Fixed #7012 (False positive uninitvar - first argument to snprintf)

cfg/std.cfg

@@ -3753,11 +3753,12 @@
     <noreturn>false</noreturn>
     <leak-ignore/>
     <arg nr="1">
-      <not-uninit/>
+      <not-null/>
       <minsize type="argvalue" arg="2"/>
     </arg>
     <arg nr="2">
       <not-uninit/>
+      <valid>1:</valid>
     </arg>
     <formatstr/>
     <arg nr="3">
@@ -3765,9 +3766,6 @@
       <not-null/>
       <not-uninit/>
     </arg>
-    <arg nr="any">
-      <not-uninit/>
-    </arg>
   </function>
   <!-- int vsnprintf(char *s, size_t n, const char *format, va_list arg); -->
   <function name="vsnprintf,std::vsnprintf">

lib/library.cpp

@@ -683,6 +683,20 @@ static std::string functionName(const Token *ftok)
     return ret;
 }
 
+bool Library::isuninitargbad(const Token *ftok, int argnr) const
+{
+    const ArgumentChecks *arg = getarg(ftok, argnr);
+    if (!arg) {
+        // non-scan format string argument should not be uninitialized
+        const std::string funcname = functionName(ftok);
+        std::map<std::string, std::pair<bool, bool> >::const_iterator it = _formatstr.find(funcname);
+        if (it != _formatstr.end() && !it->second.first)
+            return true;
+    }
+    return arg && arg->notuninit;
+}
+
+
 /** get allocation id for function */
 int Library::alloc(const Token *tok) const
 {

lib/library.h

@@ -217,10 +217,7 @@ public:
         return arg && arg->notnull;
     }
 
-    bool isuninitargbad(const Token *ftok, int argnr) const {
-        const ArgumentChecks *arg = getarg(ftok, argnr);
-        return arg && arg->notuninit;
-    }
+    bool isuninitargbad(const Token *ftok, int argnr) const;
 
     bool isargformatstr(const Token *ftok, int argnr) const {
         const ArgumentChecks *arg = getarg(ftok, argnr);