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00c43ae235
C2y adds the `_Countof` operator which returns the number of elements in an array. As with `sizeof`, `_Countof` either accepts a parenthesized type name or an expression. Its operand must be (of) an array type. When passed a constant-size array operand, the operator is a constant expression which is valid for use as an integer constant expression. This is being exposed as an extension in earlier C language modes, but not in C++. C++ already has `std::extent` and `std::size` to cover these needs, so the operator doesn't seem to get the user enough benefit to warrant carrying this as an extension. Fixes #102836
44 lines
2.2 KiB
C
44 lines
2.2 KiB
C
/* RUN: %clang_cc1 -fsyntax-only -std=c2y -pedantic -Wpre-c2y-compat -verify=compat %s
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RUN: %clang_cc1 -fsyntax-only -std=c23 -pedantic -verify %s
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RUN: %clang_cc1 -fsyntax-only -std=c89 -pedantic -verify=expected,static-assert %s
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RUN: %clang_cc1 -fsyntax-only -pedantic -verify=cpp,static-assert -x c++ %s
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*/
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/* This tests the extension behavior for _Countof in language modes before C2y.
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* It also tests the behavior of the precompat warning. And it tests the
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* behavior in C++ mode where the extension is not supported.
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*/
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#if __STDC_VERSION__ < 202400L && !defined(__cplusplus)
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#if __has_feature(c_countof)
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#error "Did not expect _Countof to be a feature in older language modes"
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#endif
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#if !__has_extension(c_countof)
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#error "Expected _Countof to be an extension in older language modes"
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#endif
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#endif /* __STDC_VERSION__ < 202400L && !defined(__cplusplus) */
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#ifdef __cplusplus
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/* C++ should not have this as a feature or as an extension. */
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#if __has_feature(c_countof) || __has_extension(c_countof)
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#error "did not expect there to be _Countof support"
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#endif
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#endif /* __cplusplus */
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int array[12];
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int x = _Countof(array); /* expected-warning {{'_Countof' is a C2y extension}}
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compat-warning {{'_Countof' is incompatible with C standards before C2y}}
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cpp-error {{use of undeclared identifier '_Countof'}}
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*/
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int y = _Countof(int[12]); /* expected-warning {{'_Countof' is a C2y extension}}
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compat-warning {{'_Countof' is incompatible with C standards before C2y}}
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cpp-error {{expected '(' for function-style cast or type construction}}
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*/
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_Static_assert(_Countof(int[12]) == 12, ""); /* expected-warning {{'_Countof' is a C2y extension}}
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compat-warning {{'_Countof' is incompatible with C standards before C2y}}
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cpp-error {{expected '(' for function-style cast or type construction}}
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static-assert-warning {{'_Static_assert' is a C11 extension}}
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*/
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