On 03/20/2017 07:42 AM, Marek Polacek wrote:
On Mon, Mar 20, 2017 at 09:37:10AM -0400, Jason Merrill wrote:
On Mon, Mar 20, 2017 at 9:28 AM, Marek Polacek <pola...@redhat.com> wrote:
#define DEF_SANITIZER_BUILTIN(ENUM, NAME, TYPE, ATTRS) \
+ do { \
+ decl = add_builtin_function ("__builtin_" NAME, TYPE, ENUM,
\
+ BUILT_IN_NORMAL, NAME, NULL_TREE); \
+ set_call_expr_flags (decl, ATTRS); \
+ set_builtin_decl (ENUM, decl, true); \
+ } while (0);
We leave out the trailing ; in a macro like this.
True, but that wasn't possible in this case, otherwise I got tons of
/home/marek/src/gcc/gcc/asan.c:2570:3: error: expected ‘;’ before ‘do’
do { \
^
/home/marek/src/gcc/gcc/sanitizer.def:459:1: note: in expansion of macro
‘DEF_SANITIZER_BUILTIN’
DEF_SANITIZER_BUILTIN(BUILT_IN_UBSAN_HANDLE_TYPE_MISMATCH_ABORT
I would view these as helpful errors and expect them to be fixed
by terminating the macro invocations with a semicolon rather than
by adding it to the macro definition itself. Is there a problem
with doing that that I'm not considering?
Martin
PS The GCC manual documents this problem in the section titled
Swallowing the Semicolon:
https://gcc.gnu.org/onlinedocs/cpp/Swallowing-the-Semicolon.html
This problem is also the subject of the CERT C Coding Standard
rule PRE11-C. Do not conclude macro definitions with a semicolon
(although the examples there are contrived).
Leaving the semicolon out also tends to confuse formatting tools.
It would be nice to be able to add a warning to help detect these
kinds of problems in macros (and others), and enable it for GCC
itself.
