[expr] Clarify performing / applying standard conversions. #3955
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We previously had a conflict between wording demanding that certain conversions be applied, and the definitions of the conversions saying they could not be applied. We now distinguish two cases: * When we say that a conversion is applied, we're talking about a change to the resulting model of the program -- we mean that the conversion actually happens (and it had better be applicable). * When we say that a conversion is performed, we're talking about performing a process, which applies the conversion if possible and otherwise has no effect. In addition, wording saying to perform the three kinds of conversion from glvalue to prvalue have been changed to say that a prvalue operand is expected.
| lvalue-to-rvalue\iref{conv.lval}, array-to-pointer\iref{conv.array}, | ||
| and function-to-pointer\iref{conv.func} standard conversions are | ||
| performed on the argument expression. | ||
| In this case, argument expression is expected to be a prvalue\iref{basic.lval}. |
| both operands were of array type | ||
| prior to these conversions\iref{depr.array.comp}. | ||
| an array-to-pointer\iref{conv.array} conversion | ||
| is applied to both operands\iref{depr.array.comp}. |
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The "operand" here means the original operand, but...
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| \pnum | ||
| The converted operands shall have arithmetic, enumeration, pointer, | ||
| The operands shall have arithmetic, enumeration, pointer, |
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The "operand" here means the converted prvalue operand. That's non-obvious.
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| \pnum | |||
| Whenever a glvalue appears as an operand of an operator that | |||
| expects a prvalue for that operand, the | |||
| expects a prvalue for that operand, an | |||
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Reading all the "expected to be" phrasings below makes me want to ask for "requires" here.
Example: "that requires a prvalue for that operand..." or "The operand is required to be a prvalue."
The "required" conveys better that, if you can't make it so, you're toast. (Just a slight wording preference, not a strong feeling.)
| The temporary materialization conversion\iref{conv.rval} is first applied | ||
| if the expression is a prvalue. | ||
| The result is a pointer to the first element of | ||
| the possibly-converted array glvalue. |
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glvalue is an expression, it doesn't have elements.
Probably you remember, but just in case: this is http://wg21.link/CWG1642 |
| and function-to-pointer\iref{conv.func} standard conversions are | ||
| performed on the second and third operands. After those conversions, one | ||
| of the following shall hold: | ||
| The resulting second and third operands are expected to be |
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Perhaps we say "possibly-converted" instead of "resulting"
| array-to-pointer\iref{conv.array}, | ||
| and function-to-pointer\iref{conv.func} | ||
| standard conversions are performed on the operands. | ||
| The operands are expected to be prvalues\iref{basic.lval}. | ||
| The comparison is deprecated if |
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Ending the previous sentence with a semicolon and continuing with "the comparison is deprecated if [...]" flows better.
| The comparison is deprecated if | ||
| both operands were of array type | ||
| prior to these conversions\iref{depr.array.comp}. | ||
| an array-to-pointer\iref{conv.array} conversion |
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The array-to-pointer conversion is a single conversion -- I think "an" should be "the" here.
| The comparison is deprecated if | ||
| both operands were of array type | ||
| prior to these conversions\iref{depr.array.comp}. | ||
| an array-to-pointer\iref{conv.array} conversion |
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The array-to-pointer conversion is a single conversion -- I think "an" should be "the" here.
zygoloid
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wg21bot
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needs rebase
We previously had a conflict between wording demanding that certain
conversions be applied, and the definitions of the conversions saying
they could not be applied. We now distinguish two cases:
change to the resulting model of the program -- we mean that the
conversion actually happens (and it had better be applicable).
performing a process, which applies the conversion if possible and
otherwise has no effect.
In addition, wording saying to perform the three kinds of conversion
from glvalue to prvalue have been changed to say that a prvalue operand
is expected.