Android 10  |  10.0.0_r6
C++程序  |  13行  |  246 B 

// RUN: %clang_cc1 %s -E | grep 'pre: 1 1 X'
// RUN: %clang_cc1 %s -E | grep 'nopre: 1A(X)'

/* Preexpansion of argument. */
#define A(X) 1 X
pre: A(A(X))

/* The ## operator disables preexpansion. */
#undef A
#define A(X) 1 ## X
nopre: A(A(X))