https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61854
Bug ID: 61854
Summary: Warning single-line comment for -std=c89?
Product: gcc
Version: 4.10.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: chengniansun at gmail dot com
Currently there is no warning on single-line comments for -std=c89. For
example, when I am compiling the following code extracted from SPEC, GCC emits
several errors and Clang emits a warning saying that the single-line comment is
not supported in the c89 language. IMHO, it is worth considering to emit such a
warning, as it is the root cause of the errors, making it easier to understand
the errors.
$: cat t.c
#include <stdio.h>
void
_E_pr_info_header(char const *f, long ln, char const *msg)
{
//SPEC lots of informationals are printed for validation; use stdout
// intead of stderr so as to prefer buffered io
/* make different format so as not to be parsed by emacs compile */
(void) fprintf(stdout, "%s: %s(%ld): ", msg, f, ln);
}
$: gcc-trunk -c -pedantic -Wall -Wextra -std=c89 t.c
t.c: In function ‘_E_pr_info_header’:
t.c:6:3: error: expected expression before ‘/’ token
//SPEC lots of informationals are printed for validation; use stdout
^
t.c:6:61: error: unknown type name ‘use’
//SPEC lots of informationals are printed for validation; use stdout
^
t.c:7:3: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘/’
token
// intead of stderr so as to prefer buffered io
^
t.c:6:61: warning: ISO C90 forbids mixed declarations and code [-Wpedantic]
//SPEC lots of informationals are printed for validation; use stdout
^
t.c:4:31: warning: unused parameter ‘f’ [-Wunused-parameter]
_E_pr_info_header(char const *f, long ln, char const *msg)
^
t.c:4:39: warning: unused parameter ‘ln’ [-Wunused-parameter]
_E_pr_info_header(char const *f, long ln, char const *msg)
^
t.c:4:55: warning: unused parameter ‘msg’ [-Wunused-parameter]
_E_pr_info_header(char const *f, long ln, char const *msg)
^
$: clang-trunk -c -pedantic -Wcomment -std=c89 t.c
t.c:6:3: warning: // comments are not allowed in this language [-Wcomment]
//SPEC lots of informationals are printed for validation; use stdout
^
1 warning generated.
