no semantic changes: factored some of the complexity of begin_func() into a pair of static functions for clarity

src/Var.cc

@@ -486,43 +486,27 @@ static bool canonical_arg_types_match(const FuncType* decl, const FuncType* impl
 	return true;
 	}
 
-void begin_func(IDPtr id, const char* module_name,
+static auto get_prototype(IDPtr id, FuncTypePtr t)
-                FunctionFlavor flavor, bool is_redef,
-                FuncTypePtr t,
-                std::unique_ptr<std::vector<AttrPtr>> attrs)
-	{
-	if ( flavor == FUNC_FLAVOR_EVENT )
-		{
-		const auto& yt = t->Yield();
-
-		if ( yt && yt->Tag() != TYPE_VOID )
-			id->Error("event cannot yield a value", t.get());
-
-		t->ClearYieldType(flavor);
-		}
-
-	std::optional<FuncType::Prototype> prototype;
-
-	if ( id->GetType() )
 	{
 	auto decl = id->GetType()->AsFuncType();
-		prototype = func_type_check(decl, t.get());
+	auto prototype = func_type_check(decl, t.get());
 
 	if ( prototype )
 		{
 		if ( decl->Flavor() == FUNC_FLAVOR_FUNCTION )
 			{
-				// If a previous declaration of the function had &default
+			// If a previous declaration of the function had
-				// params, automatically transfer any that are missing
+			// &default params, automatically transfer any that
-				// (convenience so that implementations don't need to specify
+			// are missing (convenience so that implementations
-				// the &default expression again).
+			// don't need to specify the &default expression again).
 			transfer_arg_defaults(prototype->args.get(), t->Params().get());
 			}
 		else
 			{
-				// Warn for trying to use &default parameters in hook/event
+			// Warn for trying to use &default parameters in
-				// handler body when it already has a declaration since only
+			// hook/event handler body when it already has a
-				// &default in the declaration has any effect.
+			// declaration since only &default in the declaration
+			// has any effect.
 			const auto& args = t->Params();
 
 			for ( int i = 0; i < args->NumFields(); ++i )
@@ -551,6 +535,7 @@ void begin_func(IDPtr id, const char* module_name,
 					prototype->args.get(), true);
 			}
 		}
+
 	else
 		{
 		// Allow renaming arguments, but only for the canonical
@@ -560,8 +545,80 @@ void begin_func(IDPtr id, const char* module_name,
 		else
 			t->Error("use of undeclared alternate prototype", id.get());
 		}
+
+	return prototype;
 	}
 
+static bool check_params(int i, std::optional<FuncType::Prototype> prototype,
+				const RecordTypePtr& args,
+				const RecordTypePtr& canon_args,
+				const char* module_name)
+	{
+	TypeDecl* arg_i;
+	bool hide = false;
+
+	if ( prototype )
+		{
+		auto it = prototype->offsets.find(i);
+
+		if ( it == prototype->offsets.end() )
+			{
+			// Alternate prototype hides this param
+			hide = true;
+			arg_i = canon_args->FieldDecl(i);
+			}
+		else
+			{
+			// Alternate prototype maps this param to another index
+			arg_i = args->FieldDecl(it->second);
+			}
+		}
+	else
+		{
+		if ( i < args->NumFields() )
+			arg_i = args->FieldDecl(i);
+		else
+			return false;
+		}
+
+	auto arg_id = lookup_ID(arg_i->id, module_name);
+
+	if ( arg_id && ! arg_id->IsGlobal() )
+		arg_id->Error("argument name used twice");
+
+	const char* local_name = arg_i->id;
+
+	if ( hide )
+		// Note the illegal '-' in hidden name implies we haven't
+		// clobbered any local variable names.
+		local_name = util::fmt("%s-hidden", local_name);
+
+	arg_id = install_ID(local_name, module_name, false, false);
+	arg_id->SetType(arg_i->type);
+
+	return true;
+	}
+
+void begin_func(IDPtr id, const char* module_name,
+                FunctionFlavor flavor, bool is_redef,
+                FuncTypePtr t,
+                std::unique_ptr<std::vector<AttrPtr>> attrs)
+	{
+	if ( flavor == FUNC_FLAVOR_EVENT )
+		{
+		const auto& yt = t->Yield();
+
+		if ( yt && yt->Tag() != TYPE_VOID )
+			id->Error("event cannot yield a value", t.get());
+
+		t->ClearYieldType(flavor);
+		}
+
+	std::optional<FuncType::Prototype> prototype;
+
+	if ( id->GetType() )
+		prototype = get_prototype(id, t);
+
 	else if ( is_redef )
 		id->Error("redef of not-previously-declared value");
 
@@ -604,49 +661,8 @@ void begin_func(IDPtr id, const char* module_name,
 	push_scope(std::move(id), std::move(attrs));
 
 	for ( int i = 0; i < canon_args->NumFields(); ++i )
-		{
+		if ( ! check_params(i, prototype, args, canon_args, module_name) )
-		TypeDecl* arg_i;
-		bool hide = false;
-
-		if ( prototype )
-			{
-			auto it = prototype->offsets.find(i);
-
-			if ( it == prototype->offsets.end() )
-				{
-				// Alternate prototype hides this param
-				hide = true;
-				arg_i = canon_args->FieldDecl(i);
-				}
-			else
-				{
-				// Alternate prototype maps this param to another index
-				arg_i = args->FieldDecl(it->second);
-				}
-			}
-		else
-			{
-			if ( i < args->NumFields() )
-				arg_i = args->FieldDecl(i);
-			else
 			break;
-			}
-
-		auto arg_id = lookup_ID(arg_i->id, module_name);
-
-		if ( arg_id && ! arg_id->IsGlobal() )
-			arg_id->Error("argument name used twice");
-
-		const char* local_name = arg_i->id;
-
-		if ( hide )
-			// Note the illegal '-' in hidden name implies we haven't
-			// clobbered any local variable names.
-			local_name = util::fmt("%s-hidden", local_name);
-
-		arg_id = install_ID(local_name, module_name, false, false);
-		arg_id->SetType(arg_i->type);
-		}
 
 	if ( Attr* depr_attr = find_attr(current_scope()->Attrs().get(), ATTR_DEPRECATED) )
 		current_scope()->GetID()->MakeDeprecated(depr_attr->GetExpr());