Old build problem: unpack200 failure when setting OTHER_CXXFLAGS in environment

[Kelly O'Hair]

Just seems like a very poorly written Makefile to me.

Where is the actual webrev or patch, I could not see it.

-kto

On Mar 11, 2012, at 9:48 PM, David Holmes wrote:

> This is a blast from the past:
> 
> http://mail.openjdk.java.net/pipermail/build-dev/2007-May/000026.html
> 
> but the above issue and patch seem to have been ignored. I just ran into this myself.
> 
> /export/users/dh198349/jdk8/builds/b01/se8-linux-i586-ea/tmp/sun/com.sun.java.util.jar.pack/unpack-cmd/obj/main.o: In function `unpacker::run(int, char**)':
> main.cpp:(.text+0xe0b): undefined reference to `gunzip::init(unpacker*)'
> main.cpp:(.text+0xe1d): undefined reference to `gunzip::start(int)'
> collect2: ld returned 1 exit status
> make[7]: *** [/export/users/dh198349/jdk8/builds/b01/se8-linux-i586-ea/bin/unpack200] Error 1
> 
> The basic issue is one of recursive makes, with conditionally set variables that might also be set externally in the environment. Here's an example Makefile:
> 
> build: unpack
> 
> ifdef STANDALONE
>  FLAGS+=-XstandAlone
> else
>  FLAGS+=-Xcombined
> endif
> 
> unpack:
>        @make STANDALONE=true unpack_exe
> 
> build:
>        @echo build FLAGS = $(FLAGS)
> unpack_exe:
>        @echo unpack_exe FLAGS = $(FLAGS)
> 
> .phony: build unpack unpack_exe
> 
> ---
> 
> Here's a normal run:
> 
> > make build
> make[1]: Entering directory `/scratch/dh198349'
> unpack_exe FLAGS = -XstandAlone
> make[1]: Leaving directory `/scratch/dh198349'
> build FLAGS = -Xcombined
> 
> which is what we would expect. But if you now give FLAGS an initial external value:
> 
> > FLAGS=external make build
> make[1]: Entering directory `/scratch/dh198349'
> unpack_exe FLAGS = external -Xcombined -XstandAlone
> make[1]: Leaving directory `/scratch/dh198349'
> build FLAGS = external -Xcombined
> 
> Yikes! Now unpack_exe sees both the STANDALONE and non-STANDALONE value of FLAGS. This is because make re-exports any variable that came in from the environment. So when the top-level make is called, FLAGS==external, and to that the Makefile adds -Xcombined, so the sub-make effectively becomes:
> 
> make FLAGS="external -Xcombined" STANDALONE=true unpack_exe
> 
> Here's one way to fix this:
> 
> # save original incoming FLGS
> ORIG_FLAGS := $(FLAGS)
> # hide any locally modified value of FLAGS
> unexport FLAGS
> 
> build: unpack
> 
> ifdef STANDALONE
>  # override to allow sub-make to add to FLAGS
>  override FLAGS+=-XstandAlone
> else
>  FLAGS+=-Xcombined
> endif
> 
> unpack:
>        # Send in ORIG_FLAGS as FLAGS
>        @make FLAGS=$(ORIG_FLAGS) STANDALONE=true unpack_exe
> 
> build:
>        @echo build FLAGS = $(FLAGS)
> unpack_exe:
>        @echo unpack_exe FLAGS = $(FLAGS)
> 
> .phony: build unpack unpack_exe
> 
> ----
> 
> Or as per the original Patch, use a different variable in the Makefile to that set in the environment.
> 
> David
> -----