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Replace MatchVisitor::check_in_cx with MatchVisitor::new_cx.
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The closure isn't necessary.
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@nnethercote
nnethercote committed May 7, 2020
1 parent 95f600d commit d26d187
Showing 1 changed file with 75 additions and 80 deletions.
155 changes: 75 additions & 80 deletions src/librustc_mir_build/hair/pattern/check_match.rs
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Expand Up @@ -147,15 +147,13 @@ impl<'tcx> MatchVisitor<'_, 'tcx> {
(pattern, pattern_ty)
}

fn check_in_cx(&self, hir_id: HirId, f: impl FnOnce(MatchCheckCtxt<'_, 'tcx>)) {
let module = self.tcx.parent_module(hir_id);
let cx = MatchCheckCtxt {
fn new_cx(&self, hir_id: HirId) -> MatchCheckCtxt<'_, 'tcx> {
MatchCheckCtxt {
tcx: self.tcx,
param_env: self.param_env,
module: module.to_def_id(),
module: self.tcx.parent_module(hir_id).to_def_id(),
pattern_arena: &self.pattern_arena,
};
f(cx);
}
}

fn check_match(
Expand All @@ -169,91 +167,88 @@ impl<'tcx> MatchVisitor<'_, 'tcx> {
self.check_patterns(arm.guard.is_some(), &arm.pat);
}

self.check_in_cx(scrut.hir_id, |ref mut cx| {
let mut have_errors = false;
let mut cx = self.new_cx(scrut.hir_id);

let inlined_arms: Vec<_> = arms
.iter()
.map(|hir::Arm { pat, guard, .. }| {
(self.lower_pattern(cx, pat, &mut have_errors).0, pat.hir_id, guard.is_some())
})
.collect();
let mut have_errors = false;

// Bail out early if inlining failed.
if have_errors {
return;
}
let inlined_arms: Vec<_> = arms
.iter()
.map(|hir::Arm { pat, guard, .. }| {
(self.lower_pattern(&mut cx, pat, &mut have_errors).0, pat.hir_id, guard.is_some())
})
.collect();

// Fourth, check for unreachable arms.
let matrix = check_arms(cx, &inlined_arms, source);
// Bail out early if inlining failed.
if have_errors {
return;
}

// Fourth, check for unreachable arms.
let matrix = check_arms(&mut cx, &inlined_arms, source);

// Fifth, check if the match is exhaustive.
let scrut_ty = self.tables.node_type(scrut.hir_id);
// Note: An empty match isn't the same as an empty matrix for diagnostics purposes,
// since an empty matrix can occur when there are arms, if those arms all have guards.
let is_empty_match = inlined_arms.is_empty();
check_exhaustive(cx, scrut_ty, scrut.span, &matrix, scrut.hir_id, is_empty_match);
})
// Fifth, check if the match is exhaustive.
let scrut_ty = self.tables.node_type(scrut.hir_id);
// Note: An empty match isn't the same as an empty matrix for diagnostics purposes,
// since an empty matrix can occur when there are arms, if those arms all have guards.
let is_empty_match = inlined_arms.is_empty();
check_exhaustive(&mut cx, scrut_ty, scrut.span, &matrix, scrut.hir_id, is_empty_match);
}

fn check_irrefutable(&self, pat: &'tcx Pat<'tcx>, origin: &str, sp: Option<Span>) {
self.check_in_cx(pat.hir_id, |ref mut cx| {
let (pattern, pattern_ty) = self.lower_pattern(cx, pat, &mut false);
let pats: Matrix<'_, '_> = vec![PatStack::from_pattern(pattern)].into_iter().collect();

let witnesses = match check_not_useful(cx, pattern_ty, &pats, pat.hir_id) {
Ok(_) => return,
Err(err) => err,
};

let joined_patterns = joined_uncovered_patterns(&witnesses);
let mut err = struct_span_err!(
self.tcx.sess,
pat.span,
E0005,
"refutable pattern in {}: {} not covered",
origin,
joined_patterns
);
let suggest_if_let = match &pat.kind {
hir::PatKind::Path(hir::QPath::Resolved(None, path))
if path.segments.len() == 1 && path.segments[0].args.is_none() =>
{
const_not_var(&mut err, cx.tcx, pat, path);
false
}
_ => {
err.span_label(
pat.span,
pattern_not_covered_label(&witnesses, &joined_patterns),
);
true
}
};
let mut cx = self.new_cx(pat.hir_id);

if let (Some(span), true) = (sp, suggest_if_let) {
err.note(
"`let` bindings require an \"irrefutable pattern\", like a `struct` or \
an `enum` with only one variant",
);
if let Ok(snippet) = self.tcx.sess.source_map().span_to_snippet(span) {
err.span_suggestion(
span,
"you might want to use `if let` to ignore the variant that isn't matched",
format!("if {} {{ /* */ }}", &snippet[..snippet.len() - 1]),
Applicability::HasPlaceholders,
);
}
err.note(
"for more information, visit \
https://doc.rust-lang.org/book/ch18-02-refutability.html",
let (pattern, pattern_ty) = self.lower_pattern(&mut cx, pat, &mut false);
let pats: Matrix<'_, '_> = vec![PatStack::from_pattern(pattern)].into_iter().collect();

let witnesses = match check_not_useful(&mut cx, pattern_ty, &pats, pat.hir_id) {
Ok(_) => return,
Err(err) => err,
};

let joined_patterns = joined_uncovered_patterns(&witnesses);
let mut err = struct_span_err!(
self.tcx.sess,
pat.span,
E0005,
"refutable pattern in {}: {} not covered",
origin,
joined_patterns
);
let suggest_if_let = match &pat.kind {
hir::PatKind::Path(hir::QPath::Resolved(None, path))
if path.segments.len() == 1 && path.segments[0].args.is_none() =>
{
const_not_var(&mut err, cx.tcx, pat, path);
false
}
_ => {
err.span_label(pat.span, pattern_not_covered_label(&witnesses, &joined_patterns));
true
}
};

if let (Some(span), true) = (sp, suggest_if_let) {
err.note(
"`let` bindings require an \"irrefutable pattern\", like a `struct` or \
an `enum` with only one variant",
);
if let Ok(snippet) = self.tcx.sess.source_map().span_to_snippet(span) {
err.span_suggestion(
span,
"you might want to use `if let` to ignore the variant that isn't matched",
format!("if {} {{ /* */ }}", &snippet[..snippet.len() - 1]),
Applicability::HasPlaceholders,
);
}
err.note(
"for more information, visit \
https://doc.rust-lang.org/book/ch18-02-refutability.html",
);
}

adt_defined_here(cx, &mut err, pattern_ty, &witnesses);
err.note(&format!("the matched value is of type `{}`", pattern_ty));
err.emit();
});
adt_defined_here(&mut cx, &mut err, pattern_ty, &witnesses);
err.note(&format!("the matched value is of type `{}`", pattern_ty));
err.emit();
}
}

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