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ManishearthManishearth
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Rollup merge of rust-lang#108801 - fee1-dead-contrib:c-str, r=compiler-errors
Implement RFC 3348, `c"foo"` literals RFC: rust-lang/rfcs#3348 Tracking issue: rust-lang#105723
2 parents 7157ef7 + d30c668 commit 7ba3a5a

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33 files changed

+500
-153
lines changed

33 files changed

+500
-153
lines changed

‎compiler/rustc_ast/src/ast.rs‎

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Original file line numberDiff line numberDiff line change
@@ -1821,6 +1821,8 @@ pub enum LitKind {
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/// A byte string (`b"foo"`). Not stored as a symbol because it might be
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/// non-utf8, and symbols only allow utf8 strings.
18231823
ByteStr(Lrc<[u8]>, StrStyle),
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/// A C String (`c"foo"`). Guaranteed to only have `\0` at the end.
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CStr(Lrc<[u8]>, StrStyle),
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/// A byte char (`b'f'`).
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Byte(u8),
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/// A character literal (`'a'`).
@@ -1875,6 +1877,7 @@ impl LitKind {
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// unsuffixed variants
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LitKind::Str(..)
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| LitKind::ByteStr(..)
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| LitKind::CStr(..)
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| LitKind::Byte(..)
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| LitKind::Char(..)
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| LitKind::Int(_, LitIntType::Unsuffixed)

‎compiler/rustc_ast/src/token.rs‎

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@@ -74,6 +74,8 @@ pub enum LitKind {
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StrRaw(u8), // raw string delimited by `n` hash symbols
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ByteStr,
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ByteStrRaw(u8), // raw byte string delimited by `n` hash symbols
77+
CStr,
78+
CStrRaw(u8),
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Err,
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}
7981

@@ -141,6 +143,10 @@ impl fmt::Display for Lit {
141143
delim = "#".repeat(n as usize),
142144
string = symbol
143145
)?,
146+
CStr => write!(f, "c\"{symbol}\"")?,
147+
CStrRaw(n) => {
148+
write!(f, "cr{delim}\"{symbol}\"{delim}", delim = "#".repeat(n as usize))?
149+
}
144150
Integer | Float | Bool | Err => write!(f, "{symbol}")?,
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}
146152

@@ -170,6 +176,7 @@ impl LitKind {
170176
Float => "float",
171177
Str | StrRaw(..) => "string",
172178
ByteStr | ByteStrRaw(..) => "byte string",
179+
CStr | CStrRaw(..) => "C string",
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Err => "error",
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}
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}

‎compiler/rustc_ast/src/util/literal.rs‎

Lines changed: 62 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -2,9 +2,13 @@
22
33
use crate::ast::{self, LitKind, MetaItemLit, StrStyle};
44
use crate::token::{self, Token};
5-
use rustc_lexer::unescape::{byte_from_char, unescape_byte, unescape_char, unescape_literal, Mode};
5+
use rustc_lexer::unescape::{
6+
byte_from_char, unescape_byte, unescape_c_string, unescape_char, unescape_literal, CStrUnit,
7+
Mode,
8+
};
69
use rustc_span::symbol::{kw, sym, Symbol};
710
use rustc_span::Span;
11+
use std::ops::Range;
812
use std::{ascii, fmt, str};
913

1014
// Escapes a string, represented as a symbol. Reuses the original symbol,
@@ -35,6 +39,7 @@ pub enum LitError {
3539
InvalidFloatSuffix,
3640
NonDecimalFloat(u32),
3741
IntTooLarge(u32),
42+
NulInCStr(Range<usize>),
3843
}
3944

4045
impl LitKind {
@@ -158,6 +163,52 @@ impl LitKind {
158163

159164
LitKind::ByteStr(bytes.into(), StrStyle::Raw(n))
160165
}
166+
token::CStr => {
167+
let s = symbol.as_str();
168+
let mut buf = Vec::with_capacity(s.len());
169+
let mut error = Ok(());
170+
unescape_c_string(s, Mode::CStr, &mut |span, c| match c {
171+
Ok(CStrUnit::Byte(0) | CStrUnit::Char('\0')) => {
172+
error = Err(LitError::NulInCStr(span));
173+
}
174+
Ok(CStrUnit::Byte(b)) => buf.push(b),
175+
Ok(CStrUnit::Char(c)) if c.len_utf8() == 1 => buf.push(c as u8),
176+
Ok(CStrUnit::Char(c)) => {
177+
buf.extend_from_slice(c.encode_utf8(&mut [0; 4]).as_bytes())
178+
}
179+
Err(err) => {
180+
if err.is_fatal() {
181+
error = Err(LitError::LexerError);
182+
}
183+
}
184+
});
185+
error?;
186+
buf.push(0);
187+
LitKind::CStr(buf.into(), StrStyle::Cooked)
188+
}
189+
token::CStrRaw(n) => {
190+
let s = symbol.as_str();
191+
let mut buf = Vec::with_capacity(s.len());
192+
let mut error = Ok(());
193+
unescape_c_string(s, Mode::RawCStr, &mut |span, c| match c {
194+
Ok(CStrUnit::Byte(0) | CStrUnit::Char('\0')) => {
195+
error = Err(LitError::NulInCStr(span));
196+
}
197+
Ok(CStrUnit::Byte(b)) => buf.push(b),
198+
Ok(CStrUnit::Char(c)) if c.len_utf8() == 1 => buf.push(c as u8),
199+
Ok(CStrUnit::Char(c)) => {
200+
buf.extend_from_slice(c.encode_utf8(&mut [0; 4]).as_bytes())
201+
}
202+
Err(err) => {
203+
if err.is_fatal() {
204+
error = Err(LitError::LexerError);
205+
}
206+
}
207+
});
208+
error?;
209+
buf.push(0);
210+
LitKind::CStr(buf.into(), StrStyle::Raw(n))
211+
}
161212
token::Err => LitKind::Err,
162213
})
163214
}
@@ -191,6 +242,14 @@ impl fmt::Display for LitKind {
191242
string = symbol
192243
)?;
193244
}
245+
LitKind::CStr(ref bytes, StrStyle::Cooked) => {
246+
write!(f, "c\"{}\"", escape_byte_str_symbol(bytes))?
247+
}
248+
LitKind::CStr(ref bytes, StrStyle::Raw(n)) => {
249+
// This can only be valid UTF-8.
250+
let symbol = str::from_utf8(bytes).unwrap();
251+
write!(f, "cr{delim}\"{symbol}\"{delim}", delim = "#".repeat(n as usize),)?;
252+
}
194253
LitKind::Int(n, ty) => {
195254
write!(f, "{n}")?;
196255
match ty {
@@ -237,6 +296,8 @@ impl MetaItemLit {
237296
LitKind::Str(_, ast::StrStyle::Raw(n)) => token::StrRaw(n),
238297
LitKind::ByteStr(_, ast::StrStyle::Cooked) => token::ByteStr,
239298
LitKind::ByteStr(_, ast::StrStyle::Raw(n)) => token::ByteStrRaw(n),
299+
LitKind::CStr(_, ast::StrStyle::Cooked) => token::CStr,
300+
LitKind::CStr(_, ast::StrStyle::Raw(n)) => token::CStrRaw(n),
240301
LitKind::Byte(_) => token::Byte,
241302
LitKind::Char(_) => token::Char,
242303
LitKind::Int(..) => token::Integer,

‎compiler/rustc_ast_passes/src/feature_gate.rs‎

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@@ -572,6 +572,7 @@ pub fn check_crate(krate: &ast::Crate, sess: &Session) {
572572
}
573573
};
574574
}
575+
gate_all!(c_str_literals, "`c\"..\"` literals are experimental");
575576
gate_all!(
576577
if_let_guard,
577578
"`if let` guards are experimental",

‎compiler/rustc_ast_pretty/src/pprust/state.rs‎

Lines changed: 4 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -210,6 +210,10 @@ pub fn literal_to_string(lit: token::Lit) -> String {
210210
token::ByteStrRaw(n) => {
211211
format!("br{delim}\"{string}\"{delim}", delim = "#".repeat(n as usize), string = symbol)
212212
}
213+
token::CStr => format!("c\"{symbol}\""),
214+
token::CStrRaw(n) => {
215+
format!("cr{delim}\"{symbol}\"{delim}", delim = "#".repeat(n as usize))
216+
}
213217
token::Integer | token::Float | token::Bool | token::Err => symbol.to_string(),
214218
};
215219

‎compiler/rustc_builtin_macros/src/concat.rs‎

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@@ -32,6 +32,10 @@ pub fn expand_concat(
3232
Ok(ast::LitKind::Bool(b)) => {
3333
accumulator.push_str(&b.to_string());
3434
}
35+
Ok(ast::LitKind::CStr(..)) => {
36+
cx.span_err(e.span, "cannot concatenate a C string literal");
37+
has_errors = true;
38+
}
3539
Ok(ast::LitKind::Byte(..) | ast::LitKind::ByteStr(..)) => {
3640
cx.emit_err(errors::ConcatBytestr { span: e.span });
3741
has_errors = true;

‎compiler/rustc_builtin_macros/src/concat_bytes.rs‎

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Original file line numberDiff line numberDiff line change
@@ -18,6 +18,11 @@ fn invalid_type_err(
1818
};
1919
let snippet = cx.sess.source_map().span_to_snippet(span).ok();
2020
match ast::LitKind::from_token_lit(token_lit) {
21+
Ok(ast::LitKind::CStr(_, _)) => {
22+
// FIXME(c_str_literals): should concatenation of C string literals
23+
// include the null bytes in the end?
24+
cx.span_err(span, "cannot concatenate C string literals");
25+
}
2126
Ok(ast::LitKind::Char(_)) => {
2227
let sugg =
2328
snippet.map(|snippet| ConcatBytesInvalidSuggestion::CharLit { span, snippet });

‎compiler/rustc_expand/src/proc_macro_server.rs‎

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Original file line numberDiff line numberDiff line change
@@ -61,6 +61,8 @@ impl FromInternal<token::LitKind> for LitKind {
6161
token::StrRaw(n) => LitKind::StrRaw(n),
6262
token::ByteStr => LitKind::ByteStr,
6363
token::ByteStrRaw(n) => LitKind::ByteStrRaw(n),
64+
token::CStr => LitKind::CStr,
65+
token::CStrRaw(n) => LitKind::CStrRaw(n),
6466
token::Err => LitKind::Err,
6567
token::Bool => unreachable!(),
6668
}
@@ -78,6 +80,8 @@ impl ToInternal<token::LitKind> for LitKind {
7880
LitKind::StrRaw(n) => token::StrRaw(n),
7981
LitKind::ByteStr => token::ByteStr,
8082
LitKind::ByteStrRaw(n) => token::ByteStrRaw(n),
83+
LitKind::CStr => token::CStr,
84+
LitKind::CStrRaw(n) => token::CStrRaw(n),
8185
LitKind::Err => token::Err,
8286
}
8387
}
@@ -436,6 +440,8 @@ impl server::FreeFunctions for Rustc<'_, '_> {
436440
| token::LitKind::StrRaw(_)
437441
| token::LitKind::ByteStr
438442
| token::LitKind::ByteStrRaw(_)
443+
| token::LitKind::CStr
444+
| token::LitKind::CStrRaw(_)
439445
| token::LitKind::Err => return Err(()),
440446
token::LitKind::Integer | token::LitKind::Float => {}
441447
}

‎compiler/rustc_feature/src/active.rs‎

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Original file line numberDiff line numberDiff line change
@@ -313,6 +313,8 @@ declare_features! (
313313
(active, async_closure, "1.37.0", Some(62290), None),
314314
/// Allows async functions to be declared, implemented, and used in traits.
315315
(active, async_fn_in_trait, "1.66.0", Some(91611), None),
316+
/// Allows `c"foo"` literals.
317+
(active, c_str_literals, "CURRENT_RUSTC_VERSION", Some(105723), None),
316318
/// Treat `extern "C"` function as nounwind.
317319
(active, c_unwind, "1.52.0", Some(74990), None),
318320
/// Allows using C-variadics.

‎compiler/rustc_hir/src/lang_items.rs‎

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Original file line numberDiff line numberDiff line change
@@ -333,6 +333,7 @@ language_item_table! {
333333
RangeTo, sym::RangeTo, range_to_struct, Target::Struct, GenericRequirement::None;
334334

335335
String, sym::String, string, Target::Struct, GenericRequirement::None;
336+
CStr, sym::CStr, c_str, Target::Struct, GenericRequirement::None;
336337
}
337338

338339
pub enum GenericRequirement {

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