changeset: 103415:804b71d43c85 user: Guido van Rossum date: Fri Sep 09 09:36:26 2016 -0700 files: Doc/reference/simple_stmts.rst Lib/test/test_syntax.py Misc/NEWS Python/symtable.c description: Issue #27999: Make "global after use" a SyntaxError, and ditto for nonlocal. Patch by Ivan Levkivskyi. diff -r f6a0b80ade26 -r 804b71d43c85 Doc/reference/simple_stmts.rst --- a/Doc/reference/simple_stmts.rst Fri Sep 09 09:29:42 2016 -0700 +++ b/Doc/reference/simple_stmts.rst Fri Sep 09 09:36:26 2016 -0700 @@ -903,11 +903,12 @@ Names listed in a :keyword:`global` statement must not be defined as formal parameters or in a :keyword:`for` loop control target, :keyword:`class` -definition, function definition, or :keyword:`import` statement. +definition, function definition, :keyword:`import` statement, or variable +annotation. .. impl-detail:: - The current implementation does not enforce the two restrictions, but + The current implementation does not enforce some of these restriction, but programs should not abuse this freedom, as future implementations may enforce them or silently change the meaning of the program. diff -r f6a0b80ade26 -r 804b71d43c85 Lib/test/test_syntax.py --- a/Lib/test/test_syntax.py Fri Sep 09 09:29:42 2016 -0700 +++ b/Lib/test/test_syntax.py Fri Sep 09 09:36:26 2016 -0700 @@ -366,7 +366,23 @@ ... SyntaxError: too many statically nested blocks -Misuse of the nonlocal statement can lead to a few unique syntax errors. +Misuse of the nonlocal and global statement can lead to a few unique syntax errors. + + >>> def f(): + ... x = 1 + ... global x + Traceback (most recent call last): + ... + SyntaxError: name 'x' is assigned to before global declaration + + >>> def f(): + ... x = 1 + ... def g(): + ... print(x) + ... nonlocal x + Traceback (most recent call last): + ... + SyntaxError: name 'x' is used prior to nonlocal declaration >>> def f(x): ... nonlocal x diff -r f6a0b80ade26 -r 804b71d43c85 Misc/NEWS --- a/Misc/NEWS Fri Sep 09 09:29:42 2016 -0700 +++ b/Misc/NEWS Fri Sep 09 09:36:26 2016 -0700 @@ -10,6 +10,9 @@ Core and Builtins ----------------- +- Issue #27999: Make "global after use" a SyntaxError, and ditto for nonlocal. + Patch by Ivan Levkivskyi. + - Issue #28003: Implement PEP 525 -- Asynchronous Generators. - Issue #27985: Implement PEP 526 -- Syntax for Variable Annotations. diff -r f6a0b80ade26 -r 804b71d43c85 Python/symtable.c --- a/Python/symtable.c Fri Sep 09 09:29:42 2016 -0700 +++ b/Python/symtable.c Fri Sep 09 09:36:26 2016 -0700 @@ -6,16 +6,22 @@ /* error strings used for warnings */ #define GLOBAL_AFTER_ASSIGN \ -"name '%.400s' is assigned to before global declaration" +"name '%U' is assigned to before global declaration" #define NONLOCAL_AFTER_ASSIGN \ -"name '%.400s' is assigned to before nonlocal declaration" +"name '%U' is assigned to before nonlocal declaration" #define GLOBAL_AFTER_USE \ -"name '%.400s' is used prior to global declaration" +"name '%U' is used prior to global declaration" #define NONLOCAL_AFTER_USE \ -"name '%.400s' is used prior to nonlocal declaration" +"name '%U' is used prior to nonlocal declaration" + +#define GLOBAL_ANNOT \ +"annotated name '%U' can't be global" + +#define NONLOCAL_ANNOT \ +"annotated name '%U' can't be nonlocal" #define IMPORT_STAR_WARNING "import * only allowed at module level" @@ -161,7 +167,6 @@ }; static int symtable_analyze(struct symtable *st); -static int symtable_warn(struct symtable *st, const char *msg, int lineno); static int symtable_enter_block(struct symtable *st, identifier name, _Py_block_ty block, void *ast, int lineno, int col_offset); @@ -907,27 +912,6 @@ return r; } - -static int -symtable_warn(struct symtable *st, const char *msg, int lineno) -{ - PyObject *message = PyUnicode_FromString(msg); - if (message == NULL) - return 0; - if (PyErr_WarnExplicitObject(PyExc_SyntaxWarning, message, st->st_filename, - lineno, NULL, NULL) < 0) { - Py_DECREF(message); - if (PyErr_ExceptionMatches(PyExc_SyntaxWarning)) { - PyErr_SetString(PyExc_SyntaxError, msg); - PyErr_SyntaxLocationObject(st->st_filename, st->st_cur->ste_lineno, - st->st_cur->ste_col_offset); - } - return 0; - } - Py_DECREF(message); - return 1; -} - /* symtable_enter_block() gets a reference via ste_new. This reference is released when the block is exited, via the DECREF in symtable_exit_block(). @@ -1212,9 +1196,8 @@ if ((cur & (DEF_GLOBAL | DEF_NONLOCAL)) && s->v.AnnAssign.simple) { PyErr_Format(PyExc_SyntaxError, - "annotated name '%U' can't be %s", - e_name->v.Name.id, - cur & DEF_GLOBAL ? "global" : "nonlocal"); + cur & DEF_GLOBAL ? GLOBAL_ANNOT : NONLOCAL_ANNOT, + e_name->v.Name.id); PyErr_SyntaxLocationObject(st->st_filename, s->lineno, s->col_offset); @@ -1297,31 +1280,24 @@ long cur = symtable_lookup(st, name); if (cur < 0) VISIT_QUIT(st, 0); - if (cur & DEF_ANNOT) { + if (cur & (DEF_LOCAL | USE | DEF_ANNOT)) { + char* msg; + if (cur & DEF_ANNOT) { + msg = GLOBAL_ANNOT; + } + if (cur & DEF_LOCAL) { + msg = GLOBAL_AFTER_ASSIGN; + } + else { + msg = GLOBAL_AFTER_USE; + } PyErr_Format(PyExc_SyntaxError, - "annotated name '%U' can't be global", - name); + msg, name); PyErr_SyntaxLocationObject(st->st_filename, s->lineno, s->col_offset); VISIT_QUIT(st, 0); } - if (cur & (DEF_LOCAL | USE)) { - char buf[256]; - char *c_name = _PyUnicode_AsString(name); - if (!c_name) - return 0; - if (cur & DEF_LOCAL) - PyOS_snprintf(buf, sizeof(buf), - GLOBAL_AFTER_ASSIGN, - c_name); - else - PyOS_snprintf(buf, sizeof(buf), - GLOBAL_AFTER_USE, - c_name); - if (!symtable_warn(st, buf, s->lineno)) - VISIT_QUIT(st, 0); - } if (!symtable_add_def(st, name, DEF_GLOBAL)) VISIT_QUIT(st, 0); if (!symtable_record_directive(st, name, s)) @@ -1337,31 +1313,23 @@ long cur = symtable_lookup(st, name); if (cur < 0) VISIT_QUIT(st, 0); - if (cur & DEF_ANNOT) { - PyErr_Format(PyExc_SyntaxError, - "annotated name '%U' can't be nonlocal", - name); + if (cur & (DEF_LOCAL | USE | DEF_ANNOT)) { + char* msg; + if (cur & DEF_ANNOT) { + msg = NONLOCAL_ANNOT; + } + if (cur & DEF_LOCAL) { + msg = NONLOCAL_AFTER_ASSIGN; + } + else { + msg = NONLOCAL_AFTER_USE; + } + PyErr_Format(PyExc_SyntaxError, msg, name); PyErr_SyntaxLocationObject(st->st_filename, s->lineno, s->col_offset); VISIT_QUIT(st, 0); } - if (cur & (DEF_LOCAL | USE)) { - char buf[256]; - char *c_name = _PyUnicode_AsString(name); - if (!c_name) - return 0; - if (cur & DEF_LOCAL) - PyOS_snprintf(buf, sizeof(buf), - NONLOCAL_AFTER_ASSIGN, - c_name); - else - PyOS_snprintf(buf, sizeof(buf), - NONLOCAL_AFTER_USE, - c_name); - if (!symtable_warn(st, buf, s->lineno)) - VISIT_QUIT(st, 0); - } if (!symtable_add_def(st, name, DEF_NONLOCAL)) VISIT_QUIT(st, 0); if (!symtable_record_directive(st, name, s))