From ea3e8e30e1588a381d49cc3e8ed0ef2e0cd210e5 Mon Sep 17 00:00:00 2001
From: Yap Sok Ann <sokann@gmail.com>
Date: Tue, 3 Mar 2026 21:39:16 +0700
Subject: [PATCH] Allow arbitrary arguments order for Q3C, Q3CN, and Qwen3.5
 (#1352)

This should fix the read file at offset/limit issue, where the tool
definition has offset before limit, while the model sets limit before
offset.
---
 common/chat-parser-xml-toolcall.cpp | 31 ++++++++++++++++++++---------
 common/chat-parser-xml-toolcall.h   |  3 +++
 common/chat.cpp                     | 23 +++++++++++----------
 3 files changed, 38 insertions(+), 19 deletions(-)

diff --git a/common/chat-parser-xml-toolcall.cpp b/common/chat-parser-xml-toolcall.cpp
index 8848c7e4..16fe2661 100644
--- a/common/chat-parser-xml-toolcall.cpp
+++ b/common/chat-parser-xml-toolcall.cpp
@@ -245,15 +245,28 @@ void build_grammar_xml_tool_call(common_chat_params & data, const json & tools,
 
                 auto next_arg_with_sep = builder.add_rule(name + "-last-arg-end", form.last_val_end ? gbnf_format_literal(*form.last_val_end) : gbnf_format_literal(form.val_end));
                 decltype(next_arg_with_sep) next_arg = "\"\"";
-                for (auto i = arg_rules.size() - 1; /* i >= 0 && */ i < arg_rules.size(); --i) {
-                    std::string include_this_arg = arg_rules[i].symbol_name + " " + next_arg_with_sep;
-                    next_arg = builder.add_rule(name + "-arg-after-" + std::to_string(i), arg_rules[i].is_required ?
-                            include_this_arg : "( " + include_this_arg + " ) | " + next_arg
-                    );
-                    include_this_arg = gbnf_format_literal(form.val_end) + " " + include_this_arg;
-                    next_arg_with_sep = builder.add_rule(name + "-arg-after-" + std::to_string(i) + "-with-sep", arg_rules[i].is_required ?
-                            include_this_arg : "( " + include_this_arg + " ) | " + next_arg_with_sep
-                    );
+                if (form.relax_arg) {
+                    if (!arg_rules.empty()) {
+                        std::vector<std::string> arg_symbols;
+                        arg_symbols.reserve(arg_rules.size());
+                        for (const auto & rule : arg_rules) {
+                            arg_symbols.push_back(rule.symbol_name);
+                        }
+                        auto any_arg = builder.add_rule(name + "-any-arg", string_join(arg_symbols, " | "));
+                        auto any_arg_with_end = builder.add_rule(name + "-any-arg-with-end", any_arg + " " + next_arg_with_sep);
+                        next_arg = builder.add_rule(name + "-args-relaxed", "( " + any_arg_with_end + " )*");
+                    }
+                } else {
+                    for (auto i = arg_rules.size() - 1; /* i >= 0 && */ i < arg_rules.size(); --i) {
+                        std::string include_this_arg = arg_rules[i].symbol_name + " " + next_arg_with_sep;
+                        next_arg = builder.add_rule(name + "-arg-after-" + std::to_string(i), arg_rules[i].is_required ?
+                                include_this_arg : "( " + include_this_arg + " ) | " + next_arg
+                        );
+                        include_this_arg = gbnf_format_literal(form.val_end) + " " + include_this_arg;
+                        next_arg_with_sep = builder.add_rule(name + "-arg-after-" + std::to_string(i) + "-with-sep", arg_rules[i].is_required ?
+                                include_this_arg : "( " + include_this_arg + " ) | " + next_arg_with_sep
+                        );
+                    }
                 }
 
                 std::string quoted_name = name;
diff --git a/common/chat-parser-xml-toolcall.h b/common/chat-parser-xml-toolcall.h
index b309fb66..fed28d86 100644
--- a/common/chat-parser-xml-toolcall.h
+++ b/common/chat-parser-xml-toolcall.h
@@ -32,6 +32,9 @@ struct xml_tool_call_format {
     std::optional<std::string> last_tool_end = std::nullopt;
     bool trim_raw_argval = false;
     bool allow_toolcall_in_think = false;
+    // Set true to allows function arguments in arbitrary order and without
+    // enforcing required field.
+    bool relax_arg = false;
 };
 
 // make a GBNF that accept any strings except those containing any of the forbidden strings.
diff --git a/common/chat.cpp b/common/chat.cpp
index 2248c474..c272d741 100644
--- a/common/chat.cpp
+++ b/common/chat.cpp
@@ -1250,16 +1250,19 @@ static common_chat_params common_chat_params_init_qwen3_coder_xml(const common_c
     }
 
     // build grammar for tool call
-    static const xml_tool_call_format form {
-        /* form.scope_start = */ "",
-        /* form.tool_start  = */ "\n<tool_call>\n<function=",
-        /* form.tool_sep    = */ ">\n",
-        /* form.key_start   = */ "<parameter=",
-        /* form.key_val_sep = */ ">\n",
-        /* form.val_end     = */ "\n</parameter>\n",
-        /* form.tool_end    = */ "</function>\n</tool_call>",
-        /* form.scope_end   = */ "",
-    };
+    static const xml_tool_call_format form = ([]() {
+        xml_tool_call_format form {};
+        form.scope_start = "";
+        form.tool_start  = "\n<tool_call>\n<function=";
+        form.tool_sep    = ">\n";
+        form.key_start   = "<parameter=";
+        form.key_val_sep = ">\n";
+        form.val_end     = "\n</parameter>\n";
+        form.tool_end    = "</function>\n</tool_call>";
+        form.scope_end   = "";
+        form.relax_arg   = true;
+        return form;
+    })();
     build_grammar_xml_tool_call(data, params.tools, form);
 
     return data;