sagelib: Declare build system dependencies using src/pyproject.toml

[mkoeppe]

Even after #30580, setup.py still has an import-time dependency on Cython (via sage_setup).

We declare this build system dependency by adding the PEP 517 metadata (pyproject.toml).

Adding pyproject.toml does not change how the Sage distribution installs sagelib because build/pkgs/sagelib/spkg-install uses setup.py install directly.

---

References:

• https://snarky.ca/what-the-heck-is-pyproject-toml/

CC: @tobiasdiez @jhpalmieri @dimpase

Component: build

Keywords: sd111

Branch/Commit: u/mkoeppe/pyproject_toml @ bbfc19e

Issue created by migration from https://trac.sagemath.org/ticket/30581

[mkoeppe]

Branch: u/mkoeppe/pyproject_toml

[mkoeppe]

Author: Matthias Koeppe

[mkoeppe]

Changed branch from u/mkoeppe/pyproject_toml to none

[mkoeppe]

Dependencies: #30580

[mkoeppe]

Branch: u/mkoeppe/pyproject_toml

[mkoeppe]

Commit: a05a537

[mkoeppe]

comment:4

Build fails with

    File "/private/var/folders/38/wnh4gf1552g_crsjnv2vmmww0000gp/T/pip-req-build-t5v70h8w/sage/misc/package.py", line 319, in installed_packages
      installed.update(pip_installed_packages())
    File "/private/var/folders/38/wnh4gf1552g_crsjnv2vmmww0000gp/T/pip-req-build-t5v70h8w/sage/misc/package.py", line 154, in pip_installed_packages
      for package in json.loads(stdout)}
    File "/usr/local/Cellar/python@3.8/3.8.5/Frameworks/Python.framework/Versions/3.8/lib/python3.8/json/__init__.py", line 357, in loads
      return _default_decoder.decode(s)
    File "/usr/local/Cellar/python@3.8/3.8.5/Frameworks/Python.framework/Versions/3.8/lib/python3.8/json/decoder.py", line 337, in decode
      obj, end = self.raw_decode(s, idx=_w(s, 0).end())
    File "/usr/local/Cellar/python@3.8/3.8.5/Frameworks/Python.framework/Versions/3.8/lib/python3.8/json/decoder.py", line 355, in raw_decode
      raise JSONDecodeError("Expecting value", s, err.value) from None
  json.decoder.JSONDecodeError: Expecting value: line 1 column 1 (char 0)
  ************************************************************************
  Error building the Sage library
  ************************************************************************

---

New commits:

2c1e648	src/sage_setup/command/sage_build_cython.py: Remove top-level imports from sage.env, Cython
88c4e8c	src/setup.py: Make 'setup.py sdist' work without Cython
a05a537	src/pyproject.toml: New

[mkoeppe]

Description changed:

--- 
+++ 
@@ -1,2 +1,7 @@
 Adding PEP 517 metadata
 
+---
+
+References:
+- https://snarky.ca/what-the-heck-is-pyproject-toml/
+

[mkoeppe]

Changed dependencies from #30580 to #30580, #30712

[mkoeppe]

Changed dependencies from #30580, #30712 to #30580

[mkoeppe]

Description changed:

--- 
+++ 
@@ -1,4 +1,4 @@
-Adding PEP 517 metadata
+Adding PEP 517 metadata for sagelib
 
 ---
 

[sagetrac-git]

Changed commit from a05a537 to bbfc19e

[sagetrac-git]

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

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
15a6c2b	Merge branch 't/30580/sage_setup__remove_import_time_dependency___setup_requires___on__pkgconfig____numpy_' into t/30581/pyproject_toml
310ebd1	Merge tag '9.3.beta1' into t/30581/pyproject_toml
bbfc19e	build/pkgs/sagelib/src: Apply PEP 517 changes

[mkoeppe]

Description changed:

--- 
+++ 
@@ -1,4 +1,7 @@
-Adding PEP 517 metadata for sagelib
+Even after #30580, `setup.py` still has an import-time dependency on `Cython` (via `sage_setup`). 
+
+We declare this build system dependency by adding the PEP 517 metadata (`pyproject.toml`).
+
 
 ---
 

[tobiasdiez]

Reviewer: Tobias Diez, ...