tmp/tmpf3up146t/{from.md → to.md}
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### [[expr]]: expressions <a id="diff.cpp20.expr">[[diff.cpp20.expr]]</a>
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**Change:** Change move-eligible *id-expression*s from lvalues to
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xvalues. **Rationale:** Simplify the rules for implicit move. **Effect
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on original feature:** Valid C++20 code that relies on a returned
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*id-expression*’s being an lvalue may change behavior or fail to
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compile. For example:
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``` cpp
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decltype(auto) f(int&& x) { return (x); } // returns int&&; previously returned int&
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int& g(int&& x) { return x; } // ill-formed; previously well-formed
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```
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**Change:** Change the meaning of comma in subscript expressions.
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**Rationale:** Enable repurposing a deprecated syntax to support
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multidimensional indexing. **Effect on original feature:** Valid C++20
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code that uses a comma expression within a subscript expression may fail
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to compile. For example:
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``` cpp
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arr[1, 2] // was equivalent to arr[(1, 2)],
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// now equivalent to arr.operator[](1, 2) or ill-formed
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```
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