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Auto merge of #112216 - est31:offset_of_deep_tuple, r=petrochenkov

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Support float-like tuple indices in offset_of!()

Supports invocations like `offset_of!((((), ()), ()), 0.0)`. This `0.0` gets tokenized as float literal, so it has to be broken up again.

The code that did the breaking up was returning a finished `Expr`, while we need a `Ident`, so this PR splits up the `parse_expr_tuple_field_access_float` function into:

* a function that breaks up the float literal (similar to `TokenKind::break_two_token_op`, but we do access the parser during this splitting operation, so we keep it as an inherent function on the parser)
* and a function that constructs an `Expr` from it

The former we can then re-use in `offset_of` parsing. The edge cases especially involving whitespaces are tricky so this adds a bunch of new tests as well.

fixes #112204
This commit is contained in:
bors 2023-06-09 18:53:58 +00:00
commit 43062c43d2
4 changed files with 391 additions and 43 deletions
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116
compiler/rustc_parse/src/parser/expr.rs
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@ -91,6 +91,18 @@ impl From<P<Expr>> for LhsExpr {
}
}
#[derive(Debug)]
enum DestructuredFloat {
/// 1e2
Single(Symbol, Span),
/// 1.
TrailingDot(Symbol, Span, Span),
/// 1.2 | 1.2e3
MiddleDot(Symbol, Span, Span, Symbol, Span),
/// Invalid
Error,
}
impl<'a> Parser<'a> {
/// Parses an expression.
#[inline]
@ -1013,13 +1025,8 @@ impl<'a> Parser<'a> {
// support pushing "future tokens" (would be also helpful to `break_and_eat`), or
// we should break everything including floats into more basic proc-macro style
// tokens in the lexer (probably preferable).
fn parse_expr_tuple_field_access_float(
&mut self,
lo: Span,
base: P<Expr>,
float: Symbol,
suffix: Option<Symbol>,
) -> P<Expr> {
// See also `TokenKind::break_two_token_op` which does similar splitting of `>>` into `>`.
fn break_up_float(&mut self, float: Symbol) -> DestructuredFloat {
#[derive(Debug)]
enum FloatComponent {
IdentLike(String),
@ -1056,7 +1063,7 @@ impl<'a> Parser<'a> {
match &*components {
// 1e2
[IdentLike(i)] => {
self.parse_expr_tuple_field_access(lo, base, Symbol::intern(&i), suffix, None)
DestructuredFloat::Single(Symbol::intern(&i), span)
}
// 1.
[IdentLike(i), Punct('.')] => {
@ -1068,11 +1075,8 @@ impl<'a> Parser<'a> {
} else {
(span, span)
};
assert!(suffix.is_none());
let symbol = Symbol::intern(&i);
self.token = Token::new(token::Ident(symbol, false), ident_span);
let next_token = (Token::new(token::Dot, dot_span), self.token_spacing);
self.parse_expr_tuple_field_access(lo, base, symbol, None, Some(next_token))
DestructuredFloat::TrailingDot(symbol, ident_span, dot_span)
}
// 1.2 | 1.2e3
[IdentLike(i1), Punct('.'), IdentLike(i2)] => {
@ -1088,16 +1092,8 @@ impl<'a> Parser<'a> {
(span, span, span)
};
let symbol1 = Symbol::intern(&i1);
self.token = Token::new(token::Ident(symbol1, false), ident1_span);
// This needs to be `Spacing::Alone` to prevent regressions.
// See issue #76399 and PR #76285 for more details
let next_token1 = (Token::new(token::Dot, dot_span), Spacing::Alone);
let base1 =
self.parse_expr_tuple_field_access(lo, base, symbol1, None, Some(next_token1));
let symbol2 = Symbol::intern(&i2);
let next_token2 = Token::new(token::Ident(symbol2, false), ident2_span);
self.bump_with((next_token2, self.token_spacing)); // `.`
self.parse_expr_tuple_field_access(lo, base1, symbol2, suffix, None)
DestructuredFloat::MiddleDot(symbol1, ident1_span, dot_span, symbol2, ident2_span)
}
// 1e+ | 1e- (recovered)
[IdentLike(_), Punct('+' | '-')] |
@ -1109,12 +1105,83 @@ impl<'a> Parser<'a> {
[IdentLike(_), Punct('.'), IdentLike(_), Punct('+' | '-'), IdentLike(_)] => {
// See the FIXME about `TokenCursor` above.
self.error_unexpected_after_dot();
base
DestructuredFloat::Error
}
_ => panic!("unexpected components in a float token: {:?}", components),
}
}
fn parse_expr_tuple_field_access_float(
&mut self,
lo: Span,
base: P<Expr>,
float: Symbol,
suffix: Option<Symbol>,
) -> P<Expr> {
match self.break_up_float(float) {
// 1e2
DestructuredFloat::Single(sym, _sp) => {
self.parse_expr_tuple_field_access(lo, base, sym, suffix, None)
}
// 1.
DestructuredFloat::TrailingDot(sym, ident_span, dot_span) => {
assert!(suffix.is_none());
self.token = Token::new(token::Ident(sym, false), ident_span);
let next_token = (Token::new(token::Dot, dot_span), self.token_spacing);
self.parse_expr_tuple_field_access(lo, base, sym, None, Some(next_token))
}
// 1.2 | 1.2e3
DestructuredFloat::MiddleDot(symbol1, ident1_span, dot_span, symbol2, ident2_span) => {
self.token = Token::new(token::Ident(symbol1, false), ident1_span);
// This needs to be `Spacing::Alone` to prevent regressions.
// See issue #76399 and PR #76285 for more details
let next_token1 = (Token::new(token::Dot, dot_span), Spacing::Alone);
let base1 =
self.parse_expr_tuple_field_access(lo, base, symbol1, None, Some(next_token1));
let next_token2 = Token::new(token::Ident(symbol2, false), ident2_span);
self.bump_with((next_token2, self.token_spacing)); // `.`
self.parse_expr_tuple_field_access(lo, base1, symbol2, suffix, None)
}
DestructuredFloat::Error => base,
}
}
fn parse_field_name_maybe_tuple(&mut self) -> PResult<'a, ThinVec<Ident>> {
let token::Literal(token::Lit { kind: token::Float, symbol, suffix }) = self.token.kind
else {
return Ok(thin_vec![self.parse_field_name()?]);
};
Ok(match self.break_up_float(symbol) {
// 1e2
DestructuredFloat::Single(sym, sp) => {
self.bump();
thin_vec![Ident::new(sym, sp)]
}
// 1.
DestructuredFloat::TrailingDot(sym, sym_span, dot_span) => {
assert!(suffix.is_none());
// Analogous to `Self::break_and_eat`
self.token_cursor.break_last_token = true;
// This might work, in cases like `1. 2`, and might not,
// in cases like `offset_of!(Ty, 1.)`. It depends on what comes
// after the float-like token, and therefore we have to make
// the other parts of the parser think that there is a dot literal.
self.token = Token::new(token::Ident(sym, false), sym_span);
self.bump_with((Token::new(token::Dot, dot_span), self.token_spacing));
thin_vec![Ident::new(sym, sym_span)]
}
// 1.2 | 1.2e3
DestructuredFloat::MiddleDot(symbol1, ident1_span, _dot_span, symbol2, ident2_span) => {
self.bump();
thin_vec![Ident::new(symbol1, ident1_span), Ident::new(symbol2, ident2_span)]
}
DestructuredFloat::Error => {
self.bump();
thin_vec![Ident::new(symbol, self.prev_token.span)]
}
})
}
fn parse_expr_tuple_field_access(
&mut self,
lo: Span,
@ -1821,10 +1888,11 @@ impl<'a> Parser<'a> {
let (fields, _trailing, _recovered) = self.parse_seq_to_before_end(
&TokenKind::CloseDelim(Delimiter::Parenthesis),
seq_sep,
Parser::parse_field_name,
Parser::parse_field_name_maybe_tuple,
)?;
let fields = fields.into_iter().flatten().collect::<Vec<_>>();
let span = lo.to(self.token.span);
Ok(self.mk_expr(span, ExprKind::OffsetOf(container, fields.to_vec().into())))
Ok(self.mk_expr(span, ExprKind::OffsetOf(container, fields.into())))
}
/// Returns a string literal if the next token is a string literal.