tmp/tmp5yq3vkpf/{from.md → to.md}
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### Assumption attribute <a id="dcl.attr.assume">[[dcl.attr.assume]]</a>
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The *attribute-token* `assume` may be applied to a null statement; such
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a statement is an *assumption*. An *attribute-argument-clause* shall be
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present and shall have the form:
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``` bnf
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'(' conditional-expression ')'
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```
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The expression is contextually converted to `bool` [[conv.general]]. The
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expression is not evaluated. If the converted expression would evaluate
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to `true` at the point where the assumption appears, the assumption has
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no effect. Otherwise, the behavior is undefined.
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[*Note 1*: The expression is potentially evaluated [[basic.def.odr]].
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The use of assumptions is intended to allow implementations to analyze
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the form of the expression and deduce information used to optimize the
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program. Implementations are not required to deduce any information from
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any particular assumption. — *end note*]
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[*Example 1*:
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``` cpp
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int divide_by_32(int x) {
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[[assume(x >= 0)]];
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return x/32; // The instructions produced for the division
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// may omit handling of negative values.
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}
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int f(int y) {
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[[assume(++y == 43)]]; // y is not incremented
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return y; // statement may be replaced with return 42;
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}
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```
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— *end example*]
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