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Merged
rust-bors merged 9 commits into from
Sep 20, 2026
Merged

even more cleanups for rustc_builtin_macros #162925

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f438cf8
put the check for empty `assert_fields_are_eq` at the right spot
cyrgani Sep 15, 2026
a51fdcb
micro cleanups
cyrgani Sep 15, 2026
08961a7
remove `use_foldl` arg
cyrgani Sep 16, 2026
b6d0760
split the `cs_fold` closure into three subclosures
cyrgani Sep 16, 2026
8ca7a1c
stop passing `explicit_self` around
cyrgani Sep 17, 2026
3b433cb
stop passing `nonself_arg_tys` around
cyrgani Sep 19, 2026
d7a86e4
optimize `Path::to_path`
cyrgani Sep 19, 2026
c50e0f0
just use `Self` instead of writing the type out
cyrgani Sep 17, 2026
072a61a
remove only recursively used arguments
cyrgani Sep 17, 2026
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207 changes: 72 additions & 135 deletions compiler/rustc_builtin_macros/src/deriving/generic/mod.rs
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68 changes: 18 additions & 50 deletions compiler/rustc_builtin_macros/src/deriving/generic/ty.rs
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Original file line number Diff line number Diff line change
@@ -1,8 +1,10 @@
//! A mini version of ast::Ty, which is easier to use, and features an explicit `Self` type to use
//! when specifying impls to be derived.

use std::iter::once;

pub(crate) use Ty::*;
use rustc_ast::{self as ast, GenericArg, GenericParamKind, Generics, TyKind};
use rustc_ast::{self as ast, GenericArg, TyKind};
use rustc_expand::base::ExtCtxt;
use rustc_span::{DUMMY_SP, Ident, Span, Symbol, kw};
use thin_vec::ThinVec;
Expand Down Expand Up @@ -33,21 +35,17 @@ impl Path {
Path { path, params, kind }
}

pub(crate) fn to_path(
&self,
cx: &ExtCtxt<'_>,
span: Span,
self_ty: Ident,
self_generics: &Generics,
) -> ast::Path {
let mut idents = self.path.iter().map(|s| Ident::new(*s, span)).collect::<Vec<_>>();
let tys = self.params.iter().map(|t| t.to_ty(cx, span, self_ty, self_generics));
pub(crate) fn to_path(&self, cx: &ExtCtxt<'_>, span: Span) -> ast::Path {
let idents = self.path.iter().map(|s| Ident::new(*s, span));
let tys = self.params.iter().map(|t| t.to_ty(cx, span));
let params = tys.map(GenericArg::Type).collect();

if let PathKind::Std = self.kind {
let idents = if let PathKind::Std = self.kind {
let def_site = cx.with_def_site_ctxt(DUMMY_SP);
idents.insert(0, Ident::new(kw::DollarCrate, def_site));
}
once(Ident::new(kw::DollarCrate, def_site)).chain(idents).collect()
} else {
idents.collect()
};
cx.path_all(span, false, idents, params)
}
}
Expand All @@ -72,20 +70,14 @@ pub(crate) fn self_ref() -> Ty {
}

impl Ty {
pub(crate) fn to_ty(
&self,
cx: &ExtCtxt<'_>,
span: Span,
self_ty: Ident,
self_generics: &Generics,
) -> Box<ast::Ty> {
pub(crate) fn to_ty(&self, cx: &ExtCtxt<'_>, span: Span) -> Box<ast::Ty> {
match self {
Ref(ty, mutbl) => {
let raw_ty = ty.to_ty(cx, span, self_ty, self_generics);
let raw_ty = ty.to_ty(cx, span);
cx.ty_ref(span, raw_ty, None, *mutbl)
}
Path(p) => cx.ty_path(p.to_path(cx, span, self_ty, self_generics)),
Self_ => cx.ty_path(self.to_path(cx, span, self_ty, self_generics)),
Path(p) => cx.ty_path(p.to_path(cx, span)),
Self_ => cx.ty_path(self.to_path(cx, span)),
Unit => {
let ty = ast::TyKind::Tup(ThinVec::new());
cx.ty(span, ty)
Expand All @@ -94,34 +86,10 @@ impl Ty {
}
}

pub(crate) fn to_path(
&self,
cx: &ExtCtxt<'_>,
span: Span,
self_ty: Ident,
generics: &Generics,
) -> ast::Path {
pub(crate) fn to_path(&self, cx: &ExtCtxt<'_>, span: Span) -> ast::Path {
match self {
Self_ => {
let params: Vec<_> = generics
.params
.iter()
.map(|param| match param.kind {
GenericParamKind::Lifetime => {
GenericArg::Lifetime(ast::Lifetime { id: param.id, ident: param.ident })
}
GenericParamKind::Type { .. } => {
GenericArg::Type(cx.ty_ident(span, param.ident))
}
GenericParamKind::Const { .. } => {
GenericArg::Const(cx.const_ident(span, param.ident))
}
})
.collect();

cx.path_all(span, false, vec![self_ty], params)
}
Path(p) => p.to_path(cx, span, self_ty, generics),
Self_ => cx.path_ident(span, Ident::new(kw::SelfUpper, span)),
Path(p) => p.to_path(cx, span),
AstTy(ty) => match &ty.kind {
TyKind::Path(_, path) => path.clone(),
_ => cx.dcx().span_bug(span, "non-path in a path in generic `derive`"),
Expand Down
32 changes: 13 additions & 19 deletions compiler/rustc_builtin_macros/src/deriving/ord.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -52,29 +52,23 @@ pub(crate) fn cs_cmp(cx: &ExtCtxt<'_>, span: Span, substr: Substructure<'_>) ->
// ::core::cmp::Ord::cmp(&self.y, &other.y),
// cmp => cmp,
// }
let expr = cs_fold(
// foldr nests the if-elses correctly, leaving the first field
// as the outermost one, and the last as the innermost.
false,
let expr = cs_foldr(
cx,
span,
substr,
|cx, fold| match fold {
CsFold::Single(field) => {
let [other_expr] = &field.other_selflike_exprs[..] else {
cx.dcx().span_bug(field.span, "not exactly 2 arguments in `derive(Ord)`");
};
let args = thin_vec![field.self_expr.clone(), other_expr.clone()];
cx.expr_call_global(field.span, cmp_path.clone(), args)
}
CsFold::Combine(span, expr1, expr2) => {
let eq_arm = cx.arm(span, cx.pat_path(span, equal_path.clone()), expr1);
let neq_arm =
cx.arm(span, cx.pat_ident(span, test_id), cx.expr_ident(span, test_id));
cx.expr_match(span, expr2, thin_vec![eq_arm, neq_arm])
}
CsFold::Fieldless => cx.expr_path(equal_path.clone()),
|field| {
let [other_expr] = &field.other_selflike_exprs[..] else {
cx.dcx().span_bug(field.span, "not exactly 2 arguments in `derive(Ord)`");
};
let args = thin_vec![field.self_expr.clone(), other_expr.clone()];
cx.expr_call_global(field.span, cmp_path.clone(), args)
},
|span, expr1, expr2| {
let eq_arm = cx.arm(span, cx.pat_path(span, equal_path.clone()), expr1);
let neq_arm = cx.arm(span, cx.pat_ident(span, test_id), cx.expr_ident(span, test_id));
cx.expr_match(span, expr2, thin_vec![eq_arm, neq_arm])
},
|| cx.expr_path(equal_path.clone()),
);
BlockOrExpr::new_expr(expr)
}
113 changes: 52 additions & 61 deletions compiler/rustc_builtin_macros/src/deriving/partial_ord.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -124,73 +124,64 @@ fn cs_partial_cmp(
// ::core::cmp::PartialOrd::partial_cmp(&self.y, &other.y),
// cmp => cmp,
// }
let expr = cs_fold(
// foldr nests the if-elses correctly, leaving the first field
// as the outermost one, and the last as the innermost.
false,
let expr = cs_foldr(
cx,
span,
substr,
|cx, fold| match fold {
CsFold::Single(field) => {
let [other_expr] = &field.other_selflike_exprs[..] else {
cx.dcx()
.span_bug(field.span, "not exactly 2 arguments in `derive(PartialOrd)`");
};
let args = thin_vec![field.self_expr.clone(), other_expr.clone()];
cx.expr_call_global(field.span, partial_cmp_path.clone(), args)
}
CsFold::Combine(span, mut expr1, expr2) => {
// When the item is an enum, this expands to
// ```
// match (expr2) {
// Some(Ordering::Equal) => expr1,
// cmp => cmp
// }
// ```
// where `expr2` is `partial_cmp(self_discr, other_discr)`, and `expr1` is a `match`
// against the enum variants. This means that we begin by comparing the enum discriminants,
// before either inspecting their contents (if they match), or returning
// the `cmp::Ordering` of comparing the enum discriminants.
// ```
// match partial_cmp(self_discr, other_discr) {
// Some(Ordering::Equal) => match (self, other) {
// (Self::A(self_0), Self::A(other_0)) => partial_cmp(self_0, other_0),
// (Self::B(self_0), Self::B(other_0)) => partial_cmp(self_0, other_0),
// _ => Some(Ordering::Equal)
// }
// cmp => cmp
// }
// ```
// If we have any certain enum layouts, flipping this results in better codegen
// ```
// match (self, other) {
// (Self::A(self_0), Self::A(other_0)) => partial_cmp(self_0, other_0),
// _ => partial_cmp(self_discr, other_discr)
// }
// ```
// Reference: https://github.com/rust-lang/rust/pull/103659#issuecomment-1328126354
|field| {
let [other_expr] = &field.other_selflike_exprs[..] else {
cx.dcx().span_bug(field.span, "not exactly 2 arguments in `derive(PartialOrd)`");
};
let args = thin_vec![field.self_expr.clone(), other_expr.clone()];
cx.expr_call_global(field.span, partial_cmp_path.clone(), args)
},
|span, mut expr1, expr2| {
// When the item is an enum, this expands to
// ```
// match (expr2) {
// Some(Ordering::Equal) => expr1,
// cmp => cmp
// }
// ```
// where `expr2` is `partial_cmp(self_discr, other_discr)`, and `expr1` is a `match`
// against the enum variants. This means that we begin by comparing the enum discriminants,
// before either inspecting their contents (if they match), or returning
// the `cmp::Ordering` of comparing the enum discriminants.
// ```
// match partial_cmp(self_discr, other_discr) {
// Some(Ordering::Equal) => match (self, other) {
// (Self::A(self_0), Self::A(other_0)) => partial_cmp(self_0, other_0),
// (Self::B(self_0), Self::B(other_0)) => partial_cmp(self_0, other_0),
// _ => Some(Ordering::Equal)
// }
// cmp => cmp
// }
// ```
// If we have any certain enum layouts, flipping this results in better codegen
// ```
// match (self, other) {
// (Self::A(self_0), Self::A(other_0)) => partial_cmp(self_0, other_0),
// _ => partial_cmp(self_discr, other_discr)
// }
// ```
// Reference: https://github.com/rust-lang/rust/pull/103659#issuecomment-1328126354

if !discr_then_data
&& let ExprKind::Match(_, arms, _) = &mut expr1.kind
&& let Some(last) = arms.last_mut()
&& let PatKind::Wild = last.pat.kind
{
last.body = Some(expr2);
expr1
} else {
let eq_arm = cx.arm(
span,
cx.pat_some(span, cx.pat_path(span, equal_path.clone())),
expr1,
);
let neq_arm =
cx.arm(span, cx.pat_ident(span, test_id), cx.expr_ident(span, test_id));
cx.expr_match(span, expr2, thin_vec![eq_arm, neq_arm])
}
if !discr_then_data
&& let ExprKind::Match(_, arms, _) = &mut expr1.kind
&& let Some(last) = arms.last_mut()
&& let PatKind::Wild = last.pat.kind
{
last.body = Some(expr2);
expr1
} else {
let eq_arm =
cx.arm(span, cx.pat_some(span, cx.pat_path(span, equal_path.clone())), expr1);
let neq_arm =
cx.arm(span, cx.pat_ident(span, test_id), cx.expr_ident(span, test_id));
cx.expr_match(span, expr2, thin_vec![eq_arm, neq_arm])
}
CsFold::Fieldless => cx.expr_some(span, cx.expr_path(equal_path.clone())),
},
|| cx.expr_some(span, cx.expr_path(equal_path.clone())),
);
BlockOrExpr::new_expr(expr)
}
3 changes: 1 addition & 2 deletions tests/ui/const-generics/mgca/const-ctor-overflow-eval.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -7,13 +7,12 @@ struct U;

#[derive(ConstParamTy, PartialEq, Eq)]
//~^ ERROR overflow evaluating whether `S<U>` is well-formed
//~| ERROR overflow evaluating whether `S<U>` is well-formed

struct S<const N: U>()
where
S<{ U }>:;
//~^ ERROR overflow evaluating whether `S<U>` is well-formed
//~| ERROR overflow evaluating whether `S<U>` is well-formed
//~| ERROR overflow evaluating whether `S<U>` is well-formed
//~| ERROR overflow evaluating whether `S<U>` is well-formed

fn main() {}
23 changes: 12 additions & 11 deletions tests/ui/const-generics/mgca/const-ctor-overflow-eval.stderr
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Original file line number Diff line number Diff line change
@@ -1,11 +1,11 @@
error[E0275]: overflow evaluating whether `S<U>` is well-formed
--> $DIR/const-ctor-overflow-eval.rs:14:5
--> $DIR/const-ctor-overflow-eval.rs:12:5
|
LL | S<{ U }>:;
| ^^^^^^^^
|
note: required by a bound in `S`
--> $DIR/const-ctor-overflow-eval.rs:14:5
--> $DIR/const-ctor-overflow-eval.rs:12:5
|
LL | struct S<const N: U>()
| - required by a bound in this struct
Expand All @@ -14,13 +14,13 @@ LL | S<{ U }>:;
| ^^^^^^^^ required by this bound in `S`

error[E0275]: overflow evaluating whether `S<U>` is well-formed
--> $DIR/const-ctor-overflow-eval.rs:14:5
--> $DIR/const-ctor-overflow-eval.rs:12:5
|
LL | S<{ U }>:;
| ^^^^^^^^
|
note: required by a bound in `S`
--> $DIR/const-ctor-overflow-eval.rs:14:5
--> $DIR/const-ctor-overflow-eval.rs:12:5
|
LL | struct S<const N: U>()
| - required by a bound in this struct
Expand All @@ -30,13 +30,13 @@ LL | S<{ U }>:;
= note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`

error[E0275]: overflow evaluating whether `S<U>` is well-formed
--> $DIR/const-ctor-overflow-eval.rs:14:5
--> $DIR/const-ctor-overflow-eval.rs:12:5
|
LL | S<{ U }>:;
| ^^^^^^^^
|
note: required by a bound in `S`
--> $DIR/const-ctor-overflow-eval.rs:14:5
--> $DIR/const-ctor-overflow-eval.rs:12:5
|
LL | struct S<const N: U>()
| - required by a bound in this struct
Expand All @@ -52,7 +52,7 @@ LL | #[derive(ConstParamTy, PartialEq, Eq)]
| ^^^^^^^^^
|
note: required by a bound in `S`
--> $DIR/const-ctor-overflow-eval.rs:14:5
--> $DIR/const-ctor-overflow-eval.rs:12:5
|
LL | struct S<const N: U>()
| - required by a bound in this struct
Expand All @@ -61,19 +61,20 @@ LL | S<{ U }>:;
| ^^^^^^^^ required by this bound in `S`

error[E0275]: overflow evaluating whether `S<U>` is well-formed
--> $DIR/const-ctor-overflow-eval.rs:8:35
--> $DIR/const-ctor-overflow-eval.rs:12:5
|
LL | #[derive(ConstParamTy, PartialEq, Eq)]
| ^^
LL | S<{ U }>:;
| ^^^^^^^^
|
note: required by a bound in `S`
--> $DIR/const-ctor-overflow-eval.rs:14:5
--> $DIR/const-ctor-overflow-eval.rs:12:5
|
LL | struct S<const N: U>()
| - required by a bound in this struct
LL | where
LL | S<{ U }>:;
| ^^^^^^^^ required by this bound in `S`
= note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`

error: aborting due to 5 previous errors

Expand Down
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