http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57574
Bug ID: 57574
Summary: -std=c99 inline function incorrectly has external
linkage with prior static declaration
Product: gcc
Version: 4.8.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: nszabolcs at gmail dot com
gcc emits incorrect warning for inline function with internal linkage:
$ cat example.c
static int n;
static inline int f(void);
inline int f(void) {return n;}
int g(){return f();}
$ gcc-4.8 -std=c99 -c example.c
example.c:3:28: warning: 'n' is static but used in inline function 'f' which is
not static [enabled by default]
inline int f(void) {return n;}
^
$ nm example.o
U f
00000000 T g
00000000 b n
according to C99 6.2.2p4 the linkage of an identifier
is determined by the prior declaration
(internal in this case, inline does not change that)
referencing static objects from an inline definition
only violates the constraint in C99 6.7.4p3 if the
function has external linkage
(so the diagnostic is unjustified)
it seems from the warning that gcc thinks that f
is not static, this can break code:
the inline definition of f does not provide an
external definition and if the compiler choose
not to inline then the code has undefined f symbol
if the compiler thinks f has external linkage
(as demonstrated by nm above)
