5dfa37a761
More study has discovered this to not actually be useful: because current C++20 implementations reject `#ifdef __VA_OPT__`, this can't really be used as a feature-test mechanism. And it's not too hard to detect __VA_OPT__ without this, for example: #define THIRD_ARG(a, b, c, ...) c #define HAS_VA_OPT(...) THIRD_ARG(__VA_OPT__(,), 1, 0, ) #if HAS_VA_OPT(?) Partially reverts 0436ec2128c9775ba13b0308937238fc79673fdd.
75 lines
2.0 KiB
C++
75 lines
2.0 KiB
C++
// RUN: %clang_cc1 %s -Eonly -verify -Wno-all -pedantic -std=c++20
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// RUN: %clang_cc1 %s -Eonly -verify -Wno-all -pedantic -std=c++11
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// RUN: %clang_cc1 -x c %s -Eonly -verify -Wno-all -pedantic -std=c99
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//expected-error@+1{{missing '('}}
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#define V1(...) __VA_OPT__
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#undef V1
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// OK
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#define V1(...) __VA_OPT__ ()
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#undef V1
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//expected-warning@+1{{can only appear in the expansion of a variadic macro}}
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#define V2() __VA_OPT__(x)
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#undef V2
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//expected-error@+2{{missing ')' after}}
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//expected-note@+1{{to match this '('}}
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#define V3(...) __VA_OPT__(
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#undef V3
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#define V4(...) __VA_OPT__(__VA_ARGS__)
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#undef V4
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//expected-error@+1{{nested}}
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#define V5(...) __VA_OPT__(__VA_OPT__())
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#undef V5
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//expected-error@+1{{not followed by}}
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#define V1(...) __VA_OPT__ (#)
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#undef V1
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//expected-error@+1{{cannot appear at start}}
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#define V1(...) __VA_OPT__ (##)
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#undef V1
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//expected-error@+1{{cannot appear at start}}
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#define V1(...) __VA_OPT__ (## X) x
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#undef V1
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//expected-error@+1{{cannot appear at end}}
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#define V1(...) y __VA_OPT__ (X ##)
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#undef V1
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#define FOO(x,...) # __VA_OPT__(x) #x #__VA_OPT__(__VA_ARGS__) //OK
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//expected-error@+1{{not followed by a macro parameter}}
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#define V1(...) __VA_OPT__(#)
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#undef V1
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//expected-error@+1{{cannot appear at start}}
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#define V1(...) a __VA_OPT__(##) b
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#undef V1
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//expected-error@+1{{cannot appear at start}}
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#define V1(...) a __VA_OPT__(a ## b) b __VA_OPT__(##)
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#undef V1
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#define V1(x,...) # __VA_OPT__(b x) // OK
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#undef V1
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//expected-error@+2{{missing ')' after}}
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//expected-note@+1{{to match this '('}}
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#define V1(...) __VA_OPT__ ((())
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#undef V1
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// __VA_OPT__ can't appear anywhere else.
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#if __VA_OPT__ // expected-warning {{__VA_OPT__ can only appear in the expansion of a variadic macro}}
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#endif
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#ifdef __VA_OPT__ // expected-warning {{__VA_OPT__ can only appear in the expansion of a variadic macro}}
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#endif
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#define BAD __VA_OPT__ // expected-warning {{__VA_OPT__ can only appear in the expansion of a variadic macro}}
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