Dependencies: Make use of the DependencyCandidate class

This makes the type checking more reasonable (including fixing an issue
that newer mypy is pointing out to us), consolidating special cases, and
improving code readability.

1 files changed, 20 insertions, 21 deletions

diff --git a/mesonbuild/dependencies/detect.py b/mesonbuild/dependencies/detect.py
index 206742d1b..295689db2 100644
--- a/mesonbuild/dependencies/detect.py
+++ b/mesonbuild/dependencies/detect.py
@@ -3,23 +3,23 @@
 
 from __future__ import annotations
 
-import collections, functools, importlib
+import collections, importlib
 import enum
 import typing as T
 
-from .base import ExternalDependency, DependencyException, DependencyMethods, NotFoundDependency
+from .base import DependencyCandidate, ExternalDependency, DependencyException, DependencyMethods, NotFoundDependency
 
-from ..mesonlib import listify, PerMachine
+from ..mesonlib import listify, PerMachine, MesonBugException
 from .. import mlog
 
 if T.TYPE_CHECKING:
     from ..environment import Environment
-    from .factory import DependencyFactory, WrappedFactoryFunc, DependencyGenerator
+    from .factory import DependencyFactory, DependencyGenerator, WrappedFactoryFunc
     from .base import DependencyObjectKWs
 
     TV_DepIDEntry = T.Union[str, bool, int, None, T.Tuple[str, ...]]
     TV_DepID = T.Tuple[T.Tuple[str, TV_DepIDEntry], ...]
-    PackageTypes = T.Union[T.Type[ExternalDependency], DependencyFactory, WrappedFactoryFunc]
+    PackageTypes = T.Union[T.Type[ExternalDependency], DependencyFactory, DependencyCandidate, WrappedFactoryFunc]
     # Workaround for older python
     DependencyPackagesType = collections.UserDict[str, PackageTypes]
 else:
@@ -120,8 +120,7 @@ def find_external_dependency(name: str, env: 'Environment', kwargs: DependencyOb
             d._check_version()
             pkgdep.append(d)
         except DependencyException as e:
-            assert isinstance(c, functools.partial), 'for mypy'
-            bettermsg = f'Dependency lookup for {name} with method {c.func.log_tried()!r} failed: {e}'
+            bettermsg = f'Dependency lookup for {name} with method {c.method!r} failed: {e}'
             mlog.debug(bettermsg)
             e.args = (bettermsg,)
             pkg_exc.append(e)
@@ -178,17 +177,17 @@ def _build_external_dependency_list(name: str, env: 'Environment', kwargs: Depen
     # Is there a specific dependency detector for this dependency?
     lname = name.lower()
     if lname in packages:
-        # Create the list of dependency object constructors using a factory
-        # class method, if one exists, otherwise the list just consists of the
-        # constructor
-        if isinstance(packages[lname], type):
-            entry1 = T.cast('T.Type[ExternalDependency]', packages[lname])  # mypy doesn't understand isinstance(..., type)
-            if issubclass(entry1, ExternalDependency):
-                func: T.Callable[[], 'ExternalDependency'] = functools.partial(entry1, env, kwargs)
-                dep = [func]
+        entry = packages[lname]
+        if isinstance(entry, type):
+            if issubclass(entry, ExternalDependency):
+                dep = [DependencyCandidate.from_dependency(name, entry, (env, kwargs))]
+            else:
+                raise MesonBugException(f'Got an invalid type in the dependency list: {entry!r}')
+        elif isinstance(entry, DependencyCandidate):
+            entry.arguments = (env, kwargs)
+            dep = [entry]
         else:
-            entry2 = T.cast('T.Union[DependencyFactory, WrappedFactoryFunc]', packages[lname])
-            dep = entry2(env, kwargs)
+            dep = entry(env, kwargs)
         return dep
 
     candidates: T.List['DependencyGenerator'] = []
@@ -204,24 +203,24 @@ def _build_external_dependency_list(name: str, env: 'Environment', kwargs: Depen
     # Exclusive to when it is explicitly requested
     if DependencyMethods.DUB in methods:
         from .dub import DubDependency
-        candidates.append(functools.partial(DubDependency, name, env, kwargs))
+        candidates.append(DependencyCandidate.from_dependency(name, DubDependency, (env, kwargs)))
 
     # Preferred first candidate for auto.
     if DependencyMethods.PKGCONFIG in methods:
         from .pkgconfig import PkgConfigDependency
-        candidates.append(functools.partial(PkgConfigDependency, name, env, kwargs))
+        candidates.append(DependencyCandidate.from_dependency(name, PkgConfigDependency, (env, kwargs)))
 
     # On OSX only, try framework dependency detector.
     if DependencyMethods.EXTRAFRAMEWORK in methods:
         if env.machines[kwargs['native']].is_darwin():
             from .framework import ExtraFrameworkDependency
-            candidates.append(functools.partial(ExtraFrameworkDependency, name, env, kwargs))
+            candidates.append(DependencyCandidate.from_dependency(name, ExtraFrameworkDependency, (env, kwargs)))
 
     # Only use CMake:
     # - if it's explicitly requested
     # - as a last resort, since it might not work 100% (see #6113)
     if DependencyMethods.CMAKE in methods:
         from .cmake import CMakeDependency
-        candidates.append(functools.partial(CMakeDependency, name, env, kwargs))
+        candidates.append(DependencyCandidate.from_dependency(name, CMakeDependency, (env, kwargs)))
 
     return candidates