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1 | 1 | //! Automatic migration of Rust 2021 patterns to a form valid in both Editions 2021 and 2024. |
2 | 2 |
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3 | 3 | use rustc_data_structures::fx::FxIndexMap; |
4 | | -use rustc_errors::MultiSpan; |
| 4 | +use rustc_errors::{Applicability, Diag, EmissionGuarantee, MultiSpan, pluralize}; |
5 | 5 | use rustc_hir::{BindingMode, ByRef, HirId, Mutability}; |
6 | 6 | use rustc_lint as lint; |
7 | 7 | use rustc_middle::ty::{self, Rust2024IncompatiblePatInfo, TyCtxt}; |
8 | 8 | use rustc_span::{Ident, Span}; |
9 | 9 |
|
10 | | -use crate::errors::{Rust2024IncompatiblePat, Rust2024IncompatiblePatSugg}; |
11 | | -use crate::fluent_generated as fluent; |
12 | | - |
13 | 10 | /// For patterns flagged for migration during HIR typeck, this handles constructing and emitting |
14 | 11 | /// a diagnostic suggestion. |
15 | 12 | pub(super) struct PatMigration<'a> { |
@@ -49,39 +46,90 @@ impl<'a> PatMigration<'a> { |
49 | 46 | for (span, label) in self.info.primary_labels.iter() { |
50 | 47 | spans.push_span_label(*span, label.clone()); |
51 | 48 | } |
52 | | - let sugg = Rust2024IncompatiblePatSugg { |
53 | | - suggest_eliding_modes: self.info.suggest_eliding_modes, |
54 | | - suggestion: self.suggestion, |
55 | | - ref_pattern_count: self.ref_pattern_count, |
56 | | - binding_mode_count: self.binding_mode_count, |
57 | | - default_mode_labels: self.default_mode_labels, |
58 | | - }; |
59 | 49 | // If a relevant span is from at least edition 2024, this is a hard error. |
60 | 50 | let is_hard_error = spans.primary_spans().iter().any(|span| span.at_least_rust_2024()); |
| 51 | + let primary_message = self.primary_message(is_hard_error); |
61 | 52 | if is_hard_error { |
62 | | - let mut err = |
63 | | - tcx.dcx().struct_span_err(spans, fluent::mir_build_rust_2024_incompatible_pat); |
64 | | - if let Some(info) = lint::builtin::RUST_2024_INCOMPATIBLE_PAT.future_incompatible { |
65 | | - // provide the same reference link as the lint |
66 | | - err.note(format!("for more information, see {}", info.reference)); |
67 | | - } |
68 | | - err.arg("bad_modifiers", self.info.bad_modifiers); |
69 | | - err.arg("bad_ref_pats", self.info.bad_ref_pats); |
70 | | - err.arg("is_hard_error", true); |
71 | | - err.subdiagnostic(sugg); |
| 53 | + let mut err = tcx.dcx().struct_span_err(spans, primary_message); |
| 54 | + err.note("for more information, see <https://doc.rust-lang.org/reference/patterns.html#binding-modes>"); |
| 55 | + self.format_subdiagnostics(&mut err); |
72 | 56 | err.emit(); |
73 | 57 | } else { |
74 | | - tcx.emit_node_span_lint( |
75 | | - lint::builtin::RUST_2024_INCOMPATIBLE_PAT, |
76 | | - pat_id, |
77 | | - spans, |
78 | | - Rust2024IncompatiblePat { |
79 | | - sugg, |
80 | | - bad_modifiers: self.info.bad_modifiers, |
81 | | - bad_ref_pats: self.info.bad_ref_pats, |
82 | | - is_hard_error, |
83 | | - }, |
84 | | - ); |
| 58 | + tcx.node_span_lint(lint::builtin::RUST_2024_INCOMPATIBLE_PAT, pat_id, spans, |diag| { |
| 59 | + diag.primary_message(primary_message); |
| 60 | + self.format_subdiagnostics(diag); |
| 61 | + }); |
| 62 | + } |
| 63 | + } |
| 64 | + |
| 65 | + fn primary_message(&self, is_hard_error: bool) -> String { |
| 66 | + let verb1 = match (self.info.bad_mut_modifiers, self.info.bad_ref_modifiers) { |
| 67 | + (true, true) => "write explicit binding modifiers", |
| 68 | + (true, false) => "mutably bind by value", |
| 69 | + (false, true) => "explicitly borrow", |
| 70 | + (false, false) => "explicitly dereference", |
| 71 | + }; |
| 72 | + let or_verb2 = match ( |
| 73 | + self.info.bad_mut_modifiers, |
| 74 | + self.info.bad_ref_modifiers, |
| 75 | + self.info.bad_ref_pats, |
| 76 | + ) { |
| 77 | + // We only need two verb phrases if mentioning both modifiers and reference patterns. |
| 78 | + (false, false, _) | (_, _, false) => "", |
| 79 | + // If mentioning `mut`, we don't have an "explicitly" yet. |
| 80 | + (true, _, true) => " or explicitly dereference", |
| 81 | + // If mentioning `ref`/`ref mut` but not `mut`, we already have an "explicitly". |
| 82 | + (false, true, true) => " or dereference", |
| 83 | + }; |
| 84 | + let in_rust_2024 = if is_hard_error { "" } else { " in Rust 2024" }; |
| 85 | + format!("cannot {verb1}{or_verb2} within an implicitly-borrowing pattern{in_rust_2024}") |
| 86 | + } |
| 87 | + |
| 88 | + fn format_subdiagnostics(self, diag: &mut Diag<'_, impl EmissionGuarantee>) { |
| 89 | + // Format and emit explanatory notes about default binding modes. Reversing the spans' order |
| 90 | + // means if we have nested spans, the innermost ones will be visited first. |
| 91 | + for (span, def_br_mutbl) in self.default_mode_labels.into_iter().rev() { |
| 92 | + // Don't point to a macro call site. |
| 93 | + if !span.from_expansion() { |
| 94 | + let note_msg = "matching on a reference type with a non-reference pattern implicitly borrows the contents"; |
| 95 | + let label_msg = format!( |
| 96 | + "this non-reference pattern matches on a reference type `{}_`", |
| 97 | + def_br_mutbl.ref_prefix_str() |
| 98 | + ); |
| 99 | + let mut label = MultiSpan::from(span); |
| 100 | + label.push_span_label(span, label_msg); |
| 101 | + diag.span_note(label, note_msg); |
| 102 | + } |
| 103 | + } |
| 104 | + |
| 105 | + // Format and emit the suggestion. |
| 106 | + let applicability = |
| 107 | + if self.suggestion.iter().all(|(span, _)| span.can_be_used_for_suggestions()) { |
| 108 | + Applicability::MachineApplicable |
| 109 | + } else { |
| 110 | + Applicability::MaybeIncorrect |
| 111 | + }; |
| 112 | + let plural_modes = pluralize!(self.binding_mode_count); |
| 113 | + let msg = if self.info.suggest_eliding_modes { |
| 114 | + format!("remove the unnecessary binding modifier{plural_modes}") |
| 115 | + } else { |
| 116 | + let match_on_these_references = if self.ref_pattern_count == 1 { |
| 117 | + "match on the reference with a reference pattern" |
| 118 | + } else { |
| 119 | + "match on these references with reference patterns" |
| 120 | + }; |
| 121 | + let and_explain_modes = if self.binding_mode_count > 0 { |
| 122 | + let a = if self.binding_mode_count == 1 { "a " } else { "" }; |
| 123 | + format!(" and borrow explicitly using {a}variable binding mode{plural_modes}") |
| 124 | + } else { |
| 125 | + " to avoid implicitly borrowing".to_owned() |
| 126 | + }; |
| 127 | + format!("{match_on_these_references}{and_explain_modes}") |
| 128 | + }; |
| 129 | + // FIXME(dianne): for peace of mind, don't risk emitting a 0-part suggestion (that panics!) |
| 130 | + debug_assert!(!self.suggestion.is_empty()); |
| 131 | + if !self.suggestion.is_empty() { |
| 132 | + diag.multipart_suggestion_verbose(msg, self.suggestion, applicability); |
85 | 133 | } |
86 | 134 | } |
87 | 135 |
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