sage_setup: Remove import-time dependency (`setup_requires`) on `pkgconfig`, `numpy`

[mkoeppe]

Just loading src/setup.py already pulls in Cython, numpy, and pkgconfig via sage_setup, so these distributions would have to be declared as [build_system] requires in src/pyproject.toml (ex setup_requires)

By moving some computations from import-time to runtime, we get rid of this early dependency on pkgconfig, numpy. (They are, of course, still required for building the package.)

This makes setup.py sdist work using a Python that does not have numpy or pkgconfig installed. To test (with a system python that has Cython):

  $ (cd build/pkgs/sagelib/src && python3 -u setup.py --no-user-cfg sdist)

(We also reduce the load-time dependency on Cython; however, we do not address the whole load-time dependency of setup.py on Cython (via sage_setup.find, which uses open_source_file and is_package_dir) in this ticket. This is best done after #28925.)

Depends on #30709

CC: @tobiasdiez @jhpalmieri @kiwifb @dimpase

Component: build

Author: Matthias Koeppe

Branch/Commit: 8f04684

Reviewer: Dima Pasechnik

Issue created by migration from https://trac.sagemath.org/ticket/30580

[mkoeppe]

Branch: u/mkoeppe/sage_setup__remove_import_time_dependency___setup_requires___on__pkgconfig____numpy_

[sagetrac-git]

Commit: 88c4e8c

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. New commits:

88c4e8c

src/setup.py: Make 'setup.py sdist' work without Cython

[mkoeppe]

Description changed:

--- 
+++ 
@@ -1,5 +1,8 @@
 Just loading `src/setup.py` already pulls in Cython, `numpy`, and `pkgconfig` via `sage_setup`, so these distributions would have to be declared as `[build_system] requires` in `src/pyproject.toml` (ex `setup_requires`)
 
-By moving some computations from import-time to runtime, we get rid of this dependency on `pkgconfig`, `numpy`.
+By moving some computations from import-time to runtime, we get rid of this early dependency on `pkgconfig`, `numpy`.  (They are, of course, still required for building the package.)  
 
+We also make `setup.py sdist` work using a Python that does not have Cython installed.
 
+(However, we do not address the whole load-time dependency of `setup.py` on `Cython` (via `sage_setup.find`, which uses `open_source_file` and `is_package_dir`) in this ticket. This is best done after #28925.)
+

[mkoeppe]

Author: Matthias Koeppe

[mkoeppe]

Dependencies: #30779

[sagetrac-git]

Changed commit from 88c4e8c to bb32e80

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. This was a forced push. New commits:

4f56517	Duplicate src/setup.py
6fe4d56	Merge branch 't/30779/duplicate_src_setup_py' into t/30580/sage_setup__remove_import_time_dependency___setup_requires___on__pkgconfig____numpy_
698a6ea	src/sage_setup/command/sage_build_cython.py: Remove top-level imports from sage.env, Cython
bb32e80	build/pkgs/sagelib/src/setup.py: Make 'setup.py sdist' work without Cython

[mkoeppe]

comment:6

Ready for review.

[mkoeppe]

Description changed:

--- 
+++ 
@@ -2,7 +2,11 @@
 
 By moving some computations from import-time to runtime, we get rid of this early dependency on `pkgconfig`, `numpy`.  (They are, of course, still required for building the package.)  
 
-We also make `setup.py sdist` work using a Python that does not have Cython installed.
+This makes `setup.py sdist` work using a Python that does not have `numpy `or `pkgconfig` installed.  To test (with a system python that has `Cython`):
 
-(However, we do not address the whole load-time dependency of `setup.py` on `Cython` (via `sage_setup.find`, which uses `open_source_file` and `is_package_dir`) in this ticket. This is best done after #28925.)
+```
+  $ (cd build/pkgs/sagelib/src && python3 -u setup.py --no-user-cfg sdist)
+```
 
+(We also reduce the load-time dependency on Cython; however, we do not address the whole load-time dependency of `setup.py` on `Cython` (via `sage_setup.find`, which uses `open_source_file` and `is_package_dir`) in this ticket. This is best done after #28925.)
+

[mkoeppe]

Changed dependencies from #30779 to none

[dimpase]

comment:9

the 1st line of the output seems to try to say something about --version I don't get:

$ python3 -u setup.py --no-user-cfg sdist >/tmp/res
/bin/sh: 1: --version: not found
distributions = ['']
warning: sdist: standard file not found: should have one of README, README.txt, README.rst

warning: no files found matching '*.hh' anywhere in distribution
...

[mkoeppe]

comment:10

Replying to @dimpase:

the 1st line of the output seems to try to say something about --version I don't get:

$ python3 -u setup.py --no-user-cfg sdist >/tmp/res
/bin/sh: 1: --version: not found

This is from src/sage_setup/command/sage_build_cython.py:

# Work around GCC-4.8 bug which miscompiles some sig_on() statements:
# * https://github.com/sagemath/sage-prod/issues/14460
# * https://github.com/sagemath/sage-prod/issues/20226
# * http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56982
if subprocess.call("""$CC --version | grep -i 'gcc.* 4[.]8' >/dev/null """, shell=True) == 0:
    extra_compile_args.append('-fno-tree-copyrename')

This gives an (ignored) error when CC is not set -- this defect is not new in this ticket.

[dimpase]

comment:11

Do we need to support gcc 4.8 ? The last release of gcc 4.8.* was over 5 years ago.

[dimpase]

comment:12

lgtm - the gcc version could be bumped elsewhere