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/// Dead-code detector (M18).
///
/// After Pass 2 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 mir_codebase::storage::Visibility;
use mir_issues::{Issue, IssueKind, Location, 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,
}
impl<'a> DeadCodeAnalyzer<'a> {
pub fn new(db: &'a dyn MirDatabase) -> Self {
Self { db }
}
pub fn analyze(&self) -> Vec<Issue> {
let mut issues = Vec::new();
// --- Private methods / properties on classes ---
// Walk only class-kind nodes (not interfaces/traits/enums); private
// members on the other kinds aren't subject to dead-code reporting.
for fqcn in self.db.active_class_node_fqcns() {
let Some(class_node) = self.db.lookup_class_node(fqcn.as_ref()) else {
continue;
};
if class_node.is_interface(self.db)
|| class_node.is_trait(self.db)
|| class_node.is_enum(self.db)
{
continue;
}
let fqcn_str = fqcn.as_ref();
for method in self.db.class_own_methods(fqcn_str) {
if !method.active(self.db) {
continue;
}
if method.visibility(self.db) != Visibility::Private {
continue;
}
let name = method.name(self.db);
let name_lower = name.to_lowercase();
if MAGIC_METHODS.contains(&name_lower.as_str()) {
continue;
}
if !self
.db
.has_reference(&format!("{}::{}", fqcn_str, name.to_lowercase()))
{
let (file, line) = location_from_storage(&method.location(self.db));
issues.push(Issue::new(
IssueKind::UnusedMethod {
class: fqcn_str.to_string(),
method: name.to_string(),
},
Location {
file,
line,
line_end: line,
col_start: 0,
col_end: 0,
},
));
}
}
for prop in self.db.class_own_properties(fqcn_str) {
if !prop.active(self.db) {
continue;
}
if prop.visibility(self.db) != Visibility::Private {
continue;
}
let name = prop.name(self.db);
if !self
.db
.has_reference(&format!("{}::{}", fqcn_str, name.as_ref()))
{
let (file, line) = location_from_storage(&prop.location(self.db));
issues.push(Issue::new(
IssueKind::UnusedProperty {
class: fqcn_str.to_string(),
property: name.to_string(),
},
Location {
file,
line,
line_end: line,
col_start: 0,
col_end: 0,
},
));
}
}
}
// --- Non-referenced free functions ---
let stub_vfs = StubVfs::new();
for fqn in self.db.active_function_node_fqns() {
let Some(node) = self.db.lookup_function_node(fqn.as_ref()) else {
continue;
};
if !node.active(self.db) {
continue;
}
let location = node.location(self.db);
// 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;
}
}
if !self.db.has_reference(fqn.as_ref()) {
let (file, line) = location_from_storage(&location);
issues.push(Issue::new(
IssueKind::UnusedFunction {
name: node.short_name(self.db).to_string(),
},
Location {
file,
line,
line_end: line,
col_start: 0,
col_end: 0,
},
));
}
}
// Downgrade all dead-code issues to Info
for issue in &mut issues {
issue.severity = Severity::Info;
}
issues
}
}
fn location_from_storage(
loc: &Option<mir_codebase::storage::Location>,
) -> (std::sync::Arc<str>, u32) {
match loc {
Some(l) => (l.file.clone(), 1), // byte offset → line mapping not available here
None => (std::sync::Arc::from("<unknown>"), 1),
}
}
#[cfg(test)]
mod tests {
use super::*;
use crate::project::ProjectAnalyzer;
#[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 analyzer = ProjectAnalyzer::new();
analyzer.load_stubs();
let salsa = analyzer.salsa_db_for_test();
let salsa = salsa.lock().unwrap();
let issues = DeadCodeAnalyzer::new(&salsa.0).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<_>>()
);
}
}