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/// Dead-code detector (M18).
///
/// After body analysis has recorded all method/property/function references into the
/// codebase, this analyzer walks every class and reports:
///
/// - `UnusedMethod` — private method that is never called
/// - `UnusedProperty` — private property that is never read
/// - `UnusedFunction` — non-public free function that is never called
///
/// Magic methods (`__construct`, `__destruct`, `__toString`, etc.) and
/// constructors are excluded because they are called implicitly.
use std::sync::Arc;
use mir_codebase::storage::Visibility;
use mir_issues::{Issue, IssueKind, Severity};
use crate::db::MirDatabase;
use crate::stubs::StubVfs;
// Magic PHP methods that are invoked implicitly — never flag these as unused.
const MAGIC_METHODS: &[&str] = &[
"__construct",
"__destruct",
"__call",
"__callstatic",
"__get",
"__set",
"__isset",
"__unset",
"__sleep",
"__wakeup",
"__serialize",
"__unserialize",
"__tostring",
"__invoke",
"__set_state",
"__clone",
"__debuginfo",
];
pub struct DeadCodeAnalyzer<'a> {
db: &'a dyn MirDatabase,
/// Only report dead code defined in these files (empty = all files).
/// Threading the project file set keeps the pass from materializing and
/// flagging private members of lazily-loaded vendor classes (whose bodies
/// are never analyzed, so every private member looks unreferenced).
analyzed_files: rustc_hash::FxHashSet<Arc<str>>,
}
impl<'a> DeadCodeAnalyzer<'a> {
#[allow(dead_code)]
pub fn new(db: &'a dyn MirDatabase) -> Self {
Self {
db,
analyzed_files: rustc_hash::FxHashSet::default(),
}
}
pub fn with_files(
db: &'a dyn MirDatabase,
analyzed_files: rustc_hash::FxHashSet<Arc<str>>,
) -> Self {
Self { db, analyzed_files }
}
pub fn analyze(&self) -> Vec<Issue> {
let mut issues = Vec::new();
// Walk only plain classes (not interfaces/traits/enums); private
// members on the other kinds aren't subject to dead-code reporting.
// `analyzed_class_defs` already restricts to the project file set and
// returns plain classes only, so vendor classes are never enumerated.
for (fqcn, class) in crate::db::analyzed_class_defs(self.db, &self.analyzed_files) {
let fqcn_str = fqcn.as_ref();
// Methods.
for (name, method) in class.own_methods().iter() {
if method.visibility != Visibility::Private {
continue;
}
let name_lower = name.to_ascii_lowercase();
if MAGIC_METHODS.contains(&name_lower.as_str()) {
continue;
}
if !self
.db
.has_reference(&format!("{}::{}", fqcn_str, name_lower))
{
let location =
crate::diagnostics::storage_loc_to_location(method.location.as_ref());
issues.push(Issue::new(
IssueKind::UnusedMethod {
class: fqcn_str.to_string(),
method: name.to_string(),
},
location,
));
}
}
// Properties.
if let Some(props) = class.own_properties() {
for (name, prop) in props.iter() {
if prop.visibility != Visibility::Private {
continue;
}
if !self
.db
.has_reference(&format!("{}::{}", fqcn_str, name.as_ref()))
{
let location =
crate::diagnostics::storage_loc_to_location(prop.location.as_ref());
issues.push(Issue::new(
IssueKind::UnusedProperty {
class: fqcn_str.to_string(),
property: name.to_string(),
},
location,
));
}
}
}
}
// --- Non-referenced free functions ---
let stub_vfs = StubVfs::new();
let fqns: Vec<Arc<str>> = crate::db::workspace_functions(self.db)
.iter()
.cloned()
.collect();
for fqn in fqns {
let here = crate::db::Fqcn::from_str(self.db, fqn.as_ref());
let pulled = crate::db::find_function(self.db, here);
let Some(f) = pulled.as_ref() else {
continue;
};
let (location, short_name) = (f.location.clone(), f.short_name.to_string());
// Skip PHP built-in and extension functions loaded from stubs —
// they are not user-defined dead code.
if let Some(loc) = &location {
if stub_vfs.is_stub_file(loc.file.as_ref()) {
continue;
}
// Restrict to the project file set (when scoped), mirroring the
// class-member pass: a function from a lazily-loaded vendor file
// is not user dead code.
if !self.analyzed_files.is_empty()
&& !self.analyzed_files.contains(loc.file.as_ref())
{
continue;
}
}
if !self.db.has_reference(fqn.as_ref()) {
let location = crate::diagnostics::storage_loc_to_location(location.as_ref());
issues.push(Issue::new(
IssueKind::UnusedFunction { name: short_name },
location,
));
}
}
// Downgrade all dead-code issues to Info
for issue in &mut issues {
issue.severity = Severity::Info;
}
issues
}
}
#[cfg(test)]
mod tests {
use super::*;
use crate::session::AnalysisSession;
use crate::PhpVersion;
#[test]
fn builtin_functions_not_flagged_as_unused() {
// The dead-code pass must not produce UnusedFunction for PHP built-ins
// (strlen, array_map, etc.) even when they are never called in user code.
// This test bypasses the fixture runner's file-path filter to verify the
// fix directly on the DeadCodeAnalyzer output.
let session = AnalysisSession::new(PhpVersion::LATEST);
session.ensure_all_stubs();
let db = session.snapshot_db();
let issues = DeadCodeAnalyzer::new(&db).analyze();
let builtin_false_positives: Vec<_> = issues
.iter()
.filter(|i| {
matches!(&i.kind, IssueKind::UnusedFunction { name } if
matches!(name.as_str(), "strlen" | "array_map" | "json_encode" | "preg_match")
)
})
.collect();
assert!(
builtin_false_positives.is_empty(),
"Expected no UnusedFunction for PHP builtins, got: {:?}",
builtin_false_positives
.iter()
.map(|i| i.kind.message())
.collect::<Vec<_>>()
);
}
}