4 use fmt_macros as parse;
6 use errors::DiagnosticBuilder;
7 use errors::Applicability;
11 use syntax_expand::base::{self, *};
12 use syntax::parse::token;
14 use syntax::symbol::{Symbol, sym};
15 use syntax::tokenstream::TokenStream;
16 use syntax_pos::{MultiSpan, Span};
18 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
20 use std::collections::hash_map::Entry;
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_note(args[*prev].span, "previously here")
180 // Resolve names into slots early.
181 // Since all the positional args are already seen at this point
182 // if the input is valid, we can simply append to the positional
183 // args. And remember the names.
184 let slot = args.len();
185 names.insert(name, slot);
188 let e = p.parse_expr()?;
190 let mut err = ecx.struct_span_err(
192 "positional arguments cannot follow named arguments",
194 err.span_label(e.span, "positional arguments must be before named arguments");
195 for (_, pos) in &names {
196 err.span_label(args[*pos].span, "named argument");
203 Ok((fmtstr, args, names))
206 impl<'a, 'b> Context<'a, 'b> {
207 fn resolve_name_inplace(&self, p: &mut parse::Piece<'_>) {
208 // NOTE: the `unwrap_or` branch is needed in case of invalid format
209 // arguments, e.g., `format_args!("{foo}")`.
210 let lookup = |s: Symbol| *self.names.get(&s).unwrap_or(&0);
213 parse::String(_) => {}
214 parse::NextArgument(ref mut arg) => {
215 if let parse::ArgumentNamed(s) = arg.position {
216 arg.position = parse::ArgumentIs(lookup(s));
218 if let parse::CountIsName(s) = arg.format.width {
219 arg.format.width = parse::CountIsParam(lookup(s));
221 if let parse::CountIsName(s) = arg.format.precision {
222 arg.format.precision = parse::CountIsParam(lookup(s));
228 /// Verifies one piece of a parse string, and remembers it if valid.
229 /// All errors are not emitted as fatal so we can continue giving errors
230 /// about this and possibly other format strings.
231 fn verify_piece(&mut self, p: &parse::Piece<'_>) {
233 parse::String(..) => {}
234 parse::NextArgument(ref arg) => {
235 // width/precision first, if they have implicit positional
236 // parameters it makes more sense to consume them first.
237 self.verify_count(arg.format.width);
238 self.verify_count(arg.format.precision);
240 // argument second, if it's an implicit positional parameter
241 // it's written second, so it should come after width/precision.
242 let pos = match arg.position {
243 parse::ArgumentIs(i) | parse::ArgumentImplicitlyIs(i) => Exact(i),
244 parse::ArgumentNamed(s) => Named(s),
247 let ty = Placeholder(arg.format.ty.to_string());
248 self.verify_arg_type(pos, ty);
254 fn verify_count(&mut self, c: parse::Count) {
256 parse::CountImplied |
257 parse::CountIs(..) => {}
258 parse::CountIsParam(i) => {
259 self.verify_arg_type(Exact(i), Count);
261 parse::CountIsName(s) => {
262 self.verify_arg_type(Named(s), Count);
267 fn describe_num_args(&self) -> Cow<'_, str> {
268 match self.args.len() {
269 0 => "no arguments were given".into(),
270 1 => "there is 1 argument".into(),
271 x => format!("there are {} arguments", x).into(),
275 /// Handle invalid references to positional arguments. Output different
276 /// errors for the case where all arguments are positional and for when
277 /// there are named arguments or numbered positional arguments in the
279 fn report_invalid_references(&self, numbered_position_args: bool) {
281 let sp = if self.is_literal { // Point at the formatting arguments.
282 MultiSpan::from_spans(self.arg_spans.clone())
284 MultiSpan::from_span(self.fmtsp)
289 .map(|(r, pos)| (r.to_string(), self.arg_spans.get(*pos)));
291 let mut zero_based_note = false;
293 let count = self.pieces.len() + self.arg_with_formatting
295 .filter(|fmt| fmt.precision_span.is_some())
297 if self.names.is_empty() && !numbered_position_args && count != self.args.len() {
298 e = self.ecx.struct_span_err(
301 "{} positional argument{} in format string, but {}",
304 self.describe_num_args(),
307 for arg in &self.args { // Point at the arguments that will be formatted.
308 e.span_label(arg.span, "");
311 let (mut refs, spans): (Vec<_>, Vec<_>) = refs.unzip();
312 // Avoid `invalid reference to positional arguments 7 and 7 (there is 1 argument)`
313 // for `println!("{7:7$}", 1);`
316 let (arg_list, mut sp) = if refs.len() == 1 {
317 let spans: Vec<_> = spans.into_iter().filter_map(|sp| sp.map(|sp| *sp)).collect();
319 format!("argument {}", refs[0]),
320 if spans.is_empty() {
321 MultiSpan::from_span(self.fmtsp)
323 MultiSpan::from_spans(spans)
327 let pos = MultiSpan::from_spans(spans.into_iter().map(|s| *s.unwrap()).collect());
328 let reg = refs.pop().unwrap();
331 "arguments {head} and {tail}",
332 head = refs.join(", "),
338 if !self.is_literal {
339 sp = MultiSpan::from_span(self.fmtsp);
342 e = self.ecx.struct_span_err(sp,
343 &format!("invalid reference to positional {} ({})",
345 self.describe_num_args()));
346 zero_based_note = true;
349 for fmt in &self.arg_with_formatting {
350 if let Some(span) = fmt.precision_span {
351 let span = self.fmtsp.from_inner(span);
352 match fmt.precision {
353 parse::CountIsParam(pos) if pos > self.args.len() => {
354 e.span_label(span, &format!(
355 "this precision flag expects an `usize` argument at position {}, \
358 self.describe_num_args(),
360 zero_based_note = true;
362 parse::CountIsParam(pos) => {
363 let count = self.pieces.len() + self.arg_with_formatting
365 .filter(|fmt| fmt.precision_span.is_some())
367 e.span_label(span, &format!(
368 "this precision flag adds an extra required argument at position {}, \
369 which is why there {} expected",
372 "is 1 argument".to_string()
374 format!("are {} arguments", count)
377 if let Some(arg) = self.args.get(pos) {
380 "this parameter corresponds to the precision flag",
383 zero_based_note = true;
388 if let Some(span) = fmt.width_span {
389 let span = self.fmtsp.from_inner(span);
391 parse::CountIsParam(pos) if pos > self.args.len() => {
392 e.span_label(span, &format!(
393 "this width flag expects an `usize` argument at position {}, \
396 self.describe_num_args(),
398 zero_based_note = true;
405 e.note("positional arguments are zero-based");
407 if !self.arg_with_formatting.is_empty() {
408 e.note("for information about formatting flags, visit \
409 https://doc.rust-lang.org/std/fmt/index.html");
415 /// Actually verifies and tracks a given format placeholder
416 /// (a.k.a. argument).
417 fn verify_arg_type(&mut self, arg: Position, ty: ArgumentType) {
420 if self.args.len() <= arg {
421 self.invalid_refs.push((arg, self.curpiece));
426 // record every (position, type) combination only once
427 let ref mut seen_ty = self.arg_unique_types[arg];
428 let i = seen_ty.iter().position(|x| *x == ty).unwrap_or_else(|| {
429 let i = seen_ty.len();
433 self.arg_types[arg].push(i);
436 if let Entry::Vacant(e) = self.count_positions.entry(arg) {
437 let i = self.count_positions_count;
439 self.count_args.push(Exact(arg));
440 self.count_positions_count += 1;
447 match self.names.get(&name) {
449 // Treat as positional arg.
450 self.verify_arg_type(Exact(idx), ty)
453 let msg = format!("there is no argument named `{}`", name);
454 let sp = if self.is_literal {
455 *self.arg_spans.get(self.curpiece).unwrap_or(&self.fmtsp)
459 let mut err = self.ecx.struct_span_err(sp, &msg[..]);
467 /// Builds the mapping between format placeholders and argument objects.
468 fn build_index_map(&mut self) {
469 // NOTE: Keep the ordering the same as `into_expr`'s expansion would do!
470 let args_len = self.args.len();
471 self.arg_index_map.reserve(args_len);
473 let mut sofar = 0usize;
476 for i in 0..args_len {
477 let ref arg_types = self.arg_types[i];
478 let arg_offsets = arg_types.iter().map(|offset| sofar + *offset).collect::<Vec<_>>();
479 self.arg_index_map.push(arg_offsets);
480 sofar += self.arg_unique_types[i].len();
483 // Record starting index for counts, which appear just after arguments
484 self.count_args_index_offset = sofar;
487 fn rtpath(ecx: &ExtCtxt<'_>, s: &str) -> Vec<ast::Ident> {
488 ecx.std_path(&[sym::fmt, sym::rt, sym::v1, Symbol::intern(s)])
491 fn build_count(&self, c: parse::Count) -> P<ast::Expr> {
493 let count = |c, arg| {
494 let mut path = Context::rtpath(self.ecx, "Count");
495 path.push(self.ecx.ident_of(c, sp));
497 Some(arg) => self.ecx.expr_call_global(sp, path, vec![arg]),
498 None => self.ecx.expr_path(self.ecx.path_global(sp, path)),
502 parse::CountIs(i) => count("Is", Some(self.ecx.expr_usize(sp, i))),
503 parse::CountIsParam(i) => {
504 // This needs mapping too, as `i` is referring to a macro
505 // argument. If `i` is not found in `count_positions` then
506 // the error had already been emitted elsewhere.
507 let i = self.count_positions.get(&i).cloned().unwrap_or(0)
508 + self.count_args_index_offset;
509 count("Param", Some(self.ecx.expr_usize(sp, i)))
511 parse::CountImplied => count("Implied", None),
512 // should never be the case, names are already resolved
513 parse::CountIsName(_) => panic!("should never happen"),
517 /// Build a literal expression from the accumulated string literals
518 fn build_literal_string(&mut self) -> P<ast::Expr> {
520 let s = Symbol::intern(&self.literal);
521 self.literal.clear();
522 self.ecx.expr_str(sp, s)
525 /// Builds a static `rt::Argument` from a `parse::Piece` or append
526 /// to the `literal` string.
529 piece: &parse::Piece<'a>,
530 arg_index_consumed: &mut Vec<usize>,
531 ) -> Option<P<ast::Expr>> {
534 parse::String(s) => {
535 self.literal.push_str(s);
538 parse::NextArgument(ref arg) => {
539 // Build the position
542 let mut path = Context::rtpath(self.ecx, "Position");
543 path.push(self.ecx.ident_of(c, sp));
546 let arg = self.ecx.expr_usize(sp, i);
547 self.ecx.expr_call_global(sp, path, vec![arg])
549 None => self.ecx.expr_path(self.ecx.path_global(sp, path)),
554 | parse::ArgumentImplicitlyIs(i) => {
555 // Map to index in final generated argument array
556 // in case of multiple types specified
557 let arg_idx = match arg_index_consumed.get_mut(i) {
558 None => 0, // error already emitted elsewhere
560 let ref idx_map = self.arg_index_map[i];
561 // unwrap_or branch: error already emitted elsewhere
562 let arg_idx = *idx_map.get(*offset).unwrap_or(&0);
567 pos("At", Some(arg_idx))
570 // should never be the case, because names are already
572 parse::ArgumentNamed(_) => panic!("should never happen"),
576 let simple_arg = parse::Argument {
578 // We don't have ArgumentNext any more, so we have to
579 // track the current argument ourselves.
584 format: parse::FormatSpec {
585 fill: arg.format.fill,
586 align: parse::AlignUnknown,
588 precision: parse::CountImplied,
589 precision_span: None,
590 width: parse::CountImplied,
596 let fill = arg.format.fill.unwrap_or(' ');
599 arg.position.index() == simple_arg.position.index();
601 if arg.format.precision_span.is_some() || arg.format.width_span.is_some() {
602 self.arg_with_formatting.push(arg.format);
604 if !pos_simple || arg.format != simple_arg.format || fill != ' ' {
605 self.all_pieces_simple = false;
609 let fill = self.ecx.expr_lit(sp, ast::LitKind::Char(fill));
611 let mut p = Context::rtpath(self.ecx, "Alignment");
612 p.push(self.ecx.ident_of(name, sp));
613 self.ecx.path_global(sp, p)
615 let align = match arg.format.align {
616 parse::AlignLeft => align("Left"),
617 parse::AlignRight => align("Right"),
618 parse::AlignCenter => align("Center"),
619 parse::AlignUnknown => align("Unknown"),
621 let align = self.ecx.expr_path(align);
622 let flags = self.ecx.expr_u32(sp, arg.format.flags);
623 let prec = self.build_count(arg.format.precision);
624 let width = self.build_count(arg.format.width);
625 let path = self.ecx.path_global(sp, Context::rtpath(self.ecx, "FormatSpec"));
626 let fmt = self.ecx.expr_struct(
630 self.ecx.field_imm(sp, self.ecx.ident_of("fill", sp), fill),
631 self.ecx.field_imm(sp, self.ecx.ident_of("align", sp), align),
632 self.ecx.field_imm(sp, self.ecx.ident_of("flags", sp), flags),
633 self.ecx.field_imm(sp, self.ecx.ident_of("precision", sp), prec),
634 self.ecx.field_imm(sp, self.ecx.ident_of("width", sp), width),
638 let path = self.ecx.path_global(sp, Context::rtpath(self.ecx, "Argument"));
639 Some(self.ecx.expr_struct(
643 self.ecx.field_imm(sp, self.ecx.ident_of("position", sp), pos),
644 self.ecx.field_imm(sp, self.ecx.ident_of("format", sp), fmt),
651 /// Actually builds the expression which the format_args! block will be
653 fn into_expr(self) -> P<ast::Expr> {
654 let mut locals = Vec::with_capacity(
655 (0..self.args.len()).map(|i| self.arg_unique_types[i].len()).sum()
657 let mut counts = Vec::with_capacity(self.count_args.len());
658 let mut pats = Vec::with_capacity(self.args.len());
659 let mut heads = Vec::with_capacity(self.args.len());
661 let names_pos: Vec<_> = (0..self.args.len())
662 .map(|i| self.ecx.ident_of(&format!("arg{}", i), self.macsp))
665 // First, build up the static array which will become our precompiled
667 let pieces = self.ecx.expr_vec_slice(self.fmtsp, self.str_pieces);
669 // Before consuming the expressions, we have to remember spans for
670 // count arguments as they are now generated separate from other
671 // arguments, hence have no access to the `P<ast::Expr>`'s.
672 let spans_pos: Vec<_> = self.args.iter().map(|e| e.span.clone()).collect();
674 // Right now there is a bug such that for the expression:
676 // the lifetime of `1` doesn't outlast the call to `bar`, so it's not
677 // valid for the call to `foo`. To work around this all arguments to the
678 // format! string are shoved into locals. Furthermore, we shove the address
679 // of each variable because we don't want to move out of the arguments
680 // passed to this function.
681 for (i, e) in self.args.into_iter().enumerate() {
682 let name = names_pos[i];
683 let span = self.ecx.with_def_site_ctxt(e.span);
684 pats.push(self.ecx.pat_ident(span, name));
685 for ref arg_ty in self.arg_unique_types[i].iter() {
686 locals.push(Context::format_arg(self.ecx, self.macsp, e.span, arg_ty, name));
688 heads.push(self.ecx.expr_addr_of(e.span, e));
690 for pos in self.count_args {
691 let index = match pos {
693 _ => panic!("should never happen"),
695 let name = names_pos[index];
696 let span = spans_pos[index];
697 counts.push(Context::format_arg(self.ecx, self.macsp, span, &Count, name));
700 // Now create a vector containing all the arguments
701 let args = locals.into_iter().chain(counts.into_iter());
703 let args_array = self.ecx.expr_vec(self.macsp, args.collect());
705 // Constructs an AST equivalent to:
707 // match (&arg0, &arg1) {
708 // (tmp0, tmp1) => args_array
717 // Because of #11585 the new temporary lifetime rule, the enclosing
718 // statements for these temporaries become the let's themselves.
719 // If one or more of them are RefCell's, RefCell borrow() will also
720 // end there; they don't last long enough for args_array to use them.
721 // The match expression solves the scope problem.
723 // Note, it may also very well be transformed to:
728 // ref tmp1 => args_array } } }
730 // But the nested match expression is proved to perform not as well
731 // as series of let's; the first approach does.
732 let pat = self.ecx.pat_tuple(self.macsp, pats);
733 let arm = self.ecx.arm(self.macsp, pat, args_array);
734 let head = self.ecx.expr(self.macsp, ast::ExprKind::Tup(heads));
735 let result = self.ecx.expr_match(self.macsp, head, vec![arm]);
737 let args_slice = self.ecx.expr_addr_of(self.macsp, result);
739 // Now create the fmt::Arguments struct with all our locals we created.
740 let (fn_name, fn_args) = if self.all_pieces_simple {
741 ("new_v1", vec![pieces, args_slice])
743 // Build up the static array which will store our precompiled
744 // nonstandard placeholders, if there are any.
745 let fmt = self.ecx.expr_vec_slice(self.macsp, self.pieces);
747 ("new_v1_formatted", vec![pieces, args_slice, fmt])
750 let path = self.ecx.std_path(&[sym::fmt, sym::Arguments, Symbol::intern(fn_name)]);
751 self.ecx.expr_call_global(self.macsp, path, fn_args)
761 sp = ecx.with_def_site_ctxt(sp);
762 let arg = ecx.expr_ident(sp, arg);
763 let trait_ = match *ty {
764 Placeholder(ref tyname) => {
776 let mut err = ecx.struct_span_err(
778 &format!("unknown format trait `{}`", *tyname),
780 err.note("the only appropriate formatting traits are:\n\
781 - ``, which uses the `Display` trait\n\
782 - `?`, which uses the `Debug` trait\n\
783 - `e`, which uses the `LowerExp` trait\n\
784 - `E`, which uses the `UpperExp` trait\n\
785 - `o`, which uses the `Octal` trait\n\
786 - `p`, which uses the `Pointer` trait\n\
787 - `b`, which uses the `Binary` trait\n\
788 - `x`, which uses the `LowerHex` trait\n\
789 - `X`, which uses the `UpperHex` trait");
791 return DummyResult::raw_expr(sp, true);
796 let path = ecx.std_path(&[sym::fmt, sym::ArgumentV1, sym::from_usize]);
797 return ecx.expr_call_global(macsp, path, vec![arg]);
801 let path = ecx.std_path(&[sym::fmt, Symbol::intern(trait_), sym::fmt]);
802 let format_fn = ecx.path_global(sp, path);
803 let path = ecx.std_path(&[sym::fmt, sym::ArgumentV1, sym::new]);
804 ecx.expr_call_global(macsp, path, vec![arg, ecx.expr_path(format_fn)])
808 fn expand_format_args_impl<'cx>(
809 ecx: &'cx mut ExtCtxt<'_>,
813 ) -> Box<dyn base::MacResult + 'cx> {
814 sp = ecx.with_def_site_ctxt(sp);
815 match parse_args(ecx, sp, tts) {
816 Ok((efmt, args, names)) => {
817 MacEager::expr(expand_preparsed_format_args(ecx, sp, efmt, args, names, nl))
826 pub fn expand_format_args<'cx>(
827 ecx: &'cx mut ExtCtxt<'_>,
830 ) -> Box<dyn base::MacResult + 'cx> {
831 expand_format_args_impl(ecx, sp, tts, false)
834 pub fn expand_format_args_nl<'cx>(
835 ecx: &'cx mut ExtCtxt<'_>,
838 ) -> Box<dyn base::MacResult + 'cx> {
839 expand_format_args_impl(ecx, sp, tts, true)
842 /// Take the various parts of `format_args!(efmt, args..., name=names...)`
843 /// and construct the appropriate formatting expression.
844 pub fn expand_preparsed_format_args(
845 ecx: &mut ExtCtxt<'_>,
848 args: Vec<P<ast::Expr>>,
849 names: FxHashMap<Symbol, usize>,
850 append_newline: bool,
852 // NOTE: this verbose way of initializing `Vec<Vec<ArgumentType>>` is because
853 // `ArgumentType` does not derive `Clone`.
854 let arg_types: Vec<_> = (0..args.len()).map(|_| Vec::new()).collect();
855 let arg_unique_types: Vec<_> = (0..args.len()).map(|_| Vec::new()).collect();
857 let mut macsp = ecx.call_site();
858 macsp = ecx.with_def_site_ctxt(macsp);
860 let msg = "format argument must be a string literal";
861 let fmt_sp = efmt.span;
862 let (fmt_str, fmt_style, fmt_span) = match expr_to_spanned_string(ecx, efmt, msg) {
863 Ok(mut fmt) if append_newline => {
864 fmt.0 = Symbol::intern(&format!("{}\n", fmt.0));
869 if let Some(mut err) = err {
870 let sugg_fmt = match args.len() {
871 0 => "{}".to_string(),
872 _ => format!("{}{{}}", "{} ".repeat(args.len())),
875 fmt_sp.shrink_to_lo(),
876 "you might be missing a string literal to format with",
877 format!("\"{}\", ", sugg_fmt),
878 Applicability::MaybeIncorrect,
882 return DummyResult::raw_expr(sp, true);
886 let (is_literal, fmt_snippet) = match ecx.source_map().span_to_snippet(fmt_sp) {
887 Ok(s) => (s.starts_with("\"") || s.starts_with("r#"), Some(s)),
891 let str_style = match fmt_style {
892 ast::StrStyle::Cooked => None,
893 ast::StrStyle::Raw(raw) => {
898 /// Finds the indices of all characters that have been processed and differ between the actual
899 /// written code (code snippet) and the `InternedString` that get's processed in the `Parser`
900 /// in order to properly synthethise the intra-string `Span`s for error diagnostics.
901 fn find_skips(snippet: &str, is_raw: bool) -> Vec<usize> {
902 let mut eat_ws = false;
903 let mut s = snippet.chars().enumerate().peekable();
904 let mut skips = vec![];
905 while let Some((pos, c)) = s.next() {
906 match (c, s.peek()) {
907 // skip whitespace and empty lines ending in '\\'
908 ('\\', Some((next_pos, '\n'))) if !is_raw => {
911 skips.push(*next_pos);
914 ('\\', Some((next_pos, '\n'))) |
915 ('\\', Some((next_pos, 'n'))) |
916 ('\\', Some((next_pos, 't'))) if eat_ws => {
918 skips.push(*next_pos);
923 ('\t', _) if eat_ws => {
926 ('\\', Some((next_pos, 'n'))) |
927 ('\\', Some((next_pos, 't'))) |
928 ('\\', Some((next_pos, '0'))) |
929 ('\\', Some((next_pos, '\\'))) |
930 ('\\', Some((next_pos, '\''))) |
931 ('\\', Some((next_pos, '\"'))) => {
932 skips.push(*next_pos);
935 ('\\', Some((_, 'x'))) if !is_raw => {
936 for _ in 0..3 { // consume `\xAB` literal
937 if let Some((pos, _)) = s.next() {
944 ('\\', Some((_, 'u'))) if !is_raw => {
945 if let Some((pos, _)) = s.next() {
948 if let Some((next_pos, next_c)) = s.next() {
950 skips.push(next_pos);
951 let mut i = 0; // consume up to 6 hexanumeric chars + closing `}`
952 while let (Some((next_pos, c)), true) = (s.next(), i < 7) {
954 skips.push(next_pos);
956 skips.push(next_pos);
963 } else if next_c.is_digit(16) {
964 skips.push(next_pos);
965 // We suggest adding `{` and `}` when appropriate, accept it here as if
967 let mut i = 0; // consume up to 6 hexanumeric chars
968 while let (Some((next_pos, c)), _) = (s.next(), i < 6) {
970 skips.push(next_pos);
979 _ if eat_ws => { // `take_while(|c| c.is_whitespace())`
988 let skips = if let (true, Some(ref snippet)) = (is_literal, fmt_snippet.as_ref()) {
989 let r_start = str_style.map(|r| r + 1).unwrap_or(0);
990 let r_end = str_style.map(|r| r).unwrap_or(0);
991 let s = &snippet[r_start + 1..snippet.len() - r_end - 1];
992 find_skips(s, str_style.is_some())
997 let fmt_str = &fmt_str.as_str(); // for the suggestions below
998 let mut parser = parse::Parser::new(fmt_str, str_style, skips, append_newline);
1000 let mut unverified_pieces = Vec::new();
1001 while let Some(piece) = parser.next() {
1002 if !parser.errors.is_empty() {
1005 unverified_pieces.push(piece);
1009 if !parser.errors.is_empty() {
1010 let err = parser.errors.remove(0);
1011 let sp = fmt_span.from_inner(err.span);
1012 let mut e = ecx.struct_span_err(sp, &format!("invalid format string: {}",
1014 e.span_label(sp, err.label + " in format string");
1015 if let Some(note) = err.note {
1018 if let Some((label, span)) = err.secondary_label {
1019 let sp = fmt_span.from_inner(span);
1020 e.span_label(sp, label);
1023 return DummyResult::raw_expr(sp, true);
1026 let arg_spans = parser.arg_places.iter()
1027 .map(|span| fmt_span.from_inner(*span))
1030 let named_pos: FxHashSet<usize> = names.values().cloned().collect();
1032 let mut cx = Context {
1040 arg_index_map: Vec::new(),
1041 count_args: Vec::new(),
1042 count_positions: FxHashMap::default(),
1043 count_positions_count: 0,
1044 count_args_index_offset: 0,
1045 literal: String::new(),
1046 pieces: Vec::with_capacity(unverified_pieces.len()),
1047 str_pieces: Vec::with_capacity(unverified_pieces.len()),
1048 all_pieces_simple: true,
1051 invalid_refs: Vec::new(),
1053 arg_with_formatting: Vec::new(),
1057 // This needs to happen *after* the Parser has consumed all pieces to create all the spans
1058 let pieces = unverified_pieces.into_iter().map(|mut piece| {
1059 cx.verify_piece(&piece);
1060 cx.resolve_name_inplace(&mut piece);
1062 }).collect::<Vec<_>>();
1064 let numbered_position_args = pieces.iter().any(|arg: &parse::Piece<'_>| {
1066 parse::String(_) => false,
1067 parse::NextArgument(arg) => {
1068 match arg.position {
1069 parse::Position::ArgumentIs(_) => true,
1076 cx.build_index_map();
1078 let mut arg_index_consumed = vec![0usize; cx.arg_index_map.len()];
1080 for piece in pieces {
1081 if let Some(piece) = cx.build_piece(&piece, &mut arg_index_consumed) {
1082 let s = cx.build_literal_string();
1083 cx.str_pieces.push(s);
1084 cx.pieces.push(piece);
1088 if !cx.literal.is_empty() {
1089 let s = cx.build_literal_string();
1090 cx.str_pieces.push(s);
1093 if cx.invalid_refs.len() >= 1 {
1094 cx.report_invalid_references(numbered_position_args);
1097 // Make sure that all arguments were used and all arguments have types.
1098 let errs = cx.arg_types
1101 .filter(|(i, ty)| ty.is_empty() && !cx.count_positions.contains_key(&i))
1103 let msg = if named_pos.contains(&i) {
1105 "named argument never used"
1107 // positional argument
1108 "argument never used"
1110 (cx.args[i].span, msg)
1112 .collect::<Vec<_>>();
1114 let errs_len = errs.len();
1115 if !errs.is_empty() {
1116 let args_used = cx.arg_types.len() - errs_len;
1117 let args_unused = errs_len;
1121 let (sp, msg) = errs.into_iter().next().unwrap();
1122 let mut diag = cx.ecx.struct_span_err(sp, msg);
1123 diag.span_label(sp, msg);
1126 let mut diag = cx.ecx.struct_span_err(
1127 errs.iter().map(|&(sp, _)| sp).collect::<Vec<Span>>(),
1128 "multiple unused formatting arguments",
1130 diag.span_label(cx.fmtsp, "multiple missing formatting specifiers");
1131 for (sp, msg) in errs {
1132 diag.span_label(sp, msg);
1138 // Used to ensure we only report translations for *one* kind of foreign format.
1139 let mut found_foreign = false;
1140 // Decide if we want to look for foreign formatting directives.
1141 if args_used < args_unused {
1142 use super::format_foreign as foreign;
1144 // The set of foreign substitutions we've explained. This prevents spamming the user
1145 // with `%d should be written as {}` over and over again.
1146 let mut explained = FxHashSet::default();
1148 macro_rules! check_foreign {
1150 let mut show_doc_note = false;
1152 let mut suggestions = vec![];
1153 // account for `"` and account for raw strings `r#`
1154 let padding = str_style.map(|i| i + 2).unwrap_or(1);
1155 for sub in foreign::$kind::iter_subs(fmt_str, padding) {
1156 let trn = match sub.translate() {
1159 // If it has no translation, don't call it out specifically.
1163 let pos = sub.position();
1164 let sub = String::from(sub.as_str());
1165 if explained.contains(&sub) {
1168 explained.insert(sub.clone());
1171 found_foreign = true;
1172 show_doc_note = true;
1175 if let Some(inner_sp) = pos {
1176 let sp = fmt_sp.from_inner(inner_sp);
1177 suggestions.push((sp, trn));
1179 diag.help(&format!("`{}` should be written as `{}`", sub, trn));
1186 " formatting not supported; see the documentation for `std::fmt`",
1189 if suggestions.len() > 0 {
1190 diag.multipart_suggestion(
1191 "format specifiers use curly braces",
1193 Applicability::MachineApplicable,
1199 check_foreign!(printf);
1201 check_foreign!(shell);
1204 if !found_foreign && errs_len == 1 {
1205 diag.span_label(cx.fmtsp, "formatting specifier missing");