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Rollup merge of #134272 - RalfJung:destabilize-rustc_encodable_decodable, r=oli-obk

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Remove rustc_encodable_decodable feature

This has been shown in future-compat reports since Rust 1.79 (https://github.com/rust-lang/rust/pull/116016), released June 2024. Let's see if crater still finds any issues.

Part of https://github.com/rust-lang/rust/issues/134301.

Cc ``@rust-lang/libs-api``
This commit is contained in:
Matthias Krüger 2025-02-02 18:05:22 +01:00 • committed by GitHub
commit 48aede0773
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GPG key ID: B5690EEEBB952194
16 changed files with 10 additions and 678 deletions
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2
compiler/rustc_builtin_macros/src/deriving/debug.rs
View file

@ -56,7 +56,7 @@ fn show_substructure(cx: &ExtCtxt<'_>, span: Span, substr: &Substructure<'_>) ->
let (ident, vdata, fields) = match substr.fields {
Struct(vdata, fields) => (substr.type_ident, *vdata, fields),
EnumMatching(_, v, fields) => (v.ident, &v.data, fields),
EnumMatching(v, fields) => (v.ident, &v.data, fields),
AllFieldlessEnum(enum_def) => return show_fieldless_enum(cx, span, enum_def, substr),
EnumDiscr(..) | StaticStruct(..) | StaticEnum(..) => {
cx.dcx().span_bug(span, "nonsensical .fields in `#[derive(Debug)]`")

215
compiler/rustc_builtin_macros/src/deriving/decodable.rs
View file

@ -1,215 +0,0 @@
//! The compiler code necessary for `#[derive(RustcDecodable)]`. See encodable.rs for more.
use rustc_ast::ptr::P;
use rustc_ast::{self as ast, Expr, MetaItem, Mutability};
use rustc_expand::base::{Annotatable, ExtCtxt};
use rustc_span::{Ident, Span, Symbol, sym};
use thin_vec::{ThinVec, thin_vec};
use crate::deriving::generic::ty::*;
use crate::deriving::generic::*;
use crate::deriving::pathvec_std;
pub(crate) fn expand_deriving_rustc_decodable(
cx: &ExtCtxt<'_>,
span: Span,
mitem: &MetaItem,
item: &Annotatable,
push: &mut dyn FnMut(Annotatable),
is_const: bool,
) {
let krate = sym::rustc_serialize;
let typaram = sym::__D;
let trait_def = TraitDef {
span,
path: Path::new_(vec![krate, sym::Decodable], vec![], PathKind::Global),
skip_path_as_bound: false,
needs_copy_as_bound_if_packed: true,
additional_bounds: Vec::new(),
supports_unions: false,
methods: vec![MethodDef {
name: sym::decode,
generics: Bounds {
bounds: vec![(typaram, vec![Path::new_(
vec![krate, sym::Decoder],
vec![],
PathKind::Global,
)])],
},
explicit_self: false,
nonself_args: vec![(
Ref(Box::new(Path(Path::new_local(typaram))), Mutability::Mut),
sym::d,
)],
ret_ty: Path(Path::new_(
pathvec_std!(result::Result),
vec![
Box::new(Self_),
Box::new(Path(Path::new_(vec![typaram, sym::Error], vec![], PathKind::Local))),
],
PathKind::Std,
)),
attributes: ast::AttrVec::new(),
fieldless_variants_strategy: FieldlessVariantsStrategy::Default,
combine_substructure: combine_substructure(Box::new(|a, b, c| {
decodable_substructure(a, b, c, krate)
})),
}],
associated_types: Vec::new(),
is_const,
};
trait_def.expand(cx, mitem, item, push)
}
fn decodable_substructure(
cx: &ExtCtxt<'_>,
trait_span: Span,
substr: &Substructure<'_>,
krate: Symbol,
) -> BlockOrExpr {
let decoder = substr.nonselflike_args[0].clone();
let recurse = vec![
Ident::new(krate, trait_span),
Ident::new(sym::Decodable, trait_span),
Ident::new(sym::decode, trait_span),
];
let exprdecode = cx.expr_path(cx.path_global(trait_span, recurse));
// throw an underscore in front to suppress unused variable warnings
let blkarg = Ident::new(sym::_d, trait_span);
let blkdecoder = cx.expr_ident(trait_span, blkarg);
let expr = match substr.fields {
StaticStruct(_, summary) => {
let nfields = match summary {
Unnamed(fields, _) => fields.len(),
Named(fields) => fields.len(),
};
let fn_read_struct_field_path: Vec<_> =
cx.def_site_path(&[sym::rustc_serialize, sym::Decoder, sym::read_struct_field]);
let path = cx.path_ident(trait_span, substr.type_ident);
let result =
decode_static_fields(cx, trait_span, path, summary, |cx, span, name, field| {
cx.expr_try(
span,
cx.expr_call_global(span, fn_read_struct_field_path.clone(), thin_vec![
blkdecoder.clone(),
cx.expr_str(span, name),
cx.expr_usize(span, field),
exprdecode.clone(),
]),
)
});
let result = cx.expr_ok(trait_span, result);
let fn_read_struct_path: Vec<_> =
cx.def_site_path(&[sym::rustc_serialize, sym::Decoder, sym::read_struct]);
cx.expr_call_global(trait_span, fn_read_struct_path, thin_vec![
decoder,
cx.expr_str(trait_span, substr.type_ident.name),
cx.expr_usize(trait_span, nfields),
cx.lambda1(trait_span, result, blkarg),
])
}
StaticEnum(_, fields) => {
let variant = Ident::new(sym::i, trait_span);
let mut arms = ThinVec::with_capacity(fields.len() + 1);
let mut variants = ThinVec::with_capacity(fields.len());
let fn_read_enum_variant_arg_path: Vec<_> =
cx.def_site_path(&[sym::rustc_serialize, sym::Decoder, sym::read_enum_variant_arg]);
for (i, &(ident, v_span, ref parts)) in fields.iter().enumerate() {
variants.push(cx.expr_str(v_span, ident.name));
let path = cx.path(trait_span, vec![substr.type_ident, ident]);
let decoded =
decode_static_fields(cx, v_span, path, parts, |cx, span, _, field| {
let idx = cx.expr_usize(span, field);
cx.expr_try(
span,
cx.expr_call_global(
span,
fn_read_enum_variant_arg_path.clone(),
thin_vec![blkdecoder.clone(), idx, exprdecode.clone()],
),
)
});
arms.push(cx.arm(v_span, cx.pat_lit(v_span, cx.expr_usize(v_span, i)), decoded));
}
arms.push(cx.arm_unreachable(trait_span));
let result = cx.expr_ok(
trait_span,
cx.expr_match(trait_span, cx.expr_ident(trait_span, variant), arms),
);
let lambda = cx.lambda(trait_span, vec![blkarg, variant], result);
let variant_array_ref = cx.expr_array_ref(trait_span, variants);
let fn_read_enum_variant_path: Vec<_> =
cx.def_site_path(&[sym::rustc_serialize, sym::Decoder, sym::read_enum_variant]);
let result = cx.expr_call_global(trait_span, fn_read_enum_variant_path, thin_vec![
blkdecoder,
variant_array_ref,
lambda
]);
let fn_read_enum_path: Vec<_> =
cx.def_site_path(&[sym::rustc_serialize, sym::Decoder, sym::read_enum]);
cx.expr_call_global(trait_span, fn_read_enum_path, thin_vec![
decoder,
cx.expr_str(trait_span, substr.type_ident.name),
cx.lambda1(trait_span, result, blkarg),
])
}
_ => cx.dcx().bug("expected StaticEnum or StaticStruct in derive(Decodable)"),
};
BlockOrExpr::new_expr(expr)
}
/// Creates a decoder for a single enum variant/struct:
/// - `outer_pat_path` is the path to this enum variant/struct
/// - `getarg` should retrieve the `usize`-th field with name `@str`.
fn decode_static_fields<F>(
cx: &ExtCtxt<'_>,
trait_span: Span,
outer_pat_path: ast::Path,
fields: &StaticFields,
mut getarg: F,
) -> P<Expr>
where
F: FnMut(&ExtCtxt<'_>, Span, Symbol, usize) -> P<Expr>,
{
match fields {
Unnamed(fields, is_tuple) => {
let path_expr = cx.expr_path(outer_pat_path);
if matches!(is_tuple, IsTuple::No) {
path_expr
} else {
let fields = fields
.iter()
.enumerate()
.map(|(i, &span)| getarg(cx, span, Symbol::intern(&format!("_field{i}")), i))
.collect();
cx.expr_call(trait_span, path_expr, fields)
}
}
Named(fields) => {
// use the field's span to get nicer error messages.
let fields = fields
.iter()
.enumerate()
.map(|(i, &(ident, span, _))| {
let arg = getarg(cx, span, ident.name, i);
cx.field_imm(span, ident, arg)
})
.collect();
cx.expr_struct(trait_span, outer_pat_path, fields)
}
}
}

2
compiler/rustc_builtin_macros/src/deriving/default.rs
View file

@ -42,7 +42,7 @@ pub(crate) fn expand_deriving_default(
StaticStruct(_, fields) => {
default_struct_substructure(cx, trait_span, substr, fields)
}
StaticEnum(enum_def, _) => {
StaticEnum(enum_def) => {
default_enum_substructure(cx, trait_span, enum_def, item.span())
}
_ => cx.dcx().span_bug(trait_span, "method in `derive(Default)`"),

284
compiler/rustc_builtin_macros/src/deriving/encodable.rs
View file

@ -1,284 +0,0 @@
//! The compiler code necessary to implement the `#[derive(RustcEncodable)]`
//! (and `RustcDecodable`, in `decodable.rs`) extension. The idea here is that
//! type-defining items may be tagged with
//! `#[derive(RustcEncodable, RustcDecodable)]`.
//!
//! For example, a type like:
//!
//! ```ignore (old code)
//! #[derive(RustcEncodable, RustcDecodable)]
//! struct Node { id: usize }
//! ```
//!
//! would generate two implementations like:
//!
//! ```ignore (old code)
//! # struct Node { id: usize }
//! impl<S: Encoder<E>, E> Encodable<S, E> for Node {
//! fn encode(&self, s: &mut S) -> Result<(), E> {
//! s.emit_struct("Node", 1, |this| {
//! this.emit_struct_field("id", 0, |this| {
//! Encodable::encode(&self.id, this)
//! /* this.emit_usize(self.id) can also be used */
//! })
//! })
//! }
//! }
//!
//! impl<D: Decoder<E>, E> Decodable<D, E> for Node {
//! fn decode(d: &mut D) -> Result<Node, E> {
//! d.read_struct("Node", 1, |this| {
//! match this.read_struct_field("id", 0, |this| Decodable::decode(this)) {
//! Ok(id) => Ok(Node { id: id }),
//! Err(e) => Err(e),
//! }
//! })
//! }
//! }
//! ```
//!
//! Other interesting scenarios are when the item has type parameters or
//! references other non-built-in types. A type definition like:
//!
//! ```ignore (old code)
//! # #[derive(RustcEncodable, RustcDecodable)]
//! # struct Span;
//! #[derive(RustcEncodable, RustcDecodable)]
//! struct Spanned<T> { node: T, span: Span }
//! ```
//!
//! would yield functions like:
//!
//! ```ignore (old code)
//! # #[derive(RustcEncodable, RustcDecodable)]
//! # struct Span;
//! # struct Spanned<T> { node: T, span: Span }
//! impl<
//! S: Encoder<E>,
//! E,
//! T: Encodable<S, E>
//! > Encodable<S, E> for Spanned<T> {
//! fn encode(&self, s: &mut S) -> Result<(), E> {
//! s.emit_struct("Spanned", 2, |this| {
//! this.emit_struct_field("node", 0, |this| self.node.encode(this))
//! .unwrap();
//! this.emit_struct_field("span", 1, |this| self.span.encode(this))
//! })
//! }
//! }
//!
//! impl<
//! D: Decoder<E>,
//! E,
//! T: Decodable<D, E>
//! > Decodable<D, E> for Spanned<T> {
//! fn decode(d: &mut D) -> Result<Spanned<T>, E> {
//! d.read_struct("Spanned", 2, |this| {
//! Ok(Spanned {
//! node: this.read_struct_field("node", 0, |this| Decodable::decode(this))
//! .unwrap(),
//! span: this.read_struct_field("span", 1, |this| Decodable::decode(this))
//! .unwrap(),
//! })
//! })
//! }
//! }
//! ```
use rustc_ast::{AttrVec, ExprKind, MetaItem, Mutability};
use rustc_expand::base::{Annotatable, ExtCtxt};
use rustc_span::{Ident, Span, Symbol, sym};
use thin_vec::{ThinVec, thin_vec};
use crate::deriving::generic::ty::*;
use crate::deriving::generic::*;
use crate::deriving::pathvec_std;
pub(crate) fn expand_deriving_rustc_encodable(
cx: &ExtCtxt<'_>,
span: Span,
mitem: &MetaItem,
item: &Annotatable,
push: &mut dyn FnMut(Annotatable),
is_const: bool,
) {
let krate = sym::rustc_serialize;
let typaram = sym::__S;
let trait_def = TraitDef {
span,
path: Path::new_(vec![krate, sym::Encodable], vec![], PathKind::Global),
skip_path_as_bound: false,
needs_copy_as_bound_if_packed: true,
additional_bounds: Vec::new(),
supports_unions: false,
methods: vec![MethodDef {
name: sym::encode,
generics: Bounds {
bounds: vec![(typaram, vec![Path::new_(
vec![krate, sym::Encoder],
vec![],
PathKind::Global,
)])],
},
explicit_self: true,
nonself_args: vec![(
Ref(Box::new(Path(Path::new_local(typaram))), Mutability::Mut),
sym::s,
)],
ret_ty: Path(Path::new_(
pathvec_std!(result::Result),
vec![
Box::new(Unit),
Box::new(Path(Path::new_(vec![typaram, sym::Error], vec![], PathKind::Local))),
],
PathKind::Std,
)),
attributes: AttrVec::new(),
fieldless_variants_strategy: FieldlessVariantsStrategy::Default,
combine_substructure: combine_substructure(Box::new(|a, b, c| {
encodable_substructure(a, b, c, krate)
})),
}],
associated_types: Vec::new(),
is_const,
};
trait_def.expand(cx, mitem, item, push)
}
fn encodable_substructure(
cx: &ExtCtxt<'_>,
trait_span: Span,
substr: &Substructure<'_>,
krate: Symbol,
) -> BlockOrExpr {
let encoder = substr.nonselflike_args[0].clone();
// throw an underscore in front to suppress unused variable warnings
let blkarg = Ident::new(sym::_e, trait_span);
let blkencoder = cx.expr_ident(trait_span, blkarg);
let fn_path = cx.expr_path(cx.path_global(trait_span, vec![
Ident::new(krate, trait_span),
Ident::new(sym::Encodable, trait_span),
Ident::new(sym::encode, trait_span),
]));
match substr.fields {
Struct(_, fields) => {
let fn_emit_struct_field_path =
cx.def_site_path(&[sym::rustc_serialize, sym::Encoder, sym::emit_struct_field]);
let mut stmts = ThinVec::new();
for (i, &FieldInfo { name, ref self_expr, span, .. }) in fields.iter().enumerate() {
let name = match name {
Some(id) => id.name,
None => Symbol::intern(&format!("_field{i}")),
};
let self_ref = cx.expr_addr_of(span, self_expr.clone());
let enc =
cx.expr_call(span, fn_path.clone(), thin_vec![self_ref, blkencoder.clone()]);
let lambda = cx.lambda1(span, enc, blkarg);
let call = cx.expr_call_global(span, fn_emit_struct_field_path.clone(), thin_vec![
blkencoder.clone(),
cx.expr_str(span, name),
cx.expr_usize(span, i),
lambda,
]);
// last call doesn't need a try!
let last = fields.len() - 1;
let call = if i != last {
cx.expr_try(span, call)
} else {
cx.expr(span, ExprKind::Ret(Some(call)))
};
let stmt = cx.stmt_expr(call);
stmts.push(stmt);
}
// unit structs have no fields and need to return Ok()
let blk = if stmts.is_empty() {
let ok = cx.expr_ok(trait_span, cx.expr_tuple(trait_span, ThinVec::new()));
cx.lambda1(trait_span, ok, blkarg)
} else {
cx.lambda_stmts_1(trait_span, stmts, blkarg)
};
let fn_emit_struct_path =
cx.def_site_path(&[sym::rustc_serialize, sym::Encoder, sym::emit_struct]);
let expr = cx.expr_call_global(trait_span, fn_emit_struct_path, thin_vec![
encoder,
cx.expr_str(trait_span, substr.type_ident.name),
cx.expr_usize(trait_span, fields.len()),
blk,
]);
BlockOrExpr::new_expr(expr)
}
EnumMatching(idx, variant, fields) => {
// We're not generating an AST that the borrow checker is expecting,
// so we need to generate a unique local variable to take the
// mutable loan out on, otherwise we get conflicts which don't
// actually exist.
let me = cx.stmt_let(trait_span, false, blkarg, encoder);
let encoder = cx.expr_ident(trait_span, blkarg);
let fn_emit_enum_variant_arg_path: Vec<_> =
cx.def_site_path(&[sym::rustc_serialize, sym::Encoder, sym::emit_enum_variant_arg]);
let mut stmts = ThinVec::new();
if !fields.is_empty() {
let last = fields.len() - 1;
for (i, &FieldInfo { ref self_expr, span, .. }) in fields.iter().enumerate() {
let self_ref = cx.expr_addr_of(span, self_expr.clone());
let enc = cx
.expr_call(span, fn_path.clone(), thin_vec![self_ref, blkencoder.clone()]);
let lambda = cx.lambda1(span, enc, blkarg);
let call = cx.expr_call_global(
span,
fn_emit_enum_variant_arg_path.clone(),
thin_vec![blkencoder.clone(), cx.expr_usize(span, i), lambda],
);
let call = if i != last {
cx.expr_try(span, call)
} else {
cx.expr(span, ExprKind::Ret(Some(call)))
};
stmts.push(cx.stmt_expr(call));
}
} else {
let ok = cx.expr_ok(trait_span, cx.expr_tuple(trait_span, ThinVec::new()));
let ret_ok = cx.expr(trait_span, ExprKind::Ret(Some(ok)));
stmts.push(cx.stmt_expr(ret_ok));
}
let blk = cx.lambda_stmts_1(trait_span, stmts, blkarg);
let name = cx.expr_str(trait_span, variant.ident.name);
let fn_emit_enum_variant_path: Vec<_> =
cx.def_site_path(&[sym::rustc_serialize, sym::Encoder, sym::emit_enum_variant]);
let call = cx.expr_call_global(trait_span, fn_emit_enum_variant_path, thin_vec![
blkencoder,
name,
cx.expr_usize(trait_span, *idx),
cx.expr_usize(trait_span, fields.len()),
blk,
]);
let blk = cx.lambda1(trait_span, call, blkarg);
let fn_emit_enum_path: Vec<_> =
cx.def_site_path(&[sym::rustc_serialize, sym::Encoder, sym::emit_enum]);
let expr = cx.expr_call_global(trait_span, fn_emit_enum_path, thin_vec![
encoder,
cx.expr_str(trait_span, substr.type_ident.name),
blk
]);
BlockOrExpr::new_mixed(thin_vec![me], Some(expr))
}
_ => cx.dcx().bug("expected Struct or EnumMatching in derive(Encodable)"),
}
}

26
compiler/rustc_builtin_macros/src/deriving/generic/mod.rs
View file

@ -311,7 +311,7 @@ pub(crate) enum SubstructureFields<'a> {
/// Matching variants of the enum: variant index, ast::Variant,
/// fields: the field name is only non-`None` in the case of a struct
/// variant.
EnumMatching(usize, &'a ast::Variant, Vec<FieldInfo>),
EnumMatching(&'a ast::Variant, Vec<FieldInfo>),
/// The discriminant of an enum. The first field is a `FieldInfo` for the discriminants, as
/// if they were fields. The second field is the expression to combine the
@ -322,7 +322,7 @@ pub(crate) enum SubstructureFields<'a> {
StaticStruct(&'a ast::VariantData, StaticFields),
/// A static method where `Self` is an enum.
StaticEnum(&'a ast::EnumDef, Vec<(Ident, Span, StaticFields)>),
StaticEnum(&'a ast::EnumDef),
}
/// Combine the values of all the fields together. The last argument is
@ -1270,7 +1270,7 @@ impl<'a> MethodDef<'a> {
trait_,
type_ident,
nonselflike_args,
&EnumMatching(0, variant, Vec::new()),
&EnumMatching(variant, Vec::new()),
);
}
}
@ -1282,9 +1282,8 @@ impl<'a> MethodDef<'a> {
// where each tuple has length = selflike_args.len()
let mut match_arms: ThinVec<ast::Arm> = variants
.iter()
.enumerate()
.filter(|&(_, v)| !(unify_fieldless_variants && v.data.fields().is_empty()))
.map(|(index, variant)| {
.filter(|&v| !(unify_fieldless_variants && v.data.fields().is_empty()))
.map(|variant| {
// A single arm has form (&VariantK, &VariantK, ...) => BodyK
// (see "Final wrinkle" note below for why.)
@ -1316,7 +1315,7 @@ impl<'a> MethodDef<'a> {
// expressions for referencing every field of every
// Self arg, assuming all are instances of VariantK.
// Build up code associated with such a case.
let substructure = EnumMatching(index, variant, fields);
let substructure = EnumMatching(variant, fields);
let arm_expr = self
.call_substructure_method(
cx,
@ -1344,7 +1343,7 @@ impl<'a> MethodDef<'a> {
trait_,
type_ident,
nonselflike_args,
&EnumMatching(0, v, Vec::new()),
&EnumMatching(v, Vec::new()),
)
.into_expr(cx, span),
)
@ -1407,21 +1406,12 @@ impl<'a> MethodDef<'a> {
type_ident: Ident,
nonselflike_args: &[P<Expr>],
) -> BlockOrExpr {
let summary = enum_def
.variants
.iter()
.map(|v| {
let sp = v.span.with_ctxt(trait_.span.ctxt());
let summary = trait_.summarise_struct(cx, &v.data);
(v.ident, sp, summary)
})
.collect();
self.call_substructure_method(
cx,
trait_,
type_ident,
nonselflike_args,
&StaticEnum(enum_def, summary),
&StaticEnum(enum_def),
)
}
}

2
compiler/rustc_builtin_macros/src/deriving/generic/ty.rs
View file

@ -21,7 +21,6 @@ pub(crate) struct Path {
#[derive(Clone)]
pub(crate) enum PathKind {
Local,
Global,
Std,
}
@ -57,7 +56,6 @@ impl Path {
let params = tys.map(GenericArg::Type).collect();
match self.kind {
PathKind::Global => cx.path_all(span, true, idents, params),
PathKind::Local => cx.path_all(span, false, idents, params),
PathKind::Std => {
let def_site = cx.with_def_site_ctxt(DUMMY_SP);

2
compiler/rustc_builtin_macros/src/deriving/mod.rs
View file

@ -23,9 +23,7 @@ pub(crate) mod bounds;
pub(crate) mod clone;
pub(crate) mod coerce_pointee;
pub(crate) mod debug;
pub(crate) mod decodable;
pub(crate) mod default;
pub(crate) mod encodable;
pub(crate) mod hash;
#[path = "cmp/eq.rs"]

2
compiler/rustc_builtin_macros/src/lib.rs
View file

@ -132,8 +132,6 @@ pub fn register_builtin_macros(resolver: &mut dyn ResolverExpand) {
Ord: ord::expand_deriving_ord,
PartialEq: partial_eq::expand_deriving_partial_eq,
PartialOrd: partial_ord::expand_deriving_partial_ord,
RustcDecodable: decodable::expand_deriving_rustc_decodable,
RustcEncodable: encodable::expand_deriving_rustc_encodable,
CoercePointee: coerce_pointee::expand_deriving_coerce_pointee,
}