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Make space for a new fmt::Arguments implementation.
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+85
-345
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3 files changed

+85
-345
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‎compiler/rustc_builtin_macros/src/format/expand.rs

+11-345
Original file line numberDiff line numberDiff line change
@@ -1,353 +1,19 @@
11
use super::*;
22
use rustc_ast as ast;
3-
use rustc_ast::visit::{self, Visitor};
4-
use rustc_ast::{BlockCheckMode, UnsafeSource};
5-
use rustc_data_structures::fx::FxIndexSet;
6-
use rustc_span::{sym, symbol::kw};
7-
8-
#[derive(Copy, Clone, Debug, Hash, PartialEq, Eq)]
9-
enum ArgumentType {
10-
Format(FormatTrait),
11-
Usize,
12-
}
13-
14-
fn make_argument(ecx: &ExtCtxt<'_>, sp: Span, arg: P<ast::Expr>, ty: ArgumentType) -> P<ast::Expr> {
15-
// Generate:
16-
// ::core::fmt::ArgumentV1::new_…(arg)
17-
use ArgumentType::*;
18-
use FormatTrait::*;
19-
ecx.expr_call_global(
20-
sp,
21-
ecx.std_path(&[
22-
sym::fmt,
23-
sym::ArgumentV1,
24-
match ty {
25-
Format(Display) => sym::new_display,
26-
Format(Debug) => sym::new_debug,
27-
Format(LowerExp) => sym::new_lower_exp,
28-
Format(UpperExp) => sym::new_upper_exp,
29-
Format(Octal) => sym::new_octal,
30-
Format(Pointer) => sym::new_pointer,
31-
Format(Binary) => sym::new_binary,
32-
Format(LowerHex) => sym::new_lower_hex,
33-
Format(UpperHex) => sym::new_upper_hex,
34-
Usize => sym::from_usize,
35-
},
36-
]),
37-
vec![arg],
38-
)
39-
}
40-
41-
fn make_count(
42-
ecx: &ExtCtxt<'_>,
43-
sp: Span,
44-
count: &Option<FormatCount>,
45-
argmap: &mut FxIndexSet<(usize, ArgumentType)>,
46-
) -> P<ast::Expr> {
47-
// Generate:
48-
// ::core::fmt::rt::v1::Count::…(…)
49-
match count {
50-
Some(FormatCount::Literal(n)) => ecx.expr_call_global(
51-
sp,
52-
ecx.std_path(&[sym::fmt, sym::rt, sym::v1, sym::Count, sym::Is]),
53-
vec![ecx.expr_usize(sp, *n)],
54-
),
55-
Some(FormatCount::Argument(arg)) => {
56-
if let Ok(arg_index) = arg.index {
57-
let (i, _) = argmap.insert_full((arg_index, ArgumentType::Usize));
58-
ecx.expr_call_global(
59-
sp,
60-
ecx.std_path(&[sym::fmt, sym::rt, sym::v1, sym::Count, sym::Param]),
61-
vec![ecx.expr_usize(sp, i)],
62-
)
63-
} else {
64-
DummyResult::raw_expr(sp, true)
65-
}
66-
}
67-
None => ecx.expr_path(ecx.path_global(
68-
sp,
69-
ecx.std_path(&[sym::fmt, sym::rt, sym::v1, sym::Count, sym::Implied]),
70-
)),
71-
}
72-
}
73-
74-
fn make_format_spec(
75-
ecx: &ExtCtxt<'_>,
76-
sp: Span,
77-
placeholder: &FormatPlaceholder,
78-
argmap: &mut FxIndexSet<(usize, ArgumentType)>,
79-
) -> P<ast::Expr> {
80-
// Generate:
81-
// ::core::fmt::rt::v1::Argument {
82-
// position: 0usize,
83-
// format: ::core::fmt::rt::v1::FormatSpec {
84-
// fill: ' ',
85-
// align: ::core::fmt::rt::v1::Alignment::Unknown,
86-
// flags: 0u32,
87-
// precision: ::core::fmt::rt::v1::Count::Implied,
88-
// width: ::core::fmt::rt::v1::Count::Implied,
89-
// },
90-
// }
91-
let position = match placeholder.argument.index {
92-
Ok(arg_index) => {
93-
let (i, _) =
94-
argmap.insert_full((arg_index, ArgumentType::Format(placeholder.format_trait)));
95-
ecx.expr_usize(sp, i)
96-
}
97-
Err(_) => DummyResult::raw_expr(sp, true),
98-
};
99-
let fill = ecx.expr_char(sp, placeholder.format_options.fill.unwrap_or(' '));
100-
let align = ecx.expr_path(ecx.path_global(
101-
sp,
102-
ecx.std_path(&[
103-
sym::fmt,
104-
sym::rt,
105-
sym::v1,
106-
sym::Alignment,
107-
match placeholder.format_options.alignment {
108-
Some(FormatAlignment::Left) => sym::Left,
109-
Some(FormatAlignment::Right) => sym::Right,
110-
Some(FormatAlignment::Center) => sym::Center,
111-
None => sym::Unknown,
112-
},
113-
]),
114-
));
115-
let flags = ecx.expr_u32(sp, placeholder.format_options.flags);
116-
let prec = make_count(ecx, sp, &placeholder.format_options.precision, argmap);
117-
let width = make_count(ecx, sp, &placeholder.format_options.width, argmap);
118-
ecx.expr_struct(
119-
sp,
120-
ecx.path_global(sp, ecx.std_path(&[sym::fmt, sym::rt, sym::v1, sym::Argument])),
121-
vec![
122-
ecx.field_imm(sp, Ident::new(sym::position, sp), position),
123-
ecx.field_imm(
124-
sp,
125-
Ident::new(sym::format, sp),
126-
ecx.expr_struct(
127-
sp,
128-
ecx.path_global(
129-
sp,
130-
ecx.std_path(&[sym::fmt, sym::rt, sym::v1, sym::FormatSpec]),
131-
),
132-
vec![
133-
ecx.field_imm(sp, Ident::new(sym::fill, sp), fill),
134-
ecx.field_imm(sp, Ident::new(sym::align, sp), align),
135-
ecx.field_imm(sp, Ident::new(sym::flags, sp), flags),
136-
ecx.field_imm(sp, Ident::new(sym::precision, sp), prec),
137-
ecx.field_imm(sp, Ident::new(sym::width, sp), width),
138-
],
139-
),
140-
),
141-
],
142-
)
143-
}
3+
use rustc_span::sym;
1444

1455
pub fn expand_parsed_format_args(ecx: &mut ExtCtxt<'_>, fmt: FormatArgs) -> P<ast::Expr> {
1466
let macsp = ecx.with_def_site_ctxt(ecx.call_site());
1477

148-
let lit_pieces = ecx.expr_array_ref(
149-
fmt.span,
150-
fmt.template
151-
.iter()
152-
.enumerate()
153-
.filter_map(|(i, piece)| match piece {
154-
&FormatArgsPiece::Literal(s) => Some(ecx.expr_str(fmt.span, s)),
155-
&FormatArgsPiece::Placeholder(_) => {
156-
// Inject empty string before placeholders when not already preceded by a literal piece.
157-
if i == 0 || matches!(fmt.template[i - 1], FormatArgsPiece::Placeholder(_)) {
158-
Some(ecx.expr_str(fmt.span, kw::Empty))
159-
} else {
160-
None
161-
}
162-
}
163-
})
164-
.collect(),
165-
);
166-
167-
// Whether we'll use the `Arguments::new_v1_formatted` form (true),
168-
// or the `Arguments::new_v1` form (false).
169-
let mut use_format_options = false;
8+
… // TODO
1709

171-
// Create a list of all _unique_ (argument, format trait) combinations.
172-
// E.g. "{0} {0:x} {0} {1}" -> [(0, Display), (0, LowerHex), (1, Display)]
173-
let mut argmap = FxIndexSet::default();
174-
for piece in &fmt.template {
175-
let FormatArgsPiece::Placeholder(placeholder) = piece else { continue };
176-
if placeholder.format_options != Default::default() {
177-
// Can't use basic form if there's any formatting options.
178-
use_format_options = true;
179-
}
180-
if let Ok(index) = placeholder.argument.index {
181-
if !argmap.insert((index, ArgumentType::Format(placeholder.format_trait))) {
182-
// Duplicate (argument, format trait) combination,
183-
// which we'll only put once in the args array.
184-
use_format_options = true;
185-
}
186-
}
187-
}
188-
189-
let format_options = use_format_options.then(|| {
190-
// Generate:
191-
// &[format_spec_0, format_spec_1, format_spec_2]
192-
ecx.expr_array_ref(
193-
macsp,
194-
fmt.template
195-
.iter()
196-
.filter_map(|piece| {
197-
let FormatArgsPiece::Placeholder(placeholder) = piece else { return None };
198-
Some(make_format_spec(ecx, macsp, placeholder, &mut argmap))
199-
})
200-
.collect(),
201-
)
202-
});
203-
204-
let arguments = fmt.arguments.into_vec();
205-
206-
// If the args array contains exactly all the original arguments once,
207-
// in order, we can use a simple array instead of a `match` construction.
208-
// However, if there's a yield point in any argument except the first one,
209-
// we don't do this, because an ArgumentV1 cannot be kept across yield points.
210-
let use_simple_array = argmap.len() == arguments.len()
211-
&& argmap.iter().enumerate().all(|(i, &(j, _))| i == j)
212-
&& arguments.iter().skip(1).all(|arg| !may_contain_yield_point(&arg.expr));
213-
214-
let args = if use_simple_array {
215-
// Generate:
216-
// &[
217-
// ::core::fmt::ArgumentV1::new_display(&arg0),
218-
// ::core::fmt::ArgumentV1::new_lower_hex(&arg1),
219-
// ::core::fmt::ArgumentV1::new_debug(&arg2),
220-
// ]
221-
ecx.expr_array_ref(
222-
macsp,
223-
arguments
224-
.into_iter()
225-
.zip(argmap)
226-
.map(|(arg, (_, ty))| {
227-
let sp = arg.expr.span.with_ctxt(macsp.ctxt());
228-
make_argument(ecx, sp, ecx.expr_addr_of(sp, arg.expr), ty)
229-
})
230-
.collect(),
231-
)
232-
} else {
233-
// Generate:
234-
// match (&arg0, &arg1, &arg2) {
235-
// args => &[
236-
// ::core::fmt::ArgumentV1::new_display(args.0),
237-
// ::core::fmt::ArgumentV1::new_lower_hex(args.1),
238-
// ::core::fmt::ArgumentV1::new_debug(args.0),
239-
// ]
240-
// }
241-
let args_ident = Ident::new(sym::args, macsp);
242-
let args = argmap
243-
.iter()
244-
.map(|&(arg_index, ty)| {
245-
if let Some(arg) = arguments.get(arg_index) {
246-
let sp = arg.expr.span.with_ctxt(macsp.ctxt());
247-
make_argument(
248-
ecx,
249-
sp,
250-
ecx.expr_field(
251-
sp,
252-
ecx.expr_ident(macsp, args_ident),
253-
Ident::new(sym::integer(arg_index), macsp),
254-
),
255-
ty,
256-
)
257-
} else {
258-
DummyResult::raw_expr(macsp, true)
259-
}
260-
})
261-
.collect();
262-
ecx.expr_addr_of(
263-
macsp,
264-
ecx.expr_match(
265-
macsp,
266-
ecx.expr_tuple(
267-
macsp,
268-
arguments
269-
.into_iter()
270-
.map(|arg| {
271-
ecx.expr_addr_of(arg.expr.span.with_ctxt(macsp.ctxt()), arg.expr)
272-
})
273-
.collect(),
274-
),
275-
vec![ecx.arm(macsp, ecx.pat_ident(macsp, args_ident), ecx.expr_array(macsp, args))],
276-
),
277-
)
278-
};
279-
280-
if let Some(format_options) = format_options {
281-
// Generate:
282-
// ::core::fmt::Arguments::new_v1_formatted(
283-
// lit_pieces,
284-
// args,
285-
// format_options,
286-
// unsafe { ::core::fmt::UnsafeArg::new() }
287-
// )
288-
ecx.expr_call_global(
289-
macsp,
290-
ecx.std_path(&[sym::fmt, sym::Arguments, sym::new_v1_formatted]),
291-
vec![
292-
lit_pieces,
293-
args,
294-
format_options,
295-
ecx.expr_block(P(ast::Block {
296-
stmts: vec![ecx.stmt_expr(ecx.expr_call_global(
297-
macsp,
298-
ecx.std_path(&[sym::fmt, sym::UnsafeArg, sym::new]),
299-
Vec::new(),
300-
))],
301-
id: ast::DUMMY_NODE_ID,
302-
rules: BlockCheckMode::Unsafe(UnsafeSource::CompilerGenerated),
303-
span: macsp,
304-
tokens: None,
305-
could_be_bare_literal: false,
306-
})),
307-
],
308-
)
309-
} else {
310-
// Generate:
311-
// ::core::fmt::Arguments::new_v1(
312-
// lit_pieces,
313-
// args,
314-
// )
315-
ecx.expr_call_global(
316-
macsp,
317-
ecx.std_path(&[sym::fmt, sym::Arguments, sym::new_v1]),
318-
vec![lit_pieces, args],
319-
)
320-
}
321-
}
322-
323-
fn may_contain_yield_point(e: &ast::Expr) -> bool {
324-
struct MayContainYieldPoint(bool);
325-
326-
impl Visitor<'_> for MayContainYieldPoint {
327-
fn visit_expr(&mut self, e: &ast::Expr) {
328-
if let ast::ExprKind::Await(_) | ast::ExprKind::Yield(_) = e.kind {
329-
self.0 = true;
330-
} else {
331-
visit::walk_expr(self, e);
332-
}
333-
}
334-
335-
fn visit_mac_call(&mut self, _: &ast::MacCall) {
336-
self.0 = true;
337-
}
338-
339-
fn visit_attribute(&mut self, _: &ast::Attribute) {
340-
// Conservatively assume this may be a proc macro attribute in
341-
// expression position.
342-
self.0 = true;
343-
}
344-
345-
fn visit_item(&mut self, _: &ast::Item) {
346-
// Do not recurse into nested items.
347-
}
348-
}
349-
350-
let mut visitor = MayContainYieldPoint(false);
351-
visitor.visit_expr(e);
352-
visitor.0
10+
// Generate:
11+
// ::core::fmt::Arguments::new(
12+
// …
13+
// )
14+
ecx.expr_call_global(
15+
macsp,
16+
ecx.std_path(&[sym::fmt, sym::Arguments, sym::new]),
17+
vec![…],
18+
)
35319
}

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