Indicates that the name or entity declared with this attribute is deprecated, that is, the use is allowed, but discouraged for some reason.
[[deprecated]] | (1) | |
[[deprecated( string-literal )]] | (2) |
string-literal | - | text that could be used to explain the rationale for deprecation and/or to suggest a replacing entity |
Indicates that the use of the name or entity declared with this attribute is allowed, but discouraged for some reason. Compilers typically issue warnings on such uses. The string-literal, if specified, is usually included in the warnings.
This attribute is allowed in declarations of the following names or entities:
struct [[deprecated]] S;
, [[deprecated]] typedef S* PS;
, using PS [[deprecated]] = S*;
, [[deprecated]] int x;
, union U { [[deprecated]] int n; };
, [[deprecated]] void f();
, namespace [[deprecated]] NS { int x; }
, enum [[deprecated]] E {};
, enum { A [[deprecated]], B [[deprecated]] = 42 };
, (since C++17) template<> struct [[deprecated]] X<int> {};
. A name declared non-deprecated may be redeclared deprecated. A name declared deprecated cannot be un-deprecated by redeclaring it without this attribute.
#include <iostream> [[deprecated]] void TriassicPeriod() { std::clog << "Triassic Period: [251.9 - 208.5] million years ago.\n"; } [[deprecated("Use NeogenePeriod() instead.")]] void JurassicPeriod() { std::clog << "Jurassic Period: [201.3 - 152.1] million years ago.\n"; } [[deprecated("Use calcSomethingDifferently(int).")]] int calcSomething(int x) { return x * 2; } int main() { TriassicPeriod(); JurassicPeriod(); }
Possible output:
Triassic Period: [251.9 - 208.5] million years ago. Jurassic Period: [201.3 - 152.1] million years ago. main.cpp:20:5: warning: 'TriassicPeriod' is deprecated [-Wdeprecated-declarations] TriassicPeriod(); ^ main.cpp:3:3: note: 'TriassicPeriod' has been explicitly marked deprecated here [[deprecated]] ^ main.cpp:21:5: warning: 'JurassicPeriod' is deprecated: Use NeogenePeriod() instead [-Wdeprecated-declarations] JurassicPeriod(); ^ main.cpp:8:3: note: 'JurassicPeriod' has been explicitly marked deprecated here [[deprecated("Use NeogenePeriod() instead")]] ^ 2 warnings generated.
C documentation for deprecated |
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