[3.12] gh-113785: csv: fields starting with escapechar are not quoted (GH-122110) (GH-122259)

miss-islington · MKuranowski · web-flow · commit 9d7209fc9392 · 2024-08-09T16:04:29.000Z
(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
@@ -425,6 +425,8 @@ def test_read_quoting(self):
                           quoting=csv.QUOTE_NONNUMERIC)
         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='\\')
 
     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`) which start with an escape character.
diff --git a/Modules/_csv.c b/Modules/_csv.c
@@ -701,6 +701,8 @@ parse_process_char(ReaderObj *self, _csvstate *module_state, Py_UCS4 c)
         }
         else if (c == dialect->escapechar) {
             /* possible escaped character */
+            if (dialect->quoting == QUOTE_NONNUMERIC)
+                self->numeric_field = 1;
             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`) which start with an escape character.
Original file line number	Diff line number	Diff line change
`@@ -701,6 +701,8 @@ parse_process_char(ReaderObj self, _csvstate module_state, Py_UCS4 c)`
`701`	`701`	`}`
`702`	`702`	`else if (c == dialect->escapechar) {`
`703`	`703`	`/* possible escaped character */`
	`704`	`+ if (dialect->quoting == QUOTE_NONNUMERIC)`
	`705`	`+ self->numeric_field = 1;`
`704`	`706`	`self->state = ESCAPED_CHAR;`
`705`	`707`	`}`
`706`	`708`	`else if (c == ' ' && dialect->skipinitialspace)`