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tree234: avoid an uninitialised-variable warning.

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Apparently, some compilers can't work out that the pattern

  if (!t->root) { special-case handler followed by early return }
  n = t->root;
  while (n) { ... }

will execute the while loop at least once, on the grounds that the
_first_ test for n being non-NULL must pass, because we initialised n
from t->root which can't be NULL on any code path where we didn't take
the early return. So they might give an uninitialised-variable warning
for the variable 'ki', which is initialised inside the while loop.

Compilers, eh. But it's easy enough to turn the while into a do-while,
so that even the least alert compiler will know it runs at least once.
This commit is contained in:
Simon Tatham
2021-12-11 11:32:25 +00:00
parent bb1432c0ad
commit d399a6b230
1 changed files with 2 additions and 2 deletions
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4
tree234.c
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@ -332,7 +332,7 @@ static void *add234_internal(tree234 *t, void *e, int index) {
} }
n = t->root; n = t->root;
while (n) { do {
LOG((" node %p: %p/%d \"%s\" %p/%d \"%s\" %p/%d \"%s\" %p/%d\n", LOG((" node %p: %p/%d \"%s\" %p/%d \"%s\" %p/%d \"%s\" %p/%d\n",
n, n,
n->kids[0], n->counts[0], n->elems[0], n->kids[0], n->counts[0], n->elems[0],
@ -385,7 +385,7 @@ static void *add234_internal(tree234 *t, void *e, int index) {
if (!n->kids[ki]) if (!n->kids[ki])
break; break;
n = n->kids[ki]; n = n->kids[ki];
} } while (n);
add234_insert(NULL, e, NULL, &t->root, n, ki); add234_insert(NULL, e, NULL, &t->root, n, ki);