[3.12] gh-123229: Fix valgrind warning by initializing the f-string b…

…uffers to 0 in the tokenizer (GH-123263)

(cherry picked from commit adc5190)

Co-authored-by: Pablo Galindo Salgado <[email protected]>
Signed-off-by: Pablo Galindo <[email protected]>

Misc/NEWS.d/next/Core and Builtins/2024-08-23-13-08-27.gh-issue-123229.aHm-dw.rst

@@ -0,0 +1,2 @@
+Fix valgrind warning by initializing the f-string buffers to 0 in the
+tokenizer. Patch by Pablo Galindo

Parser/tokenizer.c

@@ -65,7 +65,7 @@ static const char *type_comment_prefix = "# type: ";
 
 static struct tok_state *tok_new(void) {
   struct tok_state *tok =
-      (struct tok_state *)PyMem_Malloc(sizeof(struct tok_state));
+      (struct tok_state *)PyMem_Calloc(1, sizeof(struct tok_state));
   if (tok == NULL)
     return NULL;
   tok->buf = tok->cur = tok->inp = NULL;

lel.patch

@@ -0,0 +1,13 @@
+diff --git a/Parser/tokenizer.c b/Parser/tokenizer.c
+index 3118fb19846..9e0dee8cc38 100644
+--- a/Parser/tokenizer.c
++++ b/Parser/tokenizer.c
+@@ -65,7 +65,7 @@ static const char *type_comment_prefix = "# type: ";
+
+ static struct tok_state *tok_new(void) {
+   struct tok_state *tok =
+-      (struct tok_state *)PyMem_Malloc(sizeof(struct tok_state));
++      (struct tok_state *)PyMem_Calloc(1, sizeof(struct tok_state));
+   if (tok == NULL)
+     return NULL;
+   tok->buf = tok->cur = tok->inp = NULL;