MAINT: Use utf8 strings in more of datetime

This fixes an omission in a previous patch that did not allow μs in datetime_as_string.
This also will very slightly speed up most uses, since all but very unusual code will be passing in `str` not `bytes`.

4 files changed, 49 insertions, 44 deletions

diff --git a/numpy/core/src/multiarray/datetime_busday.c b/numpy/core/src/multiarray/datetime_busday.c
index d3cce8a37..5acba600a 100644
--- a/numpy/core/src/multiarray/datetime_busday.c
+++ b/numpy/core/src/multiarray/datetime_busday.c
@@ -834,24 +834,24 @@ static int
 PyArray_BusDayRollConverter(PyObject *roll_in, NPY_BUSDAY_ROLL *roll)
 {
     PyObject *obj = roll_in;
-    char *str;
-    Py_ssize_t len;
 
-    /* Make obj into an ASCII string */
-    Py_INCREF(obj);
-    if (PyUnicode_Check(obj)) {
-        /* accept unicode input */
-        PyObject *obj_str;
-        obj_str = PyUnicode_AsASCIIString(obj);
+    /* Make obj into an UTF8 string */
+    if (PyBytes_Check(obj)) {
+        /* accept bytes input */
+        PyObject *obj_str = PyUnicode_FromEncodedObject(obj, NULL, NULL);
         if (obj_str == NULL) {
             Py_DECREF(obj);
             return 0;
         }
-        Py_DECREF(obj);
         obj = obj_str;
     }
+    else {
+        Py_INCREF(obj);
+    }
 
-    if (PyBytes_AsStringAndSize(obj, &str, &len) < 0) {
+    Py_ssize_t len;
+    char const *str = PyUnicode_AsUTF8AndSize(obj, &len);
+    if (str == NULL) {
         Py_DECREF(obj);
         return 0;
     }
diff --git a/numpy/core/src/multiarray/datetime_busdaycal.c b/numpy/core/src/multiarray/datetime_busdaycal.c
index 2374eaa63..906e3b539 100644
--- a/numpy/core/src/multiarray/datetime_busdaycal.c
+++ b/numpy/core/src/multiarray/datetime_busdaycal.c
@@ -30,33 +30,32 @@ PyArray_WeekMaskConverter(PyObject *weekmask_in, npy_bool *weekmask)
 {
     PyObject *obj = weekmask_in;
 
-    /* Make obj into an ASCII string if it is UNICODE */
-    Py_INCREF(obj);
-    if (PyUnicode_Check(obj)) {
-        /* accept unicode input */
-        PyObject *obj_str;
-        obj_str = PyUnicode_AsASCIIString(obj);
+    /* Make obj into an UTF8 string */
+    if (PyBytes_Check(obj)) {
+        /* accept bytes input */
+        PyObject *obj_str = PyUnicode_FromEncodedObject(obj, NULL, NULL);
         if (obj_str == NULL) {
             Py_DECREF(obj);
             return 0;
         }
-        Py_DECREF(obj);
         obj = obj_str;
     }
+    else {
+        Py_INCREF(obj);
+    }
+
 
     if (PyBytes_Check(obj)) {
-        char *str;
         Py_ssize_t len;
-        int i;
-
-        if (PyBytes_AsStringAndSize(obj, &str, &len) < 0) {
+        char const *str = PyUnicode_AsUTF8AndSize(obj, &len);
+        if (str == NULL) {
             Py_DECREF(obj);
             return 0;
         }
 
         /* Length 7 is a string like "1111100" */
         if (len == 7) {
-            for (i = 0; i < 7; ++i) {
+            for (int i = 0; i < 7; ++i) {
                 switch(str[i]) {
                     case '0':
                         weekmask[i] = 0;
@@ -75,7 +74,7 @@ PyArray_WeekMaskConverter(PyObject *weekmask_in, npy_bool *weekmask)
 general_weekmask_string:
         /* a string like "SatSun" or "Mon Tue Wed" */
         memset(weekmask, 0, 7);
-        for (i = 0; i < len; i += 3) {
+        for (int i = 0; i < len; i += 3) {
             while (isspace(str[i]))
                 ++i;
 
diff --git a/numpy/core/src/multiarray/datetime_strings.c b/numpy/core/src/multiarray/datetime_strings.c
index f847c7ea8..49c7e81eb 100644
--- a/numpy/core/src/multiarray/datetime_strings.c
+++ b/numpy/core/src/multiarray/datetime_strings.c
@@ -1385,21 +1385,23 @@ array_datetime_as_string(PyObject *NPY_UNUSED(self), PyObject *args,
     /* Parse the input unit if provided */
     if (unit_in != NULL && unit_in != Py_None) {
         PyObject *strobj;
-        char *str = NULL;
-        Py_ssize_t len = 0;
 
-        if (PyUnicode_Check(unit_in)) {
-            strobj = PyUnicode_AsASCIIString(unit_in);
-            if (strobj == NULL) {
-                goto fail;
+        if (PyBytes_Check(unit_in)) {
+            /* accept bytes input */
+            PyObject *obj_str = PyUnicode_FromEncodedObject(unit_in, NULL, NULL);
+            if (obj_str == NULL) {
+                return 0;
             }
+            strobj = obj_str;
         }
         else {
+            Py_INCREF(unit_in);
             strobj = unit_in;
-            Py_INCREF(strobj);
         }
 
-        if (PyBytes_AsStringAndSize(strobj, &str, &len) < 0) {
+        Py_ssize_t len = 0;
+        char *str = PyUnicode_AsUTF8AndSize(strobj, &len);
+        if (str == NULL) {
             Py_DECREF(strobj);
             goto fail;
         }
@@ -1434,24 +1436,27 @@ array_datetime_as_string(PyObject *NPY_UNUSED(self), PyObject *args,
 
     /* Get the input time zone */
     if (timezone_obj != NULL) {
-        /* Convert to ASCII if it's unicode */
-        if (PyUnicode_Check(timezone_obj)) {
-            /* accept unicode input */
-            PyObject *obj_str;
-            obj_str = PyUnicode_AsASCIIString(timezone_obj);
+        PyObject *strobj;
+        if (PyBytes_Check(timezone_obj)) {
+            /* accept bytes input */
+            PyObject *obj_str = PyUnicode_FromEncodedObject(timezone_obj, NULL, NULL);
             if (obj_str == NULL) {
                 goto fail;
             }
-            Py_DECREF(timezone_obj);
-            timezone_obj = obj_str;
+            strobj = obj_str;
         }
+        else {
+            Py_INCREF(timezone_obj);
+            strobj = unit_in;
+        }
+
+        Py_SETREF(timezone_obj, strobj);
 
         /* Check for the supported string inputs */
-        if (PyBytes_Check(timezone_obj)) {
-            char *str;
+        if (PyUnicode_Check(timezone_obj)) {
             Py_ssize_t len;
-
-            if (PyBytes_AsStringAndSize(timezone_obj, &str, &len) < 0) {
+            char const *str = PyUnicode_AsUTF8AndSize(timezone_obj, &len);
+            if (str == NULL) {
                 goto fail;
             }
 
diff --git a/numpy/core/tests/test_datetime.py b/numpy/core/tests/test_datetime.py
index f725091c5..f58cf307a 100644
--- a/numpy/core/tests/test_datetime.py
+++ b/numpy/core/tests/test_datetime.py
@@ -1654,8 +1654,9 @@ class TestDateTime:
                      '1959-10-13T12:34:56')
         assert_equal(np.datetime_as_string(np.datetime64(datetime, 'ms')),
                      '1959-10-13T12:34:56.789')
-        assert_equal(np.datetime_as_string(np.datetime64(datetime, 'us')),
-                     '1959-10-13T12:34:56.789012')
+        for us in ['us', 'μs', b'us']:  # check non-ascii and bytes too
+            assert_equal(np.datetime_as_string(np.datetime64(datetime, us)),
+                         '1959-10-13T12:34:56.789012')
 
         datetime = '1969-12-31T23:34:56.789012345678901234'