behavior of -E with -g3

[Martin Sebor]

I was surprised to see macro definitions in the output of gcc
-E -g3 (see below). Is that behavior by design or is it a bug?
(I haven't seen anything about it in the manual, other than what
-g/leve/ mentions about debugger support for macro expansion).

Thanks
Martin

$ cat t.cpp && gcc -E t.cpp -g3 | grep -v "#define __"
#define FOO bar

# 1 "t.cpp"
# 1 "/tmp//"
# 1 "<built-in>"
#define sparc 1


#define unix 1
#define sun 1


#define _XOPEN_SOURCE 500
#define _LARGEFILE_SOURCE 1
#define _LARGEFILE64_SOURCE 1
# 1 "<command line>"
# 1 "t.cpp"
#define FOO bar