109 lines
4.6 KiB
Rust
109 lines
4.6 KiB
Rust
use rustc_session::lint::builtin::NON_EXHAUSTIVE_OMITTED_PATTERNS;
|
|
use rustc_span::ErrorGuaranteed;
|
|
use tracing::instrument;
|
|
|
|
use crate::MatchArm;
|
|
use crate::constructor::Constructor;
|
|
use crate::errors::{NonExhaustiveOmittedPattern, NonExhaustiveOmittedPatternLintOnArm, Uncovered};
|
|
use crate::pat_column::PatternColumn;
|
|
use crate::rustc::{RevealedTy, RustcPatCtxt, WitnessPat};
|
|
|
|
/// Traverse the patterns to collect any variants of a non_exhaustive enum that fail to be mentioned
|
|
/// in a given column.
|
|
#[instrument(level = "debug", skip(cx), ret)]
|
|
fn collect_nonexhaustive_missing_variants<'p, 'tcx>(
|
|
cx: &RustcPatCtxt<'p, 'tcx>,
|
|
column: &PatternColumn<'p, RustcPatCtxt<'p, 'tcx>>,
|
|
) -> Result<Vec<WitnessPat<'p, 'tcx>>, ErrorGuaranteed> {
|
|
let Some(&ty) = column.head_ty() else {
|
|
return Ok(Vec::new());
|
|
};
|
|
|
|
let set = column.analyze_ctors(cx, &ty)?;
|
|
if set.present.is_empty() {
|
|
// We can't consistently handle the case where no constructors are present (since this would
|
|
// require digging deep through any type in case there's a non_exhaustive enum somewhere),
|
|
// so for consistency we refuse to handle the top-level case, where we could handle it.
|
|
return Ok(Vec::new());
|
|
}
|
|
|
|
let mut witnesses = Vec::new();
|
|
if cx.is_foreign_non_exhaustive_enum(ty) {
|
|
witnesses.extend(
|
|
set.missing
|
|
.into_iter()
|
|
// This will list missing visible variants.
|
|
.filter(|c| !matches!(c, Constructor::Hidden | Constructor::NonExhaustive))
|
|
.map(|missing_ctor| WitnessPat::wild_from_ctor(cx, missing_ctor, ty)),
|
|
)
|
|
}
|
|
|
|
// Recurse into the fields.
|
|
for ctor in set.present {
|
|
let specialized_columns = column.specialize(cx, &ty, &ctor);
|
|
let wild_pat = WitnessPat::wild_from_ctor(cx, ctor, ty);
|
|
for (i, col_i) in specialized_columns.iter().enumerate() {
|
|
// Compute witnesses for each column.
|
|
let wits_for_col_i = collect_nonexhaustive_missing_variants(cx, col_i)?;
|
|
// For each witness, we build a new pattern in the shape of `ctor(_, _, wit, _, _)`,
|
|
// adding enough wildcards to match `arity`.
|
|
for wit in wits_for_col_i {
|
|
let mut pat = wild_pat.clone();
|
|
pat.fields[i] = wit;
|
|
witnesses.push(pat);
|
|
}
|
|
}
|
|
}
|
|
Ok(witnesses)
|
|
}
|
|
|
|
pub(crate) fn lint_nonexhaustive_missing_variants<'p, 'tcx>(
|
|
rcx: &RustcPatCtxt<'p, 'tcx>,
|
|
arms: &[MatchArm<'p, RustcPatCtxt<'p, 'tcx>>],
|
|
pat_column: &PatternColumn<'p, RustcPatCtxt<'p, 'tcx>>,
|
|
scrut_ty: RevealedTy<'tcx>,
|
|
) -> Result<(), ErrorGuaranteed> {
|
|
if !matches!(
|
|
rcx.tcx.lint_level_at_node(NON_EXHAUSTIVE_OMITTED_PATTERNS, rcx.match_lint_level).0,
|
|
rustc_session::lint::Level::Allow
|
|
) {
|
|
let witnesses = collect_nonexhaustive_missing_variants(rcx, pat_column)?;
|
|
if !witnesses.is_empty() {
|
|
// Report that a match of a `non_exhaustive` enum marked with `non_exhaustive_omitted_patterns`
|
|
// is not exhaustive enough.
|
|
//
|
|
// NB: The partner lint for structs lives in `compiler/rustc_hir_analysis/src/check/pat.rs`.
|
|
rcx.tcx.emit_node_span_lint(
|
|
NON_EXHAUSTIVE_OMITTED_PATTERNS,
|
|
rcx.match_lint_level,
|
|
rcx.scrut_span,
|
|
NonExhaustiveOmittedPattern {
|
|
scrut_ty: scrut_ty.inner(),
|
|
uncovered: Uncovered::new(rcx.scrut_span, rcx, witnesses),
|
|
},
|
|
);
|
|
}
|
|
} else {
|
|
// We used to allow putting the `#[allow(non_exhaustive_omitted_patterns)]` on a match
|
|
// arm. This no longer makes sense so we warn users, to avoid silently breaking their
|
|
// usage of the lint.
|
|
for arm in arms {
|
|
let (lint_level, lint_level_source) =
|
|
rcx.tcx.lint_level_at_node(NON_EXHAUSTIVE_OMITTED_PATTERNS, arm.arm_data);
|
|
if !matches!(lint_level, rustc_session::lint::Level::Allow) {
|
|
let decorator = NonExhaustiveOmittedPatternLintOnArm {
|
|
lint_span: lint_level_source.span(),
|
|
suggest_lint_on_match: rcx.whole_match_span.map(|span| span.shrink_to_lo()),
|
|
lint_level: lint_level.as_str(),
|
|
lint_name: "non_exhaustive_omitted_patterns",
|
|
};
|
|
|
|
use rustc_errors::LintDiagnostic;
|
|
let mut err = rcx.tcx.dcx().struct_span_warn(arm.pat.data().span, "");
|
|
decorator.decorate_lint(&mut err);
|
|
err.emit();
|
|
}
|
|
}
|
|
}
|
|
Ok(())
|
|
}
|