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bpo-35494: Improve syntax error messages for unbalanced parentheses in f-string. (GH-11161)

This commit is contained in:
Serhiy Storchaka 2019-01-12 09:46:50 +02:00 committed by GitHub
parent 44cc4822bb
commit 58159ef856
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GPG Key ID: 4AEE18F83AFDEB23
3 changed files with 51 additions and 17 deletions
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36
Lib/test/test_fstring.py
View File

@ -368,9 +368,27 @@ non-important content
])
def test_mismatched_parens(self):
self.assertAllRaise(SyntaxError, 'f-string: mismatched',
self.assertAllRaise(SyntaxError, r"f-string: closing parenthesis '\}' "
r"does not match opening parenthesis '\('",
["f'{((}'",
])
self.assertAllRaise(SyntaxError, r"f-string: closing parenthesis '\)' "
r"does not match opening parenthesis '\['",
["f'{a[4)}'",
])
self.assertAllRaise(SyntaxError, r"f-string: closing parenthesis '\]' "
r"does not match opening parenthesis '\('",
["f'{a(4]}'",
])
self.assertAllRaise(SyntaxError, r"f-string: closing parenthesis '\}' "
r"does not match opening parenthesis '\['",
["f'{a[4}'",
])
self.assertAllRaise(SyntaxError, r"f-string: closing parenthesis '\}' "
r"does not match opening parenthesis '\('",
["f'{a(4}'",
])
self.assertRaises(SyntaxError, eval, "f'{" + "("*500 + "}'")
def test_double_braces(self):
self.assertEqual(f'{{', '{')
@ -448,7 +466,9 @@ non-important content
["f'{1#}'", # error because the expression becomes "(1#)"
"f'{3(#)}'",
"f'{#}'",
"f'{)#}'", # When wrapped in parens, this becomes
])
self.assertAllRaise(SyntaxError, r"f-string: unmatched '\)'",
["f'{)#}'", # When wrapped in parens, this becomes
# '()#)'. Make sure that doesn't compile.
])
@ -577,7 +597,7 @@ non-important content
"f'{,}'", # this is (,), which is an error
])
self.assertAllRaise(SyntaxError, "f-string: expecting '}'",
self.assertAllRaise(SyntaxError, r"f-string: unmatched '\)'",
["f'{3)+(4}'",
])
@ -1003,16 +1023,6 @@ non-important content
self.assertEqual('{d[a]}'.format(d=d), 'string')
self.assertEqual('{d[0]}'.format(d=d), 'integer')
def test_invalid_expressions(self):
self.assertAllRaise(SyntaxError,
r"closing parenthesis '\)' does not match "
r"opening parenthesis '\[' \(<fstring>, line 1\)",
[r"f'{a[4)}'"])
self.assertAllRaise(SyntaxError,
r"closing parenthesis '\]' does not match "
r"opening parenthesis '\(' \(<fstring>, line 1\)",
[r"f'{a(4]}'"])
def test_errors(self):
# see issue 26287
self.assertAllRaise(TypeError, 'unsupported',

1
Misc/NEWS.d/next/Core and Builtins/2018-12-14-18-02-34.bpo-35494.IWOPtb.rst Normal file
View File

@ -0,0 +1 @@
Improved syntax error messages for unbalanced parentheses in f-string.

31
Python/ast.c
View File

@ -13,6 +13,8 @@
#include <assert.h>
#include <stdbool.h>
#define MAXLEVEL 200 /* Max parentheses level */
static int validate_stmts(asdl_seq *);
static int validate_exprs(asdl_seq *, expr_context_ty, int);
static int validate_nonempty_seq(asdl_seq *, const char *, const char *);
@ -4479,6 +4481,7 @@ fstring_find_expr(const char **str, const char *end, int raw, int recurse_lvl,
/* Keep track of nesting level for braces/parens/brackets in
expressions. */
Py_ssize_t nested_depth = 0;
char parenstack[MAXLEVEL];
/* Can only nest one level deep. */
if (recurse_lvl >= 2) {
@ -4553,10 +4556,12 @@ fstring_find_expr(const char **str, const char *end, int raw, int recurse_lvl,
/* Start looking for the end of the string. */
quote_char = ch;
} else if (ch == '[' || ch == '{' || ch == '(') {
if (nested_depth >= MAXLEVEL) {
ast_error(c, n, "f-string: too many nested parenthesis");
return -1;
}
parenstack[nested_depth] = ch;
nested_depth++;
} else if (nested_depth != 0 &&
(ch == ']' || ch == '}' || ch == ')')) {
nested_depth--;
} else if (ch == '#') {
/* Error: can't include a comment character, inside parens
or not. */
@ -4573,6 +4578,23 @@ fstring_find_expr(const char **str, const char *end, int raw, int recurse_lvl,
}
/* Normal way out of this loop. */
break;
} else if (ch == ']' || ch == '}' || ch == ')') {
if (!nested_depth) {
ast_error(c, n, "f-string: unmatched '%c'", ch);
return -1;
}
nested_depth--;
int opening = parenstack[nested_depth];
if (!((opening == '(' && ch == ')') ||
(opening == '[' && ch == ']') ||
(opening == '{' && ch == '}')))
{
ast_error(c, n,
"f-string: closing parenthesis '%c' "
"does not match opening parenthesis '%c'",
ch, opening);
return -1;
}
} else {
/* Just consume this char and loop around. */
}
@ -4587,7 +4609,8 @@ fstring_find_expr(const char **str, const char *end, int raw, int recurse_lvl,
return -1;
}
if (nested_depth) {
ast_error(c, n, "f-string: mismatched '(', '{', or '['");
int opening = parenstack[nested_depth - 1];
ast_error(c, n, "f-string: unmatched '%c'", opening);
return -1;
}