4 use fmt_macros as parse;
6 use errors::DiagnosticBuilder;
7 use errors::Applicability;
10 use syntax::ext::base::{self, *};
11 use syntax::parse::token;
13 use syntax::symbol::{Symbol, sym};
14 use syntax::tokenstream::TokenStream;
15 use syntax_pos::{MultiSpan, Span};
17 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
19 use std::collections::hash_map::Entry;
32 struct Context<'a, 'b> {
33 ecx: &'a mut ExtCtxt<'b>,
34 /// The macro's call site. References to unstable formatting internals must
35 /// use this span to pass the stability checker.
37 /// The span of the format string literal.
40 /// List of parsed argument expressions.
41 /// Named expressions are resolved early, and are appended to the end of
42 /// argument expressions.
44 /// Example showing the various data structures in motion:
46 /// * Original: `"{foo:o} {:o} {foo:x} {0:x} {1:o} {:x} {1:x} {0:o}"`
47 /// * Implicit argument resolution: `"{foo:o} {0:o} {foo:x} {0:x} {1:o} {1:x} {1:x} {0:o}"`
48 /// * Name resolution: `"{2:o} {0:o} {2:x} {0:x} {1:o} {1:x} {1:x} {0:o}"`
49 /// * `arg_types` (in JSON): `[[0, 1, 0], [0, 1, 1], [0, 1]]`
50 /// * `arg_unique_types` (in simplified JSON): `[["o", "x"], ["o", "x"], ["o", "x"]]`
51 /// * `names` (in JSON): `{"foo": 2}`
52 args: Vec<P<ast::Expr>>,
53 /// Placeholder slot numbers indexed by argument.
54 arg_types: Vec<Vec<usize>>,
55 /// Unique format specs seen for each argument.
56 arg_unique_types: Vec<Vec<ArgumentType>>,
57 /// Map from named arguments to their resolved indices.
58 names: FxHashMap<Symbol, usize>,
60 /// The latest consecutive literal strings, or empty if there weren't any.
63 /// Collection of the compiled `rt::Argument` structures
64 pieces: Vec<P<ast::Expr>>,
65 /// Collection of string literals
66 str_pieces: Vec<P<ast::Expr>>,
67 /// Stays `true` if all formatting parameters are default (as in "{}{}").
68 all_pieces_simple: bool,
70 /// Mapping between positional argument references and indices into the
71 /// final generated static argument array. We record the starting indices
72 /// corresponding to each positional argument, and number of references
73 /// consumed so far for each argument, to facilitate correct `Position`
74 /// mapping in `build_piece`. In effect this can be seen as a "flattened"
75 /// version of `arg_unique_types`.
77 /// Again with the example described above in docstring for `args`:
79 /// * `arg_index_map` (in JSON): `[[0, 1, 0], [2, 3, 3], [4, 5]]`
80 arg_index_map: Vec<Vec<usize>>,
82 /// Starting offset of count argument slots.
83 count_args_index_offset: usize,
85 /// Count argument slots and tracking data structures.
86 /// Count arguments are separately tracked for de-duplication in case
87 /// multiple references are made to one argument. For example, in this
90 /// * Original: `"{:.*} {:.foo$} {1:.*} {:.0$}"`
91 /// * Implicit argument resolution: `"{1:.0$} {2:.foo$} {1:.3$} {4:.0$}"`
92 /// * Name resolution: `"{1:.0$} {2:.5$} {1:.3$} {4:.0$}"`
93 /// * `count_positions` (in JSON): `{0: 0, 5: 1, 3: 2}`
94 /// * `count_args`: `vec![Exact(0), Exact(5), Exact(3)]`
95 count_args: Vec<Position>,
96 /// Relative slot numbers for count arguments.
97 count_positions: FxHashMap<usize, usize>,
98 /// Number of count slots assigned.
99 count_positions_count: usize,
101 /// Current position of the implicit positional arg pointer, as if it
102 /// still existed in this phase of processing.
103 /// Used only for `all_pieces_simple` tracking in `build_piece`.
105 /// Current piece being evaluated, used for error reporting.
107 /// Keep track of invalid references to positional arguments.
108 invalid_refs: Vec<(usize, usize)>,
109 /// Spans of all the formatting arguments, in order.
110 arg_spans: Vec<Span>,
111 /// All the formatting arguments that have formatting flags set, in order for diagnostics.
112 arg_with_formatting: Vec<parse::FormatSpec<'a>>,
113 /// Whether this formatting string is a literal or it comes from a macro.
117 /// Parses the arguments from the given list of tokens, returning the diagnostic
118 /// if there's a parse error so we can continue parsing other format!
121 /// If parsing succeeds, the return value is:
124 /// Some((fmtstr, parsed arguments, index map for named arguments))
127 ecx: &mut ExtCtxt<'a>,
130 ) -> Result<(P<ast::Expr>, Vec<P<ast::Expr>>, FxHashMap<Symbol, usize>), DiagnosticBuilder<'a>> {
131 let mut args = Vec::<P<ast::Expr>>::new();
132 let mut names = FxHashMap::<Symbol, usize>::default();
134 let mut p = ecx.new_parser_from_tts(tts);
136 if p.token == token::Eof {
137 return Err(ecx.struct_span_err(sp, "requires at least a format string argument"));
140 let fmtstr = p.parse_expr()?;
141 let mut first = true;
142 let mut named = false;
144 while p.token != token::Eof {
145 if !p.eat(&token::Comma) {
147 // After `format!(""` we always expect *only* a comma...
148 let mut err = ecx.struct_span_err(p.token.span, "expected token: `,`");
149 err.span_label(p.token.span, "expected `,`");
150 p.maybe_annotate_with_ascription(&mut err, false);
153 // ...after that delegate to `expect` to also include the other expected tokens.
154 return Err(p.expect(&token::Comma).err().unwrap());
158 if p.token == token::Eof {
160 } // accept trailing commas
161 if p.token.is_ident() && p.look_ahead(1, |t| *t == token::Eq) {
163 let name = if let token::Ident(name, _) = p.token.kind {
170 p.expect(&token::Eq)?;
171 let e = p.parse_expr()?;
172 if let Some(prev) = names.get(&name) {
173 ecx.struct_span_err(e.span, &format!("duplicate argument named `{}`", name))
174 .span_note(args[*prev].span, "previously here")
179 // Resolve names into slots early.
180 // Since all the positional args are already seen at this point
181 // if the input is valid, we can simply append to the positional
182 // args. And remember the names.
183 let slot = args.len();
184 names.insert(name, slot);
187 let e = p.parse_expr()?;
189 let mut err = ecx.struct_span_err(
191 "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(arg.format.ty.to_string());
247 self.verify_arg_type(pos, ty);
253 fn verify_count(&mut self, c: parse::Count) {
255 parse::CountImplied |
256 parse::CountIs(..) => {}
257 parse::CountIsParam(i) => {
258 self.verify_arg_type(Exact(i), Count);
260 parse::CountIsName(s) => {
261 self.verify_arg_type(Named(s), Count);
266 fn describe_num_args(&self) -> Cow<'_, str> {
267 match self.args.len() {
268 0 => "no arguments were given".into(),
269 1 => "there is 1 argument".into(),
270 x => format!("there are {} arguments", x).into(),
274 /// Handle invalid references to positional arguments. Output different
275 /// errors for the case where all arguments are positional and for when
276 /// there are named arguments or numbered positional arguments in the
278 fn report_invalid_references(&self, numbered_position_args: bool) {
280 let sp = if self.is_literal {
281 MultiSpan::from_spans(self.arg_spans.clone())
283 MultiSpan::from_span(self.fmtsp)
288 .map(|(r, pos)| (r.to_string(), self.arg_spans.get(*pos)));
290 let mut zero_based_note = false;
292 let count = self.pieces.len() + self.arg_with_formatting
294 .filter(|fmt| fmt.precision_span.is_some())
296 if self.names.is_empty() && !numbered_position_args && count != self.args.len() {
297 e = self.ecx.mut_span_err(
300 "{} positional argument{} in format string, but {}",
302 if count != 1 { "s" } else { "" },
303 self.describe_num_args(),
307 let (mut refs, spans): (Vec<_>, Vec<_>) = refs.unzip();
308 // Avoid `invalid reference to positional arguments 7 and 7 (there is 1 argument)`
309 // for `println!("{7:7$}", 1);`
312 let (arg_list, mut sp) = if refs.len() == 1 {
313 let spans: Vec<_> = spans.into_iter().filter_map(|sp| sp.map(|sp| *sp)).collect();
315 format!("argument {}", refs[0]),
316 if spans.is_empty() {
317 MultiSpan::from_span(self.fmtsp)
319 MultiSpan::from_spans(spans)
323 let pos = MultiSpan::from_spans(spans.into_iter().map(|s| *s.unwrap()).collect());
324 let reg = refs.pop().unwrap();
327 "arguments {head} and {tail}",
328 head = refs.join(", "),
334 if !self.is_literal {
335 sp = MultiSpan::from_span(self.fmtsp);
338 e = self.ecx.mut_span_err(sp,
339 &format!("invalid reference to positional {} ({})",
341 self.describe_num_args()));
342 zero_based_note = true;
345 for fmt in &self.arg_with_formatting {
346 if let Some(span) = fmt.precision_span {
347 let span = self.fmtsp.from_inner(span);
348 match fmt.precision {
349 parse::CountIsParam(pos) if pos > self.args.len() => {
350 e.span_label(span, &format!(
351 "this precision flag expects an `usize` argument at position {}, \
354 self.describe_num_args(),
356 zero_based_note = true;
358 parse::CountIsParam(pos) => {
359 let count = self.pieces.len() + self.arg_with_formatting
361 .filter(|fmt| fmt.precision_span.is_some())
363 e.span_label(span, &format!(
364 "this precision flag adds an extra required argument at position {}, \
365 which is why there {} expected",
368 "is 1 argument".to_string()
370 format!("are {} arguments", count)
375 "this parameter corresponds to the precision flag",
377 zero_based_note = true;
382 if let Some(span) = fmt.width_span {
383 let span = self.fmtsp.from_inner(span);
385 parse::CountIsParam(pos) if pos > self.args.len() => {
386 e.span_label(span, &format!(
387 "this width flag expects an `usize` argument at position {}, \
390 self.describe_num_args(),
392 zero_based_note = true;
399 e.note("positional arguments are zero-based");
401 if !self.arg_with_formatting.is_empty() {
402 e.note("for information about formatting flags, visit \
403 https://doc.rust-lang.org/std/fmt/index.html");
409 /// Actually verifies and tracks a given format placeholder
410 /// (a.k.a. argument).
411 fn verify_arg_type(&mut self, arg: Position, ty: ArgumentType) {
414 if self.args.len() <= arg {
415 self.invalid_refs.push((arg, self.curpiece));
420 // record every (position, type) combination only once
421 let ref mut seen_ty = self.arg_unique_types[arg];
422 let i = seen_ty.iter().position(|x| *x == ty).unwrap_or_else(|| {
423 let i = seen_ty.len();
427 self.arg_types[arg].push(i);
430 if let Entry::Vacant(e) = self.count_positions.entry(arg) {
431 let i = self.count_positions_count;
433 self.count_args.push(Exact(arg));
434 self.count_positions_count += 1;
441 match self.names.get(&name) {
443 // Treat as positional arg.
444 self.verify_arg_type(Exact(idx), ty)
447 let msg = format!("there is no argument named `{}`", name);
448 let sp = if self.is_literal {
449 *self.arg_spans.get(self.curpiece).unwrap_or(&self.fmtsp)
453 let mut err = self.ecx.struct_span_err(sp, &msg[..]);
461 /// Builds the mapping between format placeholders and argument objects.
462 fn build_index_map(&mut self) {
463 // NOTE: Keep the ordering the same as `into_expr`'s expansion would do!
464 let args_len = self.args.len();
465 self.arg_index_map.reserve(args_len);
467 let mut sofar = 0usize;
470 for i in 0..args_len {
471 let ref arg_types = self.arg_types[i];
472 let arg_offsets = arg_types.iter().map(|offset| sofar + *offset).collect::<Vec<_>>();
473 self.arg_index_map.push(arg_offsets);
474 sofar += self.arg_unique_types[i].len();
477 // Record starting index for counts, which appear just after arguments
478 self.count_args_index_offset = sofar;
481 fn rtpath(ecx: &ExtCtxt<'_>, s: &str) -> Vec<ast::Ident> {
482 ecx.std_path(&[sym::fmt, sym::rt, sym::v1, Symbol::intern(s)])
485 fn build_count(&self, c: parse::Count) -> P<ast::Expr> {
487 let count = |c, arg| {
488 let mut path = Context::rtpath(self.ecx, "Count");
489 path.push(self.ecx.ident_of(c, sp));
491 Some(arg) => self.ecx.expr_call_global(sp, path, vec![arg]),
492 None => self.ecx.expr_path(self.ecx.path_global(sp, path)),
496 parse::CountIs(i) => count("Is", Some(self.ecx.expr_usize(sp, i))),
497 parse::CountIsParam(i) => {
498 // This needs mapping too, as `i` is referring to a macro
499 // argument. If `i` is not found in `count_positions` then
500 // the error had already been emitted elsewhere.
501 let i = self.count_positions.get(&i).cloned().unwrap_or(0)
502 + self.count_args_index_offset;
503 count("Param", Some(self.ecx.expr_usize(sp, i)))
505 parse::CountImplied => count("Implied", None),
506 // should never be the case, names are already resolved
507 parse::CountIsName(_) => panic!("should never happen"),
511 /// Build a literal expression from the accumulated string literals
512 fn build_literal_string(&mut self) -> P<ast::Expr> {
514 let s = Symbol::intern(&self.literal);
515 self.literal.clear();
516 self.ecx.expr_str(sp, s)
519 /// Builds a static `rt::Argument` from a `parse::Piece` or append
520 /// to the `literal` string.
523 piece: &parse::Piece<'a>,
524 arg_index_consumed: &mut Vec<usize>,
525 ) -> Option<P<ast::Expr>> {
528 parse::String(s) => {
529 self.literal.push_str(s);
532 parse::NextArgument(ref arg) => {
533 // Build the position
536 let mut path = Context::rtpath(self.ecx, "Position");
537 path.push(self.ecx.ident_of(c, sp));
540 let arg = self.ecx.expr_usize(sp, i);
541 self.ecx.expr_call_global(sp, path, vec![arg])
543 None => self.ecx.expr_path(self.ecx.path_global(sp, path)),
548 | parse::ArgumentImplicitlyIs(i) => {
549 // Map to index in final generated argument array
550 // in case of multiple types specified
551 let arg_idx = match arg_index_consumed.get_mut(i) {
552 None => 0, // error already emitted elsewhere
554 let ref idx_map = self.arg_index_map[i];
555 // unwrap_or branch: error already emitted elsewhere
556 let arg_idx = *idx_map.get(*offset).unwrap_or(&0);
561 pos("At", Some(arg_idx))
564 // should never be the case, because names are already
566 parse::ArgumentNamed(_) => panic!("should never happen"),
570 let simple_arg = parse::Argument {
572 // We don't have ArgumentNext any more, so we have to
573 // track the current argument ourselves.
578 format: parse::FormatSpec {
579 fill: arg.format.fill,
580 align: parse::AlignUnknown,
582 precision: parse::CountImplied,
583 precision_span: None,
584 width: parse::CountImplied,
590 let fill = arg.format.fill.unwrap_or(' ');
593 arg.position.index() == simple_arg.position.index();
595 if arg.format.precision_span.is_some() || arg.format.width_span.is_some() {
596 self.arg_with_formatting.push(arg.format);
598 if !pos_simple || arg.format != simple_arg.format || fill != ' ' {
599 self.all_pieces_simple = false;
603 let fill = self.ecx.expr_lit(sp, ast::LitKind::Char(fill));
605 let mut p = Context::rtpath(self.ecx, "Alignment");
606 p.push(self.ecx.ident_of(name, sp));
607 self.ecx.path_global(sp, p)
609 let align = match arg.format.align {
610 parse::AlignLeft => align("Left"),
611 parse::AlignRight => align("Right"),
612 parse::AlignCenter => align("Center"),
613 parse::AlignUnknown => align("Unknown"),
615 let align = self.ecx.expr_path(align);
616 let flags = self.ecx.expr_u32(sp, arg.format.flags);
617 let prec = self.build_count(arg.format.precision);
618 let width = self.build_count(arg.format.width);
619 let path = self.ecx.path_global(sp, Context::rtpath(self.ecx, "FormatSpec"));
620 let fmt = self.ecx.expr_struct(
624 self.ecx.field_imm(sp, self.ecx.ident_of("fill", sp), fill),
625 self.ecx.field_imm(sp, self.ecx.ident_of("align", sp), align),
626 self.ecx.field_imm(sp, self.ecx.ident_of("flags", sp), flags),
627 self.ecx.field_imm(sp, self.ecx.ident_of("precision", sp), prec),
628 self.ecx.field_imm(sp, self.ecx.ident_of("width", sp), width),
632 let path = self.ecx.path_global(sp, Context::rtpath(self.ecx, "Argument"));
633 Some(self.ecx.expr_struct(
637 self.ecx.field_imm(sp, self.ecx.ident_of("position", sp), pos),
638 self.ecx.field_imm(sp, self.ecx.ident_of("format", sp), fmt),
645 /// Actually builds the expression which the format_args! block will be
647 fn into_expr(self) -> P<ast::Expr> {
648 let mut locals = Vec::with_capacity(
649 (0..self.args.len()).map(|i| self.arg_unique_types[i].len()).sum()
651 let mut counts = Vec::with_capacity(self.count_args.len());
652 let mut pats = Vec::with_capacity(self.args.len());
653 let mut heads = Vec::with_capacity(self.args.len());
655 let names_pos: Vec<_> = (0..self.args.len())
656 .map(|i| self.ecx.ident_of(&format!("arg{}", i), self.macsp))
659 // First, build up the static array which will become our precompiled
661 let pieces = self.ecx.expr_vec_slice(self.fmtsp, self.str_pieces);
663 // Before consuming the expressions, we have to remember spans for
664 // count arguments as they are now generated separate from other
665 // arguments, hence have no access to the `P<ast::Expr>`'s.
666 let spans_pos: Vec<_> = self.args.iter().map(|e| e.span.clone()).collect();
668 // Right now there is a bug such that for the expression:
670 // the lifetime of `1` doesn't outlast the call to `bar`, so it's not
671 // valid for the call to `foo`. To work around this all arguments to the
672 // format! string are shoved into locals. Furthermore, we shove the address
673 // of each variable because we don't want to move out of the arguments
674 // passed to this function.
675 for (i, e) in self.args.into_iter().enumerate() {
676 let name = names_pos[i];
677 let span = self.ecx.with_def_site_ctxt(e.span);
678 pats.push(self.ecx.pat_ident(span, name));
679 for ref arg_ty in self.arg_unique_types[i].iter() {
680 locals.push(Context::format_arg(self.ecx, self.macsp, e.span, arg_ty, name));
682 heads.push(self.ecx.expr_addr_of(e.span, e));
684 for pos in self.count_args {
685 let index = match pos {
687 _ => panic!("should never happen"),
689 let name = names_pos[index];
690 let span = spans_pos[index];
691 counts.push(Context::format_arg(self.ecx, self.macsp, span, &Count, name));
694 // Now create a vector containing all the arguments
695 let args = locals.into_iter().chain(counts.into_iter());
697 let args_array = self.ecx.expr_vec(self.fmtsp, args.collect());
699 // Constructs an AST equivalent to:
701 // match (&arg0, &arg1) {
702 // (tmp0, tmp1) => args_array
711 // Because of #11585 the new temporary lifetime rule, the enclosing
712 // statements for these temporaries become the let's themselves.
713 // If one or more of them are RefCell's, RefCell borrow() will also
714 // end there; they don't last long enough for args_array to use them.
715 // The match expression solves the scope problem.
717 // Note, it may also very well be transformed to:
722 // ref tmp1 => args_array } } }
724 // But the nested match expression is proved to perform not as well
725 // as series of let's; the first approach does.
726 let pat = self.ecx.pat_tuple(self.fmtsp, pats);
727 let arm = self.ecx.arm(self.fmtsp, pat, args_array);
728 let head = self.ecx.expr(self.fmtsp, ast::ExprKind::Tup(heads));
729 let result = self.ecx.expr_match(self.fmtsp, head, vec![arm]);
731 let args_slice = self.ecx.expr_addr_of(self.fmtsp, result);
733 // Now create the fmt::Arguments struct with all our locals we created.
734 let (fn_name, fn_args) = if self.all_pieces_simple {
735 ("new_v1", vec![pieces, args_slice])
737 // Build up the static array which will store our precompiled
738 // nonstandard placeholders, if there are any.
739 let fmt = self.ecx.expr_vec_slice(self.macsp, self.pieces);
741 ("new_v1_formatted", vec![pieces, args_slice, fmt])
744 let path = self.ecx.std_path(&[sym::fmt, sym::Arguments, Symbol::intern(fn_name)]);
745 self.ecx.expr_call_global(self.macsp, path, fn_args)
755 sp = ecx.with_def_site_ctxt(sp);
756 let arg = ecx.expr_ident(sp, arg);
757 let trait_ = match *ty {
758 Placeholder(ref tyname) => {
770 let mut err = ecx.struct_span_err(
772 &format!("unknown format trait `{}`", *tyname),
774 err.note("the only appropriate formatting traits are:\n\
775 - ``, which uses the `Display` trait\n\
776 - `?`, which uses the `Debug` trait\n\
777 - `e`, which uses the `LowerExp` trait\n\
778 - `E`, which uses the `UpperExp` trait\n\
779 - `o`, which uses the `Octal` trait\n\
780 - `p`, which uses the `Pointer` trait\n\
781 - `b`, which uses the `Binary` trait\n\
782 - `x`, which uses the `LowerHex` trait\n\
783 - `X`, which uses the `UpperHex` trait");
785 return DummyResult::raw_expr(sp, true);
790 let path = ecx.std_path(&[sym::fmt, sym::ArgumentV1, sym::from_usize]);
791 return ecx.expr_call_global(macsp, path, vec![arg]);
795 let path = ecx.std_path(&[sym::fmt, Symbol::intern(trait_), sym::fmt]);
796 let format_fn = ecx.path_global(sp, path);
797 let path = ecx.std_path(&[sym::fmt, sym::ArgumentV1, sym::new]);
798 ecx.expr_call_global(macsp, path, vec![arg, ecx.expr_path(format_fn)])
802 fn expand_format_args_impl<'cx>(
803 ecx: &'cx mut ExtCtxt<'_>,
807 ) -> Box<dyn base::MacResult + 'cx> {
808 sp = ecx.with_def_site_ctxt(sp);
809 match parse_args(ecx, sp, tts) {
810 Ok((efmt, args, names)) => {
811 MacEager::expr(expand_preparsed_format_args(ecx, sp, efmt, args, names, nl))
820 pub fn expand_format_args<'cx>(
821 ecx: &'cx mut ExtCtxt<'_>,
824 ) -> Box<dyn base::MacResult + 'cx> {
825 expand_format_args_impl(ecx, sp, tts, false)
828 pub fn expand_format_args_nl<'cx>(
829 ecx: &'cx mut ExtCtxt<'_>,
832 ) -> Box<dyn base::MacResult + 'cx> {
833 expand_format_args_impl(ecx, sp, tts, true)
836 /// Take the various parts of `format_args!(efmt, args..., name=names...)`
837 /// and construct the appropriate formatting expression.
838 pub fn expand_preparsed_format_args(
839 ecx: &mut ExtCtxt<'_>,
842 args: Vec<P<ast::Expr>>,
843 names: FxHashMap<Symbol, usize>,
844 append_newline: bool,
846 // NOTE: this verbose way of initializing `Vec<Vec<ArgumentType>>` is because
847 // `ArgumentType` does not derive `Clone`.
848 let arg_types: Vec<_> = (0..args.len()).map(|_| Vec::new()).collect();
849 let arg_unique_types: Vec<_> = (0..args.len()).map(|_| Vec::new()).collect();
851 let mut macsp = ecx.call_site();
852 macsp = ecx.with_def_site_ctxt(macsp);
854 let msg = "format argument must be a string literal";
855 let fmt_sp = efmt.span;
856 let (fmt_str, fmt_style, fmt_span) = match expr_to_spanned_string(ecx, efmt, msg) {
857 Ok(mut fmt) if append_newline => {
858 fmt.0 = Symbol::intern(&format!("{}\n", fmt.0));
863 if let Some(mut err) = err {
864 let sugg_fmt = match args.len() {
865 0 => "{}".to_string(),
866 _ => format!("{}{{}}", "{} ".repeat(args.len())),
869 fmt_sp.shrink_to_lo(),
870 "you might be missing a string literal to format with",
871 format!("\"{}\", ", sugg_fmt),
872 Applicability::MaybeIncorrect,
876 return DummyResult::raw_expr(sp, true);
880 let (is_literal, fmt_snippet) = match ecx.source_map().span_to_snippet(fmt_sp) {
881 Ok(s) => (s.starts_with("\"") || s.starts_with("r#"), Some(s)),
885 let str_style = match fmt_style {
886 ast::StrStyle::Cooked => None,
887 ast::StrStyle::Raw(raw) => {
892 /// Finds the indices of all characters that have been processed and differ between the actual
893 /// written code (code snippet) and the `InternedString` that get's processed in the `Parser`
894 /// in order to properly synthethise the intra-string `Span`s for error diagnostics.
895 fn find_skips(snippet: &str, is_raw: bool) -> Vec<usize> {
896 let mut eat_ws = false;
897 let mut s = snippet.chars().enumerate().peekable();
898 let mut skips = vec![];
899 while let Some((pos, c)) = s.next() {
900 match (c, s.peek()) {
901 // skip whitespace and empty lines ending in '\\'
902 ('\\', Some((next_pos, '\n'))) if !is_raw => {
905 skips.push(*next_pos);
908 ('\\', Some((next_pos, '\n'))) |
909 ('\\', Some((next_pos, 'n'))) |
910 ('\\', Some((next_pos, 't'))) if eat_ws => {
912 skips.push(*next_pos);
917 ('\t', _) if eat_ws => {
920 ('\\', Some((next_pos, 'n'))) |
921 ('\\', Some((next_pos, 't'))) |
922 ('\\', Some((next_pos, '0'))) |
923 ('\\', Some((next_pos, '\\'))) |
924 ('\\', Some((next_pos, '\''))) |
925 ('\\', Some((next_pos, '\"'))) => {
926 skips.push(*next_pos);
929 ('\\', Some((_, 'x'))) if !is_raw => {
930 for _ in 0..3 { // consume `\xAB` literal
931 if let Some((pos, _)) = s.next() {
938 ('\\', Some((_, 'u'))) if !is_raw => {
939 if let Some((pos, _)) = s.next() {
942 if let Some((next_pos, next_c)) = s.next() {
944 skips.push(next_pos);
945 let mut i = 0; // consume up to 6 hexanumeric chars + closing `}`
946 while let (Some((next_pos, c)), true) = (s.next(), i < 7) {
948 skips.push(next_pos);
950 skips.push(next_pos);
957 } else if next_c.is_digit(16) {
958 skips.push(next_pos);
959 // We suggest adding `{` and `}` when appropriate, accept it here as if
961 let mut i = 0; // consume up to 6 hexanumeric chars
962 while let (Some((next_pos, c)), _) = (s.next(), i < 6) {
964 skips.push(next_pos);
973 _ if eat_ws => { // `take_while(|c| c.is_whitespace())`
982 let skips = if let (true, Some(ref snippet)) = (is_literal, fmt_snippet.as_ref()) {
983 let r_start = str_style.map(|r| r + 1).unwrap_or(0);
984 let r_end = str_style.map(|r| r).unwrap_or(0);
985 let s = &snippet[r_start + 1..snippet.len() - r_end - 1];
986 find_skips(s, str_style.is_some())
991 let fmt_str = &*fmt_str.as_str(); // for the suggestions below
992 let mut parser = parse::Parser::new(fmt_str, str_style, skips, append_newline);
994 let mut unverified_pieces = Vec::new();
995 while let Some(piece) = parser.next() {
996 if !parser.errors.is_empty() {
999 unverified_pieces.push(piece);
1003 if !parser.errors.is_empty() {
1004 let err = parser.errors.remove(0);
1005 let sp = fmt_span.from_inner(err.span);
1006 let mut e = ecx.struct_span_err(sp, &format!("invalid format string: {}",
1008 e.span_label(sp, err.label + " in format string");
1009 if let Some(note) = err.note {
1012 if let Some((label, span)) = err.secondary_label {
1013 let sp = fmt_span.from_inner(span);
1014 e.span_label(sp, label);
1017 return DummyResult::raw_expr(sp, true);
1020 let arg_spans = parser.arg_places.iter()
1021 .map(|span| fmt_span.from_inner(*span))
1024 let named_pos: FxHashSet<usize> = names.values().cloned().collect();
1026 let mut cx = Context {
1034 arg_index_map: Vec::new(),
1035 count_args: Vec::new(),
1036 count_positions: FxHashMap::default(),
1037 count_positions_count: 0,
1038 count_args_index_offset: 0,
1039 literal: String::new(),
1040 pieces: Vec::with_capacity(unverified_pieces.len()),
1041 str_pieces: Vec::with_capacity(unverified_pieces.len()),
1042 all_pieces_simple: true,
1045 invalid_refs: Vec::new(),
1047 arg_with_formatting: Vec::new(),
1051 // This needs to happen *after* the Parser has consumed all pieces to create all the spans
1052 let pieces = unverified_pieces.into_iter().map(|mut piece| {
1053 cx.verify_piece(&piece);
1054 cx.resolve_name_inplace(&mut piece);
1056 }).collect::<Vec<_>>();
1058 let numbered_position_args = pieces.iter().any(|arg: &parse::Piece<'_>| {
1060 parse::String(_) => false,
1061 parse::NextArgument(arg) => {
1062 match arg.position {
1063 parse::Position::ArgumentIs(_) => true,
1070 cx.build_index_map();
1072 let mut arg_index_consumed = vec![0usize; cx.arg_index_map.len()];
1074 for piece in pieces {
1075 if let Some(piece) = cx.build_piece(&piece, &mut arg_index_consumed) {
1076 let s = cx.build_literal_string();
1077 cx.str_pieces.push(s);
1078 cx.pieces.push(piece);
1082 if !cx.literal.is_empty() {
1083 let s = cx.build_literal_string();
1084 cx.str_pieces.push(s);
1087 if cx.invalid_refs.len() >= 1 {
1088 cx.report_invalid_references(numbered_position_args);
1091 // Make sure that all arguments were used and all arguments have types.
1092 let errs = cx.arg_types
1095 .filter(|(i, ty)| ty.is_empty() && !cx.count_positions.contains_key(&i))
1097 let msg = if named_pos.contains(&i) {
1099 "named argument never used"
1101 // positional argument
1102 "argument never used"
1104 (cx.args[i].span, msg)
1106 .collect::<Vec<_>>();
1108 let errs_len = errs.len();
1109 if !errs.is_empty() {
1110 let args_used = cx.arg_types.len() - errs_len;
1111 let args_unused = errs_len;
1115 let (sp, msg) = errs.into_iter().next().unwrap();
1116 let mut diag = cx.ecx.struct_span_err(sp, msg);
1117 diag.span_label(sp, msg);
1120 let mut diag = cx.ecx.struct_span_err(
1121 errs.iter().map(|&(sp, _)| sp).collect::<Vec<Span>>(),
1122 "multiple unused formatting arguments",
1124 diag.span_label(cx.fmtsp, "multiple missing formatting specifiers");
1125 for (sp, msg) in errs {
1126 diag.span_label(sp, msg);
1132 // Used to ensure we only report translations for *one* kind of foreign format.
1133 let mut found_foreign = false;
1134 // Decide if we want to look for foreign formatting directives.
1135 if args_used < args_unused {
1136 use super::format_foreign as foreign;
1138 // The set of foreign substitutions we've explained. This prevents spamming the user
1139 // with `%d should be written as {}` over and over again.
1140 let mut explained = FxHashSet::default();
1142 macro_rules! check_foreign {
1144 let mut show_doc_note = false;
1146 let mut suggestions = vec![];
1147 // account for `"` and account for raw strings `r#`
1148 let padding = str_style.map(|i| i + 2).unwrap_or(1);
1149 for sub in foreign::$kind::iter_subs(fmt_str, padding) {
1150 let trn = match sub.translate() {
1153 // If it has no translation, don't call it out specifically.
1157 let pos = sub.position();
1158 let sub = String::from(sub.as_str());
1159 if explained.contains(&sub) {
1162 explained.insert(sub.clone());
1165 found_foreign = true;
1166 show_doc_note = true;
1169 if let Some(inner_sp) = pos {
1170 let sp = fmt_sp.from_inner(inner_sp);
1171 suggestions.push((sp, trn));
1173 diag.help(&format!("`{}` should be written as `{}`", sub, trn));
1180 " formatting not supported; see the documentation for `std::fmt`",
1183 if suggestions.len() > 0 {
1184 diag.multipart_suggestion(
1185 "format specifiers use curly braces",
1187 Applicability::MachineApplicable,
1193 check_foreign!(printf);
1195 check_foreign!(shell);
1198 if !found_foreign && errs_len == 1 {
1199 diag.span_label(cx.fmtsp, "formatting specifier missing");