Path: utzoo!telly!ddsw1!lll-winken!killer!mit-eddie!bloom-beacon!apple!rutgers!njin!princeton!notecnirp!drh
From: drh@notecnirp.Princeton.EDU (Dave Hanson)
Newsgroups: gnu.gcc.bug
Subject: linkage warnings
Message-ID: <12477@princeton.Princeton.EDU>
Date: 8 Oct 88 13:38:22 GMT
Sender: news@princeton.Princeton.EDU
Reply-To: drh@princeton.Princeton.EDU (Dave Hanson)
Distribution: gnu
Organization: Dept. of Computer Science, Princeton University
Lines: 37

after much reading of the 5/88 standard and K&R2, and discussions
with others here and at bell labs,
i think the convoluted explanations of linkage boil
down to ``first declaration determines linkage''.
thus, the following program specifies inconsistent
linkage for both f and g.

[709] cat bug4.c
extern int f();
int g();

static f() {}
static g() {}

gcc doesn't complain:

[710] gcc -v -S bug4.c
gcc version 1.28
 /usr/local/lib/gcc-cpp -v -undef -D__GNU__ -D__GNUC__ -Dvax -Dunix bug4.c /tmp/cc028903.cpp
GNU CPP version 1.28
 /usr/local/lib/gcc-cc1 /tmp/cc028903.cpp -quiet -dumpbase bug4.c -version -o bug4.s
GNU C version 1.28 (vax) compiled by GNU C version 1.28.

it should ellicit at least a warning, e.g.

[711] lcc -S bug4.c
bug4.c:4.12:f(): warning: inconsistent linkage for f
bug4.c:5.12:g(): warning: inconsistent linkage for g

i note that gcc does warn about other linkage errors, e.g.

f() { extern int x;}
static int x;

draws

At top level:
bug3.c:2: warning: `x' was declared `extern' and later `static'