Improve alternate event/hook prototype matching

This fixes it to again allow the old behavior of matching a handler
against the canonical prototype as long as all argument types, but not
necessarily names, match.

src/Type.cc

@@ -584,8 +584,10 @@ void FuncType::AddPrototype(Prototype p)
 
 std::optional<FuncType::Prototype> FuncType::FindPrototype(const RecordType& args) const
 	{
-	for ( const auto& p : prototypes )
+	for ( auto i = 0u; i < prototypes.size(); ++i )
 		{
+		const auto& p = prototypes[i];
+
 		if ( args.NumFields() != p.args->NumFields() )
 			continue;
 
@@ -604,11 +606,12 @@ std::optional<FuncType::Prototype> FuncType::FindPrototype(const RecordType& arg
 			auto ptype = p.args->FieldType(i);
 			auto desired_type = args.FieldType(i);
 
-			if ( same_type(ptype, desired_type) )
+			if ( ! same_type(ptype, desired_type) ||
-				continue;
+			     ! streq(args.FieldName(i), p.args->FieldName(i)) )
-
+				{
-			matched = false;
+				matched = false;
-			break;
+				break;
+				}
 			}
 
 		if ( matched )

src/Var.cc

@@ -432,6 +432,21 @@ static std::optional<FuncType::Prototype> func_type_check(const FuncType* decl,
 	return decl->FindPrototype(*impl->Args());
 	}
 
+static bool canonical_arg_types_match(const FuncType* decl, const FuncType* impl)
+	{
+	auto canon_args = decl->Args();
+	auto impl_args = impl->Args();
+
+	if ( canon_args->NumFields() != impl_args->NumFields() )
+		return false;
+
+	for ( auto i = 0; i < canon_args->NumFields(); ++i )
+		if ( ! same_type(canon_args->FieldType(i), impl_args->FieldType(i)) )
+			return false;
+
+	return true;
+	}
+
 void begin_func(ID* id, const char* module_name, function_flavor flavor,
                 bool is_redef, IntrusivePtr<FuncType> t, attr_list* attrs)
 	{
@@ -462,7 +477,16 @@ void begin_func(ID* id, const char* module_name, function_flavor flavor,
 				t->Warn("use of deprecated prototype", id);
 			}
 		else
-			t->Error("use of undeclared alternate prototype", id);
+			{
+			auto decl = id->Type()->AsFuncType();
+
+			// Allow renaming arguments, but only for the canonical
+			// prototypes of hooks/events.
+			if ( canonical_arg_types_match(decl, t.get()) )
+				prototype = decl->Prototypes()[0];
+			else
+				t->Error("use of undeclared alternate prototype", id);
+			}
 		}
 
 	else if ( is_redef )

testing/btest/Baseline/language.alternate-event-hook-prototypes-invalid-arg/out

@@ -1,2 +1,2 @@
-error in /home/jon/pro/zeek/zeek/testing/btest/.tmp/language.alternate-event-hook-prototypes-invalid-arg/alternate-event-hook-prototypes-invalid-arg.zeek, line 5 and /home/jon/pro/zeek/zeek/testing/btest/.tmp/language.alternate-event-hook-prototypes-invalid-arg/alternate-event-hook-prototypes-invalid-arg.zeek, line 4: alternate function prototype already exists (event(nope:string; cantdothis:count;) and record { s:string; c:count; })
+error in /home/jon/pro/zeek/zeek/testing/btest/.tmp/language.alternate-event-hook-prototypes-invalid-arg/alternate-event-hook-prototypes-invalid-arg.zeek, line 5 and /home/jon/pro/zeek/zeek/testing/btest/.tmp/language.alternate-event-hook-prototypes-invalid-arg/alternate-event-hook-prototypes-invalid-arg.zeek, line 4: alternate function prototype arg 'nope' not found in canonical prototype (event(nope:string; cantdothis:count;) and event(s:string; c:count;))
 error in /home/jon/pro/zeek/zeek/testing/btest/.tmp/language.alternate-event-hook-prototypes-invalid-arg/alternate-event-hook-prototypes-invalid-arg.zeek, line 8 and /home/jon/pro/zeek/zeek/testing/btest/.tmp/language.alternate-event-hook-prototypes-invalid-arg/alternate-event-hook-prototypes-invalid-arg.zeek, line 7: alternate function prototype arg 'andnotthiseither' not found in canonical prototype (hook(andnotthiseither:addr;) : bool and hook(s:string; c:count;) : bool)

testing/btest/Baseline/language.alternate-prototypes-arg-matching/out

@@ -0,0 +1,6 @@
+foo, A, B, C
+foo, A, B, C
+reverse foo, A, B, C
+foo a, A
+foo b, B
+foo c, C

testing/btest/language/alternate-prototypes-arg-matching.zeek

@@ -0,0 +1,44 @@
+# @TEST-EXEC: zeek -b %INPUT > out
+# @TEST-EXEC: btest-diff out
+
+global foo: event(a: string, b: string, c: string);
+global foo: event(c: string, b: string, a: string);
+global foo: event(a: string);
+global foo: event(b: string);
+global foo: event(c: string);
+
+event foo(a: string, b: string, c: string)
+	{
+	print "foo", a, b, c;
+	}
+
+event foo(mya: string, b: string, c: string)
+	{
+	print "foo", mya, b, c;
+	}
+
+event foo(c: string, b: string, a: string)
+	{
+	print "reverse foo", a, b, c;
+	}
+
+event foo(a: string)
+	{
+	print "foo a", a;
+	}
+
+event foo(b: string)
+	{
+	print "foo b", b;
+	}
+
+event foo(c: string)
+	{
+	print "foo c", c;
+	}
+
+event zeek_init()
+	{
+	event foo("A", "B", "C");
+	}
+