tmp/tmpj6vxh9nx/{from.md → to.md}
RENAMED
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| 1 |
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### [[dcl]]: declarations <a id="diff.cpp23.dcl.dcl">[[diff.cpp23.dcl.dcl]]</a>
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**Change:** Introduction of `trivially_relocatable_if_eligible` and
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`replaceable_if_eligible` as identifiers with special meaning
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[[lex.name]]. **Rationale:** Support declaration of trivially
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relocatable and replaceable types [[class.prop]]. **Effect on original
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feature:** Valid C++23 code can become ill-formed.
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[*Example 1*:
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``` cpp
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struct C {};
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struct C replaceable_if_eligible {}; // was well-formed (new variable replaceable_if_eligible)
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// now ill-formed (redefines C)
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```
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— *end example*]
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**Change:** Pointer comparisons between `initializer_list` objects’
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backing arrays are unspecified. **Rationale:** Permit the implementation
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to store backing arrays in static read-only memory. **Effect on original
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feature:** Valid C++23 code that relies on the result of pointer
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comparison between backing arrays may change behavior.
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[*Example 2*:
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``` cpp
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bool ne(std::initializer_list<int> a, std::initializer_list<int> b) {
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return a.begin() != b.begin() + 1;
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}
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bool b = ne({2,3}, {1,2,3}); // unspecified result; previously false
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```
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— *end example*]
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**Change:** Previously, `T...[n]` would declare a pack of function
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parameters. `T...[n]` is now a *pack-index-specifier*. **Rationale:**
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Improve the handling of packs. **Effect on original feature:** Valid
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C++23 code that declares a pack of parameters without specifying a
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*declarator-id* becomes ill-formed.
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[*Example 3*:
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``` cpp
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template <typename... T>
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void f(T... [1]);
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template <typename... T>
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void g(T... ptr[1]);
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int main() {
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f<int, double>(nullptr, nullptr); // ill-formed, previously void f<int, double>(int [1], double [1])
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g<int, double>(nullptr, nullptr); // ok
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}
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```
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— *end example*]
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**Change:** New token `:]`. **Rationale:** Required for new features.
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**Effect on original feature:** Valid C++23 code that contained an
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*attribute-specifier* with an *attribute-using-prefix* but no attributes
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and no whitespace is ill-formed in this revision of C++.
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[*Example 4*:
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``` cpp
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struct [[using CC:]] C; // ill-formed; previously well-formed
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struct [[using DD: ]] D; // OK
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```
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— *end example*]
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