From 0c1e2ceeb936ad4efdf5199fa5b42672bcbb8338 Mon Sep 17 00:00:00 2001
From: chrchr-github <78114321+chrchr-github@users.noreply.github.com>
Date: Thu, 15 Dec 2022 08:52:13 +0100
Subject: [PATCH] Fix #11289 FP wrongPrintfScanfArgNum - snprintf with
 parameter pack (#4644)

---
 lib/checkio.cpp |  2 ++
 test/testio.cpp | 11 +++++++++++
 2 files changed, 13 insertions(+)

diff --git a/lib/checkio.cpp b/lib/checkio.cpp
index fa896a7d3..8b0c49974 100644
--- a/lib/checkio.cpp
+++ b/lib/checkio.cpp
@@ -1306,6 +1306,8 @@ void CheckIO::checkFormatString(const Token * const tok,
     // Count printf/scanf parameters..
     int numFunction = 0;
     while (argListTok2) {
+        if (Token::Match(argListTok2, "%name% ...")) // bailout for parameter pack
+            return;
         numFunction++;
         argListTok2 = argListTok2->nextArgument(); // Find next argument
     }
diff --git a/test/testio.cpp b/test/testio.cpp
index ab200834a..91280a0fe 100644
--- a/test/testio.cpp
+++ b/test/testio.cpp
@@ -80,6 +80,7 @@ private:
         TEST_CASE(testPrintfAuto); // #8992
         TEST_CASE(testPrintfParenthesis); // #8489
         TEST_CASE(testStdDistance); // #10304
+        TEST_CASE(testParameterPack); // #11289
     }
 
 #define check(...) check_(__FILE__, __LINE__, __VA_ARGS__)
@@ -4868,6 +4869,16 @@ private:
               "}", /*inconclusive*/ false, /*portability*/ true);
         ASSERT_EQUALS("", errout.str());
     }
+
+    void testParameterPack() { // #11289
+        check("template <typename... Args> auto f(const char* format, const Args&... args) {\n"
+              "    return snprintf(nullptr, 0, format, args...);\n"
+              "}\n"
+              "void g() {\n"
+              "    f(\"%d%d\", 1, 2);\n"
+              "}\n");
+        ASSERT_EQUALS("", errout.str());
+    }
 };
 
 REGISTER_TEST(TestIO)