RFR: JDK-8195689 Remove generated-configure.sh and instead use autoconf

[David Holmes]

On 18/01/2018 11:28 PM, Magnus Ihse Bursie wrote:
> Currently, we require all developers who modify the configure script to 
> run autoconf locally, to update the generated-configure.sh script, which 
> is then checked in. This is the only instance of checked in "compiled" 
> code in OpenJDK, and this has brought along several problems:
> 
> * Only a specific version of autoconf, 2.69, can be used, to avoid large 
> code changes in the generated file. Unfortunately, Ubuntu ships a 
> version of autoconf that claims to be 2.69 but is actually heavily 
> patched. This requires all Ubuntu users to compiler their own autoconf 
> from source.
> 
> * The Oracle JDK closed sources has a closed version that needs to be 
> updated. In practice, this has meant that all non-Oracle developers, 
> need an Oracle sponsor for patches modifying the configure script.
> 
> * If the configure script is not properly updated, the build will fail. 
> The same happens on the Oracle side if the closed version is not in sync 
> with the open version. It is easy to miss re-generating the script after 
> the last fix of a typo in the comments in an .m4 file...
> 
> * Merging between two changes containing configure modifications is 
> almost impossible. In practice, the entire generated-configure.sh needs 
> to be thrown away and regenerated.
> 
> The entire benefit of having the file in the repo is to save first-time 
> developers the hassle of installing autoconf. On most platforms, this is 
> a no-brainer (like "apt install autoconf"), and the requirement is 
> similar to other open source projects using autoconf and "./configure". 
> It's just not worth it.

I'm not convinced just by you saying it is so - sorry. This seems to 
make an already complex build process even more complex for every single 
person who wants to build OpenJDK, for the benefit of a handful of 
people who may want to modify configure options and whom already work 
closely with the build team and so there's really little hardship in 
getting a sponsor, or just someone with access to autoconf.

It introduces a new point of failure in the build for everyone.

Has this been beta-tested with external contributors? I'd be happier 
knowing we've put this through its paces with people developing on a 
wide range of platforms, before making it the default.

Have the devkits been updated so I can try this out myself?

Thanks,
David

> Bug: https://bugs.openjdk.java.net/browse/JDK-8195689
> WebRev: 
> http://cr.openjdk.java.net/~ihse/JDK-8195689-remove-generated-configure/webrev.01 

> 
> /Magnus