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Auto merge of rust-lang#94824 - Dylan-DPC:rollup-iamc09j, r=Dylan-DPC
Rollup of 7 pull requests Successful merges: - rust-lang#93950 (Use modern formatting for format! macros) - rust-lang#94274 (Treat unstable lints as unknown) - rust-lang#94368 ([1/2] Implement macro meta-variable expressions) - rust-lang#94719 (Statically compile libstdc++ everywhere if asked) - rust-lang#94728 (Only emit pointer-like metadata for `Box<T, A>` when `A` is ZST) - rust-lang#94790 (enable portable-simd doctests in Miri) - rust-lang#94811 (Update browser-ui-test version) Failed merges: r? `@ghost` `@rustbot` modify labels: rollup
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Original file line number | Diff line number | Diff line change |
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use rustc_ast::token; | ||
use rustc_ast::tokenstream::{Cursor, TokenStream, TokenTree}; | ||
use rustc_ast::{LitIntType, LitKind}; | ||
use rustc_ast_pretty::pprust; | ||
use rustc_errors::{Applicability, PResult}; | ||
use rustc_session::parse::ParseSess; | ||
use rustc_span::symbol::Ident; | ||
use rustc_span::Span; | ||
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||
/// A meta-variable expression, for expansions based on properties of meta-variables. | ||
#[derive(Debug, Clone, PartialEq, Encodable, Decodable)] | ||
crate enum MetaVarExpr { | ||
/// The number of repetitions of an identifier, optionally limited to a number | ||
/// of outer-most repetition depths. If the depth limit is `None` then the depth is unlimited. | ||
Count(Ident, Option<usize>), | ||
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||
/// Ignore a meta-variable for repetition without expansion. | ||
Ignore(Ident), | ||
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/// The index of the repetition at a particular depth, where 0 is the inner-most | ||
/// repetition. The `usize` is the depth. | ||
Index(usize), | ||
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/// The length of the repetition at a particular depth, where 0 is the inner-most | ||
/// repetition. The `usize` is the depth. | ||
Length(usize), | ||
} | ||
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impl MetaVarExpr { | ||
/// Attempt to parse a meta-variable expression from a token stream. | ||
crate fn parse<'sess>( | ||
input: &TokenStream, | ||
outer_span: Span, | ||
sess: &'sess ParseSess, | ||
) -> PResult<'sess, MetaVarExpr> { | ||
let mut tts = input.trees(); | ||
let ident = parse_ident(&mut tts, sess, outer_span)?; | ||
let Some(TokenTree::Delimited(_, token::Paren, args)) = tts.next() else { | ||
let msg = "meta-variable expression parameter must be wrapped in parentheses"; | ||
return Err(sess.span_diagnostic.struct_span_err(ident.span, msg)); | ||
}; | ||
check_trailing_token(&mut tts, sess)?; | ||
let mut iter = args.trees(); | ||
let rslt = match &*ident.as_str() { | ||
"count" => parse_count(&mut iter, sess, ident.span)?, | ||
"ignore" => MetaVarExpr::Ignore(parse_ident(&mut iter, sess, ident.span)?), | ||
"index" => MetaVarExpr::Index(parse_depth(&mut iter, sess, ident.span)?), | ||
"length" => MetaVarExpr::Length(parse_depth(&mut iter, sess, ident.span)?), | ||
_ => { | ||
let err_msg = "unrecognized meta-variable expression"; | ||
let mut err = sess.span_diagnostic.struct_span_err(ident.span, err_msg); | ||
err.span_suggestion( | ||
ident.span, | ||
"supported expressions are count, ignore, index and length", | ||
String::new(), | ||
Applicability::MachineApplicable, | ||
); | ||
return Err(err); | ||
} | ||
}; | ||
check_trailing_token(&mut iter, sess)?; | ||
Ok(rslt) | ||
} | ||
|
||
crate fn ident(&self) -> Option<&Ident> { | ||
match self { | ||
MetaVarExpr::Count(ident, _) | MetaVarExpr::Ignore(ident) => Some(&ident), | ||
MetaVarExpr::Index(..) | MetaVarExpr::Length(..) => None, | ||
} | ||
} | ||
} | ||
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||
// Checks if there are any remaining tokens. For example, `${ignore(ident ... a b c ...)}` | ||
fn check_trailing_token<'sess>(iter: &mut Cursor, sess: &'sess ParseSess) -> PResult<'sess, ()> { | ||
if let Some(tt) = iter.next() { | ||
let mut diag = sess.span_diagnostic.struct_span_err( | ||
tt.span(), | ||
&format!("unexpected token: {}", pprust::tt_to_string(&tt)), | ||
); | ||
diag.span_note(tt.span(), "meta-variable expression must not have trailing tokens"); | ||
Err(diag) | ||
} else { | ||
Ok(()) | ||
} | ||
} | ||
|
||
/// Parse a meta-variable `count` expression: `count(ident[, depth])` | ||
fn parse_count<'sess>( | ||
iter: &mut Cursor, | ||
sess: &'sess ParseSess, | ||
span: Span, | ||
) -> PResult<'sess, MetaVarExpr> { | ||
let ident = parse_ident(iter, sess, span)?; | ||
let depth = if try_eat_comma(iter) { Some(parse_depth(iter, sess, span)?) } else { None }; | ||
Ok(MetaVarExpr::Count(ident, depth)) | ||
} | ||
|
||
/// Parses the depth used by index(depth) and length(depth). | ||
fn parse_depth<'sess>( | ||
iter: &mut Cursor, | ||
sess: &'sess ParseSess, | ||
span: Span, | ||
) -> PResult<'sess, usize> { | ||
let Some(tt) = iter.next() else { return Ok(0) }; | ||
let TokenTree::Token(token::Token { | ||
kind: token::TokenKind::Literal(lit), .. | ||
}) = tt else { | ||
return Err(sess.span_diagnostic.struct_span_err( | ||
span, | ||
"meta-variable expression depth must be a literal" | ||
)); | ||
}; | ||
if let Ok(lit_kind) = LitKind::from_lit_token(lit) | ||
&& let LitKind::Int(n_u128, LitIntType::Unsuffixed) = lit_kind | ||
&& let Ok(n_usize) = usize::try_from(n_u128) | ||
{ | ||
Ok(n_usize) | ||
} | ||
else { | ||
let msg = "only unsuffixes integer literals are supported in meta-variable expressions"; | ||
Err(sess.span_diagnostic.struct_span_err(span, msg)) | ||
} | ||
} | ||
|
||
/// Parses an generic ident | ||
fn parse_ident<'sess>( | ||
iter: &mut Cursor, | ||
sess: &'sess ParseSess, | ||
span: Span, | ||
) -> PResult<'sess, Ident> { | ||
let err_fn = |msg| sess.span_diagnostic.struct_span_err(span, msg); | ||
if let Some(tt) = iter.next() && let TokenTree::Token(token) = tt { | ||
if let Some((elem, false)) = token.ident() { | ||
return Ok(elem); | ||
} | ||
let token_str = pprust::token_to_string(&token); | ||
let mut err = err_fn(&format!("expected identifier, found `{}`", &token_str)); | ||
err.span_suggestion( | ||
token.span, | ||
&format!("try removing `{}`", &token_str), | ||
String::new(), | ||
Applicability::MaybeIncorrect, | ||
); | ||
return Err(err); | ||
} | ||
Err(err_fn("expected identifier")) | ||
} | ||
|
||
/// Tries to move the iterator forward returning `true` if there is a comma. If not, then the | ||
/// iterator is not modified and the result is `false`. | ||
fn try_eat_comma(iter: &mut Cursor) -> bool { | ||
if let Some(TokenTree::Token(token::Token { kind: token::Comma, .. })) = iter.look_ahead(0) { | ||
let _ = iter.next(); | ||
return true; | ||
} | ||
false | ||
} |
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