> But here's an alternative. Geert, what do you think of this? Never mind; that doesn't work. Plain gcc-4.9 passes, it, but it's the "-Wundef" flag that the kernel uses that triggers it.
So we're back to Geert's original suggestion. Acked-by: George Spelvin <[email protected]> ==>$ cat foo.c #ifndef FOO This is a test. #elif FOO == 1 This is another test #elif FOO + 0 == 1 who knows #endif ==>$ gcc-6 -W -Wall -Wundef -E foo.c # 1 "foo.c" # 1 "<built-in>" # 1 "<command-line>" # 31 "<command-line>" # 1 "/usr/include/stdc-predef.h" 1 3 4 # 32 "<command-line>" 2 # 1 "foo.c" This is a test. ==>$ gcc-4.9 -W -Wall -Wundef -E foo.c # 1 "foo.c" # 1 "<built-in>" # 1 "<command-line>" # 1 "/usr/include/stdc-predef.h" 1 3 4 # 1 "<command-line>" 2 # 1 "foo.c" foo.c:3:7: warning: "FOO" is not defined [-Wundef] #elif FOO == 1 ^ foo.c:5:7: warning: "FOO" is not defined [-Wundef] #elif FOO + 0 == 1 ^ This is a test.
