SCons : Need an explanation why Install not being call with scons -u

问题

There is something that I don`t understand. See following SConscript :

Import('common_env')
import os
#Grab a copy of the top environment (the one sent by the SConstruct file)
common_env = common_env.Clone()
#Because this component is compiled in both win32 and win64.
if (common_env['ENV']['CONFIG'] == "win32") or (common_env['ENV']['CONFIG'] == "win64"):
    #Grabs the library name, the name should look like libpath_of_current_component-(debug/opt)
    libName = common_env.libName()
    common_env.USE_BOOST()

    #Grab all the sources in current dir.
    sources = Glob('*.cpp')
    #Creates the library
    myLib = common_env.Library(libName, sources)
    #Install (copy) the library in LINK/lib/winX
    common_env.Install('#/LINK/lib/' + common_env['ENV']['CONFIG'], myLib)

If this script is invoke from his sub-folder, I have the following output :

scons: Entering directory `C:\svn\products\faa_mx\scons-test-speed3'
scons: Reading SConscript files ...
scons: done reading SConscript files.
scons: Building targets ...
scons: building associated VariantDir targets: build\debug\sr\speech\ASRNetworkLayer\ThinProtocol\win64
cl /Fobuild\debug\sr\speech\ASRNetworkLayer\ThinProtocol\win64\ThinProtocol.obj /c sr\speech\ASRNetworkLayer\ThinProtocol\ThinProtocol.cpp /TP /nologo -Od -D_DEBUG -RTC1 -MDd -Z7 -DBOOST_FILESYSTEM_VERSION=2 -DWIN32 -D_WIN32 -DWINDOWS -D_MBCS -DNOMINMAX -D_MSC_VER=1600 -D_WIN32_WINNT=0x0501 -D_CRT_SECURE_NO_WARNINGS -W3 -nologo -GS -GR -EHa -wd4290 -wd4996 -wd4995 -TP -DBOOST_FILESYSTEM_VERSION=2 /Iinterface\asom\api /Ifwk\simulation_fwk\utils /ILINK\include /Ibuild\debug\sr\speech\ASRNetworkLayer\ThinProtocol\win64 /Isr\speech\ASRNetworkLayer\ThinProtocol /IC:\svn\3rdParty\3rdPartyPackages\boost-1.47.0_vs2010_x64\include /Z7
ThinProtocol.cpp
cl /Fobuild\debug\sr\speech\ASRNetworkLayer\ThinProtocol\win64\ThinProtocolMessageDefinitions.obj /c sr\speech\ASRNetworkLayer\ThinProtocol\ThinProtocolMessageDefinitions.cpp /TP /nologo -Od -D_DEBUG -RTC1 -MDd -Z7 -DBOOST_FILESYSTEM_VERSION=2 -DWIN32 -D_WIN32 -DWINDOWS -D_MBCS -DNOMINMAX -D_MSC_VER=1600 -D_WIN32_WINNT=0x0501 -D_CRT_SECURE_NO_WARNINGS -W3 -nologo -GS -GR -EHa -wd4290 -wd4996 -wd4995 -TP -DBOOST_FILESYSTEM_VERSION=2 /Iinterface\asom\api /Ifwk\simulation_fwk\utils /ILINK\include /Ibuild\debug\sr\speech\ASRNetworkLayer\ThinProtocol\win64 /Isr\speech\ASRNetworkLayer\ThinProtocol /IC:\svn\3rdParty\3rdPartyPackages\boost-1.47.0_vs2010_x64\include /Z7
ThinProtocolMessageDefinitions.cpp
cl /Fobuild\debug\sr\speech\ASRNetworkLayer\ThinProtocol\win64\ThinProtocolMessaging.obj /c sr\speech\ASRNetworkLayer\ThinProtocol\ThinProtocolMessaging.cpp /TP /nologo -Od -D_DEBUG -RTC1 -MDd -Z7 -DBOOST_FILESYSTEM_VERSION=2 -DWIN32 -D_WIN32 -DWINDOWS -D_MBCS -DNOMINMAX -D_MSC_VER=1600 -D_WIN32_WINNT=0x0501 -D_CRT_SECURE_NO_WARNINGS -W3 -nologo -GS -GR -EHa -wd4290 -wd4996 -wd4995 -TP -DBOOST_FILESYSTEM_VERSION=2 /Iinterface\asom\api /Ifwk\simulation_fwk\utils /ILINK\include /Ibuild\debug\sr\speech\ASRNetworkLayer\ThinProtocol\win64 /Isr\speech\ASRNetworkLayer\ThinProtocol /IC:\svn\3rdParty\3rdPartyPackages\boost-1.47.0_vs2010_x64\include /Z7
ThinProtocolMessaging.cpp
lib /nologo /OUT:build\debug\sr\speech\ASRNetworkLayer\ThinProtocol\win64\win64\libsr_speech_ASRNetworkLayer_ThinProtocol-debug.lib build\debug\sr\speech\ASRNetworkLayer\ThinProtocol\win64\ThinProtocol.obj build\debug\sr\speech\ASRNetworkLayer\ThinProtocol\win64\ThinProtocolMessageDefinitions.obj build\debug\sr\speech\ASRNetworkLayer\ThinProtocol\win64\ThinProtocolMessaging.obj
scons: `sr\speech\ASRNetworkLayer\ThinProtocol' is up to date.
scons: done building targets.

As you can see, Install is not being call by scons at all.

If instead of calling scons -u from a sub-folder I call scons from the root, then, I have this :

Install file: "build\debug\sr\speech\ASRNetworkLayer\ThinProtocol\win64\libsr_speech_ASRNetworkLayer_ThinProtocol-debug.lib" as "LINK\lib\win64\libsr_speech_ASRNetworkLayer_ThinProtocol-debug.lib"

My question is : Why this difference? Is it because scons build system, in case of scons -u, knows that nobody needs the .lib, so Install not being called?

Thx!

回答1:

The default set of files to be built is from the current working directory down.

You can see info on this in the manpage: http://scons.org/doc/production/HTML/scons-man.html

A subset of a hierarchical tree may be built by remaining at the top-level directory (where the SConstruct file lives) and specifying the subdirectory as the target to be built:

scons src/subdir

or by changing directory and invoking scons with the -u option, which traverses up the directory hierarchy until it finds the SConstruct file, and then builds targets relatively to the current subdirectory:

cd src/subdir
scons -u .

See also this section:

-u, --up, --search-up

Walks up the directory structure until an SConstruct , Sconstruct or sconstruct file is found, and uses that as the top of the directory tree. If no targets are specified on the command line, only targets at or below the current directory will be built.

-U

Works exactly the same way as the -u option except for the way default targets are handled. When this option is used and no targets are specified on the command line, all default targets that are defined in the SConscript(s) in the current directory are built, regardless of what directory the resultant targets end up in.

So you can either make that install a Default() target, or specify it as a dependency of some other target in the current working directory.

来源：https://stackoverflow.com/questions/39937541/scons-need-an-explanation-why-install-not-being-call-with-scons-u