mmpack-build: Guess build-depends

Add mechanism to automatically guess build depends and update the source
package specs accordingly during mmpack source tarball build. The guess
mechanism is configured by the section 'guess-build-depends' in
mmpack/sources-strap file.

Change-Id: I7e5a7ef2be678e1a130de29257ea45250adc52b7

Author: nbourdau

docs/specs/package-sources-strap.rst

@@ -50,6 +50,38 @@ others.
  :patches:
    list of patch files to applied on upstream sources after fetching them
 
+ :guess-build-depends:
+   Contains a dictionnary representing the configuration of the mechanism
+   guessing the build-depends to add in package specs.
+
+The guess-build-depends section
+```````````````````````````````
+It is possible to avoid to explicitly specify the build dependencies in the
+package specs and to guess them from project sources. In such a case the
+build-depends section of mmpack/specs is added when the mmpack source package
+is created, the guessed dependencies being specified in addition to possible
+build dependencies set already in package specs. The guess mechanism performed
+per build system (not all are supported).
+
+Several fields control the guess mechanism:
+
+ :from:
+   string or list of string of all build system that must be inspected. Can be
+   python or all. If unset, all build system section listed are implied
+
+ <build-system>
+   Only python is currently supported.
+
+The <build-system> section
+..........................
+  :ignore:
+    list of guessed used dependencies that must not generate a mmpack build
+    dependency.
+
+  :remap:
+    dictionary of used dependencies associated to the mmpack package name to
+    use in the build-depends list. Use it to fix a bad guessed package name.
+
 
 Token expansion
 ---------------
@@ -73,3 +105,16 @@ Examples
    method: tar
    url: https://mirrors.edge.kernel.org/pub/software/scm/git/git-2.24.0.tar.xz
    sha256: 9f71d61973626d8b28c4cdf8e2484b4bf13870ed643fed982d68b2cfd754371b
+
+.. code-block:: yaml
+
+   guess-build-depends:
+     from: python
+
+.. code-block:: yaml
+
+   guess-build-depends:
+     python:
+       ignore: [Setuptools]
+       remap:
+         PyYaml: python3-yaml

src/mmpack_build/builddeps_guess.py

@@ -0,0 +1,62 @@
+# @mindmaze_header@
+"""
+Guess build_dependencies from sources
+"""
+
+from copy import deepcopy
+from typing import Any, Iterator
+
+from .source_strap_specs import SourceStrapSpecs
+
+
+class _BuilddepsGuess:
+    def __init__(self, cfg: dict[str, Any]):
+        self._ignore = set(cfg.get('ignore', []))
+        self._remap = cfg.get('remap', {})
+
+    def _iter_guessed_used_builddeps(self, srcdir: str) -> Iterator[str]:
+        raise NotImplementedError
+
+    def _get_mmpack_dep(self, used: str) -> str:
+        raise NotImplementedError
+
+    def guess(self, srcdir: str) -> set[str]:
+        """Get the set of mmpack package guessed to be build dependencies."""
+        used_deps = set(self._iter_guessed_used_builddeps(srcdir))
+        used_deps.difference_update(self._ignore)
+        return {self._remap.get(u, self._get_mmpack_dep(u))
+                for u in used_deps}
+
+
+_GUESS_BACKENDS: dict[str, _BuilddepsGuess] = {
+}
+
+
+def guess_build_depends(specs: SourceStrapSpecs, srcdir: str) -> set[str]:
+    """
+    Guess the build depends according to mmpack/sources-strap config
+
+    Arguments:
+        specs: specs defined in sources-strap
+        srcdir: path to sources
+    """
+    cfg = deepcopy(specs.get('guess-build-depends', {}))
+    from_builders = cfg.pop('from', None)
+    if from_builders is None:
+        from_builders = list(cfg.keys())
+    elif from_builders == 'all':
+        from_builders = list(_GUESS_BACKENDS.keys())
+    elif isinstance(from_builders, str):
+        from_builders = [from_builders]
+    elif not isinstance(from_builders, list):
+        raise ValueError('guess-build-depends/from key in mmpack/sources-strap'
+                         ' must be a list or single string')
+
+    # Run builddeps guess for all listed backends
+    guessed_deps = set()
+    for builder in from_builders:
+        backend_cls = _GUESS_BACKENDS[builder]
+        backend = backend_cls(cfg.get(builder, {}))
+        guessed_deps.update(backend.guess(srcdir))
+
+    return guessed_deps

src/mmpack_build/meson.build

@@ -19,6 +19,7 @@ mmpack_build_sources = files(
         '__main__.py',
         'base_hook.py',
         'binary_package.py',
+        'builddeps_guess.py',
         'common.py',
         'decorators.py',
         'elf_utils.py',

src/mmpack_build/source_tarball.py

@@ -19,6 +19,7 @@
 from .prefix import new_mmpack_prefix_context, prefix_install, run_build_script
 from .source_strap_specs import SourceStrapSpecs
 from .workspace import Workspace, cached_download, find_project_root_folder
+from .builddeps_guess import guess_build_depends
 
 
 class ProjectSource(NamedTuple):
@@ -291,6 +292,8 @@ def _process_source_strap(self, srcdir):
         self._run_build_script('source_strapped',
                                specs.upstream_method or 'none', srcdir)
 
+        self._guess_build_depends(specs, srcdir)
+
     def _run_build_script(self, name: str, method: str,
                           execdir: str, env: Optional[Dict[str, str]] = None):
         if env is None:
@@ -558,3 +561,20 @@ def _patch_sources(self, patches: List[str], srcdir: str):
                 run_cmd(['patch', '-d', srcdir, '-p1'], stdin=patchfile)
 
         self.trace['patches'] = patches
+
+    @staticmethod
+    def _guess_build_depends(specs: SourceStrapSpecs, srcdir: str):
+        guessed_deps = guess_build_depends(specs, srcdir)
+
+        specs_path = join_path(srcdir, 'mmpack/specs')
+        build_depends = specs_load(specs_path).get('build-depends', [])
+
+        guessed_deps.difference_update(set(build_depends))
+        if not guessed_deps:
+            return
+
+        # Add updated build dependencies at the end of specs.
+        with open(specs_path, 'a', encoding='utf-8') as stream:
+            stream.write('build-depends:\n')
+            for dep in build_depends + list(guessed_deps):
+                stream.write(f'- {dep}\n')