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syntax.c: Fix maybe-uninitialized warning (#7596)

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When building in release mode, gcc generated a maybe-initialized
warning in get_syn_options. The warning is both right and wrong;
there is an execution path where the len variable is not
initialized in the code:
...
int len;
...
for (fidx = ARRAY_SIZE(flagtab); --fidx >= 0; ) {
  p = flagtab[fidx].name;
  int i;
  for (i = 0, len = 0; p[i] != NUL; i += 2, ++len)
    if (arg[len] != p[i] && arg[len] != p[i + 1])
      break;
  // <snip>
}
...
  arg = skipwhite(arg + len);
...

The initial for loop will not execute if ARRAY_SIZE(flagtab) == 0,
and thus len will never be initialized. flagtab is a local-static
variable, initialized to a long array of structured data, so
ARRAY_SIZE(flagtab) can't be 0.

However, gcc doesn't recognize ARRAY_SIZE(flagtab) as a constant.
There are any number of reasons this could happen. In any case,
the message can be fixed with a len=0 before the first for loop.

In addition to the above warning, I've labeled flagtab and
first_letters as const. They should never change.
This commit is contained in:
Phlosioneer
2017-11-20 18:04:49 -05:00
committed by Justin M. Keyes
parent c391401648
commit 8674b0c3d1
1 changed files with 5 additions and 4 deletions
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9
src/nvim/syntax.c
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@@ -4009,10 +4009,10 @@ get_syn_options (
{
char_u *gname_start, *gname;
int syn_id;
int len;
int len = 0;
char *p;
int fidx;
static struct flag {
static const struct flag {
char *name;
int argtype;
int flags;
@@ -4035,7 +4035,7 @@ get_syn_options (
{"cCoOnNtTaAiInNsS", 1, 0},
{"cCoOnNtTaAiInNeEdDiInN", 2, 0},
{"nNeExXtTgGrRoOuUpP", 3, 0},};
static char *first_letters = "cCoOkKeEtTsSgGdDfFnN";
static const char *const first_letters = "cCoOkKeEtTsSgGdDfFnN";
if (arg == NULL) /* already detected error */
return NULL;
@@ -4055,9 +4055,10 @@ get_syn_options (
for (fidx = ARRAY_SIZE(flagtab); --fidx >= 0; ) {
p = flagtab[fidx].name;
int i;
for (i = 0, len = 0; p[i] != NUL; i += 2, ++len)
for (i = 0, len = 0; p[i] != NUL; i += 2, ++len) {
if (arg[len] != p[i] && arg[len] != p[i + 1])
break;
}
if (p[i] == NUL && (ascii_iswhite(arg[len])
|| (flagtab[fidx].argtype > 0
? arg[len] == '='