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llvm-project/clang/test/Preprocessor/macro_vaopt_expand.cpp

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[c++2a] Implement P0306 __VA_OPT__ (Comma omission and comma deletion) This patch implements an extension to the preprocessor: __VA_OPT__(contents) --> which expands into its contents if variadic arguments are supplied to the parent macro, or behaves as an empty token if none. - Currently this feature is only enabled for C++2a (this could be enabled, with some careful tweaks, for other dialects with the appropriate extension or compatibility warnings) - The patch was reviewed here: https://reviews.llvm.org/D35782 and asides from the above (and moving some of the definition and expansion recognition logic into the corresponding state machines), I believe I incorporated all of Richard's suggestions. A few technicalities (most of which were clarified through private correspondence between rsmith, hubert and thomas) are worth mentioning. Given: #define F(a,...) a #__VA_OPT__(a ## a) a ## __VA_OPT__(__VA_ARGS__) - The call F(,) Does not supply any tokens for the variadic arguments and hence VA_OPT behaves as a placeholder. - When expanding VA_OPT (for e.g. F(,1) token pasting occurs eagerly within its contents if the contents need to be stringified. - A hash or a hashhash prior to VA_OPT does not inhibit expansion of arguments if they are the first token within VA_OPT. - When a variadic argument is supplied, argument substitution occurs within the contents as does stringification - and these resulting tokens are inserted back into the macro expansions token stream just prior to the entire stream being rescanned and concatenated. See wg21.link/P0306 for further details on the feature. Acknowledgment: This patch would have been poorer if not for Richard Smith's usual thoughtful analysis and feedback. llvm-svn: 315840
2017-10-15 09:26:26 +08:00
// RUN: %clang_cc1 -E %s -pedantic -std=c++2a | FileCheck -strict-whitespace %s
#define LPAREN (
#define RPAREN )
#define A0 expandedA0
#define A1 expandedA1 A0
#define A2 expandedA2 A1
#define A3 expandedA3 A2
#define A() B LPAREN )
#define B() C LPAREN )
#define C() D LPAREN )
#define F(x, y) x + y
#define ELLIP_FUNC(...) __VA_OPT__(__VA_ARGS__)
1: ELLIP_FUNC(F, LPAREN, 'a', 'b', RPAREN);
2: ELLIP_FUNC(F LPAREN 'a', 'b' RPAREN);
#undef F
#undef ELLIP_FUNC
// CHECK: 1: F, (, 'a', 'b', );
// CHECK: 2: 'a' + 'b';
#define F(...) f(0 __VA_OPT__(,) __VA_ARGS__)
3: F(a, b, c) // replaced by f(0, a, b, c)
4: F() // replaced by f(0)
// CHECK: 3: f(0 , a, b, c)
// CHECK: 4: f(0 )
#undef F
#define G(X, ...) f(0, X __VA_OPT__(,) __VA_ARGS__)
5: G(a, b, c) // replaced by f(0, a , b, c)
6: G(a) // replaced by f(0, a)
7: G(a,) // replaced by f(0, a)
7.1: G(a,,)
// CHECK: 5: f(0, a , b, c)
// CHECK: 6: f(0, a )
// CHECK: 7: f(0, a )
// CHECK: 7.1: f(0, a , ,)
#undef G
#define HT_B() TONG
#define F(x, ...) HT_ ## __VA_OPT__(x x A() #x)
8: F(1)
9: F(A(),1)
// CHECK: 8: HT_
// CHECK: 9: TONG C ( ) B ( ) "A()"
#undef HT_B
#undef F
#define F(a,...) #__VA_OPT__(A1 a)
10: F(A())
11: F(A1 A(), 1)
// CHECK: 10: ""
// CHECK: 11: "A1 expandedA1 expandedA0 B ( )"
#undef F
#define F(a,...) a ## __VA_OPT__(A1 a) ## __VA_ARGS__ ## a
12.0: F()
12: F(,)
13: F(B,)
// CHECK: 12.0:
// CHECK: 12:
// CHECK: 13: BB
#undef F
#define F(...) #__VA_OPT__() X ## __VA_OPT__() #__VA_OPT__( )
14: F()
15: F(1)
// CHECK: 14: "" X ""
// CHECK: 15: "" X ""
#undef F
#define SDEF(sname, ...) S sname __VA_OPT__(= { __VA_ARGS__ })
16: SDEF(foo); // replaced by S foo;
17: SDEF(bar, 1, 2); // replaced by S bar = { 1, 2 };
// CHECK: 16: S foo ;
// CHECK: 17: S bar = { 1, 2 };
#undef SDEF
#define F(a,...) A() #__VA_OPT__(A3 __VA_ARGS__ a ## __VA_ARGS__ ## a ## C A3) A()
18: F()
19: F(,)
20: F(,A3)
21: F(A3, A(),A0)
// CHECK: 18: B ( ) "" B ( )
// CHECK: 19: B ( ) "" B ( )
// CHECK: 20: B ( ) "A3 expandedA3 expandedA2 expandedA1 expandedA0 A3C A3" B ( )
// CHECK: 21: B ( ) "A3 B ( ),expandedA0 A3A(),A0A3C A3" B ( )
#undef F
#define F(a,...) A() #__VA_OPT__(A3 __VA_ARGS__ a ## __VA_ARGS__ ## a ## C A3) a __VA_OPT__(A0 __VA_ARGS__ a ## __VA_ARGS__ ## a ## C A0) A()
22: F()
23: F(,)
24: F(,A0)
25: F(A0, A(),A0)
// CHECK: 22: B ( ) "" B ( )
// CHECK: 23: B ( ) "" B ( )
// CHECK: 24: B ( ) "A3 expandedA0 A0C A3" expandedA0 expandedA0 A0C expandedA0 B ( )
// CHECK: 25: B ( ) "A3 B ( ),expandedA0 A0A(),A0A0C A3" expandedA0 expandedA0 C ( ),expandedA0 A0A(),A0A0C expandedA0 B ( )
#undef F
#define F(a,...) __VA_OPT__(B a ## a) ## 1
#define G(a,...) __VA_OPT__(B a) ## 1
26: F(,1)
26_1: G(,1)
[c++20] Implement tweaked __VA_OPT__ rules from P1042R1: * __VA_OPT__ is expanded if the *expanded* __VA_ARGS__ is non-empty, not if the original argument contained no tokens. * Placemarkers at the start and end of __VA_OPT__ are retained just long enough to paste them with adjacent ## operators. We never paste "across" a discarded placemarker. llvm-svn: 359964
2019-05-04 14:46:18 +08:00
// CHECK: 26: B 1
// CHECK: 26_1: B 1
[c++2a] Implement P0306 __VA_OPT__ (Comma omission and comma deletion) This patch implements an extension to the preprocessor: __VA_OPT__(contents) --> which expands into its contents if variadic arguments are supplied to the parent macro, or behaves as an empty token if none. - Currently this feature is only enabled for C++2a (this could be enabled, with some careful tweaks, for other dialects with the appropriate extension or compatibility warnings) - The patch was reviewed here: https://reviews.llvm.org/D35782 and asides from the above (and moving some of the definition and expansion recognition logic into the corresponding state machines), I believe I incorporated all of Richard's suggestions. A few technicalities (most of which were clarified through private correspondence between rsmith, hubert and thomas) are worth mentioning. Given: #define F(a,...) a #__VA_OPT__(a ## a) a ## __VA_OPT__(__VA_ARGS__) - The call F(,) Does not supply any tokens for the variadic arguments and hence VA_OPT behaves as a placeholder. - When expanding VA_OPT (for e.g. F(,1) token pasting occurs eagerly within its contents if the contents need to be stringified. - A hash or a hashhash prior to VA_OPT does not inhibit expansion of arguments if they are the first token within VA_OPT. - When a variadic argument is supplied, argument substitution occurs within the contents as does stringification - and these resulting tokens are inserted back into the macro expansions token stream just prior to the entire stream being rescanned and concatenated. See wg21.link/P0306 for further details on the feature. Acknowledgment: This patch would have been poorer if not for Richard Smith's usual thoughtful analysis and feedback. llvm-svn: 315840
2017-10-15 09:26:26 +08:00
#undef F
#undef G
#define F(a,...) B ## __VA_OPT__(a 1) ## 1
#define G(a,...) B ## __VA_OPT__(a ## a 1) ## 1
27: F(,1)
27_1: F(A0,1)
28: G(,1)
[c++20] Implement tweaked __VA_OPT__ rules from P1042R1: * __VA_OPT__ is expanded if the *expanded* __VA_ARGS__ is non-empty, not if the original argument contained no tokens. * Placemarkers at the start and end of __VA_OPT__ are retained just long enough to paste them with adjacent ## operators. We never paste "across" a discarded placemarker. llvm-svn: 359964
2019-05-04 14:46:18 +08:00
// CHECK: 27: B 11
[c++2a] Implement P0306 __VA_OPT__ (Comma omission and comma deletion) This patch implements an extension to the preprocessor: __VA_OPT__(contents) --> which expands into its contents if variadic arguments are supplied to the parent macro, or behaves as an empty token if none. - Currently this feature is only enabled for C++2a (this could be enabled, with some careful tweaks, for other dialects with the appropriate extension or compatibility warnings) - The patch was reviewed here: https://reviews.llvm.org/D35782 and asides from the above (and moving some of the definition and expansion recognition logic into the corresponding state machines), I believe I incorporated all of Richard's suggestions. A few technicalities (most of which were clarified through private correspondence between rsmith, hubert and thomas) are worth mentioning. Given: #define F(a,...) a #__VA_OPT__(a ## a) a ## __VA_OPT__(__VA_ARGS__) - The call F(,) Does not supply any tokens for the variadic arguments and hence VA_OPT behaves as a placeholder. - When expanding VA_OPT (for e.g. F(,1) token pasting occurs eagerly within its contents if the contents need to be stringified. - A hash or a hashhash prior to VA_OPT does not inhibit expansion of arguments if they are the first token within VA_OPT. - When a variadic argument is supplied, argument substitution occurs within the contents as does stringification - and these resulting tokens are inserted back into the macro expansions token stream just prior to the entire stream being rescanned and concatenated. See wg21.link/P0306 for further details on the feature. Acknowledgment: This patch would have been poorer if not for Richard Smith's usual thoughtful analysis and feedback. llvm-svn: 315840
2017-10-15 09:26:26 +08:00
// CHECK: 27_1: BexpandedA0 11
[c++20] Implement tweaked __VA_OPT__ rules from P1042R1: * __VA_OPT__ is expanded if the *expanded* __VA_ARGS__ is non-empty, not if the original argument contained no tokens. * Placemarkers at the start and end of __VA_OPT__ are retained just long enough to paste them with adjacent ## operators. We never paste "across" a discarded placemarker. llvm-svn: 359964
2019-05-04 14:46:18 +08:00
// CHECK: 28: B 11
[c++2a] Implement P0306 __VA_OPT__ (Comma omission and comma deletion) This patch implements an extension to the preprocessor: __VA_OPT__(contents) --> which expands into its contents if variadic arguments are supplied to the parent macro, or behaves as an empty token if none. - Currently this feature is only enabled for C++2a (this could be enabled, with some careful tweaks, for other dialects with the appropriate extension or compatibility warnings) - The patch was reviewed here: https://reviews.llvm.org/D35782 and asides from the above (and moving some of the definition and expansion recognition logic into the corresponding state machines), I believe I incorporated all of Richard's suggestions. A few technicalities (most of which were clarified through private correspondence between rsmith, hubert and thomas) are worth mentioning. Given: #define F(a,...) a #__VA_OPT__(a ## a) a ## __VA_OPT__(__VA_ARGS__) - The call F(,) Does not supply any tokens for the variadic arguments and hence VA_OPT behaves as a placeholder. - When expanding VA_OPT (for e.g. F(,1) token pasting occurs eagerly within its contents if the contents need to be stringified. - A hash or a hashhash prior to VA_OPT does not inhibit expansion of arguments if they are the first token within VA_OPT. - When a variadic argument is supplied, argument substitution occurs within the contents as does stringification - and these resulting tokens are inserted back into the macro expansions token stream just prior to the entire stream being rescanned and concatenated. See wg21.link/P0306 for further details on the feature. Acknowledgment: This patch would have been poorer if not for Richard Smith's usual thoughtful analysis and feedback. llvm-svn: 315840
2017-10-15 09:26:26 +08:00
#undef F
#undef G