From a6ef3a224a697edc0166167753e8c56e972e953e Mon Sep 17 00:00:00 2001
From: Robert Reif <reif@earthlink.net>
Date: Fri, 8 Nov 2013 12:44:05 +0100
Subject: [PATCH] Fixed #5151 (false negative: improper formatstring -
 vector::at())

---
 lib/checkio.cpp | 14 ++++++++++++++
 test/testio.cpp |  7 +++++++
 2 files changed, 21 insertions(+)

diff --git a/lib/checkio.cpp b/lib/checkio.cpp
index 50721987c..531391570 100644
--- a/lib/checkio.cpp
+++ b/lib/checkio.cpp
@@ -1398,6 +1398,20 @@ CheckIO::ArgumentInfo::ArgumentInfo(const Token * tok, const Settings *settings)
                             tempToken->insertToken("wchar_t");
                     }
                     typeToken = tempToken;
+                    return;
+                }
+
+                // check for std::vector::at() and std::string::at()
+                else if (Token::Match(tok1->previous(), "%var% . at (") &&
+                         Token::Match(tok1->linkAt(2), ") [,)]")) {
+                    varTok = tok1->previous();
+                    variableInfo = varTok->variable();
+
+                    if (!isStdVectorOrString()) {
+                        variableInfo = 0;
+                        typeToken = 0;
+                    }
+
                     return;
                 } else if (!(tok1->str() == "." || tok1->type() == Token::eVariable || tok1->type() == Token::eFunction))
                     return;
diff --git a/test/testio.cpp b/test/testio.cpp
index 13eac2374..5c60abb1a 100644
--- a/test/testio.cpp
+++ b/test/testio.cpp
@@ -2091,6 +2091,13 @@ private:
               "}\n");
         ASSERT_EQUALS("", errout.str());
 
+        check("std::vector<char> v;\n" // #5151
+              "void foo() {\n"
+              "   printf(\"%c %u %f\", v.at(32), v.at(32), v.at(32));\n"
+              "}\n");
+        ASSERT_EQUALS("[test.cpp:3]: (warning) %u in format string (no. 2) requires 'unsigned int' but the argument type is 'char'.\n"
+                      "[test.cpp:3]: (warning) %f in format string (no. 3) requires 'double' but the argument type is 'char'.\n", errout.str());
+
     }
 
     void testPosixPrintfScanfParameterPosition() { // #4900  - No support for parameters in format strings