From 0f30d232513ea72b799482c9d25e057da5ad1eb1 Mon Sep 17 00:00:00 2001
From: KorsarOfficial <korsarofficial@users.noreply.github.com>
Date: Thu, 19 Mar 2026 01:01:48 +0400
Subject: [PATCH] fix: swap 'Too many'/'Too few' messages and correct
 expected/have in callback arg errors (#42)

The two error messages for callback argument count mismatches in
check-func-calls-and-vararg.cpp had their labels swapped and their
printf arguments in the wrong order:

  - The condition `call_n_params >= get_min_argn()` is false when there
    are TOO FEW arguments, but the message said "Too many arguments for
    callback".
  - The condition `get_params().size() >= call_n_params` is false when
    there are TOO MANY arguments, but the message said "Too few arguments
    for callback".
  - In both cases the "expected" and "have" values were transposed.

Fix: swap the two message strings and swap the fmt_format arguments to
match the corrected messages and mirror the non-callback pattern on
lines 271-274.
---
 compiler/pipes/check-func-calls-and-vararg.cpp | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/compiler/pipes/check-func-calls-and-vararg.cpp b/compiler/pipes/check-func-calls-and-vararg.cpp
index d9fadb3076..a887906378 100644
--- a/compiler/pipes/check-func-calls-and-vararg.cpp
+++ b/compiler/pipes/check-func-calls-and-vararg.cpp
@@ -283,10 +283,13 @@ VertexPtr CheckFuncCallsAndVarargPass::on_func_call(VertexAdaptor<op_func_call>
         int call_n_params = typed_callable->arg_types.size() + call_arg.as<op_callback_of_builtin>()->args().size();
         int delta_this = f_callback->has_implicit_this_arg() ? 1 : 0;
         auto expected_callback_signature = typed_callable->as_human_readable();
+        // Note: "Too few" fires when call_n_params < get_min_argn() (condition is false),
+        //       "Too many" fires when call_n_params > get_params().size() (condition is false).
+        // expected/have mirror the non-callback pattern on lines 271-274.
         kphp_error(call_n_params >= f_callback->get_min_argn(),
-                   fmt_format("Too many arguments for callback ({}), expected {}, have {}", expected_callback_signature, call_n_params - delta_this, f_callback->get_min_argn() - delta_this));
+                   fmt_format("Too few arguments for callback ({}), expected {}, have {}", expected_callback_signature, f_callback->get_min_argn() - delta_this, call_n_params - delta_this));
         kphp_error(f_callback->get_params().size() >= call_n_params,
-                   fmt_format("Too few arguments for callback ({}), expected {}, have {}", expected_callback_signature, call_n_params - delta_this, f_callback->get_params().size() - delta_this));
+                   fmt_format("Too many arguments for callback ({}), expected {}, have {}", expected_callback_signature, f_callback->get_params().size() - delta_this, call_n_params - delta_this));
 
         for (auto p : f_callback->get_params()) {
           kphp_error(!p.as<op_func_param>()->var()->ref_flag, "You can't pass callbacks with &references to built-in functions");