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Rollup merge of #46103 - zackmdavis:dead_code_lint_should_say_never_constructed_for_variants, r=arielb1

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dead code lint to say "never constructed" for variants

As reported in #19140, #44083, and #44565, some users were confused when
the dead-code lint reported an enum variant to be "unused" when it was
matched on (but not constructed). This wording change makes it clearer
that the lint is in fact checking for construction.

We continue to say "used" for all other items (it's tempting to say
"called" for functions and methods, but this turns out not to be
correct: functions can be passed as arguments and the dead-code lint
isn't special-casing that or anything).

Resolves #19140.

r? @pnkfelix
This commit is contained in:
kennytm 2017-11-22 01:13:00 +08:00 • committed by GitHub
commit 7eb2e79ea8
5 changed files with 23 additions and 18 deletions
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23
src/librustc/middle/dead.rs
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@ -531,13 +531,15 @@ impl<'a, 'tcx> DeadVisitor<'a, 'tcx> {
id: ast::NodeId,
span: syntax_pos::Span,
name: ast::Name,
node_type: &str) {
node_type: &str,
participle: &str) {
if !name.as_str().starts_with("_") {
self.tcx
.lint_node(lint::builtin::DEAD_CODE,
id,
span,
&format!("{} is never used: `{}`", node_type, name));
&format!("{} is never {}: `{}`",
node_type, participle, name));
}
}
}
@ -570,7 +572,8 @@ impl<'a, 'tcx> Visitor<'tcx> for DeadVisitor<'a, 'tcx> {
item.id,
span,
item.name,
item.node.descriptive_variant()
item.node.descriptive_variant(),
"used",
);
} else {
// Only continue if we didn't warn
@ -583,7 +586,8 @@ impl<'a, 'tcx> Visitor<'tcx> for DeadVisitor<'a, 'tcx> {
g: &'tcx hir::Generics,
id: ast::NodeId) {
if self.should_warn_about_variant(&variant.node) {
self.warn_dead_code(variant.node.data.id(), variant.span, variant.node.name, "variant");
self.warn_dead_code(variant.node.data.id(), variant.span, variant.node.name,
"variant", "constructed");
} else {
intravisit::walk_variant(self, variant, g, id);
}
@ -591,15 +595,15 @@ impl<'a, 'tcx> Visitor<'tcx> for DeadVisitor<'a, 'tcx> {
fn visit_foreign_item(&mut self, fi: &'tcx hir::ForeignItem) {
if self.should_warn_about_foreign_item(fi) {
self.warn_dead_code(fi.id, fi.span, fi.name, fi.node.descriptive_variant());
self.warn_dead_code(fi.id, fi.span, fi.name,
fi.node.descriptive_variant(), "used");
}
intravisit::walk_foreign_item(self, fi);
}
fn visit_struct_field(&mut self, field: &'tcx hir::StructField) {
if self.should_warn_about_field(&field) {
self.warn_dead_code(field.id, field.span,
field.name, "field");
self.warn_dead_code(field.id, field.span, field.name, "field", "used");
}
intravisit::walk_struct_field(self, field);
}
@ -611,14 +615,15 @@ impl<'a, 'tcx> Visitor<'tcx> for DeadVisitor<'a, 'tcx> {
self.warn_dead_code(impl_item.id,
impl_item.span,
impl_item.name,
"associated const");
"associated const",
"used");
}
self.visit_nested_body(body_id)
}
hir::ImplItemKind::Method(_, body_id) => {
if !self.symbol_is_live(impl_item.id, None) {
let span = self.tcx.sess.codemap().def_span(impl_item.span);
self.warn_dead_code(impl_item.id, span, impl_item.name, "method");
self.warn_dead_code(impl_item.id, span, impl_item.name, "method", "used");
}
self.visit_nested_body(body_id)
}