Skip to content

Move PatKind::Lit checking from ast_validation to ast lowering #92080

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 1 commit into from
Jan 3, 2022
Merged

Move PatKind::Lit checking from ast_validation to ast lowering #92080

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
37 changes: 34 additions & 3 deletions compiler/rustc_ast_lowering/src/pat.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -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,
Expand Down Expand Up @@ -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()),
);
}
Expand Down Expand Up @@ -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)
}
}
47 changes: 0 additions & 47 deletions compiler/rustc_ast_passes/src/ast_validation.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -302,34 +302,6 @@ impl<'a> AstValidator<'a> {
}
}

/// 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 check_expr_within_pat(&self, expr: &Expr, allow_paths: bool) {
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.err_handler().span_err(
expr.span,
"arbitrary expressions aren't allowed \
in patterns",
),
}
}

fn check_late_bound_lifetime_defs(&self, params: &[GenericParam]) {
// Check only lifetime parameters are present and that the lifetime
// parameters that are present have no bounds.
Expand Down Expand Up @@ -1426,25 +1398,6 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
visit::walk_param_bound(self, bound)
}

fn visit_pat(&mut self, pat: &'a Pat) {
match &pat.kind {
PatKind::Lit(expr) => {
self.check_expr_within_pat(expr, false);
}
PatKind::Range(start, end, _) => {
if let Some(expr) = start {
self.check_expr_within_pat(expr, true);
}
if let Some(expr) = end {
self.check_expr_within_pat(expr, true);
}
}
_ => {}
}

visit::walk_pat(self, pat)
}

fn visit_poly_trait_ref(&mut self, t: &'a PolyTraitRef, m: &'a TraitBoundModifier) {
self.check_late_bound_lifetime_defs(&t.bound_generic_params);
visit::walk_poly_trait_ref(self, t, m);
Expand Down
8 changes: 4 additions & 4 deletions src/test/ui/match/expr_before_ident_pat.stderr
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -1,14 +1,14 @@
error: arbitrary expressions aren't allowed in patterns
error[E0425]: cannot find value `a` in this scope
--> $DIR/expr_before_ident_pat.rs:12:12
|
LL | funny!(a, a);
| ^
| ^ not found in this scope

error[E0425]: cannot find value `a` in this scope
error: arbitrary expressions aren't allowed in patterns
--> $DIR/expr_before_ident_pat.rs:12:12
|
LL | funny!(a, a);
| ^ not found in this scope
| ^

error: aborting due to 2 previous errors

Expand Down
36 changes: 36 additions & 0 deletions src/test/ui/pattern/issue-92074-macro-ice.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,36 @@
pub enum En {
A(Vec<u8>)
}

fn get_usize() -> usize {
0
}

macro_rules! force_expr {
($e:expr) => { $e }
}

macro_rules! force_pat {
($a:expr, $b:expr) => { $a..=$b }
}

macro_rules! make_vec {
() => { force_expr!(Vec::new()) } //~ ERROR arbitrary expressions aren't allowed
}

macro_rules! make_pat {
() => { force_pat!(get_usize(), get_usize()) }
//~^ ERROR arbitrary expressions aren't allowed
//~| ERROR arbitrary expressions aren't allowed
}

#[allow(unreachable_code)]
fn f() -> Result<(), impl core::fmt::Debug> {
let x: En = loop {};

assert!(matches!(x, En::A(make_vec!())));
assert!(matches!(5, make_pat!()));
Ok::<(), &'static str>(())
}

fn main() {}
35 changes: 35 additions & 0 deletions src/test/ui/pattern/issue-92074-macro-ice.stderr
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,35 @@
error: arbitrary expressions aren't allowed in patterns
--> $DIR/issue-92074-macro-ice.rs:18:25
|
LL | () => { force_expr!(Vec::new()) }
| ^^^^^^^^^^
...
LL | assert!(matches!(x, En::A(make_vec!())));
| ----------- in this macro invocation
|
= note: this error originates in the macro `make_vec` (in Nightly builds, run with -Z macro-backtrace for more info)

error: arbitrary expressions aren't allowed in patterns
--> $DIR/issue-92074-macro-ice.rs:22:24
|
LL | () => { force_pat!(get_usize(), get_usize()) }
| ^^^^^^^^^^^
...
LL | assert!(matches!(5, make_pat!()));
| ----------- in this macro invocation
|
= note: this error originates in the macro `make_pat` (in Nightly builds, run with -Z macro-backtrace for more info)

error: arbitrary expressions aren't allowed in patterns
--> $DIR/issue-92074-macro-ice.rs:22:37
|
LL | () => { force_pat!(get_usize(), get_usize()) }
| ^^^^^^^^^^^
...
LL | assert!(matches!(5, make_pat!()));
| ----------- in this macro invocation
|
= note: this error originates in the macro `make_pat` (in Nightly builds, run with -Z macro-backtrace for more info)

error: aborting due to 3 previous errors