[diff.cpp11] - C++14 → C++17

Files changed (1) hide show

tmp/tmpbgmmccci/{from.md → to.md} +67 -5

tmp/tmpbgmmccci/{from.md → to.md} RENAMED Viewed

@@ -15,33 +15,67 @@ International Standard, but the macro invocation produces different
 outcomes because the single quotes delimit a character literal in C++11,
 whereas they are digit separators in this International Standard:
 ``` cpp
 #define M(x, ...) __VA_ARGS__
-int x[2] = { M(1'2,3'4) };
-// int x[2] = {\ \ \ \ \ } --- C++11
-// int x[2] = { 3'4 } --- this International Standard
 ```
 ### Clause  [[basic]]: basic concepts <a id="diff.cpp11.basic">[[diff.cpp11.basic]]</a>
 [[basic.stc.dynamic.deallocation]] **Change:** New usual (non-placement)
-deallocator **Rationale:** Required for sized deallocation. **Effect on
 original feature:** Valid C++11code could declare a global placement
 allocation function and deallocation function as follows:
 ``` cpp
-void operator new(std::size_t, std::size_t);
 void operator delete(void*, std::size_t) noexcept;
 ```
 In this International Standard, however, the declaration of
 `operator delete` might match a predefined usual (non-placement)
 `operator delete` ([[basic.stc.dynamic]]). If so, the program is
 ill-formed, as it was for class member allocation functions and
 deallocation functions ([[expr.new]]).
 ### Clause  [[dcl.dcl]]: declarations <a id="diff.cpp11.dcl.dcl">[[diff.cpp11.dcl.dcl]]</a>
 [[dcl.constexpr]] **Change:** `constexpr` non-static member functions
 are not implicitly `const` member functions. **Rationale:** Necessary to
 allow `constexpr` member functions to mutate the object. **Effect on
@@ -55,10 +89,38 @@ struct S {
   constexpr const int &f();
   int &f();
 };
 ```
 ### Clause  [[input.output]]: input/output library <a id="diff.cpp11.input.output">[[diff.cpp11.input.output]]</a>
 [[c.files]] **Change:** `gets` is not defined. **Rationale:** Use of
 `gets` is considered dangerous. **Effect on original feature:** Valid
 C++11code that uses the `gets` function may fail to compile in this

 outcomes because the single quotes delimit a character literal in C++11,
 whereas they are digit separators in this International Standard:
 ``` cpp
 #define M(x, ...) __VA_ARGS__
+int x[2] = { M(1'2,3'4, 5) };
+// int x[2] = { 5 \ \ \ \ \ } --- C++11
+// int x[2] = { 3'4, 5 } --- this International Standard
 ```
 ### Clause  [[basic]]: basic concepts <a id="diff.cpp11.basic">[[diff.cpp11.basic]]</a>
 [[basic.stc.dynamic.deallocation]] **Change:** New usual (non-placement)
+deallocator. **Rationale:** Required for sized deallocation. **Effect on
 original feature:** Valid C++11code could declare a global placement
 allocation function and deallocation function as follows:
 ``` cpp
+void* operator new(std::size_t, std::size_t);
 void operator delete(void*, std::size_t) noexcept;
 ```
 In this International Standard, however, the declaration of
 `operator delete` might match a predefined usual (non-placement)
 `operator delete` ([[basic.stc.dynamic]]). If so, the program is
 ill-formed, as it was for class member allocation functions and
 deallocation functions ([[expr.new]]).
+### Clause  [[expr]]: expressions <a id="diff.cpp11.expr">[[diff.cpp11.expr]]</a>
+[[expr.cond]] **Change:** A conditional expression with a throw
+expression as its second or third operand keeps the type and value
+category of the other operand. **Rationale:** Formerly mandated
+conversions (lvalue-to-rvalue ([[conv.lval]]), array-to-pointer (
+[[conv.array]]), and function-to-pointer ([[conv.func]]) standard
+conversions), especially the creation of the temporary due to
+lvalue-to-rvalue conversion, were considered gratuitous and surprising.
+**Effect on original feature:** Valid C++11code that relies on the
+conversions may behave differently in this International Standard:
+``` cpp
+struct S {
+  int x = 1;
+  void mf() { x = 2; }
+};
+int f(bool cond) {
+  S s;
+  (cond ? s : throw 0).mf();
+  return s.x;
+}
+```
+In C++11, `f(true)` returns `1`. In this International Standard, it
+returns `2`.
+``` cpp
+sizeof(true ? "" : throw 0)
+```
+In C++11, the expression yields `sizeof(const char*)`. In this
+International Standard, it yields `sizeof(const char[1])`.
 ### Clause  [[dcl.dcl]]: declarations <a id="diff.cpp11.dcl.dcl">[[diff.cpp11.dcl.dcl]]</a>
 [[dcl.constexpr]] **Change:** `constexpr` non-static member functions
 are not implicitly `const` member functions. **Rationale:** Necessary to
 allow `constexpr` member functions to mutate the object. **Effect on
   constexpr const int &f();
   int &f();
 };
 ```
+### Clause  [[dcl.decl]]: declarators <a id="diff.cpp11.dcl.decl">[[diff.cpp11.dcl.decl]]</a>
+[[dcl.init.aggr]] **Change:** Classes with default member initializers
+can be aggregates. **Rationale:** Necessary to allow default member
+initializers to be used by aggregate initialization. **Effect on
+original feature:** Valid C++11code may fail to compile or may change
+meaning in this International Standard.
+``` cpp
+struct S { // Aggregate in C++14onwards.
+  int m = 1;
+};
+struct X {
+  operator int();
+  operator S();
+};
+X a{};
+S b{a};  // uses copy constructor in C++11,
+         // performs aggregate initialization in this International Standard
+```
+### Clause  [[library]]: library introduction <a id="diff.cpp11.library">[[diff.cpp11.library]]</a>
+[[headers]] **Change:** New header. **Rationale:** New functionality.
+**Effect on original feature:** The C++header `<shared_mutex>` is new.
+Valid C++11code that `#include`s a header with that name may be invalid
+in this International Standard.
 ### Clause  [[input.output]]: input/output library <a id="diff.cpp11.input.output">[[diff.cpp11.input.output]]</a>
 [[c.files]] **Change:** `gets` is not defined. **Rationale:** Use of
 `gets` is considered dangerous. **Effect on original feature:** Valid
 C++11code that uses the `gets` function may fail to compile in this

Diff to HTML by rtfpessoa