bjoernager/rust
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Move PatKind::Lit checking from ast_validation to ast lowering

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Fixes #92074

This allows us to insert an `ExprKind::Err` when an invalid expression
is used in a literal pattern, preventing later stages of compilation
from seeing an unexpected literal pattern.
This commit is contained in:
Aaron Hill 2021-12-18 12:23:49 -05:00
parent 4f49627c6f
commit 137c374c41
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GPG key ID: B4087E510E98B164
5 changed files with 111 additions and 56 deletions
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37
compiler/rustc_ast_lowering/src/pat.rs
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@ -24,7 +24,9 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
let lower_sub = |this: &mut Self| sub.as_ref().map(|s| this.lower_pat(&*s));
break self.lower_pat_ident(pattern, binding_mode, ident, lower_sub);
}
PatKind::Lit(ref e) => break hir::PatKind::Lit(self.lower_expr(e)),
PatKind::Lit(ref e) => {
break hir::PatKind::Lit(self.lower_expr_within_pat(e, false));
}
PatKind::TupleStruct(ref qself, ref path, ref pats) => {
let qpath = self.lower_qpath(
pattern.id,
@ -81,8 +83,8 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
}
PatKind::Range(ref e1, ref e2, Spanned { node: ref end, .. }) => {
break hir::PatKind::Range(
e1.as_deref().map(|e| self.lower_expr(e)),
e2.as_deref().map(|e| self.lower_expr(e)),
e1.as_deref().map(|e| self.lower_expr_within_pat(e, true)),
e2.as_deref().map(|e| self.lower_expr_within_pat(e, true)),
self.lower_range_end(end, e2.is_some()),
);
}
@ -314,4 +316,33 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
RangeEnd::Excluded | RangeEnd::Included(_) => hir::RangeEnd::Included,
}
}
/// Matches `'-' lit | lit (cf. parser::Parser::parse_literal_maybe_minus)`,
/// or paths for ranges.
//
// FIXME: do we want to allow `expr -> pattern` conversion to create path expressions?
// That means making this work:
//
// ```rust,ignore (FIXME)
// struct S;
// macro_rules! m {
// ($a:expr) => {
// let $a = S;
// }
// }
// m!(S);
// ```
fn lower_expr_within_pat(&mut self, expr: &Expr, allow_paths: bool) -> &'hir hir::Expr<'hir> {
match expr.kind {
ExprKind::Lit(..) | ExprKind::ConstBlock(..) | ExprKind::Err => {}
ExprKind::Path(..) if allow_paths => {}
ExprKind::Unary(UnOp::Neg, ref inner) if matches!(inner.kind, ExprKind::Lit(_)) => {}
_ => {
self.diagnostic()
.span_err(expr.span, "arbitrary expressions aren't allowed in patterns");
return self.arena.alloc(self.expr_err(expr.span));
}
}
self.lower_expr(expr)
}
}