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macros: simplify field ordering in diag derive

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Following the approach taken in earlier commits to separate formatting
initialization from use in the subdiagnostic derive, simplify the
diagnostic derive by removing the field-ordering logic that previously
solved this problem.

Signed-off-by: David Wood <david.wood@huawei.com>
This commit is contained in:
David Wood 2022-10-03 16:10:34 +01:00
parent 7e20929e55
commit fbac1f288b
3 changed files with 39 additions and 103 deletions
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60
compiler/rustc_macros/src/diagnostics/utils.rs
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@ -5,13 +5,12 @@ use proc_macro::Span;
use proc_macro2::TokenStream;
use quote::{format_ident, quote, ToTokens};
use std::cell::RefCell;
use std::cmp::Ordering;
use std::collections::{BTreeSet, HashMap};
use std::fmt;
use std::str::FromStr;
use syn::{spanned::Spanned, Attribute, Field, Meta, Type, TypeTuple};
use syn::{MetaList, MetaNameValue, NestedMeta, Path};
use synstructure::{BindStyle, BindingInfo, VariantInfo};
use synstructure::{BindingInfo, VariantInfo};
use super::error::invalid_nested_attr;
@ -650,65 +649,8 @@ impl quote::IdentFragment for SubdiagnosticKind {
}
}
/// Wrapper around `synstructure::BindStyle` which implements `Ord`.
#[derive(PartialEq, Eq)]
pub(super) struct OrderedBindStyle(pub(super) BindStyle);
impl OrderedBindStyle {
/// Is `BindStyle::Move` or `BindStyle::MoveMut`?
pub(super) fn is_move(&self) -> bool {
matches!(self.0, BindStyle::Move | BindStyle::MoveMut)
}
}
impl Ord for OrderedBindStyle {
fn cmp(&self, other: &Self) -> Ordering {
match (self.is_move(), other.is_move()) {
// If both `self` and `other` are the same, then ordering is equal.
(true, true) | (false, false) => Ordering::Equal,
// If `self` is not a move then it should be considered less than `other` (so that
// references are sorted first).
(false, _) => Ordering::Less,
// If `self` is a move then it must be greater than `other` (again, so that references
// are sorted first).
(true, _) => Ordering::Greater,
}
}
}
impl PartialOrd for OrderedBindStyle {
fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
Some(self.cmp(other))
}
}
/// Returns `true` if `field` should generate a `set_arg` call rather than any other diagnostic
/// call (like `span_label`).
pub(super) fn should_generate_set_arg(field: &Field) -> bool {
field.attrs.is_empty()
}
/// Returns `true` if `field` needs to have code generated in the by-move branch of the
/// generated derive rather than the by-ref branch.
pub(super) fn bind_style_of_field(field: &Field) -> OrderedBindStyle {
let generates_set_arg = should_generate_set_arg(field);
let is_multispan = type_matches_path(&field.ty, &["rustc_errors", "MultiSpan"]);
// FIXME(davidtwco): better support for one field needing to be in the by-move and
// by-ref branches.
let is_subdiagnostic = field
.attrs
.iter()
.map(|attr| attr.path.segments.last().unwrap().ident.to_string())
.any(|attr| attr == "subdiagnostic");
// `set_arg` calls take their argument by-move..
let needs_move = generates_set_arg
// If this is a `MultiSpan` field then it needs to be moved to be used by any
// attribute..
|| is_multispan
// If this a `#[subdiagnostic]` then it needs to be moved as the other diagnostic is
// unlikely to be `Copy`..
|| is_subdiagnostic;
OrderedBindStyle(if needs_move { BindStyle::Move } else { BindStyle::Ref })
}