[bug #59762] make --touch produce local spurious empty files with out-of-tree Makefile strategy

[anonymous]

URL:
  <https://savannah.gnu.org/bugs/?59762>

                 Summary: make --touch produce local spurious empty files with
out-of-tree Makefile strategy
                 Project: make
            Submitted by: None
            Submitted on: Thu 24 Dec 2020 03:43:44 PM UTC
                Severity: 3 - Normal
              Item Group: Bug
                  Status: None
                 Privacy: Public
             Assigned to: None
             Open/Closed: Open
         Discussion Lock: Any
       Component Version: 4.1
        Operating System: POSIX-Based
           Fixed Release: None
           Triage Status: None

    _______________________________________________________

Details:

We implemented the out-of-tree compilation strategy
(http://make.mad-scientist.net/papers/multi-architecture-builds/#target.mk)
described by Paul D. Smith on his blog (http://mad-scientist.net/).
We are very thankful for this method as it helped simplify a lot our
multi-architecture compilation process.

However, when using `make --touch` it also `touch` files in the root
directory, files named after all targets that needed to be touched (it also
touch the proper targets in their own build directories).

I observed this issue with `make` 4.1  on Ubuntu 18.04.2 LST and 4.2.1 on
Debian 10 and SUSE Linux Enterprise Server 15.

I made a simplified reproduction usecase which is available on gitlab and can
be obtained with

git clone https://gitlab.com/martn/makeTouchIssue.git

I also attach the simplified `Makefile` and `target.mk` for easier reference
(the actual sources are just dummy files).

Here is the scenario:
make
pgm.o: file1.o file2.o
file2.o: file1.o

The compilation follows the out-of-tree strategy above mentioned; it compiles
in `./build`.

0 I make a full build of a project

$ ls src/
file1.f90  file2.f90  pgm.f90
$ make 
compiling file1.o
compiling file2.o
compiling pgm.o
linking pgm.x
:
$ ls build/
file1.o  file2.o  pgm.o  pgm.x


0 I touch `src/file1.f90` (simulating a modification to the code that would
not change any interface)

0 `make` would then want to rebuild everything
But in fact I would just need to recompile `file1.o` and relink `pgm.x`.

0 So I recompile `file1.o` and use `make --touch` to prevent recompiling the
other objects

$ make file1.o
compiling file1.o
:
$ make --touch file2.o pgm.o
touch file2.o
touch pgm.o
touch file2.o
touch pgm.o

Here is the issue; it did touch the object files in `./build` but also touched
two (empty) files in `./`:

$ ls 
build  file2.o  Makefile  pgm.o  README.md  src  target.mk


Although I am not sure, I think it is related to the `target.mk` mechanics; so
it might not be a bug, but simply an unwanted side effect.

After concerting with my colleagues we thought pertinent to mention it.
Obviously for real project, these spurious files can seriously clutter the
root directory.



    _______________________________________________________

File Attachments:


-------------------------------------------------------
Date: Thu 24 Dec 2020 03:43:44 PM UTC  Name: Makefile  Size: 835B   By: None

<http://savannah.gnu.org/bugs/download.php?file_id=50561>
-------------------------------------------------------
Date: Thu 24 Dec 2020 03:43:44 PM UTC  Name: target.mk  Size: 322B   By: None

<http://savannah.gnu.org/bugs/download.php?file_id=50562>

    _______________________________________________________

Reply to this item at:

  <https://savannah.gnu.org/bugs/?59762>

_______________________________________________
  Message sent via Savannah
  https://savannah.gnu.org/