python module: implicitly add python dep to extensions

If there isn't a preexisting dependency on python, append one. It's
almost assuredly needed, so just do the right thing out of the box.

2 files changed, 16 insertions, 3 deletions

diff --git a/docs/markdown/Python-module.md b/docs/markdown/Python-module.md
index 8809fd0..bf40ce4 100644
--- a/docs/markdown/Python-module.md
+++ b/docs/markdown/Python-module.md
@@ -99,9 +99,9 @@ Additionally, the following diverge from [[shared_module]]'s default behavior:
   of Python that support this (the python headers define `PyMODINIT_FUNC` has
   default visibility).
 
-`extension_module` does not add any dependencies to the library so
-user may need to add `dependencies : py_installation.dependency()`,
-see [[dependency]].
+*since 0.63.0* `extension_module` automatically adds a dependency to the library
+if one is not explicitly provided. To support older versions, the user may need to
+add `dependencies : py_installation.dependency()`, see [[dependency]].
 
 **Returns**: a [[@build_tgt]] object
 
diff --git a/docs/markdown/snippets/python-extension-module-implicit-dependency.md b/docs/markdown/snippets/python-extension-module-implicit-dependency.md
new file mode 100644
index 0000000..1b98df8
--- /dev/null
+++ b/docs/markdown/snippets/python-extension-module-implicit-dependency.md
@@ -0,0 +1,13 @@
+## Python extension modules now depend on the python library by default
+
+Python extension modules are usually expected to link to the python library
+and/or its headers in order to build correctly (via the default `embed: false`,
+which may not actually link to the library itself). This means that every
+single use of `.extension_module()` needed to include the `dependencies:
+py_installation.dependency()` kwarg explicitly.
+
+In the interest of doing the right thing out of the box, this is now the
+default for extension modules that don't already include a dependency on
+python. This is not expected to break anything, because it should always be
+needed. Nevertheless, `py_installation.dependency().partial_dependency()` will
+be detected as already included while providing no compile/link args.