rustc_pattern_analysis/
lints.rs1use rustc_middle::lint::LevelAndSource;
2use rustc_session::lint::builtin::NON_EXHAUSTIVE_OMITTED_PATTERNS;
3use rustc_span::ErrorGuaranteed;
4use tracing::instrument;
5
6use crate::MatchArm;
7use crate::constructor::Constructor;
8use crate::errors::{NonExhaustiveOmittedPattern, NonExhaustiveOmittedPatternLintOnArm, Uncovered};
9use crate::pat_column::PatternColumn;
10use crate::rustc::{RevealedTy, RustcPatCtxt, WitnessPat};
11
12#[instrument(level = "debug", skip(cx), ret)]
15fn collect_nonexhaustive_missing_variants<'p, 'tcx>(
16 cx: &RustcPatCtxt<'p, 'tcx>,
17 column: &PatternColumn<'p, RustcPatCtxt<'p, 'tcx>>,
18) -> Result<Vec<WitnessPat<'p, 'tcx>>, ErrorGuaranteed> {
19 let Some(&ty) = column.head_ty() else {
20 return Ok(Vec::new());
21 };
22
23 let set = column.analyze_ctors(cx, &ty)?;
24 if set.present.is_empty() {
25 return Ok(Vec::new());
29 }
30
31 let mut witnesses = Vec::new();
32 if cx.is_foreign_non_exhaustive_enum(ty) {
33 witnesses.extend(
34 set.missing
35 .into_iter()
36 .filter(|c| !matches!(c, Constructor::Hidden | Constructor::NonExhaustive))
38 .map(|missing_ctor| WitnessPat::wild_from_ctor(cx, missing_ctor, ty)),
39 )
40 }
41
42 for ctor in set.present {
44 let specialized_columns = column.specialize(cx, &ty, &ctor);
45 let wild_pat = WitnessPat::wild_from_ctor(cx, ctor, ty);
46 for (i, col_i) in specialized_columns.iter().enumerate() {
47 let wits_for_col_i = collect_nonexhaustive_missing_variants(cx, col_i)?;
49 for wit in wits_for_col_i {
52 let mut pat = wild_pat.clone();
53 pat.fields[i] = wit;
54 witnesses.push(pat);
55 }
56 }
57 }
58 Ok(witnesses)
59}
60
61pub(crate) fn lint_nonexhaustive_missing_variants<'p, 'tcx>(
62 rcx: &RustcPatCtxt<'p, 'tcx>,
63 arms: &[MatchArm<'p, RustcPatCtxt<'p, 'tcx>>],
64 pat_column: &PatternColumn<'p, RustcPatCtxt<'p, 'tcx>>,
65 scrut_ty: RevealedTy<'tcx>,
66) -> Result<(), ErrorGuaranteed> {
67 if !matches!(
68 rcx.tcx.lint_level_at_node(NON_EXHAUSTIVE_OMITTED_PATTERNS, rcx.match_lint_level).level,
69 rustc_session::lint::Level::Allow
70 ) {
71 let witnesses = collect_nonexhaustive_missing_variants(rcx, pat_column)?;
72 if !witnesses.is_empty() {
73 rcx.tcx.emit_node_span_lint(
78 NON_EXHAUSTIVE_OMITTED_PATTERNS,
79 rcx.match_lint_level,
80 rcx.scrut_span,
81 NonExhaustiveOmittedPattern {
82 scrut_ty: scrut_ty.inner(),
83 uncovered: Uncovered::new(rcx.scrut_span, rcx, witnesses),
84 },
85 );
86 }
87 } else {
88 for arm in arms {
92 let LevelAndSource { level, src, .. } =
93 rcx.tcx.lint_level_at_node(NON_EXHAUSTIVE_OMITTED_PATTERNS, arm.arm_data);
94 if !matches!(level, rustc_session::lint::Level::Allow) {
95 let decorator = NonExhaustiveOmittedPatternLintOnArm {
96 lint_span: src.span(),
97 suggest_lint_on_match: rcx.whole_match_span.map(|span| span.shrink_to_lo()),
98 lint_level: level.as_str(),
99 lint_name: "non_exhaustive_omitted_patterns",
100 };
101
102 use rustc_errors::LintDiagnostic;
103 let mut err = rcx.tcx.dcx().struct_span_warn(arm.pat.data().span, "");
104 decorator.decorate_lint(&mut err);
105 err.emit();
106 }
107 }
108 }
109 Ok(())
110}