[3.13] gh-113785: csv: fields starting with escapechar are not quoted (GH-122110) (GH-122258)

miss-islington · MKuranowski · web-flow · commit 6933c4ace915 · 2024-07-25T07:29:36.000Z
(cherry picked from commit a3327db) Co-authored-by: Mikołaj Kuranowski <mkuranowski@gmail.com>
diff --git a/Lib/test/test_csv.py b/Lib/test/test_csv.py
@@ -454,6 +454,10 @@ def test_read_quoting(self):
                           quoting=csv.QUOTE_STRINGS)
         self._read_test(['1,@,3,@,5'], [['1', ',3,', '5']], quotechar='@')
         self._read_test(['1,\0,3,\0,5'], [['1', ',3,', '5']], quotechar='\0')
+        self._read_test(['1\\.5,\\.5,.5'], [[1.5, 0.5, 0.5]],
+                        quoting=csv.QUOTE_NONNUMERIC, escapechar='\\')
+        self._read_test(['1\\.5,\\.5,"\\.5"'], [[1.5, 0.5, ".5"]],
+                        quoting=csv.QUOTE_STRINGS, escapechar='\\')
 
     def test_read_skipinitialspace(self):
         self._read_test(['no space, space,  spaces,\ttab'],
diff --git a/Misc/NEWS.d/next/Library/2024-07-22-08-14-04.gh-issue-113785.6B_KNB.rst b/Misc/NEWS.d/next/Library/2024-07-22-08-14-04.gh-issue-113785.6B_KNB.rst
@@ -0,0 +1 @@
+:mod:`csv` now correctly parses numeric fields (when used with :const:`csv.QUOTE_NONNUMERIC` or :const:`csv.QUOTE_STRINGS`) which start with an escape character.
diff --git a/Modules/_csv.c b/Modules/_csv.c
@@ -749,7 +749,6 @@ parse_process_char(ReaderObj *self, _csvstate *module_state, Py_UCS4 c)
         }
         else if (c == dialect->escapechar) {
             /* possible escaped character */
-            self->unquoted_field = false;
             self->state = ESCAPED_CHAR;
         }
         else if (c == ' ' && dialect->skipinitialspace)

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1 @@`
	`1`	+:mod:`csv` now correctly parses numeric fields (when used with :const:`csv.QUOTE_NONNUMERIC` or :const:`csv.QUOTE_STRINGS`) which start with an escape character.
Original file line number	Diff line number	Diff line change
`@@ -749,7 +749,6 @@ parse_process_char(ReaderObj self, _csvstate module_state, Py_UCS4 c)`
`749`	`749`	`}`
`750`	`750`	`else if (c == dialect->escapechar) {`
`751`	`751`	`/* possible escaped character */`
`752`		`- self->unquoted_field = false;`
`753`	`752`	`self->state = ESCAPED_CHAR;`
`754`	`753`	`}`
`755`	`754`	`else if (c == ' ' && dialect->skipinitialspace)`