The compile ignores constant statements and emit a SyntaxWarning warning.

Don't emit the warning for string statement because triple quoted string is a
common syntax for multiline comments.

Don't emit the warning on ellipis neither: 'def f(): ...' is a legit syntax for
abstract functions.

Changes:

* test_ast: ignore SyntaxWarning when compiling test statements. Modify
  test_load_const() to use assignment expressions rather than constant
  expression.
* test_code: add more kinds of constant statements, ignore SyntaxWarning when
  testing that the compiler removes constant statements.
* test_grammar: ignore SyntaxWarning on the statement "1"

* Constant statements will be ignored and the compiler will emit a
  SyntaxWarning.
* Replace constant statement (ex: "1") with an expression statement
  (ex: "x=1").
* test_traceback: use context manager on the file.

Issue #26204.

* Use ast.parse() to get the AST for a statement
* Use str%args syntax for format a line

Issue #26204.

when the iteration is finished, but when it was failed with error.

when the iteration is finished, but when it was failed with error.

needed.

Based on patch by Guido van Rossum.

overflow in parsing "es#" and "et#" format units.  SystemError is now raised
instead of TypeError on programmical error in parsing format string.

Fixed the documented about buffer overflow error for "es#" and "et#" format
units.

* Various sections were pointing to the section on the string.Formatter
  class, when the section on the common format string syntax is probably more
  appropriate
* Fix references to various format() functions and methods
* Nested replacement fields may contain conversions and format specifiers,
  and this is tested; see Issue #19729 for instance

Patch by Thomas Kluyver.

Fix issue 26287: While handling FORMAT_VALUE opcode, the top of stack was being corrupted if an error occurred in PyObject_Format().

Based on patches by Brian Brazil and Daniel Rocco.

Reported by Denis Akhiyarov on docs@

Reported by Jon Tetlak on docs@

Fixed a crash when unpickle the functools.partial object with wrong state.
Fixed a leak in failed functools.partial constructor.
"args" and "keywords" attributes of functools.partial have now always types
tuple and dict correspondingly.

Based on patch by Aviv Palivoda.