[Scons-users] scons checking targets actually built?

[Gary Oberbrunner]

Hi Robert; some people make fake targets in SCons (like Make) so if SCons
complained about those people's builds would probably break.  I think it's
expected behavior at least in that case.
On Apr 18, 2013 7:13 PM, "robert zeigler" <robert.zeigler at gmail.com> wrote:


> Hi,

>

> Fairly new to scons. I have been playing with it the last few days and

> like what I see. However, I stumbled on behavior today that has me troubled.

>

> Consider a very simple build script:

>

> Command(['a.txt'],[],"echo hi > $TARGET")

> Command(['b.txt'],['a.txt'],"cat $SOURCE > $TARGET && echo foo >> $TARGET")

>

> This runs fine:

>

> scons: Reading SConscript files ...

> scons: done reading SConscript files.

> scons: Building targets ...

> echo hi > a.txt

> cat a.txt > b.txt && echo foo >> b.txt

> scons: done building targets.

>

> Now consider an alternative command for building a:

>

> Command(['a.txt'],[],"echo hi > $TARGET && rm $TARGET")

>

> Then you get:

>

> scons: Reading SConscript files ...

> scons: done reading SConscript files.

> scons: Building targets ...

> echo hi > a.txt && rm a.txt

> cat a.txt > b.txt && echo humbug >> b.txt

> cat: a.txt: No such file or directory

> scons: *** [b.txt] Error 1

> scons: building terminated because of errors.

>

> The build fails, of course, but what troubles me is that it doesn't fail

> until we attempt to build b.txt. I would have expected scons to verify that

> the target was actually build by the command; failing that, I'm surprised

> that it attempted to build b.txt when a.txt was clearly not present for

> b.txt to be built?

>

> Clarification on this is greatly appreciated. Although the case above is

> trivial, I ran into this issue in a non-trivial case, as well.

>

> Robert

>

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