py/objstr: Support '{:08}'.format("Jan") like Python 3.10.

jepler · dpgeorge · commit 037b2c72a1d5 · 2022-01-19T15:34:32.000+11:00
The new test has an .exp file, because it is not compatible with Python 3.9 and lower. See CPython version of the issue at https://bugs.python.org/issue27772 Signed-off-by: Jeff Epler <jepler@gmail.com>
diff --git a/py/objstr.c b/py/objstr.c
@@ -1163,7 +1163,7 @@ STATIC vstr_t mp_obj_str_format_helper(const char *str, const char *top, int *ar
                 s++;
             }
             if (*s == '0') {
-                if (!align) {
+                if (!align && arg_looks_numeric(arg)) {
                     align = '=';
                 }
                 if (!fill) {
diff --git a/tests/basics/string_format_cp310.py b/tests/basics/string_format_cp310.py
@@ -0,0 +1,9 @@
+# Python 3.10+ functionality test for {} format string
+
+def test(fmt, *args):
+    print('{:8s}'.format(fmt) + '>' +  fmt.format(*args) + '<')
+
+test("{:0s}", "ab")
+test("{:06s}", "ab")
+test("{:<06s}", "ab")
+test("{:>06s}", "ab")
diff --git a/tests/basics/string_format_cp310.py.exp b/tests/basics/string_format_cp310.py.exp
@@ -0,0 +1,4 @@
+{:0s}   >ab<
+{:06s}  >ab0000<
+{:<06s} >ab0000<
+{:>06s} >0000ab<
diff --git a/tests/basics/string_format_error.py b/tests/basics/string_format_error.py
@@ -1,7 +1,7 @@
 # tests for errors in {} format string
 
 try:
-    '{0:0}'.format('zzz')
+    '{0:=}'.format('zzz')
 except (ValueError):
     print('ValueError')
 

Original file line number	Diff line number	Diff line change
`@@ -1163,7 +1163,7 @@ STATIC vstr_t mp_obj_str_format_helper(const char str, const char top, int *ar`
`1163`	`1163`	`s++;`
`1164`	`1164`	`}`
`1165`	`1165`	`if (*s == '0') {`
`1166`		`- if (!align) {`
	`1166`	`+ if (!align && arg_looks_numeric(arg)) {`
`1167`	`1167`	`align = '=';`
`1168`	`1168`	`}`
`1169`	`1169`	`if (!fill) {`