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Reversed order of Lifetime.1 and .2

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hsutter 2017-05-11 19:09:56 -07:00
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CppCoreGuidelines.md
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@ -19128,52 +19128,12 @@ The following are specific rules that are being enforced.
Lifetime safety profile summary:
* [Lifetime.1: Don't dereference a possibly null pointer.](#Pro-lifetime-null-deref)
* [Lifetime.2: Don't dereference a possibly invalid pointer.](#Pro-lifetime-invalid-deref)
* [Lifetime.1: Don't dereference a possibly invalid pointer.](#Pro-lifetime-invalid-deref)
* [Lifetime.2: Don't dereference a possibly null pointer.](#Pro-lifetime-null-deref)
* [Lifetime.3: Don't pass a possibly invalid pointer to a function.](#Pro-lifetime-invalid-argument)
### <a name="Pro-lifetime-null-deref"></a>Lifetime.1: Don't dereference a possibly null pointer.
##### Reason
It is undefined behavior.
##### Example, bad
void f(int* p1)
{
*p1 = 42; // BAD, p1 might be null
int i = 0;
int* p2 = condition() ? &i : nullptr;
*p2 = 42; // BAD, p2 might be null
}
##### Example, good
void f(int* p1, not_null<int*> p3)
{
if (p1 != nullptr) {
*p1 = 42; // OK, must be not null in this branch
}
int i = 0;
int* p2 = condition() ? &i : nullptr;
if (p2 != nullptr) {
*p2 = 42; // OK, must be not null in this branch
}
*p3 = 42; // OK, not_null does not need to be tested for nullness
}
##### Enforcement
* Issue a diagnostic for any dereference of a pointer that could have been set to null along a local code path leading to the dereference. To fix: Add a null check and dereference the pointer only in a branch that has tested to ensure non-null.
### <a name="Pro-lifetime-invalid-deref"></a>Lifetime.2: Don't dereference a possibly invalid pointer.
### <a name="Pro-lifetime-invalid-deref"></a>Lifetime.1: Don't dereference a possibly invalid pointer.
##### Reason
@ -19217,6 +19177,46 @@ To resolve the problem, either extend the lifetime of the object the pointer is
### <a name="Pro-lifetime-null-deref"></a>Lifetime.2: Don't dereference a possibly null pointer.
##### Reason
It is undefined behavior.
##### Example, bad
void f(int* p1)
{
*p1 = 42; // BAD, p1 might be null
int i = 0;
int* p2 = condition() ? &i : nullptr;
*p2 = 42; // BAD, p2 might be null
}
##### Example, good
void f(int* p1, not_null<int*> p3)
{
if (p1 != nullptr) {
*p1 = 42; // OK, must be not null in this branch
}
int i = 0;
int* p2 = condition() ? &i : nullptr;
if (p2 != nullptr) {
*p2 = 42; // OK, must be not null in this branch
}
*p3 = 42; // OK, not_null does not need to be tested for nullness
}
##### Enforcement
* Issue a diagnostic for any dereference of a pointer that could have been set to null along a local code path leading to the dereference. To fix: Add a null check and dereference the pointer only in a branch that has tested to ensure non-null.
### <a name="Pro-lifetime-invalid-argument"></a>Lifetime.3: Don't pass a possibly invalid pointer to a function.
##### Reason