llvm-project/clang/test/Preprocessor/macro_paste_hashhash.c

// RUN: %clang_cc1 -E %s | FileCheck %s
#define hash_hash # ## # 
#define mkstr(a) # a 
#define in_between(a) mkstr(a) 
#define join(c, d) in_between(c hash_hash d) 
// CHECK: "x ## y";
join(x, y);

#define FOO(x) A x B
// CHECK: A ## B;
FOO(##);
When expanding macro arguments, treat '##' coming from an argument as a normal token. e.g. #define M(x) A x B M(##) // should expand to 'A ## B', not 'AB' llvm-svn: 134588 2011-07-07 03:40:37 +00:00			`// RUN: %clang_cc1 -E %s \| FileCheck %s`
new testcase llvm-svn: 38741 2006-07-19 08:01:28 +00:00			`#define hash_hash # ## #`
			`#define mkstr(a) # a`
			`#define in_between(a) mkstr(a)`
			`#define join(c, d) in_between(c hash_hash d)`
When expanding macro arguments, treat '##' coming from an argument as a normal token. e.g. #define M(x) A x B M(##) // should expand to 'A ## B', not 'AB' llvm-svn: 134588 2011-07-07 03:40:37 +00:00			`// CHECK: "x ## y";`
new testcase llvm-svn: 38741 2006-07-19 08:01:28 +00:00			`join(x, y);`

When expanding macro arguments, treat '##' coming from an argument as a normal token. e.g. #define M(x) A x B M(##) // should expand to 'A ## B', not 'AB' llvm-svn: 134588 2011-07-07 03:40:37 +00:00			`#define FOO(x) A x B`
			`// CHECK: A ## B;`
			`FOO(##);`