packaging: integrate signing into run_wix_packaging() Previously, signing was implemented via a separate function which called build_installer() and then called signing functionality. In this model, in order to implement an alternative build mechanism, we would have to invent a new variant to handle signing as well. This commit merges the signing logic into the function invoking wix. If we pass an argument holding metadata about how to sign, we sign hg.exe and the installer. This means all we have to do is pass in signing info and the signing just works. A slight change here is that signing of hg.exe happens in the staging directory as opposed to before the staging directory is populated. I don't think this matters. Differential Revision: https://phab.mercurial-scm.org/D8475

packaging: isolate invocation of WiX to own function Like we did for Inno, we want to split out the building of Mercurial from invoking the packaging tool so that we can introduce an alternate build mechanism. As part of this refactor, there are inconsequential changes to file layouts. Before, some shared files such as the WiX binaries and merge modules would be installed under build/. Now, they are installed under build/wix-*. This is to keep implementation simpler. But it also helps keep build state more isolated. Differential Revision: https://phab.mercurial-scm.org/D8474

packaging: support building Inno installer with PyOxidizer We want to start distributing Mercurial on Python 3 on Windows. PyOxidizer will be our vehicle for achieving that. This commit implements basic support for producing Inno installers using PyOxidizer. While it is an eventual goal of PyOxidizer to produce installers, those features aren't yet implemented. So our strategy for producing Mercurial installers is similar to what we've been doing with py2exe: invoke a build system to produce files then stage those files into a directory so they can be turned into an installer. We had to make significant alterations to the pyoxidizer.bzl config file to get it to produce the files that we desire for a Windows install. This meant differentiating the build targets so we can target Windows specifically. We've added a new module to hgpackaging to deal with interacting with PyOxidizer. It is similar to pyexe: we invoke a build process then copy files to a staging directory. Ideally these extra files would be defined in pyoxidizer.bzl. But I don't think it is worth doing at this time, as PyOxidizer's config files are lacking some features to make this turnkey. The rest of the change is introducing a variant of the Inno installer code that invokes PyOxidizer instead of py2exe. Comparing the Python 2.7 based Inno installers with this one, the following changes were observed: * No lib/*.{pyd, dll} files * No Microsoft.VC90.CRT.manifest * No msvc{m,p,r}90.dll files * python27.dll replaced with python37.dll * Add vcruntime140.dll file The disappearance of the .pyd and .dll files is acceptable, as PyOxidizer has embedded these in hg.exe and loads them from memory. The disappearance of the *90* files is acceptable because those provide the Visual C++ 9 runtime, as required by Python 2.7. Similarly, the appearance of vcruntime140.dll is a requirement of Python 3.7. Differential Revision: https://phab.mercurial-scm.org/D8473

packaging: split Inno installer building from Mercurial building We want to make the logic for producing the installer agnostic about how Mercurial is built to allow for alternate build methods (like PyOxidizer). Differential Revision: https://phab.mercurial-scm.org/D8472

packaging: remove pyoxidizer.bzl from packaging directory We have another version in rust/hgcli that is more modern and is already associated with our Rust CLI project. Differential Revision: https://phab.mercurial-scm.org/D8471

contrib: install PyOxidizer in Linux and Windows environments For Linux, this was trivial. For Windows, we need to teach the powershell script to install Rust as well. This was also pretty straightforward. Differential Revision: https://phab.mercurial-scm.org/D8468

diff: re-establish linear runtime performance The previous method with sum() and list() creates a new list object for every hunk. Then sum() is used to flatten out this sequence of lists. The sum() function is not "lazy", but creates a new list object for every "+" operation and so this code had quadratic runtime behaviour.