bpo-2180: Treat line continuation at EOF as a `SyntaxError` (GH-13401)

This makes the parser consistent with the tokenize module (already the case
in `pypy`).

sample
------

```python
x = 5\
```

before
------

```console
$ python3 t.py
$ python3 -mtokenize t.py
t.py:2:0: error: EOF in multi-line statement
```

after
-----

```console
$ ./python t.py
  File "t.py", line 3
    x = 5\

         ^
SyntaxError: unexpected EOF while parsing
$ ./python -m tokenize t.py
t.py:2:0: error: EOF in multi-line statement
```



https://bugs.python.org/issue2180

1 files changed, 10 insertions, 1 deletions

diff --git a/Parser/tokenizer.c b/Parser/tokenizer.c
index 5dc2ae6..e52d498 100644
--- a/Parser/tokenizer.c
+++ b/Parser/tokenizer.c
@@ -983,7 +983,8 @@ tok_nextc(struct tok_state *tok)
                         return EOF;
                     /* Last line does not end in \n,
                        fake one */
-                    strcpy(tok->inp, "\n");
+                    if (tok->inp[-1] != '\n')
+                        strcpy(tok->inp, "\n");
                 }
                 tok->inp = strchr(tok->inp, '\0');
                 done = tok->inp[-1] == '\n';
@@ -1674,6 +1675,14 @@ tok_get(struct tok_state *tok, char **p_start, char **p_end)
             tok->cur = tok->inp;
             return ERRORTOKEN;
         }
+        c = tok_nextc(tok);
+        if (c == EOF) {
+            tok->done = E_EOF;
+            tok->cur = tok->inp;
+            return ERRORTOKEN;
+        } else {
+            tok_backup(tok, c);
+        }
         tok->cont_line = 1;
         goto again; /* Read next line */
     }