1 // Copyright 2012 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 use self::ArgumentType::*;
12 use self::Position::*;
14 use fmt_macros as parse;
17 use syntax::ext::base;
18 use syntax::ext::base::*;
19 use syntax::ext::build::AstBuilder;
20 use syntax::feature_gate;
21 use syntax::parse::token;
23 use syntax::symbol::Symbol;
24 use syntax::tokenstream;
25 use syntax_pos::{MultiSpan, Span, DUMMY_SP};
27 use std::collections::hash_map::Entry;
28 use std::collections::{HashMap, HashSet};
41 struct Context<'a, 'b: 'a> {
42 ecx: &'a mut ExtCtxt<'b>,
43 /// The macro's call site. References to unstable formatting internals must
44 /// use this span to pass the stability checker.
46 /// The span of the format string literal.
49 /// List of parsed argument expressions.
50 /// Named expressions are resolved early, and are appended to the end of
51 /// argument expressions.
53 /// Example showing the various data structures in motion:
55 /// * Original: `"{foo:o} {:o} {foo:x} {0:x} {1:o} {:x} {1:x} {0:o}"`
56 /// * Implicit argument resolution: `"{foo:o} {0:o} {foo:x} {0:x} {1:o} {1:x} {1:x} {0:o}"`
57 /// * Name resolution: `"{2:o} {0:o} {2:x} {0:x} {1:o} {1:x} {1:x} {0:o}"`
58 /// * `arg_types` (in JSON): `[[0, 1, 0], [0, 1, 1], [0, 1]]`
59 /// * `arg_unique_types` (in simplified JSON): `[["o", "x"], ["o", "x"], ["o", "x"]]`
60 /// * `names` (in JSON): `{"foo": 2}`
61 args: Vec<P<ast::Expr>>,
62 /// Placeholder slot numbers indexed by argument.
63 arg_types: Vec<Vec<usize>>,
64 /// Unique format specs seen for each argument.
65 arg_unique_types: Vec<Vec<ArgumentType>>,
66 /// Map from named arguments to their resolved indices.
67 names: HashMap<String, usize>,
69 /// The latest consecutive literal strings, or empty if there weren't any.
72 /// Collection of the compiled `rt::Argument` structures
73 pieces: Vec<P<ast::Expr>>,
74 /// Collection of string literals
75 str_pieces: Vec<P<ast::Expr>>,
76 /// Stays `true` if all formatting parameters are default (as in "{}{}").
77 all_pieces_simple: bool,
79 /// Mapping between positional argument references and indices into the
80 /// final generated static argument array. We record the starting indices
81 /// corresponding to each positional argument, and number of references
82 /// consumed so far for each argument, to facilitate correct `Position`
83 /// mapping in `build_piece`. In effect this can be seen as a "flattened"
84 /// version of `arg_unique_types`.
86 /// Again with the example described above in docstring for `args`:
88 /// * `arg_index_map` (in JSON): `[[0, 1, 0], [2, 3, 3], [4, 5]]`
89 arg_index_map: Vec<Vec<usize>>,
91 /// Starting offset of count argument slots.
92 count_args_index_offset: usize,
94 /// Count argument slots and tracking data structures.
95 /// Count arguments are separately tracked for de-duplication in case
96 /// multiple references are made to one argument. For example, in this
99 /// * Original: `"{:.*} {:.foo$} {1:.*} {:.0$}"`
100 /// * Implicit argument resolution: `"{1:.0$} {2:.foo$} {1:.3$} {4:.0$}"`
101 /// * Name resolution: `"{1:.0$} {2:.5$} {1:.3$} {4:.0$}"`
102 /// * `count_positions` (in JSON): `{0: 0, 5: 1, 3: 2}`
103 /// * `count_args`: `vec![Exact(0), Exact(5), Exact(3)]`
104 count_args: Vec<Position>,
105 /// Relative slot numbers for count arguments.
106 count_positions: HashMap<usize, usize>,
107 /// Number of count slots assigned.
108 count_positions_count: usize,
110 /// Current position of the implicit positional arg pointer, as if it
111 /// still existed in this phase of processing.
112 /// Used only for `all_pieces_simple` tracking in `build_piece`.
114 /// Current piece being evaluated, used for error reporting.
116 /// Keep track of invalid references to positional arguments.
117 invalid_refs: Vec<(usize, usize)>,
118 /// Spans of all the formatting arguments, in order.
119 arg_spans: Vec<Span>,
120 /// Wether this formatting string is a literal or it comes from a macro.
124 /// Parses the arguments from the given list of tokens, returning None
125 /// if there's a parse error so we can continue parsing other format!
128 /// If parsing succeeds, the return value is:
131 /// Some((fmtstr, parsed arguments, index map for named arguments))
133 fn parse_args(ecx: &mut ExtCtxt,
135 tts: &[tokenstream::TokenTree])
136 -> Option<(P<ast::Expr>, Vec<P<ast::Expr>>, HashMap<String, usize>)> {
137 let mut args = Vec::<P<ast::Expr>>::new();
138 let mut names = HashMap::<String, usize>::new();
140 let mut p = ecx.new_parser_from_tts(tts);
142 if p.token == token::Eof {
143 ecx.span_err(sp, "requires at least a format string argument");
146 let fmtstr = panictry!(p.parse_expr());
147 let mut named = false;
148 while p.token != token::Eof {
149 if !p.eat(&token::Comma) {
150 ecx.span_err(sp, "expected token: `,`");
153 if p.token == token::Eof {
155 } // accept trailing commas
156 if named || (p.token.is_ident() && p.look_ahead(1, |t| *t == token::Eq)) {
158 let ident = match p.token {
159 token::Ident(i, _) => {
166 "expected ident, positional arguments cannot follow named arguments",
174 "expected ident for named argument, found `{}`",
175 p.this_token_to_string()
181 let name: &str = &ident.as_str();
183 panictry!(p.expect(&token::Eq));
184 let e = panictry!(p.parse_expr());
185 if let Some(prev) = names.get(name) {
186 ecx.struct_span_err(e.span, &format!("duplicate argument named `{}`", name))
187 .span_note(args[*prev].span, "previously here")
192 // Resolve names into slots early.
193 // Since all the positional args are already seen at this point
194 // if the input is valid, we can simply append to the positional
195 // args. And remember the names.
196 let slot = args.len();
197 names.insert(name.to_string(), slot);
200 args.push(panictry!(p.parse_expr()));
203 Some((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| *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.to_string()),
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.to_string()), Count);
267 fn describe_num_args(&self) -> String {
268 match self.args.len() {
269 0 => "no arguments were given".to_string(),
270 1 => "there is 1 argument".to_string(),
271 x => format!("there are {} arguments", x),
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 {
282 MultiSpan::from_spans(self.arg_spans.clone())
284 MultiSpan::from_span(self.fmtsp)
286 let mut refs: Vec<_> = self
289 .map(|(r, pos)| (r.to_string(), self.arg_spans.get(*pos)))
292 if self.names.is_empty() && !numbered_position_args {
293 e = self.ecx.mut_span_err(
296 "{} positional argument{} in format string, but {}",
298 if self.pieces.len() > 1 { "s" } else { "" },
299 self.describe_num_args()
303 let (arg_list, mut sp) = match refs.len() {
305 let (reg, pos) = refs.pop().unwrap();
307 format!("argument {}", reg),
308 MultiSpan::from_span(*pos.unwrap_or(&self.fmtsp)),
313 MultiSpan::from_spans(refs.iter().map(|(_, p)| *p.unwrap()).collect());
314 let mut refs: Vec<String> = refs.iter().map(|(s, _)| s.to_owned()).collect();
315 let reg = refs.pop().unwrap();
318 "arguments {head} and {tail}",
320 head = refs.join(", ")
326 if !self.is_literal {
327 sp = MultiSpan::from_span(self.fmtsp);
330 e = self.ecx.mut_span_err(sp,
331 &format!("invalid reference to positional {} ({})",
333 self.describe_num_args()));
334 e.note("positional arguments are zero-based");
340 /// Actually verifies and tracks a given format placeholder
341 /// (a.k.a. argument).
342 fn verify_arg_type(&mut self, arg: Position, ty: ArgumentType) {
345 if self.args.len() <= arg {
346 self.invalid_refs.push((arg, self.curpiece));
351 // record every (position, type) combination only once
352 let ref mut seen_ty = self.arg_unique_types[arg];
353 let i = match seen_ty.iter().position(|x| *x == ty) {
356 let i = seen_ty.len();
361 self.arg_types[arg].push(i);
364 match self.count_positions.entry(arg) {
365 Entry::Vacant(e) => {
366 let i = self.count_positions_count;
368 self.count_args.push(Exact(arg));
369 self.count_positions_count += 1;
371 Entry::Occupied(_) => {}
378 let idx = match self.names.get(&name) {
381 let msg = format!("there is no argument named `{}`", name);
382 let sp = if self.is_literal {
383 *self.arg_spans.get(self.curpiece).unwrap_or(&self.fmtsp)
387 let mut err = self.ecx.struct_span_err(sp, &msg[..]);
392 // Treat as positional arg.
393 self.verify_arg_type(Exact(idx), ty)
398 /// Builds the mapping between format placeholders and argument objects.
399 fn build_index_map(&mut self) {
400 // NOTE: Keep the ordering the same as `into_expr`'s expansion would do!
401 let args_len = self.args.len();
402 self.arg_index_map.reserve(args_len);
404 let mut sofar = 0usize;
407 for i in 0..args_len {
408 let ref arg_types = self.arg_types[i];
409 let arg_offsets = arg_types.iter().map(|offset| sofar + *offset).collect::<Vec<_>>();
410 self.arg_index_map.push(arg_offsets);
411 sofar += self.arg_unique_types[i].len();
414 // Record starting index for counts, which appear just after arguments
415 self.count_args_index_offset = sofar;
418 fn rtpath(ecx: &ExtCtxt, s: &str) -> Vec<ast::Ident> {
419 ecx.std_path(&["fmt", "rt", "v1", s])
422 fn build_count(&self, c: parse::Count) -> P<ast::Expr> {
424 let count = |c, arg| {
425 let mut path = Context::rtpath(self.ecx, "Count");
426 path.push(self.ecx.ident_of(c));
428 Some(arg) => self.ecx.expr_call_global(sp, path, vec![arg]),
429 None => self.ecx.expr_path(self.ecx.path_global(sp, path)),
433 parse::CountIs(i) => count("Is", Some(self.ecx.expr_usize(sp, i))),
434 parse::CountIsParam(i) => {
435 // This needs mapping too, as `i` is referring to a macro
437 let i = match self.count_positions.get(&i) {
439 None => 0, // error already emitted elsewhere
441 let i = i + self.count_args_index_offset;
442 count("Param", Some(self.ecx.expr_usize(sp, i)))
444 parse::CountImplied => count("Implied", None),
445 // should never be the case, names are already resolved
446 parse::CountIsName(_) => panic!("should never happen"),
450 /// Build a literal expression from the accumulated string literals
451 fn build_literal_string(&mut self) -> P<ast::Expr> {
453 let s = Symbol::intern(&self.literal);
454 self.literal.clear();
455 self.ecx.expr_str(sp, s)
458 /// Build a static `rt::Argument` from a `parse::Piece` or append
459 /// to the `literal` string.
460 fn build_piece(&mut self,
461 piece: &parse::Piece,
462 arg_index_consumed: &mut Vec<usize>)
463 -> Option<P<ast::Expr>> {
466 parse::String(s) => {
467 self.literal.push_str(s);
470 parse::NextArgument(ref arg) => {
471 // Build the position
474 let mut path = Context::rtpath(self.ecx, "Position");
475 path.push(self.ecx.ident_of(c));
478 let arg = self.ecx.expr_usize(sp, i);
479 self.ecx.expr_call_global(sp, path, vec![arg])
481 None => self.ecx.expr_path(self.ecx.path_global(sp, path)),
486 | parse::ArgumentImplicitlyIs(i) => {
487 // Map to index in final generated argument array
488 // in case of multiple types specified
489 let arg_idx = match arg_index_consumed.get_mut(i) {
490 None => 0, // error already emitted elsewhere
492 let ref idx_map = self.arg_index_map[i];
493 // unwrap_or branch: error already emitted elsewhere
494 let arg_idx = *idx_map.get(*offset).unwrap_or(&0);
499 pos("At", Some(arg_idx))
502 // should never be the case, because names are already
504 parse::ArgumentNamed(_) => panic!("should never happen"),
508 let simple_arg = parse::Argument {
510 // We don't have ArgumentNext any more, so we have to
511 // track the current argument ourselves.
516 format: parse::FormatSpec {
517 fill: arg.format.fill,
518 align: parse::AlignUnknown,
520 precision: parse::CountImplied,
521 width: parse::CountImplied,
526 let fill = match arg.format.fill {
531 if *arg != simple_arg || fill != ' ' {
532 self.all_pieces_simple = false;
536 let fill = self.ecx.expr_lit(sp, ast::LitKind::Char(fill));
538 let mut p = Context::rtpath(self.ecx, "Alignment");
539 p.push(self.ecx.ident_of(name));
540 self.ecx.path_global(sp, p)
542 let align = match arg.format.align {
543 parse::AlignLeft => align("Left"),
544 parse::AlignRight => align("Right"),
545 parse::AlignCenter => align("Center"),
546 parse::AlignUnknown => align("Unknown"),
548 let align = self.ecx.expr_path(align);
549 let flags = self.ecx.expr_u32(sp, arg.format.flags);
550 let prec = self.build_count(arg.format.precision);
551 let width = self.build_count(arg.format.width);
552 let path = self.ecx.path_global(sp, Context::rtpath(self.ecx, "FormatSpec"));
553 let fmt = self.ecx.expr_struct(
557 self.ecx.field_imm(sp, self.ecx.ident_of("fill"), fill),
558 self.ecx.field_imm(sp, self.ecx.ident_of("align"), align),
559 self.ecx.field_imm(sp, self.ecx.ident_of("flags"), flags),
560 self.ecx.field_imm(sp, self.ecx.ident_of("precision"), prec),
561 self.ecx.field_imm(sp, self.ecx.ident_of("width"), width),
565 let path = self.ecx.path_global(sp, Context::rtpath(self.ecx, "Argument"));
566 Some(self.ecx.expr_struct(
570 self.ecx.field_imm(sp, self.ecx.ident_of("position"), pos),
571 self.ecx.field_imm(sp, self.ecx.ident_of("format"), fmt),
578 /// Actually builds the expression which the format_args! block will be
580 fn into_expr(self) -> P<ast::Expr> {
581 let mut locals = Vec::with_capacity(
582 (0..self.args.len()).map(|i| self.arg_unique_types[i].len()).sum()
584 let mut counts = Vec::with_capacity(self.count_args.len());
585 let mut pats = Vec::with_capacity(self.args.len());
586 let mut heads = Vec::with_capacity(self.args.len());
588 let names_pos: Vec<_> = (0..self.args.len())
589 .map(|i| self.ecx.ident_of(&format!("arg{}", i)).gensym())
592 // First, build up the static array which will become our precompiled
594 let pieces = self.ecx.expr_vec_slice(self.fmtsp, self.str_pieces);
596 // Before consuming the expressions, we have to remember spans for
597 // count arguments as they are now generated separate from other
598 // arguments, hence have no access to the `P<ast::Expr>`'s.
599 let spans_pos: Vec<_> = self.args.iter().map(|e| e.span.clone()).collect();
601 // Right now there is a bug such that for the expression:
603 // the lifetime of `1` doesn't outlast the call to `bar`, so it's not
604 // valid for the call to `foo`. To work around this all arguments to the
605 // format! string are shoved into locals. Furthermore, we shove the address
606 // of each variable because we don't want to move out of the arguments
607 // passed to this function.
608 for (i, e) in self.args.into_iter().enumerate() {
609 let name = names_pos[i];
611 DUMMY_SP.with_ctxt(e.span.ctxt().apply_mark(self.ecx.current_expansion.mark));
612 pats.push(self.ecx.pat_ident(span, name));
613 for ref arg_ty in self.arg_unique_types[i].iter() {
614 locals.push(Context::format_arg(self.ecx, self.macsp, e.span, arg_ty, name));
616 heads.push(self.ecx.expr_addr_of(e.span, e));
618 for pos in self.count_args {
619 let index = match pos {
621 _ => panic!("should never happen"),
623 let name = names_pos[index];
624 let span = spans_pos[index];
625 counts.push(Context::format_arg(self.ecx, self.macsp, span, &Count, name));
628 // Now create a vector containing all the arguments
629 let args = locals.into_iter().chain(counts.into_iter());
631 let args_array = self.ecx.expr_vec(self.fmtsp, args.collect());
633 // Constructs an AST equivalent to:
635 // match (&arg0, &arg1) {
636 // (tmp0, tmp1) => args_array
645 // Because of #11585 the new temporary lifetime rule, the enclosing
646 // statements for these temporaries become the let's themselves.
647 // If one or more of them are RefCell's, RefCell borrow() will also
648 // end there; they don't last long enough for args_array to use them.
649 // The match expression solves the scope problem.
651 // Note, it may also very well be transformed to:
656 // ref tmp1 => args_array } } }
658 // But the nested match expression is proved to perform not as well
659 // as series of let's; the first approach does.
660 let pat = self.ecx.pat_tuple(self.fmtsp, pats);
661 let arm = self.ecx.arm(self.fmtsp, vec![pat], args_array);
662 let head = self.ecx.expr(self.fmtsp, ast::ExprKind::Tup(heads));
663 let result = self.ecx.expr_match(self.fmtsp, head, vec![arm]);
665 let args_slice = self.ecx.expr_addr_of(self.fmtsp, result);
667 // Now create the fmt::Arguments struct with all our locals we created.
668 let (fn_name, fn_args) = if self.all_pieces_simple {
669 ("new_v1", vec![pieces, args_slice])
671 // Build up the static array which will store our precompiled
672 // nonstandard placeholders, if there are any.
673 let fmt = self.ecx.expr_vec_slice(self.macsp, self.pieces);
675 ("new_v1_formatted", vec![pieces, args_slice, fmt])
678 let path = self.ecx.std_path(&["fmt", "Arguments", fn_name]);
679 self.ecx.expr_call_global(self.macsp, path, fn_args)
682 fn format_arg(ecx: &ExtCtxt,
688 sp = sp.apply_mark(ecx.current_expansion.mark);
689 let arg = ecx.expr_ident(sp, arg);
690 let trait_ = match *ty {
691 Placeholder(ref tyname) => {
703 ecx.span_err(sp, &format!("unknown format trait `{}`", *tyname));
709 let path = ecx.std_path(&["fmt", "ArgumentV1", "from_usize"]);
710 return ecx.expr_call_global(macsp, path, vec![arg]);
714 let path = ecx.std_path(&["fmt", trait_, "fmt"]);
715 let format_fn = ecx.path_global(sp, path);
716 let path = ecx.std_path(&["fmt", "ArgumentV1", "new"]);
717 ecx.expr_call_global(macsp, path, vec![arg, ecx.expr_path(format_fn)])
721 pub fn expand_format_args<'cx>(ecx: &'cx mut ExtCtxt,
723 tts: &[tokenstream::TokenTree])
724 -> Box<dyn base::MacResult + 'cx> {
725 sp = sp.apply_mark(ecx.current_expansion.mark);
726 match parse_args(ecx, sp, tts) {
727 Some((efmt, args, names)) => {
728 MacEager::expr(expand_preparsed_format_args(ecx, sp, efmt, args, names, false))
730 None => DummyResult::expr(sp),
734 pub fn expand_format_args_nl<'cx>(
735 ecx: &'cx mut ExtCtxt,
737 tts: &[tokenstream::TokenTree],
738 ) -> Box<dyn base::MacResult + 'cx> {
739 //if !ecx.ecfg.enable_allow_internal_unstable() {
741 // For some reason, the only one that actually works for `println` is the first check
742 if !sp.allows_unstable() // the enclosing span is marked as `#[allow_insternal_unsable]`
743 && !ecx.ecfg.enable_allow_internal_unstable() // NOTE: when is this enabled?
744 && !ecx.ecfg.enable_format_args_nl() // enabled using `#[feature(format_args_nl]`
746 feature_gate::emit_feature_err(&ecx.parse_sess,
749 feature_gate::GateIssue::Language,
750 feature_gate::EXPLAIN_FORMAT_ARGS_NL);
751 return base::DummyResult::expr(sp);
753 sp = sp.apply_mark(ecx.current_expansion.mark);
754 match parse_args(ecx, sp, tts) {
755 Some((efmt, args, names)) => {
756 MacEager::expr(expand_preparsed_format_args(ecx, sp, efmt, args, names, true))
758 None => DummyResult::expr(sp),
762 /// Take the various parts of `format_args!(efmt, args..., name=names...)`
763 /// and construct the appropriate formatting expression.
764 pub fn expand_preparsed_format_args(ecx: &mut ExtCtxt,
767 args: Vec<P<ast::Expr>>,
768 names: HashMap<String, usize>,
769 append_newline: bool)
771 // NOTE: this verbose way of initializing `Vec<Vec<ArgumentType>>` is because
772 // `ArgumentType` does not derive `Clone`.
773 let arg_types: Vec<_> = (0..args.len()).map(|_| Vec::new()).collect();
774 let arg_unique_types: Vec<_> = (0..args.len()).map(|_| Vec::new()).collect();
775 let mut macsp = ecx.call_site();
776 macsp = macsp.apply_mark(ecx.current_expansion.mark);
777 let msg = "format argument must be a string literal";
778 let fmt_sp = efmt.span;
779 let fmt = match expr_to_spanned_string(ecx, efmt, msg) {
780 Ok(mut fmt) if append_newline => {
781 fmt.node.0 = Symbol::intern(&format!("{}\n", fmt.node.0));
786 let sugg_fmt = match args.len() {
787 0 => "{}".to_string(),
788 _ => format!("{}{{}}", "{} ".repeat(args.len())),
791 fmt_sp.shrink_to_lo(),
792 "you might be missing a string literal to format with",
793 format!("\"{}\", ", sugg_fmt),
796 return DummyResult::raw_expr(sp);
799 let is_literal = match ecx.codemap().span_to_snippet(fmt_sp) {
800 Ok(ref s) if s.starts_with("\"") || s.starts_with("r#") => true,
804 let mut cx = Context {
812 arg_index_map: Vec::new(),
813 count_args: Vec::new(),
814 count_positions: HashMap::new(),
815 count_positions_count: 0,
816 count_args_index_offset: 0,
817 literal: String::new(),
819 str_pieces: Vec::new(),
820 all_pieces_simple: true,
823 invalid_refs: Vec::new(),
824 arg_spans: Vec::new(),
828 let fmt_str = &*fmt.node.0.as_str();
829 let str_style = match fmt.node.1 {
830 ast::StrStyle::Cooked => None,
831 ast::StrStyle::Raw(raw) => Some(raw as usize),
833 let mut parser = parse::Parser::new(fmt_str, str_style);
834 let mut unverified_pieces = vec![];
835 let mut pieces = vec![];
837 while let Some(piece) = parser.next() {
838 if !parser.errors.is_empty() {
841 unverified_pieces.push(piece);
844 cx.arg_spans = parser.arg_places.iter()
845 .map(|&(start, end)| fmt.span.from_inner_byte_pos(start, end))
848 // This needs to happen *after* the Parser has consumed all pieces to create all the spans
849 for mut piece in unverified_pieces {
850 cx.verify_piece(&piece);
851 cx.resolve_name_inplace(&mut piece);
855 let numbered_position_args = pieces.iter().any(|arg: &parse::Piece| {
857 parse::String(_) => false,
858 parse::NextArgument(arg) => {
860 parse::Position::ArgumentIs(_) => true,
867 cx.build_index_map();
869 let mut arg_index_consumed = vec![0usize; cx.arg_index_map.len()];
870 for piece in pieces {
871 if let Some(piece) = cx.build_piece(&piece, &mut arg_index_consumed) {
872 let s = cx.build_literal_string();
873 cx.str_pieces.push(s);
874 cx.pieces.push(piece);
878 if !parser.errors.is_empty() {
879 let err = parser.errors.remove(0);
880 let sp = cx.fmtsp.from_inner_byte_pos(err.start, err.end);
881 let mut e = cx.ecx.struct_span_err(sp, &format!("invalid format string: {}",
883 e.span_label(sp, err.label + " in format string");
884 if let Some(note) = err.note {
888 return DummyResult::raw_expr(sp);
890 if !cx.literal.is_empty() {
891 let s = cx.build_literal_string();
892 cx.str_pieces.push(s);
895 if cx.invalid_refs.len() >= 1 {
896 cx.report_invalid_references(numbered_position_args);
899 // Make sure that all arguments were used and all arguments have types.
900 let num_pos_args = cx.args.len() - cx.names.len();
901 let mut errs = vec![];
902 for (i, ty) in cx.arg_types.iter().enumerate() {
904 if cx.count_positions.contains_key(&i) {
907 let msg = if i >= num_pos_args {
909 "named argument never used"
911 // positional argument
912 "argument never used"
914 errs.push((cx.args[i].span, msg));
917 let errs_len = errs.len();
919 let args_used = cx.arg_types.len() - errs_len;
920 let args_unused = errs_len;
924 let (sp, msg) = errs.into_iter().next().unwrap();
925 cx.ecx.struct_span_err(sp, msg)
927 let mut diag = cx.ecx.struct_span_err(
928 errs.iter().map(|&(sp, _)| sp).collect::<Vec<Span>>(),
929 "multiple unused formatting arguments",
931 diag.span_label(cx.fmtsp, "multiple missing formatting specifiers");
936 // Used to ensure we only report translations for *one* kind of foreign format.
937 let mut found_foreign = false;
938 // Decide if we want to look for foreign formatting directives.
939 if args_used < args_unused {
940 use super::format_foreign as foreign;
942 // The set of foreign substitutions we've explained. This prevents spamming the user
943 // with `%d should be written as {}` over and over again.
944 let mut explained = HashSet::new();
946 macro_rules! check_foreign {
948 let mut show_doc_note = false;
950 let mut suggestions = vec![];
951 for sub in foreign::$kind::iter_subs(fmt_str) {
952 let trn = match sub.translate() {
955 // If it has no translation, don't call it out specifically.
959 let pos = sub.position();
960 let sub = String::from(sub.as_str());
961 if explained.contains(&sub) {
964 explained.insert(sub.clone());
967 found_foreign = true;
968 show_doc_note = true;
971 if let Some((start, end)) = pos {
972 // account for `"` and account for raw strings `r#`
973 let padding = str_style.map(|i| i + 2).unwrap_or(1);
974 let sp = fmt_sp.from_inner_byte_pos(start + padding, end + padding);
975 suggestions.push((sp, trn));
977 diag.help(&format!("`{}` should be written as `{}`", sub, trn));
984 " formatting not supported; see the documentation for `std::fmt`",
987 if suggestions.len() > 0 {
988 diag.multipart_suggestion(
989 "format specifiers use curly braces",
996 check_foreign!(printf);
998 check_foreign!(shell);
1001 if !found_foreign && errs_len == 1 {
1002 diag.span_label(cx.fmtsp, "formatting specifier missing");