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Auto merge of #116236 - dtolnay:builtinmacrocomment, r=cjgillot
Modernize rustc_builtin_macros generics helpers - Rustfmt-compatible formatting for the code snippets in comments - Eliminate an _"Extra scope required"_ obsoleted by NLL
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c716f180e8
@ -37,8 +37,9 @@
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//! following snippet
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//!
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//! ```rust
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//! # #![allow(dead_code)]
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//! struct A { x : i32 }
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//! struct A {
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//! x: i32,
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//! }
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//!
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//! struct B(i32);
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//!
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@ -74,6 +75,7 @@
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//! trait PartialEq {
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//! fn eq(&self, other: &Self) -> bool;
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//! }
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//!
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//! impl PartialEq for i32 {
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//! fn eq(&self, other: &i32) -> bool {
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//! *self == *other
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@ -90,22 +92,22 @@
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//!
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//! ```text
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//! Struct(vec![FieldInfo {
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//! span: <span of x>
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//! name: Some(<ident of x>),
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//! self_: <expr for &self.x>,
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//! other: vec![<expr for &other.x]
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//! }])
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//! span: <span of x>,
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//! name: Some(<ident of x>),
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//! self_: <expr for &self.x>,
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//! other: vec![<expr for &other.x>],
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//! }])
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//! ```
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//!
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//! For the `B` impl, called with `B(a)` and `B(b)`,
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//!
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//! ```text
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//! Struct(vec![FieldInfo {
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//! span: <span of `i32`>,
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//! name: None,
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//! self_: <expr for &a>
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//! other: vec![<expr for &b>]
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//! }])
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//! span: <span of i32>,
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//! name: None,
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//! self_: <expr for &a>,
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//! other: vec![<expr for &b>],
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//! }])
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//! ```
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//!
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//! ## Enums
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@ -114,33 +116,42 @@
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//! == C0(b)`, the SubstructureFields is
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//!
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//! ```text
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//! EnumMatching(0, <ast::Variant for C0>,
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//! vec![FieldInfo {
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//! span: <span of i32>
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//! name: None,
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//! self_: <expr for &a>,
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//! other: vec![<expr for &b>]
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//! }])
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//! EnumMatching(
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//! 0,
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//! <ast::Variant for C0>,
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//! vec![FieldInfo {
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//! span: <span of i32>,
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//! name: None,
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//! self_: <expr for &a>,
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//! other: vec![<expr for &b>],
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//! }],
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//! )
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//! ```
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//!
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//! For `C1 {x}` and `C1 {x}`,
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//!
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//! ```text
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//! EnumMatching(1, <ast::Variant for C1>,
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//! vec![FieldInfo {
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//! span: <span of x>
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//! name: Some(<ident of x>),
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//! self_: <expr for &self.x>,
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//! other: vec![<expr for &other.x>]
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//! }])
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//! EnumMatching(
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//! 1,
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//! <ast::Variant for C1>,
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//! vec![FieldInfo {
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//! span: <span of x>,
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//! name: Some(<ident of x>),
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//! self_: <expr for &self.x>,
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//! other: vec![<expr for &other.x>],
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//! }],
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//! )
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//! ```
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//!
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//! For the tags,
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//!
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//! ```text
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//! EnumTag(
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//! &[<ident of self tag>, <ident of other tag>], <expr to combine with>)
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//! &[<ident of self tag>, <ident of other tag>],
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//! <expr to combine with>,
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//! )
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//! ```
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//!
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//! Note that this setup doesn't allow for the brute-force "match every variant
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//! against every other variant" approach, which is bad because it produces a
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//! quadratic amount of code (see #15375).
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@ -154,9 +165,13 @@
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//!
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//! StaticStruct(<ast::VariantData of B>, Unnamed(vec![<span of x>]))
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//!
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//! StaticEnum(<ast::EnumDef of C>,
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//! vec![(<ident of C0>, <span of C0>, Unnamed(vec![<span of i32>])),
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//! (<ident of C1>, <span of C1>, Named(vec![(<ident of x>, <span of x>)]))])
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//! StaticEnum(
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//! <ast::EnumDef of C>,
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//! vec![
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//! (<ident of C0>, <span of C0>, Unnamed(vec![<span of i32>])),
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//! (<ident of C1>, <span of C1>, Named(vec![(<ident of x>, <span of x>)])),
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//! ],
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//! )
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//! ```
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pub use StaticFields::*;
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@ -522,7 +537,10 @@ impl<'a> TraitDef<'a> {
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/// Given that we are deriving a trait `DerivedTrait` for a type like:
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///
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/// ```ignore (only-for-syntax-highlight)
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/// struct Struct<'a, ..., 'z, A, B: DeclaredTrait, C, ..., Z> where C: WhereTrait {
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/// struct Struct<'a, ..., 'z, A, B: DeclaredTrait, C, ..., Z>
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/// where
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/// C: WhereTrait,
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/// {
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/// a: A,
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/// b: B::Item,
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/// b1: <B as DeclaredTrait>::Item,
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@ -535,12 +553,13 @@ impl<'a> TraitDef<'a> {
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/// create an impl like:
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///
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/// ```ignore (only-for-syntax-highlight)
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/// impl<'a, ..., 'z, A, B: DeclaredTrait, C, ... Z> where
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/// C: WhereTrait,
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/// impl<'a, ..., 'z, A, B: DeclaredTrait, C, ..., Z>
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/// where
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/// C: WhereTrait,
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/// A: DerivedTrait + B1 + ... + BN,
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/// B: DerivedTrait + B1 + ... + BN,
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/// C: DerivedTrait + B1 + ... + BN,
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/// B::Item: DerivedTrait + B1 + ... + BN,
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/// B::Item: DerivedTrait + B1 + ... + BN,
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/// <C as WhereTrait>::Item: DerivedTrait + B1 + ... + BN,
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/// ...
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/// {
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@ -676,65 +695,59 @@ impl<'a> TraitDef<'a> {
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}
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}));
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{
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// Extra scope required here so ty_params goes out of scope before params is moved
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let ty_param_names: Vec<Symbol> = params
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.iter()
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.filter(|param| matches!(param.kind, ast::GenericParamKind::Type { .. }))
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.map(|ty_param| ty_param.ident.name)
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.collect();
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let mut ty_params = params
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.iter()
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.filter(|param| matches!(param.kind, ast::GenericParamKind::Type { .. }))
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.peekable();
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if !ty_param_names.is_empty() {
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for field_ty in field_tys {
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let field_ty_params = find_type_parameters(&field_ty, &ty_param_names, cx);
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if ty_params.peek().is_some() {
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let ty_param_names: Vec<Symbol> =
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ty_params.map(|ty_param| ty_param.ident.name).collect();
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for field_ty in field_tys {
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let field_ty_params = find_type_parameters(&field_ty, &ty_param_names, cx);
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for field_ty_param in field_ty_params {
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// if we have already handled this type, skip it
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if let ast::TyKind::Path(_, p) = &field_ty_param.ty.kind
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&& let [sole_segment] = &*p.segments
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&& ty_param_names.contains(&sole_segment.ident.name)
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{
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continue;
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}
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let mut bounds: Vec<_> = self
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.additional_bounds
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.iter()
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.map(|p| {
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cx.trait_bound(
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p.to_path(cx, self.span, type_ident, generics),
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self.is_const,
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)
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})
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.collect();
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// Require the current trait.
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if !self.skip_path_as_bound {
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bounds.push(cx.trait_bound(trait_path.clone(), self.is_const));
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}
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// Add a `Copy` bound if required.
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if is_packed && self.needs_copy_as_bound_if_packed {
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let p = deriving::path_std!(marker::Copy);
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bounds.push(cx.trait_bound(
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for field_ty_param in field_ty_params {
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// if we have already handled this type, skip it
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if let ast::TyKind::Path(_, p) = &field_ty_param.ty.kind
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&& let [sole_segment] = &*p.segments
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&& ty_param_names.contains(&sole_segment.ident.name)
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{
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continue;
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}
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let mut bounds: Vec<_> = self
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.additional_bounds
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.iter()
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.map(|p| {
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cx.trait_bound(
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p.to_path(cx, self.span, type_ident, generics),
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self.is_const,
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));
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}
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)
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})
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.collect();
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if !bounds.is_empty() {
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let predicate = ast::WhereBoundPredicate {
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span: self.span,
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bound_generic_params: field_ty_param.bound_generic_params,
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bounded_ty: field_ty_param.ty,
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bounds,
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};
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// Require the current trait.
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if !self.skip_path_as_bound {
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bounds.push(cx.trait_bound(trait_path.clone(), self.is_const));
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}
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let predicate = ast::WherePredicate::BoundPredicate(predicate);
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where_clause.predicates.push(predicate);
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}
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// Add a `Copy` bound if required.
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if is_packed && self.needs_copy_as_bound_if_packed {
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let p = deriving::path_std!(marker::Copy);
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bounds.push(cx.trait_bound(
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p.to_path(cx, self.span, type_ident, generics),
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self.is_const,
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));
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}
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if !bounds.is_empty() {
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let predicate = ast::WhereBoundPredicate {
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span: self.span,
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bound_generic_params: field_ty_param.bound_generic_params,
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bounded_ty: field_ty_param.ty,
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bounds,
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};
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let predicate = ast::WherePredicate::BoundPredicate(predicate);
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where_clause.predicates.push(predicate);
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}
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}
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}
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@ -1026,6 +1039,7 @@ impl<'a> MethodDef<'a> {
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}
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/// The normal case uses field access.
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///
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/// ```
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/// #[derive(PartialEq)]
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/// # struct Dummy;
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@ -1038,10 +1052,12 @@ impl<'a> MethodDef<'a> {
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/// }
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/// }
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/// ```
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///
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/// But if the struct is `repr(packed)`, we can't use something like
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/// `&self.x` because that might cause an unaligned ref. So for any trait
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/// method that takes a reference, we use a local block to force a copy.
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/// This requires that the field impl `Copy`.
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///
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/// ```rust,ignore (example)
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/// # struct A { x: u8, y: u8 }
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/// impl PartialEq for A {
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@ -1053,7 +1069,7 @@ impl<'a> MethodDef<'a> {
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/// impl Hash for A {
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/// fn hash<__H: ::core::hash::Hasher>(&self, state: &mut __H) -> () {
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/// ::core::hash::Hash::hash(&{ self.x }, state);
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/// ::core::hash::Hash::hash(&{ self.y }, state)
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/// ::core::hash::Hash::hash(&{ self.y }, state);
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/// }
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/// }
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/// ```
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@ -1107,7 +1123,9 @@ impl<'a> MethodDef<'a> {
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/// A2(i32)
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/// }
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/// ```
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///
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/// is equivalent to:
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///
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/// ```
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/// #![feature(core_intrinsics)]
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/// enum A {
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@ -1119,15 +1137,15 @@ impl<'a> MethodDef<'a> {
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/// fn eq(&self, other: &A) -> bool {
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/// let __self_tag = ::core::intrinsics::discriminant_value(self);
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/// let __arg1_tag = ::core::intrinsics::discriminant_value(other);
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/// __self_tag == __arg1_tag &&
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/// match (self, other) {
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/// (A::A2(__self_0), A::A2(__arg1_0)) =>
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/// *__self_0 == *__arg1_0,
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/// __self_tag == __arg1_tag
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/// && match (self, other) {
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/// (A::A2(__self_0), A::A2(__arg1_0)) => *__self_0 == *__arg1_0,
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/// _ => true,
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/// }
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/// }
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/// }
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/// ```
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///
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/// Creates a tag check combined with a match for a tuple of all
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/// `selflike_args`, with an arm for each variant with fields, possibly an
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/// arm for each fieldless variant (if `unify_fieldless_variants` is not
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@ -1349,7 +1367,7 @@ impl<'a> MethodDef<'a> {
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// (Variant1, Variant1, ...) => Body1
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// (Variant2, Variant2, ...) => Body2,
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// ...
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// _ => ::core::intrinsics::unreachable()
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// _ => ::core::intrinsics::unreachable(),
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// }
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let get_match_expr = |mut selflike_args: ThinVec<P<Expr>>| {
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let match_arg = if selflike_args.len() == 1 {
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