comparison mercurial/__init__.py @ 43085:eef9a2d67051

py3: manually import pycompat.open into files that need it

We want to eliminate the source transformer. Currently it inserts
a `from mercurial.pycompat import ...` at the top of files to alias
some builtins.

This commit replaces the implicit import of `open` with an explicit
import on files that need it and changes the source transformer to
no longer import `open`.

As part of this, we needed to store an explicit local for `open` in
the Python 2 code path in `pycompat` so the import works. (Builtins
that are automatically in scope cannot be imported.)

Differential Revision: https://phab.mercurial-scm.org/D7005

43084:c2e284cee333

                    continue
                r, c = t.start
                l = (
                    b'; from mercurial.pycompat import '
                    b'delattr, getattr, hasattr, setattr, '
                    b'open, unicode\n'
                )
                for u in tokenize.tokenize(io.BytesIO(l).readline):
                    if u.type in (tokenize.ENCODING, token.ENDMARKER):
                        continue
                    yield u._replace(

    # Header to add to bytecode files. This MUST be changed when
    # ``replacetoken`` or any mechanism that changes semantics of module
    # loading is changed. Otherwise cached bytecode may get loaded without
    # the new transformation mechanisms applied.
    BYTECODEHEADER = b'HG\x00\x0c'

    class hgloader(importlib.machinery.SourceFileLoader):
        """Custom module loader that transforms source code.

        When the source code is converted to a code object, we transform

43085:eef9a2d67051

                    continue
                r, c = t.start
                l = (
                    b'; from mercurial.pycompat import '
                    b'delattr, getattr, hasattr, setattr, '
                    b'unicode\n'
                )
                for u in tokenize.tokenize(io.BytesIO(l).readline):
                    if u.type in (tokenize.ENCODING, token.ENDMARKER):
                        continue
                    yield u._replace(

    # Header to add to bytecode files. This MUST be changed when
    # ``replacetoken`` or any mechanism that changes semantics of module
    # loading is changed. Otherwise cached bytecode may get loaded without
    # the new transformation mechanisms applied.
    BYTECODEHEADER = b'HG\x00\x0d'

    class hgloader(importlib.machinery.SourceFileLoader):
        """Custom module loader that transforms source code.

        When the source code is converted to a code object, we transform