Issue #22445: PyBuffer_IsContiguous() now implements precise contiguity
tests, compatible with NumPy's NPY_RELAXED_STRIDES_CHECKING compilation
flag. Previously the function reported false negatives for corner cases.
diff --git a/Objects/abstract.c b/Objects/abstract.c
index 9ab60f2..92d1ac8 100644
--- a/Objects/abstract.c
+++ b/Objects/abstract.c
@@ -367,16 +367,35 @@
Py_ssize_t sd, dim;
int i;
- if (view->ndim == 0) return 1;
- if (view->strides == NULL) return (view->ndim == 1);
+ /* 1) len = product(shape) * itemsize
+ 2) itemsize > 0
+ 3) len = 0 <==> exists i: shape[i] = 0 */
+ if (view->len == 0) return 1;
+ if (view->strides == NULL) { /* C-contiguous by definition */
+ /* Trivially F-contiguous */
+ if (view->ndim <= 1) return 1;
+
+ /* ndim > 1 implies shape != NULL */
+ assert(view->shape != NULL);
+
+ /* Effectively 1-d */
+ sd = 0;
+ for (i=0; i<view->ndim; i++) {
+ if (view->shape[i] > 1) sd += 1;
+ }
+ return sd <= 1;
+ }
+
+ /* strides != NULL implies both of these */
+ assert(view->ndim > 0);
+ assert(view->shape != NULL);
sd = view->itemsize;
- if (view->ndim == 1) return (view->shape[0] == 1 ||
- sd == view->strides[0]);
for (i=0; i<view->ndim; i++) {
dim = view->shape[i];
- if (dim == 0) return 1;
- if (view->strides[i] != sd) return 0;
+ if (dim > 1 && view->strides[i] != sd) {
+ return 0;
+ }
sd *= dim;
}
return 1;
@@ -388,16 +407,22 @@
Py_ssize_t sd, dim;
int i;
- if (view->ndim == 0) return 1;
- if (view->strides == NULL) return 1;
+ /* 1) len = product(shape) * itemsize
+ 2) itemsize > 0
+ 3) len = 0 <==> exists i: shape[i] = 0 */
+ if (view->len == 0) return 1;
+ if (view->strides == NULL) return 1; /* C-contiguous by definition */
+
+ /* strides != NULL implies both of these */
+ assert(view->ndim > 0);
+ assert(view->shape != NULL);
sd = view->itemsize;
- if (view->ndim == 1) return (view->shape[0] == 1 ||
- sd == view->strides[0]);
for (i=view->ndim-1; i>=0; i--) {
dim = view->shape[i];
- if (dim == 0) return 1;
- if (view->strides[i] != sd) return 0;
+ if (dim > 1 && view->strides[i] != sd) {
+ return 0;
+ }
sd *= dim;
}
return 1;