Re: can't always get make to auto create build directory

[LMH]

Paul Smith wrote:
> On Wed, 2016-06-29 at 12:41 -0400, LMH wrote:
> > Apparently the forum I posted to forwards posts to a mailing list.
>
> The GNU/FSF mailing lists have existed since the 1990's.  In that time
> various external sites have come along and begun mirroring the mailing
> lists, and some of them also provide the ability to post back to the
> list.  We aren't involved with this.  If you have an issue with how
> they do it, you should bring it up with them.

I don't generally have an issue with anyone who is trying to be helpful, though the 
nabble methodology seems to leave a bit to be desired in this case. It's just as easy 
to post directly to the mailing list if that is preferable.

> The mot reliable way to ask questions is to send directly to the
> mailing lists, using text-mode rather than HTML.

I also never read email in HTML as it can be a considerable security risk. It is nice 
to have code tags to preserve indents and such but in the case of a make file, that 
should not be an issue. I just didn't realize that I was composing email.

Below is the text of my original post as I expected it would appear. Please let me 
know if there are any questions or if I need to post any additional information.

Note:
I have added the line for my "all" target as it was left out of my earlier post.

LMH



Hello,

I have a make file that gathers some local information and uses it (in theory) to 
create a locally named build directory if it doesn't exist.

SOURCELOC = ./src

# get version of g++
CMP := $(shell g++ --version | cut -d ' ' -f 3 | sed q)
CMP := gcc-$(CMP)

# create build location name
OS   := $(shell uname -s)
ARCH := $(shell uname -m)
KERN := $(shell uname -r | cut -d. -f 1,2)
BDIR := bld_$(OS)_$(KERN).$(ARCH)_$(CMP)

#test print
$(info OS is  : $(OS))
$(info BDIR is: $(BDIR))

# create build directory if it doesn't exist
$(BDIR):
        @mkdir -p $(BDIR)

all: $(BDIR)/SMD2_i386.exe


The test print code prints what I would expect,

OS is  : CYGWIN_NT-5.1
BDIR is: bld_CYGWIN_NT-5.1_2.3.i686_gcc-4.9.3


When I run this from "make -f makefile all" I get an error,

Assembler messages:
Fatal error: can't create bld_CYGWIN_NT-5.1_2.3.i686_gcc-4.9.3/main.o: No such file 
or directory
MAKE_SMD1.mak:73: recipe for target 
'bld_CYGWIN_NT-5.1_2.3.i686_gcc-4.9.3/main.o' failed
make: *** [bld_CYGWIN_NT-5.1_2.3.i686_gcc-4.9.3/main.o] Error 1


If I manually create the build directory, bld_CYGWIN_NT-5.1_2.3.i686_gcc-4.9.3, the 
compiler continues and creates the first object, main.o. I have had this issue off 
and on and can't seem to identify where the problem is. In some cases, the directory 
doesn't get created and in others it does. I use the same syntax for mkdir in every 
make file, so I'm not sure where I am going wrong. It's not the end of the world to 
have to manually create a directory but I am trying to set up some of this to be 
automated based on whatever system I am booted into. The "@ mkdir" statement is 
indented with a tab if that isn't clear with this formatting.

For now, I have replaced the make command,

# create build directory if it doesn't exist
$(BDIR):
        @mkdir -p $(BDIR)


with some shell commands,

# run ls to determine if build directory exists
EXISTS := $(shell ls -d $(BDIR))
# if the output of ls is empty, create directory
ifeq "$(EXISTS)" ""
   $(shell mkdir $(BDIR))
endif


This seems to work. The code creates the directory when it is not present and does 
nothing when it is. There are no error messages to deal with.

I would prefer to get this working with make commands instead of going to the shell 
but I do need to get this working with some solution. Can anyone point out why my 
make commands fail to create the directory when it doesn't exist? Is the shell method 
above a reasonable solution, meaning will it likely work on most platforms?

Suggestions would be appreciated.