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Handle macro calls in anon const def creation take 2

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This commit is contained in:
Boxy 2024-09-15 21:21:31 +01:00
parent 1d68e6dd1d
commit 781ec111b7
15 changed files with 210 additions and 28 deletions
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11
compiler/rustc_ast/src/ast.rs
View File

@ -1187,8 +1187,8 @@ impl Expr {
/// `min_const_generics` as more complex expressions are not supported.
///
/// Does not ensure that the path resolves to a const param, the caller should check this.
pub fn is_potential_trivial_const_arg(&self) -> bool {
let this = self.maybe_unwrap_block();
pub fn is_potential_trivial_const_arg(&self, strip_identity_block: bool) -> bool {
let this = if strip_identity_block { self.maybe_unwrap_block().1 } else { self };
if let ExprKind::Path(None, path) = &this.kind
&& path.is_potential_trivial_const_arg()
@ -1199,14 +1199,15 @@ pub fn is_potential_trivial_const_arg(&self) -> bool {
}
}
pub fn maybe_unwrap_block(&self) -> &Expr {
/// Returns an expression with (when possible) *one* outter brace removed
pub fn maybe_unwrap_block(&self) -> (bool, &Expr) {
if let ExprKind::Block(block, None) = &self.kind
&& let [stmt] = block.stmts.as_slice()
&& let StmtKind::Expr(expr) = &stmt.kind
{
expr
(true, expr)
} else {
self
(false, self)
}
}

2
compiler/rustc_ast_lowering/src/asm.rs
View File

@ -220,7 +220,7 @@ pub(crate) fn lower_inline_asm(
let parent_def_id = self.current_def_id_parent;
let node_id = self.next_node_id();
// HACK(min_generic_const_args): see lower_anon_const
if !expr.is_potential_trivial_const_arg() {
if !expr.is_potential_trivial_const_arg(true) {
self.create_def(
parent_def_id,
node_id,

2
compiler/rustc_ast_lowering/src/expr.rs
View File

@ -387,7 +387,7 @@ fn lower_legacy_const_generics(
let node_id = self.next_node_id();
// HACK(min_generic_const_args): see lower_anon_const
if !arg.is_potential_trivial_const_arg() {
if !arg.is_potential_trivial_const_arg(true) {
// Add a definition for the in-band const def.
self.create_def(parent_def_id, node_id, kw::Empty, DefKind::AnonConst, f.span);
}

2
compiler/rustc_ast_lowering/src/lib.rs
View File

@ -2441,7 +2441,7 @@ fn lower_anon_const_to_const_arg_direct(&mut self, anon: &AnonConst) -> hir::Con
/// See [`hir::ConstArg`] for when to use this function vs
/// [`Self::lower_anon_const_to_const_arg`].
fn lower_anon_const_to_anon_const(&mut self, c: &AnonConst) -> &'hir hir::AnonConst {
if c.value.is_potential_trivial_const_arg() {
if c.value.is_potential_trivial_const_arg(true) {
// HACK(min_generic_const_args): see DefCollector::visit_anon_const
// Over there, we guess if this is a bare param and only create a def if
// we think it's not. However we may can guess wrong (see there for example)

104
compiler/rustc_resolve/src/def_collector.rs
View File

@ -138,6 +138,61 @@ fn visit_macro_invoc(&mut self, id: NodeId) {
);
assert!(old_parent.is_none(), "parent `LocalDefId` is reset for an invocation");
}
/// Determines whether the const argument `AnonConst` is a simple macro call, optionally
/// surrounded with braces.
///
/// If this const argument *is* a trivial macro call then the id for the macro call is
/// returned along with the information required to build the anon const's def if
/// the macro call expands to a non-trivial expression.
fn is_const_arg_trivial_macro_expansion(
&self,
anon_const: &'a AnonConst,
) -> Option<(PendingAnonConstInfo, NodeId)> {
let (block_was_stripped, expr) = anon_const.value.maybe_unwrap_block();
match expr {
Expr { kind: ExprKind::MacCall(..), id, .. } => Some((
PendingAnonConstInfo {
id: anon_const.id,
span: anon_const.value.span,
block_was_stripped,
},
*id,
)),
_ => None,
}
}
/// Determines whether the expression `const_arg_sub_expr` is a simple macro call, sometimes
/// surrounded with braces if a set of braces has not already been entered. This is required
/// as `{ N }` is treated as equivalent to a bare parameter `N` whereas `{{ N }}` is treated as
/// a real block expression and is lowered to an anonymous constant which is not allowed to use
/// generic parameters.
///
/// If this expression is a trivial macro call then the id for the macro call is
/// returned along with the information required to build the anon const's def if
/// the macro call expands to a non-trivial expression.
fn is_const_arg_sub_expr_trivial_macro_expansion(
&self,
const_arg_sub_expr: &'a Expr,
) -> Option<(PendingAnonConstInfo, NodeId)> {
let pending_anon = self.pending_anon_const_info.unwrap_or_else(||
panic!("Checking expr is trivial macro call without having entered anon const: `{const_arg_sub_expr:?}`"),
);
let (block_was_stripped, expr) = if pending_anon.block_was_stripped {
(true, const_arg_sub_expr)
} else {
const_arg_sub_expr.maybe_unwrap_block()
};
match expr {
Expr { kind: ExprKind::MacCall(..), id, .. } => {
Some((PendingAnonConstInfo { block_was_stripped, ..pending_anon }, *id))
}
_ => None,
}
}
}
impl<'a, 'ra, 'tcx> visit::Visitor<'a> for DefCollector<'a, 'ra, 'tcx> {
@ -354,12 +409,12 @@ fn visit_anon_const(&mut self, constant: &'a AnonConst) {
// items will be messed up, but that's ok because there can't be any if we're just looking
// for bare idents.
if matches!(constant.value.maybe_unwrap_block().kind, ExprKind::MacCall(..)) {
// See self.pending_anon_const_info for explanation
self.pending_anon_const_info =
Some(PendingAnonConstInfo { id: constant.id, span: constant.value.span });
return visit::walk_anon_const(self, constant);
} else if constant.value.is_potential_trivial_const_arg() {
if let Some((pending_anon, macro_invoc)) =
self.is_const_arg_trivial_macro_expansion(constant)
{
self.pending_anon_const_info = Some(pending_anon);
return self.visit_macro_invoc(macro_invoc);
} else if constant.value.is_potential_trivial_const_arg(true) {
return visit::walk_anon_const(self, constant);
}
@ -368,23 +423,36 @@ fn visit_anon_const(&mut self, constant: &'a AnonConst) {
}
fn visit_expr(&mut self, expr: &'a Expr) {
if matches!(expr.kind, ExprKind::MacCall(..)) {
return self.visit_macro_invoc(expr.id);
// If we're visiting the expression of a const argument that was a macro call then
// check if it is *still* unknown whether it is a trivial const arg or not. If so
// recurse into the macro call and delay creating the anon const def until expansion.
if self.pending_anon_const_info.is_some()
&& let Some((pending_anon, macro_invoc)) =
self.is_const_arg_sub_expr_trivial_macro_expansion(expr)
{
self.pending_anon_const_info = Some(pending_anon);
return self.visit_macro_invoc(macro_invoc);
}
let grandparent_def = if let Some(pending_anon) = self.pending_anon_const_info.take() {
// See self.pending_anon_const_info for explanation
if !expr.is_potential_trivial_const_arg() {
// See self.pending_anon_const_info for explanation
let parent_def = self
.pending_anon_const_info
.take()
// If we already stripped away a set of braces then do not do it again when determining
// if the macro expanded to a trivial const arg. This arises in cases such as:
// `Foo<{ bar!() }>` where `bar!()` expands to `{ N }`. This should not be considered a
// trivial const argument even though `{ N }` by itself *is*.
.filter(|pending_anon| {
!expr.is_potential_trivial_const_arg(!pending_anon.block_was_stripped)
})
.map(|pending_anon| {
self.create_def(pending_anon.id, kw::Empty, DefKind::AnonConst, pending_anon.span)
} else {
self.parent_def
}
} else {
self.parent_def
};
})
.unwrap_or(self.parent_def);
self.with_parent(grandparent_def, |this| {
self.with_parent(parent_def, |this| {
let parent_def = match expr.kind {
ExprKind::MacCall(..) => return this.visit_macro_invoc(expr.id),
ExprKind::Closure(..) | ExprKind::Gen(..) => {
this.create_def(expr.id, kw::Empty, DefKind::Closure, expr.span)
}

4
compiler/rustc_resolve/src/late.rs
View File

@ -4524,7 +4524,7 @@ fn resolve_anon_const(&mut self, constant: &'ast AnonConst, anon_const_kind: Ano
);
self.resolve_anon_const_manual(
constant.value.is_potential_trivial_const_arg(),
constant.value.is_potential_trivial_const_arg(true),
anon_const_kind,
|this| this.resolve_expr(&constant.value, None),
)
@ -4688,7 +4688,7 @@ fn resolve_expr(&mut self, expr: &'ast Expr, parent: Option<&'ast Expr>) {
// that is how they will be later lowered to HIR.
if const_args.contains(&idx) {
self.resolve_anon_const_manual(
argument.is_potential_trivial_const_arg(),
argument.is_potential_trivial_const_arg(true),
AnonConstKind::ConstArg(IsRepeatExpr::No),
|this| this.resolve_expr(argument, None),
);

5
compiler/rustc_resolve/src/lib.rs
View File

@ -190,6 +190,11 @@ impl InvocationParent {
#[derive(Copy, Debug, Clone)]
struct PendingAnonConstInfo {
// A const arg is only a "trivial" const arg if it has at *most* one set of braces
// around the argument. We track whether we have stripped an outter brace so that
// if a macro expands to a braced expression *and* the macro was itself inside of
// some braces then we can consider it to be a non-trivial const argument.
block_was_stripped: bool,
id: NodeId,
span: Span,
}

14
tests/ui/const-generics/early/trivial-const-arg-macro-braced-expansion.rs Normal file
View File

@ -0,0 +1,14 @@
macro_rules! y {
() => {
N
};
}
struct A<const N: usize>;
fn foo<const N: usize>() -> A<{ y!() }> {
A::<1>
//~^ ERROR: mismatched types
}
fn main() {}

14
tests/ui/const-generics/early/trivial-const-arg-macro-braced-expansion.stderr Normal file
View File

@ -0,0 +1,14 @@
error[E0308]: mismatched types
--> $DIR/trivial-const-arg-macro-braced-expansion.rs:10:5
|
LL | fn foo<const N: usize>() -> A<{ y!() }> {
| ----------- expected `A<N>` because of return type
LL | A::<1>
| ^^^^^^ expected `N`, found `1`
|
= note: expected struct `A<N>`
found struct `A<1>`
error: aborting due to 1 previous error
For more information about this error, try `rustc --explain E0308`.

15
tests/ui/const-generics/early/trivial-const-arg-macro-nested-braces-2.rs Normal file
View File

@ -0,0 +1,15 @@
macro_rules! y {
() => {
N
//~^ ERROR: generic parameters may not be used in const operations
};
}
struct A<const N: usize>;
#[rustfmt::skip]
fn foo<const N: usize>() -> A<{{ y!() }}> {
A::<1>
}
fn main() {}

15
tests/ui/const-generics/early/trivial-const-arg-macro-nested-braces-2.stderr Normal file
View File

@ -0,0 +1,15 @@
error: generic parameters may not be used in const operations
--> $DIR/trivial-const-arg-macro-nested-braces-2.rs:3:9
|
LL | N
| ^ cannot perform const operation using `N`
...
LL | fn foo<const N: usize>() -> A<{{ y!() }}> {
| ---- in this macro invocation
|
= help: const parameters may only be used as standalone arguments, i.e. `N`
= help: add `#![feature(generic_const_exprs)]` to allow generic const expressions
= note: this error originates in the macro `y` (in Nightly builds, run with -Z macro-backtrace for more info)
error: aborting due to 1 previous error

15
tests/ui/const-generics/early/trivial-const-arg-macro-nested-braces.rs Normal file
View File

@ -0,0 +1,15 @@
#[rustfmt::skip]
macro_rules! y {
() => {
{ N }
//~^ ERROR: generic parameters may not be used in const operations
};
}
struct A<const N: usize>;
fn foo<const N: usize>() -> A<{ y!() }> {
A::<1>
}
fn main() {}

15
tests/ui/const-generics/early/trivial-const-arg-macro-nested-braces.stderr Normal file
View File

@ -0,0 +1,15 @@
error: generic parameters may not be used in const operations
--> $DIR/trivial-const-arg-macro-nested-braces.rs:4:11
|
LL | { N }
| ^ cannot perform const operation using `N`
...
LL | fn foo<const N: usize>() -> A<{ y!() }> {
| ---- in this macro invocation
|
= help: const parameters may only be used as standalone arguments, i.e. `N`
= help: add `#![feature(generic_const_exprs)]` to allow generic const expressions
= note: this error originates in the macro `y` (in Nightly builds, run with -Z macro-backtrace for more info)
error: aborting due to 1 previous error

9
tests/ui/const-generics/early/trivial-const-arg-nested-braces.rs Normal file
View File

@ -0,0 +1,9 @@
struct A<const N: usize>;
#[rustfmt::skip]
fn foo<const N: usize>() -> A<{ { N } }> {
//~^ ERROR: generic parameters may not be used in const operations
A::<1>
}
fn main() {}

11
tests/ui/const-generics/early/trivial-const-arg-nested-braces.stderr Normal file
View File

@ -0,0 +1,11 @@
error: generic parameters may not be used in const operations
--> $DIR/trivial-const-arg-nested-braces.rs:4:35
|
LL | fn foo<const N: usize>() -> A<{ { N } }> {
| ^ cannot perform const operation using `N`
|
= help: const parameters may only be used as standalone arguments, i.e. `N`
= help: add `#![feature(generic_const_exprs)]` to allow generic const expressions
error: aborting due to 1 previous error