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Improve compiler error for c-strings in pre-2021
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3 files changed

+158
-7
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3 files changed

+158
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‎compiler/rustc_parse/src/parser/diagnostics.rs

+29-7
Original file line numberDiff line numberDiff line change
@@ -10,13 +10,13 @@ use crate::errors::{
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ConstGenericWithoutBracesSugg, DocCommentDoesNotDocumentAnything, DocCommentOnParamType,
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DoubleColonInBound, ExpectedIdentifier, ExpectedSemi, ExpectedSemiSugg,
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GenericParamsWithoutAngleBrackets, GenericParamsWithoutAngleBracketsSugg,
13-
HelpIdentifierStartsWithNumber, InInTypo, IncorrectAwait, IncorrectSemicolon,
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IncorrectUseOfAwait, PatternMethodParamWithoutBody, QuestionMarkInType, QuestionMarkInTypeSugg,
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SelfParamNotFirst, StructLiteralBodyWithoutPath, StructLiteralBodyWithoutPathSugg,
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StructLiteralNeedingParens, StructLiteralNeedingParensSugg, SuggAddMissingLetStmt,
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SuggEscapeIdentifier, SuggRemoveComma, TernaryOperator, UnexpectedConstInGenericParam,
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UnexpectedConstParamDeclaration, UnexpectedConstParamDeclarationSugg, UnmatchedAngleBrackets,
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UseEqInstead, WrapType,
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HelpIdentifierStartsWithNumber, HelpUseLatestEdition, InInTypo, IncorrectAwait,
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IncorrectSemicolon, IncorrectUseOfAwait, PatternMethodParamWithoutBody, QuestionMarkInType,
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QuestionMarkInTypeSugg, SelfParamNotFirst, StructLiteralBodyWithoutPath,
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StructLiteralBodyWithoutPathSugg, StructLiteralNeedingParens, StructLiteralNeedingParensSugg,
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SuggAddMissingLetStmt, SuggEscapeIdentifier, SuggRemoveComma, TernaryOperator,
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UnexpectedConstInGenericParam, UnexpectedConstParamDeclaration,
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UnexpectedConstParamDeclarationSugg, UnmatchedAngleBrackets, UseEqInstead, WrapType,
2020
};
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use crate::fluent_generated as fluent;
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use crate::parser;
@@ -640,6 +640,28 @@ impl<'a> Parser<'a> {
640640
}
641641
}
642642

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// Try to detect an intended c-string literal while using a pre-2021 edition. The heuristic
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// here is to identify a cooked, uninterpolated `c` id immediately followed by a string, or
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// a cooked, uninterpolated `cr` id immediately followed by a string or a `#`, in an edition
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// where c-string literals are not allowed. There is the very slight possibility of a false
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// positive for a `cr#` that wasn't intended to start a c-string literal, but identifying
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// that in the parser requires unbounded lookahead, so we only add a hint to the existing
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// error rather than replacing it entirely.
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if ((self.prev_token.kind == TokenKind::Ident(sym::c, false)
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&& matches!(&self.token.kind, TokenKind::Literal(token::Lit { kind: token::Str, .. })))
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|| (self.prev_token.kind == TokenKind::Ident(sym::cr, false)
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&& matches!(
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&self.token.kind,
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TokenKind::Literal(token::Lit { kind: token::Str, .. }) | token::Pound
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)))
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&& self.prev_token.span.hi() == self.token.span.lo()
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&& !self.token.span.at_least_rust_2021()
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{
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err.note("you may be trying to write a c-string literal");
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err.note("c-string literals require Rust 2021 or later");
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HelpUseLatestEdition::new().add_to_diagnostic(&mut err);
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}
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643665
// `pub` may be used for an item or `pub(crate)`
644666
if self.prev_token.is_ident_named(sym::public)
645667
&& (self.token.can_begin_item()

‎tests/ui/editions/edition-cstr-2015-2018.rs

+62
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,62 @@
1+
macro_rules! construct { ($x:ident) => { $x"str" } }
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//~^ ERROR expected one of `!`, `.`, `::`, `;`, `?`, `{`, `}`, or an operator, found `"str"`
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//~| NOTE expected one of 8 possible tokens
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macro_rules! contain { () => { c"str" } }
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//~^ ERROR expected one of `!`, `.`, `::`, `;`, `?`, `{`, `}`, or an operator, found `"str"`
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//~| NOTE expected one of 8 possible tokens
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//~| NOTE you may be trying to write a c-string literal
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//~| NOTE c-string literals require Rust 2021 or later
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//~| HELP pass `--edition 2021` to `rustc`
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//~| NOTE for more on editions, read https://doc.rust-lang.org/edition-guide
12+
13+
fn check_macro_construct() {
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construct!(c); //~ NOTE in this expansion of construct!
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}
16+
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fn check_macro_contain() {
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contain!();
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//~^ NOTE in this expansion of contain!
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//~| NOTE in this expansion of contain!
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//~| NOTE in this expansion of contain!
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//~| NOTE in this expansion of contain!
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//~| NOTE in this expansion of contain!
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}
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fn check_basic() {
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c"str";
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//~^ ERROR expected one of `!`, `.`, `::`, `;`, `?`, `{`, `}`, or an operator, found `"str"`
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//~| NOTE expected one of 8 possible tokens
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//~| NOTE you may be trying to write a c-string literal
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//~| NOTE c-string literals require Rust 2021 or later
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//~| HELP pass `--edition 2021` to `rustc`
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//~| NOTE for more on editions, read https://doc.rust-lang.org/edition-guide
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}
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fn check_craw() {
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cr"str";
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//~^ ERROR expected one of `!`, `.`, `::`, `;`, `?`, `{`, `}`, or an operator, found `"str"`
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//~| NOTE expected one of 8 possible tokens
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//~| NOTE you may be trying to write a c-string literal
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//~| NOTE c-string literals require Rust 2021 or later
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//~| HELP pass `--edition 2021` to `rustc`
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//~| NOTE for more on editions, read https://doc.rust-lang.org/edition-guide
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}
45+
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fn check_craw_hash() {
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cr##"str"##;
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//~^ ERROR expected one of `!`, `.`, `::`, `;`, `?`, `{`, `}`, or an operator, found `#`
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//~| NOTE expected one of 8 possible tokens
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//~| NOTE you may be trying to write a c-string literal
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//~| NOTE c-string literals require Rust 2021 or later
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//~| HELP pass `--edition 2021` to `rustc`
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//~| NOTE for more on editions, read https://doc.rust-lang.org/edition-guide
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}
55+
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fn check_cstr_space() {
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c "str";
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//~^ ERROR expected one of `!`, `.`, `::`, `;`, `?`, `{`, `}`, or an operator, found `"str"`
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//~| NOTE expected one of 8 possible tokens
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}
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fn main() {}

‎tests/ui/editions/edition-cstr-2015-2018.stderr

+67
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,67 @@
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error: expected one of `!`, `.`, `::`, `;`, `?`, `{`, `}`, or an operator, found `"str"`
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--> $DIR/edition-cstr-2015-2018.rs:27:6
3+
|
4+
LL | c"str";
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| ^^^^^ expected one of 8 possible tokens
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|
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= note: you may be trying to write a c-string literal
8+
= note: c-string literals require Rust 2021 or later
9+
= help: pass `--edition 2021` to `rustc`
10+
= note: for more on editions, read https://doc.rust-lang.org/edition-guide
11+
12+
error: expected one of `!`, `.`, `::`, `;`, `?`, `{`, `}`, or an operator, found `"str"`
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--> $DIR/edition-cstr-2015-2018.rs:37:7
14+
|
15+
LL | cr"str";
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| ^^^^^ expected one of 8 possible tokens
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|
18+
= note: you may be trying to write a c-string literal
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= note: c-string literals require Rust 2021 or later
20+
= help: pass `--edition 2021` to `rustc`
21+
= note: for more on editions, read https://doc.rust-lang.org/edition-guide
22+
23+
error: expected one of `!`, `.`, `::`, `;`, `?`, `{`, `}`, or an operator, found `#`
24+
--> $DIR/edition-cstr-2015-2018.rs:47:7
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|
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LL | cr##"str"##;
27+
| ^ expected one of 8 possible tokens
28+
|
29+
= note: you may be trying to write a c-string literal
30+
= note: c-string literals require Rust 2021 or later
31+
= help: pass `--edition 2021` to `rustc`
32+
= note: for more on editions, read https://doc.rust-lang.org/edition-guide
33+
34+
error: expected one of `!`, `.`, `::`, `;`, `?`, `{`, `}`, or an operator, found `"str"`
35+
--> $DIR/edition-cstr-2015-2018.rs:57:7
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|
37+
LL | c "str";
38+
| ^^^^^ expected one of 8 possible tokens
39+
40+
error: expected one of `!`, `.`, `::`, `;`, `?`, `{`, `}`, or an operator, found `"str"`
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--> $DIR/edition-cstr-2015-2018.rs:1:44
42+
|
43+
LL | macro_rules! construct { ($x:ident) => { $x"str" } }
44+
| ^^^^^ expected one of 8 possible tokens
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...
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LL | construct!(c);
47+
| ------------- in this macro invocation
48+
|
49+
= note: this error originates in the macro `construct` (in Nightly builds, run with -Z macro-backtrace for more info)
50+
51+
error: expected one of `!`, `.`, `::`, `;`, `?`, `{`, `}`, or an operator, found `"str"`
52+
--> $DIR/edition-cstr-2015-2018.rs:5:33
53+
|
54+
LL | macro_rules! contain { () => { c"str" } }
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| ^^^^^ expected one of 8 possible tokens
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...
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LL | contain!();
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| ---------- in this macro invocation
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|
60+
= note: you may be trying to write a c-string literal
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= note: c-string literals require Rust 2021 or later
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= help: pass `--edition 2021` to `rustc`
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= note: for more on editions, read https://doc.rust-lang.org/edition-guide
64+
= note: this error originates in the macro `contain` (in Nightly builds, run with -Z macro-backtrace for more info)
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error: aborting due to 6 previous errors
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