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Auto merge of #117472 - jmillikin:stable-c-str-literals, r=Nilstrieb
Stabilize C string literals RFC: https://rust-lang.github.io/rfcs/3348-c-str-literal.html Tracking issue: #105723 Documentation PR (reference manual): rust-lang/reference#1423 # Stabilization report Stabilizes C string and raw C string literals (`c"..."` and `cr#"..."#`), which are expressions of type [`&CStr`](https://doc.rust-lang.org/stable/core/ffi/struct.CStr.html). Both new literals require Rust edition 2021 or later. ```rust const HELLO: &core::ffi::CStr = c"Hello, world!"; ``` C strings may contain any byte other than `NUL` (`b'\x00'`), and their in-memory representation is guaranteed to end with `NUL`. ## Implementation Originally implemented by PR #108801, which was reverted due to unintentional changes to lexer behavior in Rust editions < 2021. The current implementation landed in PR #113476, which restricts C string literals to Rust edition >= 2021. ## Resolutions to open questions from the RFC * Adding C character literals (`c'.'`) of type `c_char` is not part of this feature. * Support for `c"..."` literals does not prevent `c'.'` literals from being added in the future. * C string literals should not be blocked on making `&CStr` a thin pointer. * It's possible to declare constant expressions of type `&'static CStr` in stable Rust (as of v1.59), so C string literals are not adding additional coupling on the internal representation of `CStr`. * The unstable `concat_bytes!` macro should not accept `c"..."` literals. * C strings have two equally valid `&[u8]` representations (with or without terminal `NUL`), so allowing them to be used in `concat_bytes!` would be ambiguous. * Adding a type to represent C strings containing valid UTF-8 is not part of this feature. * Support for a hypothetical `&Utf8CStr` may be explored in the future, should such a type be added to Rust.
2 parents 071f8f6 + e3a1555 commit 3a76090

6 files changed

+22
-26
lines changed

‎tests/ui/needless_raw_string.fixed

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@@ -1,6 +1,5 @@
11
#![allow(clippy::needless_raw_string_hashes, clippy::no_effect, unused)]
22
#![warn(clippy::needless_raw_strings)]
3-
#![feature(c_str_literals)]
43

54
fn main() {
65
"aaa";

‎tests/ui/needless_raw_string.rs

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@@ -1,6 +1,5 @@
11
#![allow(clippy::needless_raw_string_hashes, clippy::no_effect, unused)]
22
#![warn(clippy::needless_raw_strings)]
3-
#![feature(c_str_literals)]
43

54
fn main() {
65
r#"aaa"#;

‎tests/ui/needless_raw_string.stderr

+7-7
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@@ -1,5 +1,5 @@
11
error: unnecessary raw string literal
2-
--> $DIR/needless_raw_string.rs:6:5
2+
--> $DIR/needless_raw_string.rs:5:5
33
|
44
LL | r#"aaa"#;
55
| ^^^^^^^^
@@ -13,7 +13,7 @@ LL + "aaa";
1313
|
1414

1515
error: unnecessary raw string literal
16-
--> $DIR/needless_raw_string.rs:9:5
16+
--> $DIR/needless_raw_string.rs:8:5
1717
|
1818
LL | br#"aaa"#;
1919
| ^^^^^^^^^
@@ -25,7 +25,7 @@ LL + b"aaa";
2525
|
2626

2727
error: unnecessary raw string literal
28-
--> $DIR/needless_raw_string.rs:12:5
28+
--> $DIR/needless_raw_string.rs:11:5
2929
|
3030
LL | cr#"aaa"#;
3131
| ^^^^^^^^^
@@ -37,7 +37,7 @@ LL + c"aaa";
3737
|
3838

3939
error: unnecessary raw string literal
40-
--> $DIR/needless_raw_string.rs:16:5
40+
--> $DIR/needless_raw_string.rs:15:5
4141
|
4242
LL | / r#"
4343
LL | | a
@@ -56,7 +56,7 @@ LL ~ ";
5656
|
5757

5858
error: unnecessary raw string literal
59-
--> $DIR/needless_raw_string.rs:22:5
59+
--> $DIR/needless_raw_string.rs:21:5
6060
|
6161
LL | r"no hashes";
6262
| ^^^^^^^^^^^^
@@ -68,7 +68,7 @@ LL + "no hashes";
6868
|
6969

7070
error: unnecessary raw string literal
71-
--> $DIR/needless_raw_string.rs:23:5
71+
--> $DIR/needless_raw_string.rs:22:5
7272
|
7373
LL | br"no hashes";
7474
| ^^^^^^^^^^^^^
@@ -80,7 +80,7 @@ LL + b"no hashes";
8080
|
8181

8282
error: unnecessary raw string literal
83-
--> $DIR/needless_raw_string.rs:24:5
83+
--> $DIR/needless_raw_string.rs:23:5
8484
|
8585
LL | cr"no hashes";
8686
| ^^^^^^^^^^^^^

‎tests/ui/needless_raw_string_hashes.fixed

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@@ -1,6 +1,5 @@
11
#![allow(clippy::no_effect, unused)]
22
#![warn(clippy::needless_raw_string_hashes)]
3-
#![feature(c_str_literals)]
43

54
fn main() {
65
r"\aaa";

‎tests/ui/needless_raw_string_hashes.rs

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@@ -1,6 +1,5 @@
11
#![allow(clippy::no_effect, unused)]
22
#![warn(clippy::needless_raw_string_hashes)]
3-
#![feature(c_str_literals)]
43

54
fn main() {
65
r#"\aaa"#;

‎tests/ui/needless_raw_string_hashes.stderr

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Original file line numberDiff line numberDiff line change
@@ -1,5 +1,5 @@
11
error: unnecessary hashes around raw string literal
2-
--> $DIR/needless_raw_string_hashes.rs:6:5
2+
--> $DIR/needless_raw_string_hashes.rs:5:5
33
|
44
LL | r#"\aaa"#;
55
| ^^^^^^^^^
@@ -13,7 +13,7 @@ LL + r"\aaa";
1313
|
1414

1515
error: unnecessary hashes around raw string literal
16-
--> $DIR/needless_raw_string_hashes.rs:7:5
16+
--> $DIR/needless_raw_string_hashes.rs:6:5
1717
|
1818
LL | r##"Hello "world"!"##;
1919
| ^^^^^^^^^^^^^^^^^^^^^
@@ -25,7 +25,7 @@ LL + r#"Hello "world"!"#;
2525
|
2626

2727
error: unnecessary hashes around raw string literal
28-
--> $DIR/needless_raw_string_hashes.rs:8:5
28+
--> $DIR/needless_raw_string_hashes.rs:7:5
2929
|
3030
LL | r######" "### "## "# "######;
3131
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -37,7 +37,7 @@ LL + r####" "### "## "# "####;
3737
|
3838

3939
error: unnecessary hashes around raw string literal
40-
--> $DIR/needless_raw_string_hashes.rs:9:5
40+
--> $DIR/needless_raw_string_hashes.rs:8:5
4141
|
4242
LL | r######" "aa" "# "## "######;
4343
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -49,7 +49,7 @@ LL + r###" "aa" "# "## "###;
4949
|
5050

5151
error: unnecessary hashes around raw string literal
52-
--> $DIR/needless_raw_string_hashes.rs:10:5
52+
--> $DIR/needless_raw_string_hashes.rs:9:5
5353
|
5454
LL | br#"\aaa"#;
5555
| ^^^^^^^^^^
@@ -61,7 +61,7 @@ LL + br"\aaa";
6161
|
6262

6363
error: unnecessary hashes around raw string literal
64-
--> $DIR/needless_raw_string_hashes.rs:11:5
64+
--> $DIR/needless_raw_string_hashes.rs:10:5
6565
|
6666
LL | br##"Hello "world"!"##;
6767
| ^^^^^^^^^^^^^^^^^^^^^^
@@ -73,7 +73,7 @@ LL + br#"Hello "world"!"#;
7373
|
7474

7575
error: unnecessary hashes around raw string literal
76-
--> $DIR/needless_raw_string_hashes.rs:12:5
76+
--> $DIR/needless_raw_string_hashes.rs:11:5
7777
|
7878
LL | br######" "### "## "# "######;
7979
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -85,7 +85,7 @@ LL + br####" "### "## "# "####;
8585
|
8686

8787
error: unnecessary hashes around raw string literal
88-
--> $DIR/needless_raw_string_hashes.rs:13:5
88+
--> $DIR/needless_raw_string_hashes.rs:12:5
8989
|
9090
LL | br######" "aa" "# "## "######;
9191
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -97,7 +97,7 @@ LL + br###" "aa" "# "## "###;
9797
|
9898

9999
error: unnecessary hashes around raw string literal
100-
--> $DIR/needless_raw_string_hashes.rs:14:5
100+
--> $DIR/needless_raw_string_hashes.rs:13:5
101101
|
102102
LL | cr#"\aaa"#;
103103
| ^^^^^^^^^^
@@ -109,7 +109,7 @@ LL + cr"\aaa";
109109
|
110110

111111
error: unnecessary hashes around raw string literal
112-
--> $DIR/needless_raw_string_hashes.rs:15:5
112+
--> $DIR/needless_raw_string_hashes.rs:14:5
113113
|
114114
LL | cr##"Hello "world"!"##;
115115
| ^^^^^^^^^^^^^^^^^^^^^^
@@ -121,7 +121,7 @@ LL + cr#"Hello "world"!"#;
121121
|
122122

123123
error: unnecessary hashes around raw string literal
124-
--> $DIR/needless_raw_string_hashes.rs:16:5
124+
--> $DIR/needless_raw_string_hashes.rs:15:5
125125
|
126126
LL | cr######" "### "## "# "######;
127127
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -133,7 +133,7 @@ LL + cr####" "### "## "# "####;
133133
|
134134

135135
error: unnecessary hashes around raw string literal
136-
--> $DIR/needless_raw_string_hashes.rs:17:5
136+
--> $DIR/needless_raw_string_hashes.rs:16:5
137137
|
138138
LL | cr######" "aa" "# "## "######;
139139
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -145,7 +145,7 @@ LL + cr###" "aa" "# "## "###;
145145
|
146146

147147
error: unnecessary hashes around raw string literal
148-
--> $DIR/needless_raw_string_hashes.rs:19:5
148+
--> $DIR/needless_raw_string_hashes.rs:18:5
149149
|
150150
LL | / r#"
151151
LL | | \a
@@ -164,7 +164,7 @@ LL ~ ";
164164
|
165165

166166
error: unnecessary hashes around raw string literal
167-
--> $DIR/needless_raw_string_hashes.rs:25:5
167+
--> $DIR/needless_raw_string_hashes.rs:24:5
168168
|
169169
LL | r###"rust"###;
170170
| ^^^^^^^^^^^^^
@@ -176,7 +176,7 @@ LL + r"rust";
176176
|
177177

178178
error: unnecessary hashes around raw string literal
179-
--> $DIR/needless_raw_string_hashes.rs:26:5
179+
--> $DIR/needless_raw_string_hashes.rs:25:5
180180
|
181181
LL | r#"hello world"#;
182182
| ^^^^^^^^^^^^^^^^

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