mirror of
https://github.com/isocpp/CppCoreGuidelines.git
synced 2024-03-22 13:30:58 +08:00
parent
a58ec3ee69
commit
2fdc6960b4
|
@ -1,6 +1,6 @@
|
|||
# <a name="main"></a>C++ Core Guidelines
|
||||
|
||||
June 17, 2019
|
||||
December 8, 2019
|
||||
|
||||
|
||||
Editors:
|
||||
|
@ -19243,7 +19243,7 @@ Container rule summary:
|
|||
* [SL.con.1: Prefer using STL `array` or `vector` instead of a C array](#Rsl-arrays)
|
||||
* [SL.con.2: Prefer using STL `vector` by default unless you have a reason to use a different container](#Rsl-vector)
|
||||
* [SL.con.3: Avoid bounds errors](#Rsl-bounds)
|
||||
* ???
|
||||
* [SL.con.4: don't use `memset` or `memcpy` for arguments that are not non-trivially-copyable](#Rsl-copy)
|
||||
|
||||
### <a name="Rsl-arrays"></a>SL.con.1: Prefer using STL `array` or `vector` instead of a C array
|
||||
|
||||
|
@ -19395,6 +19395,48 @@ If code is using an unmodified standard library, then there are still workaround
|
|||
|
||||
This rule is part of the [bounds profile](#SS-bounds).
|
||||
|
||||
|
||||
### <a name="Rsl-copy"></a>SL.con.4: don't use `memset` or `memcpy` for arguments that are not non-trivially-copyable
|
||||
|
||||
##### Reason
|
||||
|
||||
Doing so messes the semantics of the objects (e.g., by overwriting a `vptr`).
|
||||
|
||||
##### Note
|
||||
|
||||
Similarly for (w)memset, (w)memcpy, (w)memmove, and (w)memcmp
|
||||
|
||||
##### Example
|
||||
|
||||
struct base {
|
||||
virtual void update() = 0;
|
||||
};
|
||||
|
||||
struct derived : public base {
|
||||
void update() override {}
|
||||
};
|
||||
|
||||
|
||||
void f (derived& a, derived& b) // goodbye v-tables
|
||||
{
|
||||
memset(&a, 0, sizeof(derived));
|
||||
memcpy(&a, &b, sizeof(derived));
|
||||
memcmp(&a, &b, sizeof(derived));
|
||||
}
|
||||
|
||||
Insted, define proper default initialization, copy, and comparison functions
|
||||
|
||||
void g(derived& a, derived& b)
|
||||
{
|
||||
a = {}; // default initialize
|
||||
b = a; // copy
|
||||
if (a == b) do_something(a,b);
|
||||
}
|
||||
|
||||
##### Enforcement
|
||||
|
||||
* Flag the use of those functions for types theat are not trivially copyable
|
||||
|
||||
**TODO Notes**:
|
||||
|
||||
* Impact on the standard library will require close coordination with WG21, if only to ensure compatibility even if never standardized.
|
||||
|
|
Loading…
Reference in New Issue
Block a user