gh-120155: Fix optimize_and_assemble_code_unit() error handling

vstinner · vstinner · commit 9cbc9149c2de · 2024-06-07T15:51:49.000+02:00
Don't use 'g' before it's being initialized: don't use the 'error'
label if consts_dict_keys_inorder() failed.

Fix the Coverity issue:

Error: UNINIT (CWE-457):
Python-3.12.2/Python/compile.c:7670:5: skipped_decl: Jumping over declaration of ""g"".
Python-3.12.2/Python/compile.c:7714:5: uninit_use_in_call: Using uninitialized value ""g.g_block_list"" when calling ""_PyCfgBuilder_Fini"".
Python-3.12.2/Python/compile.c:7714:5: uninit_use_in_call: Using uninitialized value ""g.g_entryblock"" when calling ""_PyCfgBuilder_Fini"".
  7712|       Py_XDECREF(consts);
  7713|       instr_sequence_fini(&amp;optimized_instrs);
  7714|-&gt;     _PyCfgBuilder_Fini(&amp;g);
  7715|       return co;
  7716|   }
diff --git a/Python/compile.c b/Python/compile.c
@@ -7682,7 +7682,7 @@ optimize_and_assemble_code_unit(struct compiler_unit *u, PyObject *const_cache,
     PyCodeObject *co = NULL;
     PyObject *consts = consts_dict_keys_inorder(u->u_metadata.u_consts);
     if (consts == NULL) {
-        goto error;
+        return NULL;
     }
     cfg_builder g;
     if (instr_sequence_to_cfg(&u->u_instr_sequence, &g) < 0) {

Original file line number	Diff line number	Diff line change
`@@ -7682,7 +7682,7 @@ optimize_and_assemble_code_unit(struct compiler_unit u, PyObject const_cache,`
`7682`	`7682`	`PyCodeObject *co = NULL;`
`7683`	`7683`	`PyObject *consts = consts_dict_keys_inorder(u->u_metadata.u_consts);`
`7684`	`7684`	`if (consts == NULL) {`
`7685`		`- goto error;`
	`7685`	`+ return NULL;`
`7686`	`7686`	`}`
`7687`	`7687`	`cfg_builder g;`
`7688`	`7688`	`if (instr_sequence_to_cfg(&u->u_instr_sequence, &g) < 0) {`