6 use rustc_ast
::tokenstream
::TokenStream
;
7 use rustc_ast
::visit
::{self, Visitor}
;
8 use rustc_ast
::{token, BlockCheckMode, UnsafeSource}
;
9 use rustc_data_structures
::fx
::{FxHashMap, FxHashSet}
;
10 use rustc_errors
::{pluralize, Applicability, PResult}
;
11 use rustc_expand
::base
::{self, *}
;
12 use rustc_parse_format
as parse
;
13 use rustc_span
::symbol
::{sym, Ident, Symbol}
;
14 use rustc_span
::{InnerSpan, MultiSpan, Span}
;
15 use smallvec
::SmallVec
;
18 use std
::collections
::hash_map
::Entry
;
22 Placeholder(&'
static str),
29 Named(Symbol
, InnerSpan
),
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 /// The number of arguments that were added by implicit capturing.
54 num_captured_args
: usize,
55 /// Placeholder slot numbers indexed by argument.
56 arg_types
: Vec
<Vec
<usize>>,
57 /// Unique format specs seen for each argument.
58 arg_unique_types
: Vec
<Vec
<ArgumentType
>>,
59 /// Map from named arguments to their resolved indices.
60 names
: FxHashMap
<Symbol
, usize>,
62 /// The latest consecutive literal strings, or empty if there weren't any.
65 /// Collection of the compiled `rt::Argument` structures
66 pieces
: Vec
<P
<ast
::Expr
>>,
67 /// Collection of string literals
68 str_pieces
: Vec
<P
<ast
::Expr
>>,
69 /// Stays `true` if all formatting parameters are default (as in "{}{}").
70 all_pieces_simple
: bool
,
72 /// Mapping between positional argument references and indices into the
73 /// final generated static argument array. We record the starting indices
74 /// corresponding to each positional argument, and number of references
75 /// consumed so far for each argument, to facilitate correct `Position`
76 /// mapping in `build_piece`. In effect this can be seen as a "flattened"
77 /// version of `arg_unique_types`.
79 /// Again with the example described above in docstring for `args`:
81 /// * `arg_index_map` (in JSON): `[[0, 1, 0], [2, 3, 3], [4, 5]]`
82 arg_index_map
: Vec
<Vec
<usize>>,
84 /// Starting offset of count argument slots.
85 count_args_index_offset
: usize,
87 /// Count argument slots and tracking data structures.
88 /// Count arguments are separately tracked for de-duplication in case
89 /// multiple references are made to one argument. For example, in this
92 /// * Original: `"{:.*} {:.foo$} {1:.*} {:.0$}"`
93 /// * Implicit argument resolution: `"{1:.0$} {2:.foo$} {1:.3$} {4:.0$}"`
94 /// * Name resolution: `"{1:.0$} {2:.5$} {1:.3$} {4:.0$}"`
95 /// * `count_positions` (in JSON): `{0: 0, 5: 1, 3: 2}`
96 /// * `count_args`: `vec![0, 5, 3]`
97 count_args
: Vec
<usize>,
98 /// Relative slot numbers for count arguments.
99 count_positions
: FxHashMap
<usize, usize>,
100 /// Number of count slots assigned.
101 count_positions_count
: usize,
103 /// Current position of the implicit positional arg pointer, as if it
104 /// still existed in this phase of processing.
105 /// Used only for `all_pieces_simple` tracking in `build_piece`.
107 /// Current piece being evaluated, used for error reporting.
109 /// Keep track of invalid references to positional arguments.
110 invalid_refs
: Vec
<(usize, usize)>,
111 /// Spans of all the formatting arguments, in order.
112 arg_spans
: Vec
<Span
>,
113 /// All the formatting arguments that have formatting flags set, in order for diagnostics.
114 arg_with_formatting
: Vec
<parse
::FormatSpec
<'a
>>,
116 /// Whether this format string came from a string literal, as opposed to a macro.
120 /// Parses the arguments from the given list of tokens, returning the diagnostic
121 /// if there's a parse error so we can continue parsing other format!
124 /// If parsing succeeds, the return value is:
127 /// Some((fmtstr, parsed arguments, index map for named arguments))
130 ecx
: &mut ExtCtxt
<'a
>,
133 ) -> PResult
<'a
, (P
<ast
::Expr
>, Vec
<P
<ast
::Expr
>>, FxHashMap
<Symbol
, usize>)> {
134 let mut args
= Vec
::<P
<ast
::Expr
>>::new();
135 let mut names
= FxHashMap
::<Symbol
, usize>::default();
137 let mut p
= ecx
.new_parser_from_tts(tts
);
139 if p
.token
== token
::Eof
{
140 return Err(ecx
.struct_span_err(sp
, "requires at least a format string argument"));
143 let first_token
= &p
.token
;
144 let fmtstr
= match first_token
.kind
{
145 token
::TokenKind
::Literal(token
::Lit
{
146 kind
: token
::LitKind
::Str
| token
::LitKind
::StrRaw(_
),
149 // If the first token is a string literal, then a format expression
150 // is constructed from it.
152 // This allows us to properly handle cases when the first comma
153 // after the format string is mistakenly replaced with any operator,
154 // which cause the expression parser to eat too much tokens.
155 p
.parse_literal_maybe_minus()?
158 // Otherwise, we fall back to the expression parser.
163 let mut first
= true;
164 let mut named
= false;
166 while p
.token
!= token
::Eof
{
167 if !p
.eat(&token
::Comma
) {
169 p
.clear_expected_tokens();
172 match p
.expect(&token
::Comma
) {
174 match token
::TokenKind
::Comma
.similar_tokens() {
175 Some(tks
) if tks
.contains(&p
.token
.kind
) => {
176 // If a similar token is found, then it may be a typo. We
177 // consider it as a comma, and continue parsing.
181 // Otherwise stop the parsing and return the error.
182 _
=> return Err(err
),
191 if p
.token
== token
::Eof
{
193 } // accept trailing commas
194 match p
.token
.ident() {
195 Some((ident
, _
)) if p
.look_ahead(1, |t
| *t
== token
::Eq
) => {
198 p
.expect(&token
::Eq
)?
;
199 let e
= p
.parse_expr()?
;
200 if let Some(prev
) = names
.get(&ident
.name
) {
201 ecx
.struct_span_err(e
.span
, &format
!("duplicate argument named `{}`", ident
))
202 .span_label(args
[*prev
].span
, "previously here")
203 .span_label(e
.span
, "duplicate argument")
208 // Resolve names into slots early.
209 // Since all the positional args are already seen at this point
210 // if the input is valid, we can simply append to the positional
211 // args. And remember the names.
212 let slot
= args
.len();
213 names
.insert(ident
.name
, slot
);
217 let e
= p
.parse_expr()?
;
219 let mut err
= ecx
.struct_span_err(
221 "positional arguments cannot follow named arguments",
223 err
.span_label(e
.span
, "positional arguments must be before named arguments");
224 for pos
in names
.values() {
225 err
.span_label(args
[*pos
].span
, "named argument");
233 Ok((fmtstr
, args
, names
))
236 impl<'a
, 'b
> Context
<'a
, 'b
> {
237 /// The number of arguments that were explicitly given.
238 fn num_args(&self) -> usize {
239 self.args
.len() - self.num_captured_args
242 fn resolve_name_inplace(&self, p
: &mut parse
::Piece
<'_
>) {
243 // NOTE: the `unwrap_or` branch is needed in case of invalid format
244 // arguments, e.g., `format_args!("{foo}")`.
245 let lookup
= |s
: Symbol
| *self.names
.get(&s
).unwrap_or(&0);
248 parse
::String(_
) => {}
249 parse
::NextArgument(ref mut arg
) => {
250 if let parse
::ArgumentNamed(s
, _
) = arg
.position
{
251 arg
.position
= parse
::ArgumentIs(lookup(s
));
253 if let parse
::CountIsName(s
, _
) = arg
.format
.width
{
254 arg
.format
.width
= parse
::CountIsParam(lookup(s
));
256 if let parse
::CountIsName(s
, _
) = arg
.format
.precision
{
257 arg
.format
.precision
= parse
::CountIsParam(lookup(s
));
263 /// Verifies one piece of a parse string, and remembers it if valid.
264 /// All errors are not emitted as fatal so we can continue giving errors
265 /// about this and possibly other format strings.
266 fn verify_piece(&mut self, p
: &parse
::Piece
<'_
>) {
268 parse
::String(..) => {}
269 parse
::NextArgument(ref arg
) => {
270 // width/precision first, if they have implicit positional
271 // parameters it makes more sense to consume them first.
272 self.verify_count(arg
.format
.width
);
273 self.verify_count(arg
.format
.precision
);
275 // argument second, if it's an implicit positional parameter
276 // it's written second, so it should come after width/precision.
277 let pos
= match arg
.position
{
278 parse
::ArgumentIs(i
) | parse
::ArgumentImplicitlyIs(i
) => Exact(i
),
279 parse
::ArgumentNamed(s
, span
) => Named(s
, span
),
282 let ty
= Placeholder(match arg
.format
.ty
{
293 let fmtsp
= self.fmtsp
;
294 let sp
= arg
.format
.ty_span
.map(|sp
| fmtsp
.from_inner(sp
));
295 let mut err
= self.ecx
.struct_span_err(
297 &format
!("unknown format trait `{}`", arg
.format
.ty
),
300 "the only appropriate formatting traits are:\n\
301 - ``, which uses the `Display` trait\n\
302 - `?`, which uses the `Debug` trait\n\
303 - `e`, which uses the `LowerExp` trait\n\
304 - `E`, which uses the `UpperExp` trait\n\
305 - `o`, which uses the `Octal` trait\n\
306 - `p`, which uses the `Pointer` trait\n\
307 - `b`, which uses the `Binary` trait\n\
308 - `x`, which uses the `LowerHex` trait\n\
309 - `X`, which uses the `UpperHex` trait",
311 if let Some(sp
) = sp
{
312 for (fmt
, name
) in &[
323 // FIXME: rustfix (`run-rustfix`) fails to apply suggestions.
324 // > "Cannot replace slice of data that was already replaced"
325 err
.tool_only_span_suggestion(
327 &format
!("use the `{}` trait", name
),
329 Applicability
::MaybeIncorrect
,
337 self.verify_arg_type(pos
, ty
);
343 fn verify_count(&mut self, c
: parse
::Count
) {
345 parse
::CountImplied
| parse
::CountIs(..) => {}
346 parse
::CountIsParam(i
) => {
347 self.verify_arg_type(Exact(i
), Count
);
349 parse
::CountIsName(s
, span
) => {
350 self.verify_arg_type(Named(s
, span
), Count
);
355 fn describe_num_args(&self) -> Cow
<'_
, str> {
356 match self.num_args() {
357 0 => "no arguments were given".into(),
358 1 => "there is 1 argument".into(),
359 x
=> format
!("there are {} arguments", x
).into(),
363 /// Handle invalid references to positional arguments. Output different
364 /// errors for the case where all arguments are positional and for when
365 /// there are named arguments or numbered positional arguments in the
367 fn report_invalid_references(&self, numbered_position_args
: bool
) {
369 let sp
= if !self.arg_spans
.is_empty() {
370 // Point at the formatting arguments.
371 MultiSpan
::from_spans(self.arg_spans
.clone())
373 MultiSpan
::from_span(self.fmtsp
)
376 self.invalid_refs
.iter().map(|(r
, pos
)| (r
.to_string(), self.arg_spans
.get(*pos
)));
378 let mut zero_based_note
= false;
380 let count
= self.pieces
.len()
381 + self.arg_with_formatting
.iter().filter(|fmt
| fmt
.precision_span
.is_some()).count();
382 if self.names
.is_empty() && !numbered_position_args
&& count
!= self.num_args() {
383 e
= self.ecx
.struct_span_err(
386 "{} positional argument{} in format string, but {}",
389 self.describe_num_args(),
392 for arg
in &self.args
{
393 // Point at the arguments that will be formatted.
394 e
.span_label(arg
.span
, "");
397 let (mut refs
, spans
): (Vec
<_
>, Vec
<_
>) = refs
.unzip();
398 // Avoid `invalid reference to positional arguments 7 and 7 (there is 1 argument)`
399 // for `println!("{7:7$}", 1);`
402 let spans
: Vec
<_
> = spans
.into_iter().filter_map(|sp
| sp
.copied()).collect();
403 let sp
= if self.arg_spans
.is_empty() || spans
.is_empty() {
404 MultiSpan
::from_span(self.fmtsp
)
406 MultiSpan
::from_spans(spans
)
408 let arg_list
= if refs
.len() == 1 {
409 format
!("argument {}", refs
[0])
411 let reg
= refs
.pop().unwrap();
412 format
!("arguments {head} and {tail}", head
= refs
.join(", "), tail
= reg
)
415 e
= self.ecx
.struct_span_err(
418 "invalid reference to positional {} ({})",
420 self.describe_num_args()
423 zero_based_note
= true;
426 for fmt
in &self.arg_with_formatting
{
427 if let Some(span
) = fmt
.precision_span
{
428 let span
= self.fmtsp
.from_inner(span
);
429 match fmt
.precision
{
430 parse
::CountIsParam(pos
) if pos
> self.num_args() => {
434 "this precision flag expects an `usize` argument at position {}, \
437 self.describe_num_args(),
440 zero_based_note
= true;
442 parse
::CountIsParam(pos
) => {
443 let count
= self.pieces
.len()
447 .filter(|fmt
| fmt
.precision_span
.is_some())
449 e
.span_label(span
, &format
!(
450 "this precision flag adds an extra required argument at position {}, \
451 which is why there {} expected",
454 "is 1 argument".to_string()
456 format
!("are {} arguments", count
)
459 if let Some(arg
) = self.args
.get(pos
) {
462 "this parameter corresponds to the precision flag",
465 zero_based_note
= true;
470 if let Some(span
) = fmt
.width_span
{
471 let span
= self.fmtsp
.from_inner(span
);
473 parse
::CountIsParam(pos
) if pos
> self.num_args() => {
477 "this width flag expects an `usize` argument at position {}, \
480 self.describe_num_args(),
483 zero_based_note
= true;
490 e
.note("positional arguments are zero-based");
492 if !self.arg_with_formatting
.is_empty() {
494 "for information about formatting flags, visit \
495 https://doc.rust-lang.org/std/fmt/index.html",
502 /// Actually verifies and tracks a given format placeholder
503 /// (a.k.a. argument).
504 fn verify_arg_type(&mut self, arg
: Position
, ty
: ArgumentType
) {
505 if let Exact(arg
) = arg
{
506 if arg
>= self.num_args() {
507 self.invalid_refs
.push((arg
, self.curpiece
));
513 Exact(arg
) | Capture(arg
) => {
516 // record every (position, type) combination only once
517 let seen_ty
= &mut self.arg_unique_types
[arg
];
518 let i
= seen_ty
.iter().position(|x
| *x
== ty
).unwrap_or_else(|| {
519 let i
= seen_ty
.len();
523 self.arg_types
[arg
].push(i
);
526 if let Entry
::Vacant(e
) = self.count_positions
.entry(arg
) {
527 let i
= self.count_positions_count
;
529 self.count_args
.push(arg
);
530 self.count_positions_count
+= 1;
536 Named(name
, span
) => {
537 match self.names
.get(&name
) {
539 // Treat as positional arg.
540 self.verify_arg_type(Capture(idx
), ty
)
543 // For the moment capturing variables from format strings expanded from macros is
544 // disabled (see RFC #2795)
546 // Treat this name as a variable to capture from the surrounding scope
547 let idx
= self.args
.len();
548 self.arg_types
.push(Vec
::new());
549 self.arg_unique_types
.push(Vec
::new());
550 let span
= if self.is_literal
{
551 self.fmtsp
.from_inner(span
)
555 self.num_captured_args
+= 1;
556 self.args
.push(self.ecx
.expr_ident(span
, Ident
::new(name
, span
)));
557 self.names
.insert(name
, idx
);
558 self.verify_arg_type(Capture(idx
), ty
)
560 let msg
= format
!("there is no argument named `{}`", name
);
561 let sp
= if self.is_literal
{
562 self.fmtsp
.from_inner(span
)
566 let mut err
= self.ecx
.struct_span_err(sp
, &msg
);
569 "did you intend to capture a variable `{}` from \
570 the surrounding scope?",
574 "to avoid ambiguity, `format_args!` cannot capture variables \
575 when the format string is expanded from a macro",
586 /// Builds the mapping between format placeholders and argument objects.
587 fn build_index_map(&mut self) {
588 // NOTE: Keep the ordering the same as `into_expr`'s expansion would do!
589 let args_len
= self.args
.len();
590 self.arg_index_map
.reserve(args_len
);
592 let mut sofar
= 0usize
;
595 for i
in 0..args_len
{
596 let arg_types
= &self.arg_types
[i
];
597 let arg_offsets
= arg_types
.iter().map(|offset
| sofar
+ *offset
).collect
::<Vec
<_
>>();
598 self.arg_index_map
.push(arg_offsets
);
599 sofar
+= self.arg_unique_types
[i
].len();
602 // Record starting index for counts, which appear just after arguments
603 self.count_args_index_offset
= sofar
;
606 fn rtpath(ecx
: &ExtCtxt
<'_
>, s
: Symbol
) -> Vec
<Ident
> {
607 ecx
.std_path(&[sym
::fmt
, sym
::rt
, sym
::v1
, s
])
610 fn build_count(&self, c
: parse
::Count
) -> P
<ast
::Expr
> {
612 let count
= |c
, arg
| {
613 let mut path
= Context
::rtpath(self.ecx
, sym
::Count
);
614 path
.push(Ident
::new(c
, sp
));
616 Some(arg
) => self.ecx
.expr_call_global(sp
, path
, vec
![arg
]),
617 None
=> self.ecx
.expr_path(self.ecx
.path_global(sp
, path
)),
621 parse
::CountIs(i
) => count(sym
::Is
, Some(self.ecx
.expr_usize(sp
, i
))),
622 parse
::CountIsParam(i
) => {
623 // This needs mapping too, as `i` is referring to a macro
624 // argument. If `i` is not found in `count_positions` then
625 // the error had already been emitted elsewhere.
626 let i
= self.count_positions
.get(&i
).cloned().unwrap_or(0)
627 + self.count_args_index_offset
;
628 count(sym
::Param
, Some(self.ecx
.expr_usize(sp
, i
)))
630 parse
::CountImplied
=> count(sym
::Implied
, None
),
631 // should never be the case, names are already resolved
632 parse
::CountIsName(..) => panic
!("should never happen"),
636 /// Build a literal expression from the accumulated string literals
637 fn build_literal_string(&mut self) -> P
<ast
::Expr
> {
639 let s
= Symbol
::intern(&self.literal
);
640 self.literal
.clear();
641 self.ecx
.expr_str(sp
, s
)
644 /// Builds a static `rt::Argument` from a `parse::Piece` or append
645 /// to the `literal` string.
648 piece
: &parse
::Piece
<'a
>,
649 arg_index_consumed
: &mut Vec
<usize>,
650 ) -> Option
<P
<ast
::Expr
>> {
653 parse
::String(s
) => {
654 self.literal
.push_str(s
);
657 parse
::NextArgument(ref arg
) => {
658 // Build the position
661 parse
::ArgumentIs(i
) | parse
::ArgumentImplicitlyIs(i
) => {
662 // Map to index in final generated argument array
663 // in case of multiple types specified
664 let arg_idx
= match arg_index_consumed
.get_mut(i
) {
665 None
=> 0, // error already emitted elsewhere
667 let idx_map
= &self.arg_index_map
[i
];
668 // unwrap_or branch: error already emitted elsewhere
669 let arg_idx
= *idx_map
.get(*offset
).unwrap_or(&0);
674 self.ecx
.expr_usize(sp
, arg_idx
)
677 // should never be the case, because names are already
679 parse
::ArgumentNamed(..) => panic
!("should never happen"),
683 let simple_arg
= parse
::Argument
{
685 // We don't have ArgumentNext any more, so we have to
686 // track the current argument ourselves.
691 format
: parse
::FormatSpec
{
692 fill
: arg
.format
.fill
,
693 align
: parse
::AlignUnknown
,
695 precision
: parse
::CountImplied
,
696 precision_span
: None
,
697 width
: parse
::CountImplied
,
700 ty_span
: arg
.format
.ty_span
,
704 let fill
= arg
.format
.fill
.unwrap_or(' '
);
706 let pos_simple
= arg
.position
.index() == simple_arg
.position
.index();
708 if arg
.format
.precision_span
.is_some() || arg
.format
.width_span
.is_some() {
709 self.arg_with_formatting
.push(arg
.format
);
711 if !pos_simple
|| arg
.format
!= simple_arg
.format
|| fill
!= ' '
{
712 self.all_pieces_simple
= false;
716 let fill
= self.ecx
.expr_lit(sp
, ast
::LitKind
::Char(fill
));
718 let mut p
= Context
::rtpath(self.ecx
, sym
::Alignment
);
719 p
.push(Ident
::new(name
, sp
));
720 self.ecx
.path_global(sp
, p
)
722 let align
= match arg
.format
.align
{
723 parse
::AlignLeft
=> align(sym
::Left
),
724 parse
::AlignRight
=> align(sym
::Right
),
725 parse
::AlignCenter
=> align(sym
::Center
),
726 parse
::AlignUnknown
=> align(sym
::Unknown
),
728 let align
= self.ecx
.expr_path(align
);
729 let flags
= self.ecx
.expr_u32(sp
, arg
.format
.flags
);
730 let prec
= self.build_count(arg
.format
.precision
);
731 let width
= self.build_count(arg
.format
.width
);
732 let path
= self.ecx
.path_global(sp
, Context
::rtpath(self.ecx
, sym
::FormatSpec
));
733 let fmt
= self.ecx
.expr_struct(
737 self.ecx
.field_imm(sp
, Ident
::new(sym
::fill
, sp
), fill
),
738 self.ecx
.field_imm(sp
, Ident
::new(sym
::align
, sp
), align
),
739 self.ecx
.field_imm(sp
, Ident
::new(sym
::flags
, sp
), flags
),
740 self.ecx
.field_imm(sp
, Ident
::new(sym
::precision
, sp
), prec
),
741 self.ecx
.field_imm(sp
, Ident
::new(sym
::width
, sp
), width
),
745 let path
= self.ecx
.path_global(sp
, Context
::rtpath(self.ecx
, sym
::Argument
));
746 Some(self.ecx
.expr_struct(
750 self.ecx
.field_imm(sp
, Ident
::new(sym
::position
, sp
), pos
),
751 self.ecx
.field_imm(sp
, Ident
::new(sym
::format
, sp
), fmt
),
758 /// Actually builds the expression which the format_args! block will be
760 fn into_expr(self) -> P
<ast
::Expr
> {
761 let mut original_args
= self.args
;
762 let mut fmt_args
= Vec
::with_capacity(
763 self.arg_unique_types
.iter().map(|v
| v
.len()).sum
::<usize>() + self.count_args
.len(),
766 // First, build up the static array which will become our precompiled
768 let pieces
= self.ecx
.expr_vec_slice(self.fmtsp
, self.str_pieces
);
770 // We need to construct a &[ArgumentV1] to pass into the fmt::Arguments
771 // constructor. In general the expressions in this slice might be
772 // permuted from their order in original_args (such as in the case of
773 // "{1} {0}"), or may have multiple entries referring to the same
774 // element of original_args ("{0} {0}").
776 // The following vector has one item per element of our output slice,
777 // identifying the index of which element of original_args it's passing,
778 // and that argument's type.
779 let mut fmt_arg_index_and_ty
= SmallVec
::<[(usize, &ArgumentType
); 8]>::new();
780 for (i
, unique_types
) in self.arg_unique_types
.iter().enumerate() {
781 fmt_arg_index_and_ty
.extend(unique_types
.iter().map(|ty
| (i
, ty
)));
783 fmt_arg_index_and_ty
.extend(self.count_args
.iter().map(|&i
| (i
, &Count
)));
785 // Figure out whether there are permuted or repeated elements. If not,
786 // we can generate simpler code.
788 // The sequence has no indices out of order or repeated if: for every
789 // adjacent pair of elements, the first one's index is less than the
790 // second one's index.
792 fmt_arg_index_and_ty
.array_windows().all(|[(i
, _i_ty
), (j
, _j_ty
)]| i
< j
);
796 // [ArgumentV1::new(&$arg0, …), ArgumentV1::new(&$arg1, …), …]
798 // However, it's only legal to do so if $arg0, $arg1, … were written in
799 // exactly that order by the programmer. When arguments are permuted, we
800 // want them evaluated in the order written by the programmer, not in
801 // the order provided to fmt::Arguments. When arguments are repeated, we
802 // want the expression evaluated only once.
804 // Further, if any arg _after the first one_ contains a yield point such
805 // as `await` or `yield`, the above short form is inconvenient for the
806 // caller because it would keep a temporary of type ArgumentV1 alive
807 // across the yield point. ArgumentV1 can't implement Send since it
808 // holds a type-erased arbitrary type.
810 // Thus in the not nicely ordered case, and in the yielding case, we
811 // emit the following instead:
813 // match (&$arg0, &$arg1, …) {
814 // args => [ArgumentV1::new(args.$i, …), ArgumentV1::new(args.$j, …), …]
817 // for the sequence of indices $i, $j, … governed by fmt_arg_index_and_ty.
818 // This more verbose representation ensures that all arguments are
819 // evaluated a single time each, in the order written by the programmer,
820 // and that the surrounding future/generator (if any) is Send whenever
822 let no_need_for_match
=
823 nicely_ordered
&& !original_args
.iter().skip(1).any(|e
| may_contain_yield_point(e
));
825 for (arg_index
, arg_ty
) in fmt_arg_index_and_ty
{
826 let e
= &mut original_args
[arg_index
];
828 let arg
= if no_need_for_match
{
829 let expansion_span
= e
.span
.with_ctxt(self.macsp
.ctxt());
830 // The indices are strictly ordered so e has not been taken yet.
831 self.ecx
.expr_addr_of(expansion_span
, P(e
.take()))
833 let def_site
= self.ecx
.with_def_site_ctxt(span
);
834 let args_tuple
= self.ecx
.expr_ident(def_site
, Ident
::new(sym
::args
, def_site
));
835 let member
= Ident
::new(sym
::integer(arg_index
), def_site
);
836 self.ecx
.expr(def_site
, ast
::ExprKind
::Field(args_tuple
, member
))
838 fmt_args
.push(Context
::format_arg(self.ecx
, self.macsp
, span
, arg_ty
, arg
));
841 let args_array
= self.ecx
.expr_vec(self.macsp
, fmt_args
);
842 let args_slice
= self.ecx
.expr_addr_of(
844 if no_need_for_match
{
847 // In the !no_need_for_match case, none of the exprs were moved
848 // away in the previous loop.
850 // This uses the arg span for `&arg` so that borrowck errors
851 // point to the specific expression passed to the macro (the
852 // span is otherwise unavailable in the MIR used by borrowck).
853 let heads
= original_args
855 .map(|e
| self.ecx
.expr_addr_of(e
.span
.with_ctxt(self.macsp
.ctxt()), e
))
858 let pat
= self.ecx
.pat_ident(self.macsp
, Ident
::new(sym
::args
, self.macsp
));
859 let arm
= self.ecx
.arm(self.macsp
, pat
, args_array
);
860 let head
= self.ecx
.expr(self.macsp
, ast
::ExprKind
::Tup(heads
));
861 self.ecx
.expr_match(self.macsp
, head
, vec
![arm
])
865 // Now create the fmt::Arguments struct with all our locals we created.
866 let (fn_name
, fn_args
) = if self.all_pieces_simple
{
867 ("new_v1", vec
![pieces
, args_slice
])
869 // Build up the static array which will store our precompiled
870 // nonstandard placeholders, if there are any.
871 let fmt
= self.ecx
.expr_vec_slice(self.macsp
, self.pieces
);
873 let path
= self.ecx
.std_path(&[sym
::fmt
, sym
::UnsafeArg
, sym
::new
]);
874 let unsafe_arg
= self.ecx
.expr_call_global(self.macsp
, path
, Vec
::new());
875 let unsafe_expr
= self.ecx
.expr_block(P(ast
::Block
{
876 stmts
: vec
![self.ecx
.stmt_expr(unsafe_arg
)],
877 id
: ast
::DUMMY_NODE_ID
,
878 rules
: BlockCheckMode
::Unsafe(UnsafeSource
::CompilerGenerated
),
881 could_be_bare_literal
: false,
884 ("new_v1_formatted", vec
![pieces
, args_slice
, fmt
, unsafe_expr
])
887 let path
= self.ecx
.std_path(&[sym
::fmt
, sym
::Arguments
, Symbol
::intern(fn_name
)]);
888 self.ecx
.expr_call_global(self.macsp
, path
, fn_args
)
898 sp
= ecx
.with_def_site_ctxt(sp
);
899 let trait_
= match *ty
{
900 Placeholder(trait_
) if trait_
== "<invalid>" => return DummyResult
::raw_expr(sp
, true),
901 Placeholder(trait_
) => trait_
,
903 let path
= ecx
.std_path(&[sym
::fmt
, sym
::ArgumentV1
, sym
::from_usize
]);
904 return ecx
.expr_call_global(macsp
, path
, vec
![arg
]);
907 let new_fn_name
= match trait_
{
908 "Display" => "new_display",
909 "Debug" => "new_debug",
910 "LowerExp" => "new_lower_exp",
911 "UpperExp" => "new_upper_exp",
912 "Octal" => "new_octal",
913 "Pointer" => "new_pointer",
914 "Binary" => "new_binary",
915 "LowerHex" => "new_lower_hex",
916 "UpperHex" => "new_upper_hex",
920 let path
= ecx
.std_path(&[sym
::fmt
, sym
::ArgumentV1
, Symbol
::intern(new_fn_name
)]);
921 ecx
.expr_call_global(sp
, path
, vec
![arg
])
925 fn expand_format_args_impl
<'cx
>(
926 ecx
: &'cx
mut ExtCtxt
<'_
>,
930 ) -> Box
<dyn base
::MacResult
+ 'cx
> {
931 sp
= ecx
.with_def_site_ctxt(sp
);
932 match parse_args(ecx
, sp
, tts
) {
933 Ok((efmt
, args
, names
)) => {
934 MacEager
::expr(expand_preparsed_format_args(ecx
, sp
, efmt
, args
, names
, nl
))
943 pub fn expand_format_args
<'cx
>(
944 ecx
: &'cx
mut ExtCtxt
<'_
>,
947 ) -> Box
<dyn base
::MacResult
+ 'cx
> {
948 expand_format_args_impl(ecx
, sp
, tts
, false)
951 pub fn expand_format_args_nl
<'cx
>(
952 ecx
: &'cx
mut ExtCtxt
<'_
>,
955 ) -> Box
<dyn base
::MacResult
+ 'cx
> {
956 expand_format_args_impl(ecx
, sp
, tts
, true)
959 /// Take the various parts of `format_args!(efmt, args..., name=names...)`
960 /// and construct the appropriate formatting expression.
961 pub fn expand_preparsed_format_args(
962 ecx
: &mut ExtCtxt
<'_
>,
965 args
: Vec
<P
<ast
::Expr
>>,
966 names
: FxHashMap
<Symbol
, usize>,
967 append_newline
: bool
,
969 // NOTE: this verbose way of initializing `Vec<Vec<ArgumentType>>` is because
970 // `ArgumentType` does not derive `Clone`.
971 let arg_types
: Vec
<_
> = (0..args
.len()).map(|_
| Vec
::new()).collect();
972 let arg_unique_types
: Vec
<_
> = (0..args
.len()).map(|_
| Vec
::new()).collect();
974 let mut macsp
= ecx
.call_site();
975 macsp
= ecx
.with_def_site_ctxt(macsp
);
977 let msg
= "format argument must be a string literal";
978 let fmt_sp
= efmt
.span
;
979 let efmt_kind_is_lit
: bool
= matches
!(efmt
.kind
, ast
::ExprKind
::Lit(_
));
980 let (fmt_str
, fmt_style
, fmt_span
) = match expr_to_spanned_string(ecx
, efmt
, msg
) {
981 Ok(mut fmt
) if append_newline
=> {
982 fmt
.0 = Symbol
::intern(&format
!("{}\n", fmt
.0));
987 if let Some((mut err
, suggested
)) = err
{
988 let sugg_fmt
= match args
.len() {
989 0 => "{}".to_string(),
990 _
=> format
!("{}{{}}", "{} ".repeat(args
.len())),
994 fmt_sp
.shrink_to_lo(),
995 "you might be missing a string literal to format with",
996 format
!("\"{}\", ", sugg_fmt
),
997 Applicability
::MaybeIncorrect
,
1002 return DummyResult
::raw_expr(sp
, true);
1006 let str_style
= match fmt_style
{
1007 ast
::StrStyle
::Cooked
=> None
,
1008 ast
::StrStyle
::Raw(raw
) => Some(raw
as usize),
1011 let fmt_str
= fmt_str
.as_str(); // for the suggestions below
1012 let fmt_snippet
= ecx
.source_map().span_to_snippet(fmt_sp
).ok();
1013 let mut parser
= parse
::Parser
::new(
1018 parse
::ParseMode
::Format
,
1021 let mut unverified_pieces
= Vec
::new();
1022 while let Some(piece
) = parser
.next() {
1023 if !parser
.errors
.is_empty() {
1026 unverified_pieces
.push(piece
);
1030 if !parser
.errors
.is_empty() {
1031 let err
= parser
.errors
.remove(0);
1032 let sp
= if efmt_kind_is_lit
{
1033 fmt_span
.from_inner(err
.span
)
1035 // The format string could be another macro invocation, e.g.:
1036 // format!(concat!("abc", "{}"), 4);
1037 // However, `err.span` is an inner span relative to the *result* of
1038 // the macro invocation, which is why we would get a nonsensical
1039 // result calling `fmt_span.from_inner(err.span)` as above, and
1040 // might even end up inside a multibyte character (issue #86085).
1041 // Therefore, we conservatively report the error for the entire
1042 // argument span here.
1045 let mut e
= ecx
.struct_span_err(sp
, &format
!("invalid format string: {}", err
.description
));
1046 e
.span_label(sp
, err
.label
+ " in format string");
1047 if let Some(note
) = err
.note
{
1050 if let Some((label
, span
)) = err
.secondary_label
{
1051 if efmt_kind_is_lit
{
1052 e
.span_label(fmt_span
.from_inner(span
), label
);
1056 return DummyResult
::raw_expr(sp
, true);
1059 let arg_spans
= parser
.arg_places
.iter().map(|span
| fmt_span
.from_inner(*span
)).collect();
1061 let named_pos
: FxHashSet
<usize> = names
.values().cloned().collect();
1063 let mut cx
= Context
{
1066 num_captured_args
: 0,
1072 arg_index_map
: Vec
::new(),
1073 count_args
: Vec
::new(),
1074 count_positions
: FxHashMap
::default(),
1075 count_positions_count
: 0,
1076 count_args_index_offset
: 0,
1077 literal
: String
::new(),
1078 pieces
: Vec
::with_capacity(unverified_pieces
.len()),
1079 str_pieces
: Vec
::with_capacity(unverified_pieces
.len()),
1080 all_pieces_simple
: true,
1083 invalid_refs
: Vec
::new(),
1085 arg_with_formatting
: Vec
::new(),
1086 is_literal
: parser
.is_literal
,
1089 // This needs to happen *after* the Parser has consumed all pieces to create all the spans
1090 let pieces
= unverified_pieces
1093 cx
.verify_piece(&piece
);
1094 cx
.resolve_name_inplace(&mut piece
);
1097 .collect
::<Vec
<_
>>();
1099 let numbered_position_args
= pieces
.iter().any(|arg
: &parse
::Piece
<'_
>| match *arg
{
1100 parse
::String(_
) => false,
1101 parse
::NextArgument(arg
) => matches
!(arg
.position
, parse
::Position
::ArgumentIs(_
)),
1104 cx
.build_index_map();
1106 let mut arg_index_consumed
= vec
![0usize
; cx
.arg_index_map
.len()];
1108 for piece
in pieces
{
1109 if let Some(piece
) = cx
.build_piece(&piece
, &mut arg_index_consumed
) {
1110 let s
= cx
.build_literal_string();
1111 cx
.str_pieces
.push(s
);
1112 cx
.pieces
.push(piece
);
1116 if !cx
.literal
.is_empty() {
1117 let s
= cx
.build_literal_string();
1118 cx
.str_pieces
.push(s
);
1121 if !cx
.invalid_refs
.is_empty() {
1122 cx
.report_invalid_references(numbered_position_args
);
1125 // Make sure that all arguments were used and all arguments have types.
1130 .filter(|(i
, ty
)| ty
.is_empty() && !cx
.count_positions
.contains_key(&i
))
1132 let msg
= if named_pos
.contains(&i
) {
1134 "named argument never used"
1136 // positional argument
1137 "argument never used"
1139 (cx
.args
[i
].span
, msg
)
1141 .collect
::<Vec
<_
>>();
1143 let errs_len
= errs
.len();
1144 if !errs
.is_empty() {
1145 let args_used
= cx
.arg_types
.len() - errs_len
;
1146 let args_unused
= errs_len
;
1149 if let [(sp
, msg
)] = &errs
[..] {
1150 let mut diag
= cx
.ecx
.struct_span_err(*sp
, *msg
);
1151 diag
.span_label(*sp
, *msg
);
1154 let mut diag
= cx
.ecx
.struct_span_err(
1155 errs
.iter().map(|&(sp
, _
)| sp
).collect
::<Vec
<Span
>>(),
1156 "multiple unused formatting arguments",
1158 diag
.span_label(cx
.fmtsp
, "multiple missing formatting specifiers");
1159 for (sp
, msg
) in errs
{
1160 diag
.span_label(sp
, msg
);
1166 // Used to ensure we only report translations for *one* kind of foreign format.
1167 let mut found_foreign
= false;
1168 // Decide if we want to look for foreign formatting directives.
1169 if args_used
< args_unused
{
1170 use super::format_foreign
as foreign
;
1172 // The set of foreign substitutions we've explained. This prevents spamming the user
1173 // with `%d should be written as {}` over and over again.
1174 let mut explained
= FxHashSet
::default();
1176 macro_rules
! check_foreign
{
1178 let mut show_doc_note
= false;
1180 let mut suggestions
= vec
![];
1181 // account for `"` and account for raw strings `r#`
1182 let padding
= str_style
.map(|i
| i
+ 2).unwrap_or(1);
1183 for sub
in foreign
::$kind
::iter_subs(fmt_str
, padding
) {
1184 let (trn
, success
) = match sub
.translate() {
1185 Ok(trn
) => (trn
, true),
1186 Err(Some(msg
)) => (msg
, false),
1188 // If it has no translation, don't call it out specifically.
1192 let pos
= sub
.position();
1193 let sub
= String
::from(sub
.as_str());
1194 if explained
.contains(&sub
) {
1197 explained
.insert(sub
.clone());
1200 found_foreign
= true;
1201 show_doc_note
= true;
1204 if let Some(inner_sp
) = pos
{
1205 let sp
= fmt_sp
.from_inner(inner_sp
);
1208 suggestions
.push((sp
, trn
));
1212 &format
!("format specifiers use curly braces, and {}", trn
),
1217 diag
.help(&format
!("`{}` should be written as `{}`", sub
, trn
));
1220 "`{}` should use curly braces, and {}",
1230 " formatting not supported; see the documentation for `std::fmt`",
1233 if suggestions
.len() > 0 {
1234 diag
.multipart_suggestion(
1235 "format specifiers use curly braces",
1237 Applicability
::MachineApplicable
,
1243 check_foreign
!(printf
);
1245 check_foreign
!(shell
);
1248 if !found_foreign
&& errs_len
== 1 {
1249 diag
.span_label(cx
.fmtsp
, "formatting specifier missing");
1258 fn may_contain_yield_point(e
: &ast
::Expr
) -> bool
{
1259 struct MayContainYieldPoint(bool
);
1261 impl Visitor
<'_
> for MayContainYieldPoint
{
1262 fn visit_expr(&mut self, e
: &ast
::Expr
) {
1263 if let ast
::ExprKind
::Await(_
) | ast
::ExprKind
::Yield(_
) = e
.kind
{
1266 visit
::walk_expr(self, e
);
1270 fn visit_mac_call(&mut self, _
: &ast
::MacCall
) {
1274 fn visit_attribute(&mut self, _
: &ast
::Attribute
) {
1275 // Conservatively assume this may be a proc macro attribute in
1276 // expression position.
1280 fn visit_item(&mut self, _
: &ast
::Item
) {
1281 // Do not recurse into nested items.
1285 let mut visitor
= MayContainYieldPoint(false);
1286 visitor
.visit_expr(e
);