This fixes issue 8996 by improving the alias checking by using lifetime analysis. It also extends the lifetime checker to handle constructors and initializer lists for containers and arrays.
This will now warn for cases like this:
```cpp
auto& f() {
std::vector<int> x;
return x[0];
}
```
It also improves the handling of address of operator, so it can now warn across some function calls, like this:
```cpp
int& f(int& a) {
return a;
}
int* hello() {
int x = 0;
return &f(x);
}
```
Even if `ptr` is a local variable, the object `ptr->item` might be not.
So taking address of `ptr->item` is definitely not unsafe in general.
This commit fixes false positives triggered by commit
1.85-249-gf42648fe2 on the following code of sssd:
https://github.com/SSSD/sssd/blob/d409df33/src/sbus/request/sbus_request.c#L359
This will use the lifetime checker for dangling references. It will find these cases for indirectly assigned reference:
```cpp
int &foo()
{
int s = 0;
int& x = s;
return x;
}
```
This will also fix issue 510 as well:
```cpp
int &f( int k )
{
static int &r = k;
return r;
}
```
This fixes issue in:
```cpp
void f()
{
char stack[512];
RGNDATA *data;
if (data_size > sizeof (stack))
data = malloc (data_size);
else
data = (RGNDATA *)stack;
if ((char *)data != stack)
free (data); // <- data is not stack
}
```
It seems the `ProgramMemory` can't handle two known values(such as int and tok) together. So instead `ValueFlowAfterAssign` runs `ValueFlowForward` with tok values and then runs it with the other values.
This fixes several FPs in the lifetime checker. It also fixes issue [8846](https://trac.cppcheck.net/ticket/8846):
```cpp
int * f(int a[])
{
return a;
}
```
* Use lifetime analysis for pointers as well
* Fix issue 1143: Pointer to local array
* Update message when using pointers
* Avoid infinite loop in tracing lifetimes
* Inital valueflow lifetime checker
* Forward values
* Add initial tests
* Fix deplicate messages
* Fix traversing nested lambdas
* Turn test case into a todo
* Skip if returning a container
* Fix FP when using references
* Add missing header
* Fix FP from broken scopes
* Fix FP with static variable
* Add test for more FPs
* Parse lambda functions
* Check for capture by value
* Add tests for using a container and lambda together
* Fix cppcheck errors
* Add test for nextAfterAstRightmostLeaf
* Add valueflow tests
* Update error message
* Check for correct lambda token
* Improve error path reporting
* Fix hang when parsing arrays that look almlost like lambdas
Paul Fultz II
Daniel Marjamäki
Frank Zingsheim
amai2012
Kamil Dudka
practicalswift
IOBYTE