),
920 /// Finds the indices of all characters that have been processed and differ between the actual
921 /// written code (code snippet) and the `InternedString` that get's processed in the `Parser`
922 /// in order to properly synthethise the intra-string `Span`s for error diagnostics.
923 fn find_skips(snippet: &str, is_raw: bool) -> Vec<usize> {
924 let mut eat_ws = false;
925 let mut s = snippet.chars().enumerate().peekable();
926 let mut skips = vec![];
927 while let Some((pos, c)) = s.next() {
928 match (c, s.peek()) {
929 // skip whitespace and empty lines ending in '\\'
930 ('\\', Some((next_pos, '\n'))) if !is_raw => {
933 skips.push(*next_pos);
936 ('\\', Some((next_pos, '\n')))
937 | ('\\', Some((next_pos, 'n')))
938 | ('\\', Some((next_pos, 't')))
942 skips.push(*next_pos);
945 (' ', _) | ('\n', _) | ('\t', _) if eat_ws => {
948 ('\\', Some((next_pos, 'n')))
949 | ('\\', Some((next_pos, 't')))
950 | ('\\', Some((next_pos, '0')))
951 | ('\\', Some((next_pos, '\\')))
952 | ('\\', Some((next_pos, '\'')))
953 | ('\\', Some((next_pos, '\"'))) => {
954 skips.push(*next_pos);
957 ('\\', Some((_, 'x'))) if !is_raw => {
959 // consume `\xAB` literal
960 if let Some((pos, _)) = s.next() {
967 ('\\', Some((_, 'u'))) if !is_raw => {
968 if let Some((pos, _)) = s.next() {
971 if let Some((next_pos, next_c)) = s.next() {
973 skips.push(next_pos);
974 let mut i = 0; // consume up to 6 hexanumeric chars + closing `}`
975 while let (Some((next_pos, c)), true) = (s.next(), i < 7) {
977 skips.push(next_pos);
979 skips.push(next_pos);
986 } else if next_c.is_digit(16) {
987 skips.push(next_pos);
988 // We suggest adding `{` and `}` when appropriate, accept it here as if
990 let mut i = 0; // consume up to 6 hexanumeric chars
991 while let (Some((next_pos, c)), _) = (s.next(), i < 6) {
993 skips.push(next_pos);
1003 // `take_while(|c| c.is_whitespace())`
1012 let skips = if let (true, Some(ref snippet)) = (is_literal, fmt_snippet.as_ref()) {
1013 let r_start = str_style.map(|r| r + 1).unwrap_or(0);
1014 let r_end = str_style.map(|r| r).unwrap_or(0);
1015 let s = &snippet[r_start + 1..snippet.len() - r_end - 1];
1016 find_skips(s, str_style.is_some())
1021 let fmt_str = &fmt_str.as_str(); // for the suggestions below
1022 let mut parser = parse::Parser::new(fmt_str, str_style, skips, append_newline);
1024 let mut unverified_pieces = Vec::new();
1025 while let Some(piece) = parser.next() {
1026 if !parser.errors.is_empty() {
1029 unverified_pieces.push(piece);
1033 if !parser.errors.is_empty() {
1034 let err = parser.errors.remove(0);
1035 let sp = fmt_span.from_inner(err.span);
1036 let mut e = ecx.struct_span_err(sp, &format!("invalid format string: {}", err.description));
1037 e.span_label(sp, err.label + " in format string");
1038 if let Some(note) = err.note {
1041 if let Some((label, span)) = err.secondary_label {
1042 let sp = fmt_span.from_inner(span);
1043 e.span_label(sp, label);
1046 return DummyResult::raw_expr(sp, true);
1049 let arg_spans = parser.arg_places.iter().map(|span| fmt_span.from_inner(*span)).collect();
1051 let named_pos: FxHashSet<usize> = names.values().cloned().collect();
1053 let mut cx = Context {
1061 arg_index_map: Vec::new(),
1062 count_args: Vec::new(),
1063 count_positions: FxHashMap::default(),
1064 count_positions_count: 0,
1065 count_args_index_offset: 0,
1066 literal: String::new(),
1067 pieces: Vec::with_capacity(unverified_pieces.len()),
1068 str_pieces: Vec::with_capacity(unverified_pieces.len()),
1069 all_pieces_simple: true,
1072 invalid_refs: Vec::new(),
1074 arg_with_formatting: Vec::new(),
1078 // This needs to happen *after* the Parser has consumed all pieces to create all the spans
1079 let pieces = unverified_pieces
1082 cx.verify_piece(&piece);
1083 cx.resolve_name_inplace(&mut piece);
1086 .collect::<Vec<_>>();
1088 let numbered_position_args = pieces.iter().any(|arg: &parse::Piece<'_>| match *arg {
1089 parse::String(_) => false,
1090 parse::NextArgument(arg) => match arg.position {
1091 parse::Position::ArgumentIs(_) => true,
1096 cx.build_index_map();
1098 let mut arg_index_consumed = vec![0usize; cx.arg_index_map.len()];
1100 for piece in pieces {
1101 if let Some(piece) = cx.build_piece(&piece, &mut arg_index_consumed) {
1102 let s = cx.build_literal_string();
1103 cx.str_pieces.push(s);
1104 cx.pieces.push(piece);
1108 if !cx.literal.is_empty() {
1109 let s = cx.build_literal_string();
1110 cx.str_pieces.push(s);
1113 if cx.invalid_refs.len() >= 1 {
1114 cx.report_invalid_references(numbered_position_args);
1117 // Make sure that all arguments were used and all arguments have types.
1122 .filter(|(i, ty)| ty.is_empty() && !cx.count_positions.contains_key(&i))
1124 let msg = if named_pos.contains(&i) {
1126 "named argument never used"
1128 // positional argument
1129 "argument never used"
1131 (cx.args[i].span, msg)
1133 .collect::<Vec<_>>();
1135 let errs_len = errs.len();
1136 if !errs.is_empty() {
1137 let args_used = cx.arg_types.len() - errs_len;
1138 let args_unused = errs_len;
1142 let (sp, msg) = errs.into_iter().next().unwrap();
1143 let mut diag = cx.ecx.struct_span_err(sp, msg);
1144 diag.span_label(sp, msg);
1147 let mut diag = cx.ecx.struct_span_err(
1148 errs.iter().map(|&(sp, _)| sp).collect::<Vec<Span>>(),
1149 "multiple unused formatting arguments",
1151 diag.span_label(cx.fmtsp, "multiple missing formatting specifiers");
1152 for (sp, msg) in errs {
1153 diag.span_label(sp, msg);
1159 // Used to ensure we only report translations for *one* kind of foreign format.
1160 let mut found_foreign = false;
1161 // Decide if we want to look for foreign formatting directives.
1162 if args_used < args_unused {
1163 use super::format_foreign as foreign;
1165 // The set of foreign substitutions we've explained. This prevents spamming the user
1166 // with `%d should be written as {}` over and over again.
1167 let mut explained = FxHashSet::default();
1169 macro_rules! check_foreign {
1171 let mut show_doc_note = false;
1173 let mut suggestions = vec![];
1174 // account for `"` and account for raw strings `r#`
1175 let padding = str_style.map(|i| i + 2).unwrap_or(1);
1176 for sub in foreign::$kind::iter_subs(fmt_str, padding) {
1177 let trn = match sub.translate() {
1180 // If it has no translation, don't call it out specifically.
1184 let pos = sub.position();
1185 let sub = String::from(sub.as_str());
1186 if explained.contains(&sub) {
1189 explained.insert(sub.clone());
1192 found_foreign = true;
1193 show_doc_note = true;
1196 if let Some(inner_sp) = pos {
1197 let sp = fmt_sp.from_inner(inner_sp);
1198 suggestions.push((sp, trn));
1200 diag.help(&format!("`{}` should be written as `{}`", sub, trn));
1207 " formatting not supported; see the documentation for `std::fmt`",
1210 if suggestions.len() > 0 {
1211 diag.multipart_suggestion(
1212 "format specifiers use curly braces",
1214 Applicability::MachineApplicable,
1220 check_foreign!(printf);
1222 check_foreign!(shell);
1225 if !found_foreign && errs_len == 1 {
1226 diag.span_label(cx.fmtsp, "formatting specifier missing");