"print" not emitting POP_TOP

[hathawsh]

BPO	431422
Nosy	@freddrake, @hathawsh
Files	patch

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = <Date 2001-07-04.05:41:28.000>
created_at = <Date 2001-06-08.15:54:35.000>
labels = ['interpreter-core']
title = '&quot;print&quot; not emitting POP_TOP'
updated_at = <Date 2001-07-04.05:41:28.000>
user = 'https://github.com/hathawsh'

bugs.python.org fields:

activity = <Date 2001-07-04.05:41:28.000>
actor = 'fdrake'
assignee = 'jhylton'
closed = True
closed_date = None
closer = None
components = ['Interpreter Core']
creation = <Date 2001-06-08.15:54:35.000>
creator = 'hathawsh'
dependencies = []
files = ['3360']
hgrepos = []
issue_num = 431422
keywords = ['patch']
message_count = 3.0
messages = ['36761', '36762', '36763']
nosy_count = 3.0
nosy_names = ['jhylton', 'fdrake', 'hathawsh']
pr_nums = []
priority = 'normal'
resolution = 'accepted'
stage = None
status = 'closed'
superseder = None
type = None
url = 'https://bugs.python.org/issue431422'
versions = []

[hathawsh]

The Python-based compiler module (in Tools) has a bug
in the visitPrint() method of
pycodegen.CodeGenerator. It does not emit a trailing
POP_TOP instruction, which AFAICT it should emit only
when outputting to a stream and there is a trailing
comma (indicating no newline). I've attached the
patch applied to Zope's RestrictedPython module; if
there is anything incorrect about it please tell me
right away. Otherwise please apply the patch to
Tools/compiler/pycodgen.py.

[hathawsh]

Logged In: YES
user_id=16701

Oops, it turns out the patch is incorrect! POP_TOP should
only be added to the *last* print node. Here are the
revised visitPrint() and visitPrintnl() methods. This is
what is being used in Zope now.

    def visitPrint(self, node, newline=0):
        self.set_lineno(node)
        if node.dest:
            self.visit(node.dest)
        for child in node.nodes:
            if node.dest:
                self.emit('DUP_TOP')
            self.visit(child)
            if node.dest:
                self.emit('ROT_TWO')
                self.emit('PRINT_ITEM_TO')
            else:
                self.emit('PRINT_ITEM')
        if node.dest and not newline:
            self.emit('POP_TOP')

    def visitPrintnl(self, node):
        self.visitPrint(node, 1)
        if node.dest:
            self.emit('PRINT_NEWLINE_TO')
        else:
            self.emit('PRINT_NEWLINE')

[freddrake]

Logged In: YES
user_id=3066

Assigned to Jeremy since the compiler package is his.