Merge branch 'master' into jacobl.macbuild

This commit is contained in:
Jacob Langley
2017-02-07 10:26:30 -08:00
2 changed files with 64 additions and 22 deletions

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@@ -1,6 +1,6 @@
# <a name="main"></a>C++ Core Guidelines
February 1, 2017
February 6, 2017
Editors:
@@ -6562,11 +6562,49 @@ This a relatively rare use because implementation can often be organized into a
##### Reason
???
Without a using declaration, member functions in the derived class hide the entire inherited overload sets.
##### Example
##### Example, bad
???
#include <iostream>
class B {
public:
virtual int f(int i) { std::cout << "f(int): "; return i; }
virtual double f(double d) { std::cout << "f(double): "; return d; }
};
class D: public B {
public:
int f(int i) override { std::cout << "f(int): "; return i+1; }
};
int main()
{
D d;
std::cout << d.f(2) << '\n'; // prints "f(int): 3"
std::cout << d.f(2.3) << '\n'; // prints "f(int): 3"
}
##### Example, good
class D: public B {
public:
int f(int i) override { std::cout << "f(int): "; return i+1; }
using B::f; // exposes f(double)
};
##### Note
This issue affects both virtual and non-virtual member functions
For variadic bases, C++17 introduced a variadic form of the using-declaration,
template <class... Ts>
struct Overloader : Ts... {
using Ts::operator()...; // exposes operator() from every base
};
##### Enforcement
Diagnose name hiding
### <a name="Rh-final"></a>C.139: Use `final` sparingly
@@ -11659,16 +11697,16 @@ this can be a security risk.
##### Enforcement
Some is possible, do at least something.
There are commercial and open-source tools that try to address this problem, but static tools often have many false positives and run-time tools often have a significant cost.
We hope for better tools.
When possible, rely on tooling enforcement, but be aware that any tooling
solution has costs and blind spots. Defense in depth (multiple tools, multiple
approaches) is particularly valuable here.
Help the tools:
There are other ways you can mitigate the chance of data races:
* less global data
* fewer `static` variables
* more use of stack memory (and don't pass pointers around too much)
* more immutable data (literals, `constexpr`, and `const`)
* Avoid global data
* Avoid `static` variables
* More use of value types on the stack (and don't pass pointers around too much)
* More use of immutable data (literals, `constexpr`, and `const`)
### <a name="Rconc-data"></a>CP.3: Minimize explicit sharing of writable data

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@@ -1,7 +1,9 @@
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@@ -69,6 +71,7 @@ CComPtr
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@@ -492,6 +495,7 @@ toolchains
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