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matthiaskrgrmatthiaskrgr
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Rollup merge of rust-lang#118691 - chfogelman:improve-cstr-error, r=fmease
Add check for possible CStr literals in pre-2021 Fixes [rust-lang#118654](rust-lang#118654) Adds information to errors caused by possible CStr literals in pre-2021. The lexer separates `c"str"` into two tokens if the edition is less than 2021, which later causes an error when parsing. This error now has a more helpful message that directs them to information about editions. However, the user might also have written `c "str"` in a later edition, so to not confuse people who _are_ using a recent edition, I also added a note about whitespace. We could probably figure out exactly which scenario has been encountered by examining spans and editions, but I figured it would be better not to overcomplicate the creation of the error too much. This is my first code PR and I tried to follow existing conventions as much as possible, but I probably missed something, so let me know!
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‎compiler/rustc_parse/src/parser/diagnostics.rs

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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,
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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,
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};
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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> {
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}
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}
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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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// `pub` may be used for an item or `pub(crate)`
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if self.prev_token.is_ident_named(sym::public)
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&& (self.token.can_begin_item()

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

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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
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fn check_macro_construct() {
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construct!(c); //~ NOTE in this expansion of construct!
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}
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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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}
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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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}
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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

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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
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|
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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
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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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error: expected one of `!`, `.`, `::`, `;`, `?`, `{`, `}`, or an operator, found `"str"`
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--> $DIR/edition-cstr-2015-2018.rs:37:7
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|
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LL | cr"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
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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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error: expected one of `!`, `.`, `::`, `;`, `?`, `{`, `}`, or an operator, found `#`
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--> $DIR/edition-cstr-2015-2018.rs:47:7
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|
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LL | cr##"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
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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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error: expected one of `!`, `.`, `::`, `;`, `?`, `{`, `}`, or an operator, found `"str"`
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--> $DIR/edition-cstr-2015-2018.rs:57:7
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|
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LL | c "str";
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| ^^^^^ expected one of 8 possible tokens
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error: expected one of `!`, `.`, `::`, `;`, `?`, `{`, `}`, or an operator, found `"str"`
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--> $DIR/edition-cstr-2015-2018.rs:1:44
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|
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LL | macro_rules! construct { ($x:ident) => { $x"str" } }
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| ^^^^^ expected one of 8 possible tokens
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...
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LL | construct!(c);
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| ------------- in this macro invocation
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|
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= note: this error originates in the macro `construct` (in Nightly builds, run with -Z macro-backtrace for more info)
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error: expected one of `!`, `.`, `::`, `;`, `?`, `{`, `}`, or an operator, found `"str"`
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--> $DIR/edition-cstr-2015-2018.rs:5:33
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|
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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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|
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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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= 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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