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Add ConstArgKind::Path and make ConstArg its own HIR node
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This is a very large commit since a lot needs to be changed in order to
make the tests pass. The salient changes are:

- `ConstArgKind` gets a new `Path` variant, and all const params are now
  represented using it. Non-param paths still use `ConstArgKind::Anon`
  to prevent this change from getting too large, but they will soon use
  the `Path` variant too.

- `ConstArg` gets a distinct `hir_id` field and its own variant in
  `hir::Node`. This affected many parts of the compiler that expected
  the parent of an `AnonConst` to be the containing context (e.g., an
  array repeat expression). They have been changed to check the
  "grandparent" where necessary.

- Some `ast::AnonConst`s now have their `DefId`s created in
  rustc_ast_lowering rather than `DefCollector`. This is because in some
  cases they will end up becoming a `ConstArgKind::Path` instead, which
  has no `DefId`. We have to solve this in a hacky way where we guess
  whether the `AnonConst` could end up as a path const since we can't
  know for sure until after name resolution (`N` could refer to a free
  const or a nullary struct). If it has no chance as being a const
  param, then we create a `DefId` in `DefCollector` -- otherwise we
  decide during ast_lowering. This will have to be updated once all path
  consts use `ConstArgKind::Path`.

- We explicitly use `ConstArgHasType` for array lengths, rather than
  implicitly relying on anon const type feeding -- this is due to the
  addition of `ConstArgKind::Path`.

- Some tests have their outputs changed, but the changes are for the
  most part minor (including removing duplicate or almost-duplicate
  errors). One test now ICEs, but it is for an incomplete, unstable
  feature and is now tracked at #127009.
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camelid committed Jul 17, 2024
1 parent 6e99e2d commit f2c1265
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Showing 5 changed files with 21 additions and 11 deletions.
13 changes: 6 additions & 7 deletions clippy_lints/src/utils/author.rs
Original file line number Diff line number Diff line change
Expand Up @@ -271,15 +271,14 @@ impl<'a, 'tcx> PrintVisitor<'a, 'tcx> {

fn const_arg(&self, const_arg: &Binding<&ConstArg<'_>>) {
match const_arg.value.kind {
// FIXME: uncomment for ConstArgKind::Path
// ConstArgKind::Path(ref qpath) => {
// bind!(self, qpath);
// chain!(self, "let ConstArgKind::Path(ref {qpath}) = {const_arg}.kind");
// self.qpath(qpath);
// },
ConstArgKind::Path(ref qpath) => {
bind!(self, qpath);
chain!(self, "let ConstArgKind::Path(ref {qpath}) = {const_arg}.kind");
self.qpath(qpath);
},
ConstArgKind::Anon(anon_const) => {
bind!(self, anon_const);
chain!(self, "let ConstArgKind::({anon_const}) = {const_arg}.kind");
chain!(self, "let ConstArgKind::Anon({anon_const}) = {const_arg}.kind");
self.body(field!(anon_const.body));
},
}
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6 changes: 6 additions & 0 deletions clippy_utils/src/hir_utils.rs
Original file line number Diff line number Diff line change
Expand Up @@ -421,7 +421,12 @@ impl HirEqInterExpr<'_, '_, '_> {

fn eq_const_arg(&mut self, left: &ConstArg<'_>, right: &ConstArg<'_>) -> bool {
match (&left.kind, &right.kind) {
(ConstArgKind::Path(l_p), ConstArgKind::Path(r_p)) => self.eq_qpath(l_p, r_p),
(ConstArgKind::Anon(l_an), ConstArgKind::Anon(r_an)) => self.eq_body(l_an.body, r_an.body),
// Use explicit match for now since ConstArg is undergoing flux.
(ConstArgKind::Path(..), ConstArgKind::Anon(..)) | (ConstArgKind::Anon(..), ConstArgKind::Path(..)) => {
false
},
}
}

Expand Down Expand Up @@ -1142,6 +1147,7 @@ impl<'a, 'tcx> SpanlessHash<'a, 'tcx> {

fn hash_const_arg(&mut self, const_arg: &ConstArg<'_>) {
match &const_arg.kind {
ConstArgKind::Path(path) => self.hash_qpath(path),
ConstArgKind::Anon(anon) => self.hash_body(anon.body),
}
}
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2 changes: 0 additions & 2 deletions clippy_utils/src/lib.rs
Original file line number Diff line number Diff line change
Expand Up @@ -904,7 +904,6 @@ pub fn is_default_equivalent(cx: &LateContext<'_>, e: &Expr<'_>) -> bool {
},
ExprKind::Tup(items) | ExprKind::Array(items) => items.iter().all(|x| is_default_equivalent(cx, x)),
ExprKind::Repeat(x, ArrayLen::Body(len)) => {
#[allow(irrefutable_let_patterns)] // FIXME
if let ConstArgKind::Anon(anon_const) = len.kind
&& let ExprKind::Lit(const_lit) = cx.tcx.hir().body(anon_const.body).value.kind
&& let LitKind::Int(v, _) = const_lit.node
Expand Down Expand Up @@ -935,7 +934,6 @@ fn is_default_equivalent_from(cx: &LateContext<'_>, from_func: &Expr<'_>, arg: &
}) => return sym.is_empty() && is_path_lang_item(cx, ty, LangItem::String),
ExprKind::Array([]) => return is_path_diagnostic_item(cx, ty, sym::Vec),
ExprKind::Repeat(_, ArrayLen::Body(len)) => {
#[allow(irrefutable_let_patterns)] // FIXME
if let ConstArgKind::Anon(anon_const) = len.kind
&& let ExprKind::Lit(const_lit) = cx.tcx.hir().body(anon_const.body).value.kind
&& let LitKind::Int(v, _) = const_lit.node
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3 changes: 2 additions & 1 deletion tests/ui/author/repeat.stdout
Original file line number Diff line number Diff line change
@@ -1,7 +1,8 @@
if let ExprKind::Repeat(value, length) = expr.kind
&& let ExprKind::Lit(ref lit) = value.kind
&& let LitKind::Int(1, LitIntType::Unsigned(UintTy::U8)) = lit.node
&& let ArrayLen::Body(anon_const) = length
&& let ArrayLen::Body(const_arg) = length
&& let ConstArgKind::Anon(anon_const) = const_arg.kind
&& expr1 = &cx.tcx.hir().body(anon_const.body).value
&& let ExprKind::Lit(ref lit1) = expr1.kind
&& let LitKind::Int(5, LitIntType::Unsuffixed) = lit1.node
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8 changes: 7 additions & 1 deletion tests/ui/min_ident_chars.stderr
Original file line number Diff line number Diff line change
Expand Up @@ -193,5 +193,11 @@ error: this ident consists of a single char
LL | fn wrong_pythagoras(a: f32, b: f32) -> f32 {
| ^

error: aborting due to 32 previous errors
error: this ident consists of a single char
--> tests/ui/min_ident_chars.rs:93:41
|
LL | struct Array<T, const N: usize>([T; N]);
| ^

error: aborting due to 33 previous errors

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