mirror of
https://github.com/carbon-language/carbon-lang.git
synced 2026-09-29 22:02:42 +01:00
fdb188ccfd
Implementation of unused pattern bindings #2022, continued. Whereas previous PR #6460 took care of parsing, and PR #6479 prepared the stage by using _ in some test cases, this PR has the the actual implementation, using a simple dataflow analysis. --------- Co-authored-by: Burak Emir <bqe@google.com> Co-authored-by: jonmeow <jperkins@google.com>
55 lines
1.9 KiB
C++
55 lines
1.9 KiB
C++
// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
|
|
// Exceptions. See /LICENSE for license information.
|
|
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
|
|
|
|
#include "toolchain/check/unused.h"
|
|
|
|
#include "toolchain/base/kind_switch.h"
|
|
#include "toolchain/check/context.h"
|
|
#include "toolchain/check/diagnostic_helpers.h"
|
|
|
|
namespace Carbon::Check {
|
|
|
|
auto CheckUnusedBinding(Context& context, SemIR::NameId name_id,
|
|
const LexicalLookup::Result& result) -> void {
|
|
// Don't warn about the special name `_`. Other special names, such as `self`,
|
|
// are warned if unused. `.Self` is also excluded as it is often implicit.
|
|
if (name_id == SemIR::NameId::Underscore ||
|
|
name_id == SemIR::NameId::PeriodSelf) {
|
|
return;
|
|
}
|
|
|
|
// Don't warn about names that aren't in the current file.
|
|
auto decl_loc = context.insts().GetCanonicalLocId(result.inst_id);
|
|
if (decl_loc.kind() == SemIR::LocId::Kind::ImportIRInstId) {
|
|
return;
|
|
}
|
|
|
|
auto binding = context.insts().TryGetAs<SemIR::AnyBinding>(result.inst_id);
|
|
if (!binding) {
|
|
return;
|
|
}
|
|
|
|
const auto& entity_name = context.entity_names().Get(binding->entity_name_id);
|
|
if (entity_name.is_unused) {
|
|
if (result.use_loc_id.has_value()) {
|
|
CARBON_DIAGNOSTIC(UnusedButUsed, Error,
|
|
"variable `{0}` marked `unused` but used",
|
|
SemIR::NameId);
|
|
CARBON_DIAGNOSTIC(UnusedButUsedHere, Note, "usage here");
|
|
context.emitter()
|
|
.Build(decl_loc, UnusedButUsed, name_id)
|
|
.Note(result.use_loc_id, UnusedButUsedHere)
|
|
.Emit();
|
|
}
|
|
} else {
|
|
if (!result.use_loc_id.has_value() && result.is_decl_reachable) {
|
|
CARBON_DIAGNOSTIC(UnusedBinding, Warning, "binding `{0}` unused",
|
|
SemIR::NameId);
|
|
context.emitter().Emit(decl_loc, UnusedBinding, name_id);
|
|
}
|
|
}
|
|
}
|
|
|
|
} // namespace Carbon::Check
|