Response files

[PetrWolf]

This pull request adds support for response files to ninja.

Response files are common practice on Windows, where the maximal length of a command line is limited. In a nutshell, this change allows ninja to create response files using two new syntax elements (rspfile and rspfile_content) in rules definition.

For details see:

• the current discussion: http://groups.google.com/group/ninja-build/browse_thread/thread/6b394fae9b74763c:
• the original design discussion: Too-long command lines should be handled #53 (comment)
• previous proposal: https://gist.github.com/1605288

[evmar]

This looks great. The only piece I don't understand is the "incl_rsp_file" parameter to EvaluateCommand(). What is it needed for? It appears to be part of the build log key, is it just for that?

[syntheticpp]

What about renaming 'rspfile_content'? It looks a bit ugly besides the other rule variables.
Maybe 'rspin'?

[PetrWolf]

Thanks for comments!

RE incl_rsp_file: Yes, it's only used to get the whole command line including the contents of the rsp file, so that it can be stored (and compared) in the log. Maybe a specific method (EvaluateFullCommand) or a different name of the attribute would make more sense. What do you think?

RE typos, whitespaces: Will do.

RE rspfile_content/rspin: It's more of a "content" (the file can contain anything) then "in" (a list of direct dependencies) really. So rspfile_content makes sense to me, but I don't mind changing it to something nicer. Any suggestions?

[syntheticpp]

Maybe "rspcontent"?

Another point: Is it by design that no temporary filenames are used, or is it a missing feature?

[PetrWolf]

The names of the rsp files are fixed (not temporary) by design - it is easy for the generator of a .ninja file to make up such name (e.g. name of the output + ".rsp"). This makes investigations of failures as well as internal handling of build log entries easier.

[PetrWolf]

Added some updates based on comments above.

Please let me now if further changes are required.

[syntheticpp]

OK, a known name is better than a generated one by the system.

[syntheticpp]

But what I don't like is that always a response file is used, even when the content is very small.
Couldn't be checked if the content exceeds a limit, and only then a file is created?
The generator couldn't know the exact length of the content.

[PetrWolf]

I believe this choice does belong to the generator - to be done once (even if it may not be 100% precise) and recorded in the .ninja files.

Note that it's not only a question of (not) creating the response file. We're talking about two essentially different commands here:

• one without the @rspfile option and with all other options in it
• the other one with some @rspfile options and with some options in a file.

[syntheticpp]

Yes, that' the problem, you need two rules for the same command just to support response files.

[philipcraig]

This "problem" is a reflection of the true state of the world. They correctly are two different commands and rules.

[syntheticpp]

I had a look at the CMake code, and indeed, they check for response files.

So, I would rename rspfile_content into rspcontent or something similar and merge the patch.

[evmar]

I'm gonna merge this as-is and we can discuss it further from there.