[Python-Dev] Bug in build system for cross-platform builds (original) (raw)

Martin Panter vadmium+py at gmail.com
Mon Mar 14 20:49:36 EDT 2016

On 14 March 2016 at 13:26, R. David Murray <rdmurray at bitdance.com> wrote:

On Mon, 14 Mar 2016 03:04:08 -0000, "Gregory P. Smith" <greg at krypto.org> wrote:

On Sun, Mar 13, 2016 at 7:41 PM Martin Panter <vadmium+py at gmail.com> wrote: > Include/graminit.h > Python/graminit.c > Python/importlib.h > Python/importlibexternal.h > > A question for other Python developers: Why are these generated files > stored in the repository? [. . .]

They should not be regenerated every build, if they are, that seems like a bug in the makefile to me (or else the timestamp checks that make does vs how your code checkout happened).

The reason the current Python 3 build regenerates some files, is because of the makefile prerequisites. For example, Include/graminit.h currently depends on Parser/pgen, which needs to be compiled for the native build host.

Having them checked in is convenient for cross builds as it is one less thing that needs a build-host-arch build. [. . .] And yes, checking in these platform-independent artifacts is very intentional: less to build, fewer external dependencies in the build process...you don't need to have python to build python, which you would have to if they were not checked in.

Okay so it sounds like the generated files (more listed in .hgtouch) have to stay. Reasons given:

One more idea I am considering is to decouple the makefile rules from the main build. So to update the generated files you would have to run a separate command like “make graminit” or “make frozen”. The normal build would never regenerate them; although perhaps it could still result in an error or warning if they appear out of date.

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