[mypyc] Propagate errors in Unicode operations

mypyc/lib-rt/str_ops.c

@@ -130,10 +130,7 @@ PyObject *CPyStr_GetItem(PyObject *str, CPyTagged index) {
             return NULL;
         }
     } else {
-        PyObject *index_obj = CPyTagged_AsObject(index);
-        PyObject *result = PyObject_GetItem(str, index_obj);
-        Py_DECREF(index_obj);
-        return result;
+        return NULL;
     }
 }
 
@@ -218,7 +215,11 @@ PyObject *CPyStr_Build(Py_ssize_t len, ...) {
             Py_ssize_t itemlen = PyUnicode_GET_LENGTH(item);
             if (itemlen != 0) {
 #if CPY_3_13_FEATURES
-                PyUnicode_CopyCharacters(res, res_offset, item, 0, itemlen);
+                if (PyUnicode_CopyCharacters(res, res_offset, item, 0, itemlen) < 0) {
+                    va_end(args);
+                    Py_DECREF(res);
+                    return NULL;
+                }
 #else
                 _PyUnicode_FastCopyCharacters(res, res_offset, item, 0, itemlen);
 #endif
@@ -419,6 +420,9 @@ int CPyStr_Startswith(PyObject *self, PyObject *subobj) {
                 return 2;
             }
             int result = PyUnicode_Tailmatch(self, substring, start, end, -1);
+            if (result < 0) {
+                return 2;
+            }
             if (result) {
                 return 1;
             }
@@ -443,6 +447,9 @@ int CPyStr_Endswith(PyObject *self, PyObject *subobj) {
                 return 2;
             }
             int result = PyUnicode_Tailmatch(self, substring, start, end, 1);
+            if (result < 0) {
+                return 2;
+            }
             if (result) {
                 return 1;
             }
@@ -455,6 +462,9 @@ int CPyStr_Endswith(PyObject *self, PyObject *subobj) {
 PyObject *CPyStr_Removeprefix(PyObject *self, PyObject *prefix) {
     Py_ssize_t end = PyUnicode_GET_LENGTH(self);
     int match = PyUnicode_Tailmatch(self, prefix, 0, end, -1);
+    if (match < 0) {
+        return NULL;
+    }
     if (match) {
         Py_ssize_t prefix_end = PyUnicode_GET_LENGTH(prefix);
         return PyUnicode_Substring(self, prefix_end, end);
@@ -465,6 +475,9 @@ PyObject *CPyStr_Removeprefix(PyObject *self, PyObject *prefix) {
 PyObject *CPyStr_Removesuffix(PyObject *self, PyObject *suffix) {
     Py_ssize_t end = PyUnicode_GET_LENGTH(self);
     int match = PyUnicode_Tailmatch(self, suffix, 0, end, 1);
+    if (match < 0) {
+        return NULL;
+    }
     if (match) {
         Py_ssize_t suffix_end = PyUnicode_GET_LENGTH(suffix);
         return PyUnicode_Substring(self, 0, end - suffix_end);

mypyc/primitives/str_ops.py

@@ -265,7 +265,7 @@
     arg_types=[str_rprimitive, str_rprimitive],
     return_type=str_rprimitive,
     c_function_name="CPyStr_Removeprefix",
-    error_kind=ERR_NEVER,
+    error_kind=ERR_MAGIC,
 )
 
 # str.removesuffix(str)
@@ -274,7 +274,7 @@
     arg_types=[str_rprimitive, str_rprimitive],
     return_type=str_rprimitive,
     c_function_name="CPyStr_Removesuffix",
-    error_kind=ERR_NEVER,
+    error_kind=ERR_MAGIC,
 )
 
 # str.split(...) and str.rsplit(...)

mypyc/test-data/exceptions.test

@@ -24,6 +24,25 @@ L3:
     r2 = <error> :: int
     return r2
 
+[case testStrRemovePrefixSuffixError]
+def f(s: str, prefix: str, suffix: str) -> str:
+    return s.removeprefix(prefix).removesuffix(suffix)
+[out]
+def f(s, prefix, suffix):
+    s, prefix, suffix, r0, r1, r2 :: str
+L0:
+    r0 = CPyStr_Removeprefix(s, prefix)
+    if is_error(r0) goto L3 (error at f:2) else goto L1
+L1:
+    r1 = CPyStr_Removesuffix(r0, suffix)
+    dec_ref r0
+    if is_error(r1) goto L3 (error at f:2) else goto L2
+L2:
+    return r1
+L3:
+    r2 = <error> :: str
+    return r2
+
 [case testListAppendAndSetItemError]
 from typing import List
 def f(x: List[int], y: int, z: int) -> None:

mypyc/test-data/run-strings.test

@@ -91,6 +91,12 @@ assert match_tuple_literal_args('abc', 'z', 'c') == (False, True)
 assert remove_prefix_suffix('', '') == ('', '')
 assert remove_prefix_suffix('abc', 'a') == ('bc', 'abc')
 assert remove_prefix_suffix('abc', 'c') == ('abc', 'ab')
+assert remove_prefix_suffix('abc', '') == ('abc', 'abc')
+assert remove_prefix_suffix('abc', 'abc') == ('', '')
+assert remove_prefix_suffix('abc', 'abcd') == ('abc', 'abc')
+assert remove_prefix_suffix('abc', 'b') == ('abc', 'abc')
+assert remove_prefix_suffix('\u1234abc\U0001f600', '\u1234') == ('abc\U0001f600', '\u1234abc\U0001f600')
+assert remove_prefix_suffix('\u1234abc\U0001f600', '\U0001f600') == ('\u1234abc\U0001f600', '\u1234abc')
 
 [case testStringEquality]
 def eq(a: str, b: str) -> bool: