Functions with locals of structs with lifecycle hooks are not pure.

zeek · May 16, 2023 · f8378cd · f8378cd
1 parent e01c950
commit f8378cd
Showing 1 changed file with 19 additions and 5 deletions.
diff --git a/hilti/toolchain/src/compiler/optimizer.cc b/hilti/toolchain/src/compiler/optimizer.cc
@@ -1834,6 +1834,17 @@ struct DeadCodeVisitor : OptimizerVisitor, visitor::PreOrder<bool, DeadCodeVisit
     }
 };
 
+bool hasLifecycleHooks(const type::Struct& s) {
+    // NOLINTNEXTLINE(readability-use-anyofallof)
+    for ( const auto& f : s.fields() ) {
+        // Currently the only lifecycle hook we have is `~finally`.
+        if ( f.id().str() == "~finally" )
+            return true;
+    }
+
+    return false;
+};
+
 // An optimizer pass which annotates pure functions. This
 // information can be used by other passes to remove dead code.
 struct PureFunctionVisitor : OptimizerVisitor, visitor::PreOrder<bool, PureFunctionVisitor> {
@@ -1927,9 +1938,15 @@ struct PureFunctionVisitor : OptimizerVisitor, visitor::PreOrder<bool, PureFunct
             if ( auto id = child.node.tryAs<expression::ResolvedID>() ) {
                 const auto& decl = id->declaration();
 
-                if ( decl.isA<declaration::LocalVariable>() )
-                    // Functions accessing local variables can be pure.
+                if ( auto local = decl.tryAs<declaration::LocalVariable>() ) {
+                    // Functions accessing local variables can be pure if they
+                    // do not construct struct values of types with lifecycle
+                    // hooks attached.
+                    if ( auto s = local->type().tryAs<type::Struct>(); s && hasLifecycleHooks(*s) )
+                        return {};
+
                     continue;
+                }
 
                 else if ( decl.isA<declaration::GlobalVariable>() )
                     // Functions accessing global variables cannot be pure.
@@ -1941,9 +1958,6 @@ struct PureFunctionVisitor : OptimizerVisitor, visitor::PreOrder<bool, PureFunct
                         return {};
                 }
 
-                // FIXME(bbannier): If we construct a struct we can trigger life-cycle
-                // hooks making such functions not pure. Reject them here.
-
                 // Accessing keywords is side-effect free.
                 else if ( const auto& e = decl.tryAs<declaration::Expression>();
                           e && e->expression().isA<expression::Keyword>() ) {