Bug#845716: gcc-4.9: "#define something" doesn't work

[Stie <contact@it-kovac.com>]

Package: gcc-4.9
Version: 4.9.2-10
Severity: important

Dear Maintainer,

Tried to build the legacy LineMode web browser, version 0.11a (available on browserarchive.org: http://cdn.browserarchive.org/worldwideweb/NeXT/WWWLineMode_0.11a.tar.gz)

When issuing the command "make", gcc outputs the following error:
cc -c  -I../../../Implementation/ -I../ ../../../Implementation/HTFTP.c
.../../../Implementation/HTFTP.c:46:20: error: expected identifier before numeric constant
 #define IPPORT_FTP 21
                    ^
.../CommonMakefile:52: recipe for target 'HTFTP.o' failed
make: *** [HTFTP.o] Error 1

Note that the line where the error occurs in HTFTP.c is wrapped by an ifndef / endif:

#ifndef IPPORT_FTP
#define IPPORT_FTP 21
#endif


Whilst I would expect some compatibility issues with this code from the early 90s, "#define IPPORT_FTP 21" should work just fine (see also http://stackoverflow.com/questions/40804244 for a very similar issue involving the same GCC version). 
Something definitely seems broken in this specific version of GCC (4.9.2-10), with the way #define directives are processed.
Any confirmation of whether this happens in higher versions would be welcome.



-- System Information:
Debian Release: 8.6
  APT prefers stable-updates
  APT policy: (500, 'stable-updates'), (500, 'stable')
Architecture: should not matter for this bug

Kernel: should not matter for this bug
Locale: LANG=C, LC_CTYPE=C (charmap=ANSI_X3.4-1968)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)

Versions of packages gcc-4.9 depends on:
ii  binutils        2.25-5
ii  cpp-4.9         4.9.2-10
ii  gcc-4.9-base    4.9.2-10
ii  libc6           2.19-18+deb8u6
ii  libcloog-isl4   0.18.2-1+b2
ii  libgcc-4.9-dev  4.9.2-10
ii  libgmp10        2:6.0.0+dfsg-6
ii  libisl10        0.12.2-2
ii  libmpc3         1.0.2-1
ii  libmpfr4        3.1.2-2
ii  zlib1g          1:1.2.8.dfsg-2+b1

Versions of packages gcc-4.9 recommends:
ii  libc6-dev  2.19-18+deb8u6

Versions of packages gcc-4.9 suggests:
pn  gcc-4.9-doc       <none>
pn  gcc-4.9-locales   <none>
ii  gcc-4.9-multilib  4.9.2-10
pn  libasan1-dbg      <none>
pn  libatomic1-dbg    <none>
pn  libcilkrts5-dbg   <none>
pn  libgcc1-dbg       <none>
pn  libgomp1-dbg      <none>
pn  libitm1-dbg       <none>
pn  liblsan0-dbg      <none>
pn  libquadmath-dbg   <none>
pn  libtsan0-dbg      <none>
pn  libubsan0-dbg     <none>

-- no debconf information