Rollup merge of #118691 - chfogelman:improve-cstr-error, r=fmease

Add check for possible CStr literals in pre-2021

Fixes [#118654](https://github.com/rust-lang/rust/issues/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!
This commit is contained in:
Matthias Krüger 2023-12-20 09:46:10 +01:00 committed by GitHub
commit f3f9b3043e
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3 changed files with 158 additions and 7 deletions

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@ -10,13 +10,13 @@ use crate::errors::{
ConstGenericWithoutBracesSugg, DocCommentDoesNotDocumentAnything, DocCommentOnParamType,
DoubleColonInBound, ExpectedIdentifier, ExpectedSemi, ExpectedSemiSugg,
GenericParamsWithoutAngleBrackets, GenericParamsWithoutAngleBracketsSugg,
HelpIdentifierStartsWithNumber, InInTypo, IncorrectAwait, IncorrectSemicolon,
IncorrectUseOfAwait, PatternMethodParamWithoutBody, QuestionMarkInType, QuestionMarkInTypeSugg,
SelfParamNotFirst, StructLiteralBodyWithoutPath, StructLiteralBodyWithoutPathSugg,
StructLiteralNeedingParens, StructLiteralNeedingParensSugg, SuggAddMissingLetStmt,
SuggEscapeIdentifier, SuggRemoveComma, TernaryOperator, UnexpectedConstInGenericParam,
UnexpectedConstParamDeclaration, UnexpectedConstParamDeclarationSugg, UnmatchedAngleBrackets,
UseEqInstead, WrapType,
HelpIdentifierStartsWithNumber, HelpUseLatestEdition, InInTypo, IncorrectAwait,
IncorrectSemicolon, IncorrectUseOfAwait, PatternMethodParamWithoutBody, QuestionMarkInType,
QuestionMarkInTypeSugg, SelfParamNotFirst, StructLiteralBodyWithoutPath,
StructLiteralBodyWithoutPathSugg, StructLiteralNeedingParens, StructLiteralNeedingParensSugg,
SuggAddMissingLetStmt, SuggEscapeIdentifier, SuggRemoveComma, TernaryOperator,
UnexpectedConstInGenericParam, UnexpectedConstParamDeclaration,
UnexpectedConstParamDeclarationSugg, UnmatchedAngleBrackets, UseEqInstead, WrapType,
};
use crate::fluent_generated as fluent;
use crate::parser;
@ -640,6 +640,28 @@ impl<'a> Parser<'a> {
}
}
// Try to detect an intended c-string literal while using a pre-2021 edition. The heuristic
// here is to identify a cooked, uninterpolated `c` id immediately followed by a string, or
// a cooked, uninterpolated `cr` id immediately followed by a string or a `#`, in an edition
// where c-string literals are not allowed. There is the very slight possibility of a false
// positive for a `cr#` that wasn't intended to start a c-string literal, but identifying
// that in the parser requires unbounded lookahead, so we only add a hint to the existing
// error rather than replacing it entirely.
if ((self.prev_token.kind == TokenKind::Ident(sym::c, false)
&& matches!(&self.token.kind, TokenKind::Literal(token::Lit { kind: token::Str, .. })))
|| (self.prev_token.kind == TokenKind::Ident(sym::cr, false)
&& matches!(
&self.token.kind,
TokenKind::Literal(token::Lit { kind: token::Str, .. }) | token::Pound
)))
&& self.prev_token.span.hi() == self.token.span.lo()
&& !self.token.span.at_least_rust_2021()
{
err.note("you may be trying to write a c-string literal");
err.note("c-string literals require Rust 2021 or later");
HelpUseLatestEdition::new().add_to_diagnostic(&mut err);
}
// `pub` may be used for an item or `pub(crate)`
if self.prev_token.is_ident_named(sym::public)
&& (self.token.can_begin_item()

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

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@ -0,0 +1,67 @@
error: expected one of `!`, `.`, `::`, `;`, `?`, `{`, `}`, or an operator, found `"str"`
--> $DIR/edition-cstr-2015-2018.rs:27:6
|
LL | c"str";
| ^^^^^ expected one of 8 possible tokens
|
= note: you may be trying to write a c-string literal
= note: c-string literals require Rust 2021 or later
= help: pass `--edition 2021` to `rustc`
= note: for more on editions, read https://doc.rust-lang.org/edition-guide
error: expected one of `!`, `.`, `::`, `;`, `?`, `{`, `}`, or an operator, found `"str"`
--> $DIR/edition-cstr-2015-2018.rs:37:7
|
LL | cr"str";
| ^^^^^ expected one of 8 possible tokens
|
= note: you may be trying to write a c-string literal
= note: c-string literals require Rust 2021 or later
= help: pass `--edition 2021` to `rustc`
= note: for more on editions, read https://doc.rust-lang.org/edition-guide
error: expected one of `!`, `.`, `::`, `;`, `?`, `{`, `}`, or an operator, found `#`
--> $DIR/edition-cstr-2015-2018.rs:47:7
|
LL | cr##"str"##;
| ^ expected one of 8 possible tokens
|
= note: you may be trying to write a c-string literal
= note: c-string literals require Rust 2021 or later
= help: pass `--edition 2021` to `rustc`
= note: for more on editions, read https://doc.rust-lang.org/edition-guide
error: expected one of `!`, `.`, `::`, `;`, `?`, `{`, `}`, or an operator, found `"str"`
--> $DIR/edition-cstr-2015-2018.rs:57:7
|
LL | c "str";
| ^^^^^ expected one of 8 possible tokens
error: expected one of `!`, `.`, `::`, `;`, `?`, `{`, `}`, or an operator, found `"str"`
--> $DIR/edition-cstr-2015-2018.rs:1:44
|
LL | macro_rules! construct { ($x:ident) => { $x"str" } }
| ^^^^^ expected one of 8 possible tokens
...
LL | construct!(c);
| ------------- in this macro invocation
|
= note: this error originates in the macro `construct` (in Nightly builds, run with -Z macro-backtrace for more info)
error: expected one of `!`, `.`, `::`, `;`, `?`, `{`, `}`, or an operator, found `"str"`
--> $DIR/edition-cstr-2015-2018.rs:5:33
|
LL | macro_rules! contain { () => { c"str" } }
| ^^^^^ expected one of 8 possible tokens
...
LL | contain!();
| ---------- in this macro invocation
|
= note: you may be trying to write a c-string literal
= note: c-string literals require Rust 2021 or later
= help: pass `--edition 2021` to `rustc`
= note: for more on editions, read https://doc.rust-lang.org/edition-guide
= note: this error originates in the macro `contain` (in Nightly builds, run with -Z macro-backtrace for more info)
error: aborting due to 6 previous errors