Skip to content

bpo-39934: Account for control blocks in 'except' in compiler.#22395

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
markshannon merged 2 commits into from
Sep 25, 2020
Merged

bpo-39934: Account for control blocks in 'except' in compiler. #22395

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
300314b
Account for control blocks in 'except' in compiler. Fixes #39934.
markshannon Sep 24, 2020
945e68f
Change nesting test from doctest to unittest.
markshannon Sep 25, 2020
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
9 changes: 9 additions & 0 deletions Lib/test/test_syntax.py
View file
Open in desktop
Original file line numberDiff line numberDiff line change
Expand Up@@ -950,6 +950,15 @@ def test_empty_line_after_linecont(self):
except SyntaxError:
self.fail("Empty line after a line continuation character is valid.")

@support.cpython_only
def test_nested_named_except_blocks(self):
code = ""
for i in range(12):
code += f"{' '*i}try:\n"
code += f"{' '*(i+1)}raise Exception\n"
code += f"{' '*i}except Exception as e:\n"
code += f"{' '*4*12}pass"
self._check_error(code, "too many statically nested blocks")

def test_main():
support.run_unittest(SyntaxTestCase)
Expand Down
3 changes: 3 additions & 0 deletions Misc/NEWS.d/next/Core and Builtins/2020-09-24-12-15-45.bpo-39934.YVHTCF.rst
View file
Open in desktop
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,3 @@
Correctly count control blocks in 'except' in compiler. Ensures that a
syntax error, rather a fatal error, occurs for deeply nested, named
exception handlers.
19 changes: 11 additions & 8 deletions Python/compile.c
View file
Open in desktop
Original file line numberDiff line numberDiff line change
Expand Up@@ -108,8 +108,8 @@ It's called a frame block to distinguish it from a basic block in the
compiler IR.
*/

enum fblocktype{WHILE_LOOP, FOR_LOOP, EXCEPT, FINALLY_TRY, FINALLY_END,
WITH, ASYNC_WITH, HANDLER_CLEANUP, POP_VALUE };
enum fblocktype{WHILE_LOOP, FOR_LOOP, TRY_EXCEPT, FINALLY_TRY, FINALLY_END,
WITH, ASYNC_WITH, HANDLER_CLEANUP, POP_VALUE, EXCEPTION_HANDLER };

struct fblockinfo{
enum fblocktype fb_type;
Expand DownExpand Up@@ -1623,9 +1623,7 @@ compiler_push_fblock(struct compiler *c, enum fblocktype t, basicblock *b,
{
struct fblockinfo *f;
if (c->u->u_nfblocks >= CO_MAXBLOCKS){
PyErr_SetString(PyExc_SyntaxError,
"too many statically nested blocks");
return 0;
return compiler_error(c, "too many statically nested blocks");
}
f = &c->u->u_fblock[c->u->u_nfblocks++];
f->fb_type = t;
Expand DownExpand Up@@ -1665,6 +1663,7 @@ compiler_unwind_fblock(struct compiler *c, struct fblockinfo *info,
{
switch (info->fb_type){
case WHILE_LOOP:
case EXCEPTION_HANDLER:
return 1;

case FOR_LOOP:
Expand All@@ -1675,7 +1674,7 @@ compiler_unwind_fblock(struct compiler *c, struct fblockinfo *info,
ADDOP(c, POP_TOP);
return 1;

case EXCEPT:
case TRY_EXCEPT:
ADDOP(c, POP_BLOCK);
return 1;

Expand DownExpand Up@@ -3060,14 +3059,17 @@ compiler_try_except(struct compiler *c, stmt_ty s)
return 0;
ADDOP_JUMP(c, SETUP_FINALLY, except);
compiler_use_next_block(c, body);
if (!compiler_push_fblock(c, EXCEPT, body, NULL, NULL))
if (!compiler_push_fblock(c, TRY_EXCEPT, body, NULL, NULL))
return 0;
VISIT_SEQ(c, stmt, s->v.Try.body);
ADDOP(c, POP_BLOCK);
compiler_pop_fblock(c, EXCEPT, body);
compiler_pop_fblock(c, TRY_EXCEPT, body);
ADDOP_JUMP(c, JUMP_FORWARD, orelse);
n = asdl_seq_LEN(s->v.Try.handlers);
compiler_use_next_block(c, except);
/* Runtime will push a block here, so we need to account for that */
if (!compiler_push_fblock(c, EXCEPTION_HANDLER, NULL, NULL, NULL))
return 0;
for (i = 0; i < n; i++){
excepthandler_ty handler = (excepthandler_ty)asdl_seq_GET(
s->v.Try.handlers, i);
Expand DownExpand Up@@ -3152,6 +3154,7 @@ compiler_try_except(struct compiler *c, stmt_ty s)
}
compiler_use_next_block(c, except);
}
compiler_pop_fblock(c, EXCEPTION_HANDLER, NULL);
ADDOP(c, RERAISE);
compiler_use_next_block(c, orelse);
VISIT_SEQ(c, stmt, s->v.Try.orelse);
Expand Down