How to: Specify Additional Code Information by Using __analysis_assume
Note
This article applies to Visual Studio 2015. If you're looking for the latest Visual Studio documentation, see Visual Studio documentation. We recommend upgrading to the latest version of Visual Studio. Download it here
You can provide hints to the code analysis tool for C/C++ code that will help the analysis process and reduce warnings. To provide additional information, use the following function:
__analysis_assume( expr )
expr - any expression that is assumed to evaluate to true.
The code analysis tool assumes that the condition represented by the expression is true at the point where the function appears and remains true until expression is altered, for example, by assignment to a variable.
Note
__analysis_assume does not impact code optimization. Outside the code analysis tool, __analysis_assume is defined as a no-op.
Example
The following code uses __analysis_assume to correct the code analysis warning C6388:
#include<windows.h>
#include<codeanalysis\sourceannotations.h>
using namespace vc_attributes;
// calls free and sets ch to null
void FreeAndNull(char* ch);
//requires pc to be null
void f([Pre(Null=Yes)] char* pc);
void test( )
{
char *pc = (char*)malloc(5);
FreeAndNull(pc);
__analysis_assume(pc == NULL);
f(pc);
}