From a77aac4fca9723b8fd52a832f3e9df13beb25113 Mon Sep 17 00:00:00 2001
From: Pablo Galindo <Pablogsal@gmail.com>
Date: Fri, 23 Apr 2021 14:27:05 +0100
Subject: bpo-43914: Highlight invalid ranges in SyntaxErrors (#25525)

To improve the user experience understanding what part of the error messages associated with SyntaxErrors is wrong, we can highlight the whole error range and not only place the caret at the first character. In this way:

>>> foo(x, z for z in range(10), t, w)
  File "<stdin>", line 1
    foo(x, z for z in range(10), t, w)
           ^
SyntaxError: Generator expression must be parenthesized

becomes

>>> foo(x, z for z in range(10), t, w)
  File "<stdin>", line 1
    foo(x, z for z in range(10), t, w)
           ^^^^^^^^^^^^^^^^^^^^
SyntaxError: Generator expression must be parenthesized
---
 Python/errors.c | 44 ++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 42 insertions(+), 2 deletions(-)

(limited to 'Python/errors.c')

diff --git a/Python/errors.c b/Python/errors.c
index d73ba93b02..f743d3089e 100644
--- a/Python/errors.c
+++ b/Python/errors.c
@@ -1545,14 +1545,17 @@ PyErr_SyntaxLocation(const char *filename, int lineno)
    If the exception is not a SyntaxError, also sets additional attributes
    to make printing of exceptions believe it is a syntax error. */
 
-void
-PyErr_SyntaxLocationObject(PyObject *filename, int lineno, int col_offset)
+static void
+PyErr_SyntaxLocationObjectEx(PyObject *filename, int lineno, int col_offset,
+                             int end_lineno, int end_col_offset)
 {
     PyObject *exc, *v, *tb, *tmp;
     _Py_IDENTIFIER(filename);
     _Py_IDENTIFIER(lineno);
+    _Py_IDENTIFIER(end_lineno);
     _Py_IDENTIFIER(msg);
     _Py_IDENTIFIER(offset);
+    _Py_IDENTIFIER(end_offset);
     _Py_IDENTIFIER(print_file_and_line);
     _Py_IDENTIFIER(text);
     PyThreadState *tstate = _PyThreadState_GET();
@@ -1582,6 +1585,32 @@ PyErr_SyntaxLocationObject(PyObject *filename, int lineno, int col_offset)
         _PyErr_Clear(tstate);
     }
     Py_XDECREF(tmp);
+
+    tmp = NULL;
+    if (end_lineno >= 0) {
+        tmp = PyLong_FromLong(end_lineno);
+        if (tmp == NULL) {
+            _PyErr_Clear(tstate);
+        }
+    }
+    if (_PyObject_SetAttrId(v, &PyId_end_lineno, tmp ? tmp : Py_None)) {
+        _PyErr_Clear(tstate);
+    }
+    Py_XDECREF(tmp);
+
+    tmp = NULL;
+    if (end_col_offset >= 0) {
+        tmp = PyLong_FromLong(end_col_offset);
+        if (tmp == NULL) {
+            _PyErr_Clear(tstate);
+        }
+    }
+    if (_PyObject_SetAttrId(v, &PyId_end_offset, tmp ? tmp : Py_None)) {
+        _PyErr_Clear(tstate);
+    }
+    Py_XDECREF(tmp);
+
+    tmp = NULL;
     if (filename != NULL) {
         if (_PyObject_SetAttrId(v, &PyId_filename, filename)) {
             _PyErr_Clear(tstate);
@@ -1633,6 +1662,17 @@ PyErr_SyntaxLocationObject(PyObject *filename, int lineno, int col_offset)
     _PyErr_Restore(tstate, exc, v, tb);
 }
 
+void
+PyErr_SyntaxLocationObject(PyObject *filename, int lineno, int col_offset) {
+    PyErr_SyntaxLocationObjectEx(filename, lineno, col_offset, lineno, -1);
+}
+
+void
+PyErr_RangedSyntaxLocationObject(PyObject *filename, int lineno, int col_offset,
+                                 int end_lineno, int end_col_offset) {
+    PyErr_SyntaxLocationObjectEx(filename, lineno, col_offset, end_lineno, end_col_offset);
+}
+
 void
 PyErr_SyntaxLocationEx(const char *filename, int lineno, int col_offset)
 {
-- 
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