Add command line option similar to GNU make --question

[sgraham]

(I feel like we had this discussion before, but I can't find it now)

http://www.gnu.org/software/make/manual/make.html#Running

-q seems like the wrong name, as it could be "quiet" as well. But to confirm no-op builds in Chromium, that project would like to have ninja emit a status code when the build is dirty.

[sgraham]

See also https://code.google.com/p/chromium/issues/detail?id=451499

[dpranke]

+1. I also think this would be a nice switch to have.

[dpranke]

You could also add a '-t up-to-date' or something to avoid having to add a new top-level argument.

[sgraham]

(I actually think log parsing is just fine, but opened this per bikeshedding over there.)

[nico]

I too think log parsing is fine, the "no work to do" change isn't ever going to change anyway.

But this seems like a reasonable feature request anyhow.

[riannucci]

Bikeshedder jumping in to defend himself: a well-intentioned addition of internationalization to ninja would break your assumptions 😛

[riannucci]

Alternately: as long as you promise that I won't be on the hook for maintaining the log parsing ever, then I'm fine with it ^_^

[sgraham]

It's true. (We also have to emit "ninja: Entering directory `out\Release'" to match something in Emacs. English or bust!)

[evmar]

I feel bad about the Emacs thing but it's soooo convenient.

BTW this is what Emacs has to say about the default value of the pattern:

compilation-directory-matcher's value is ("\\(?:Entering\\|Leavin\\(g\\)\\) directory `\\(.+\\)'$"
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