Difference between revisions of "cpp/language/attributes/maybe unused"
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< cpp | language | attributes
m (T. Canens moved page cpp/attribute/maybe unused to cpp/language/attributes/maybe unused without leaving a redirect: Text replace - "cpp/attribute" to "cpp/language/attributes") |
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If the compiler issues warnings on unused entities, that warning is suppressed for any entity declared maybe_unused. | If the compiler issues warnings on unused entities, that warning is suppressed for any entity declared maybe_unused. | ||
Revision as of 07:46, 24 June 2018
If the compiler issues warnings on unused entities, that warning is suppressed for any entity declared maybe_unused.
Syntax
class-key [[maybe_unused]] class-name ;
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(1) | ||||||||
class-key [[maybe_unused]] class-name final(optional) base-clause(optional) { member-specification }
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(2) | ||||||||
using identifier [[maybe_unused]] = defining-type-id ;
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(3) | ||||||||
[[maybe_unused]] declaration
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(4) | ||||||||
declarator-id [[maybe_unused]]
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(5) | ||||||||
enum-key [[maybe_unused]] enumeration-name enum-base(optional) ;
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(6) | ||||||||
enum-key [[maybe_unused]] enumeration-name enum-base(optional) { enumerator-list }
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(7) | ||||||||
enumerator [[maybe_unused]]
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(8) | ||||||||
Explanation
Appears in the declaration of a class, a typedef, a variable, a nonstatic data member, a function, an enumeration, or an enumerator.
If the compiler issues warnings on unused entities, that warning is suppressed for any entity declared maybe_unused.
Example
Run this code
[[maybe_unused]] void f([[maybe_unused]] bool thing1, [[maybe_unused]] bool thing2) { [[maybe_unused]] bool b = thing1 && thing2; assert(b); // in release mode, assert is compiled out, and b is unused // no warning because it is declared [[maybe_unused]] } // parameters thing1 and thing2 are not used, no warning
