Richard Sandiford <richard.sandif...@linaro.org> writes:
| Gabriel Dos Reis <g...@cs.tamu.edu> writes:
| > Andrew Pinski <pins...@gmail.com> writes:
| >
| > | On Wed, Apr 27, 2011 at 6:48 PM, Gabriel Dos Reis <g...@cs.tamu.edu>
wrote:
| > | > A local `extern' declaration does not give the entity an external
linkage
| > | > -- irrespective of the linkage of the function enclosing the
declaration.
| > | > It just makes the name locally available for name lookup
| > | > purpose. A variable declared const has
| > | > -- external linkage by default in C
| > | > -- internal linkage by default in C++
| > | >
| > | > So before the patch: the variables had external linkage in C, but
| > | > internal linkage in C++. That meant that a link will fail in C++, but
| > | > succeeds in C. All my patch did was to give the external linkage
| > | > explicitly (both in C and in C++.)
| > |
| > | Then I think a better fix is to do:
| > | Index: internal-fn.c
| > | ===================================================================
| > | --- internal-fn.c (revision 172940)
| > | +++ internal-fn.c (working copy)
| > | @@ -27,6 +27,7 @@ along with GCC; see the file COPYING3.
| > | #include "gimple.h"
| > |
| > | /* The names of each internal function, indexed by function number. */
| > | +extern const char *const internal_fn_name_array[];
| > | const char *const internal_fn_name_array[] = {
| > | #define DEF_INTERNAL_FN(CODE, FLAGS) #CODE,
| > | #include "internal-fn.def"
| > | @@ -35,6 +36,7 @@ const char *const internal_fn_name_array
| > | };
| > |
| > | /* The ECF_* flags of each internal function, indexed by function
number. */
| > | +extern const int internal_fn_flags_array[];
| > | const int internal_fn_flags_array[] = {
| > | #define DEF_INTERNAL_FN(CODE, FLAGS) FLAGS,
| > | #include "internal-fn.def"
| > | --- CUT ---
| > | So nobody is tempted to use those arrays directly from the code but
| > | rather only use the static inline functions.
| >
| > Well, anybody who can put those extern declarations anywhere and use
| > them directly. The real issue is that the array variables have external
| > linkage.
| >
| > So, I think the patch is largely stylistic but equivalent; I'll defer to
| > you which one should "prevail".
|
| FWIW, I prefer Andrew's patch, but since yours has been applied,
| I suppose there's no point changing it.
when we come to agree on coding style guidelines for GCC in C++, I hope we
recommend against local extern declarations.
-- Gaby
