allow passing generated objects in the "objects" keyword argument

Generated objects can already be passed in the "objects" keyword argument
as long as you go through an extract_objects() indirection.  Allow the
same even directly, since that is more intuitive than having to add them
to "sources".

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

4 files changed, 22 insertions, 8 deletions

diff --git a/docs/markdown/snippets/gen_objects.md b/docs/markdown/snippets/gen_objects.md
new file mode 100644
index 0000000..fecd701
--- /dev/null
+++ b/docs/markdown/snippets/gen_objects.md
@@ -0,0 +1,6 @@
+## Generated objects can be passed in the `objects:` keyword argument
+
+In previous versions of Meson, generated objects could only be
+passed as sources of a build target.  This was confusing, therefore
+generated objects can now be passed in the `objects:` keyword
+argument as well.
diff --git a/docs/yaml/functions/_build_target_base.yaml b/docs/yaml/functions/_build_target_base.yaml
index 46eedc1..767c4da 100644
--- a/docs/yaml/functions/_build_target_base.yaml
+++ b/docs/yaml/functions/_build_target_base.yaml
@@ -194,8 +194,11 @@ kwargs:
     type: list[extracted_obj | file | str]
     description: |
       List of object files that should be linked in this target.
-      These can include third party products you don't have source to,
-      or object files produced by other build targets.
+
+      **Since 1.1.0** this can include generated files in addition to
+      object files that you don't have source to or that object files
+      produced by other build targets.  In earlier release, generated
+      object files had to be placed in `sources`.
 
   name_prefix:
     type: str | list[void]
diff --git a/mesonbuild/build.py b/mesonbuild/build.py
index db2c309..9d55bf9 100644
--- a/mesonbuild/build.py
+++ b/mesonbuild/build.py
@@ -777,12 +777,11 @@ class BuildTarget(Target):
         for s in objects:
             if isinstance(s, (str, File, ExtractedObjects)):
                 self.objects.append(s)
-            elif isinstance(s, (GeneratedList, CustomTarget)):
-                msg = 'Generated files are not allowed in the \'objects\' kwarg ' + \
-                    f'for target {self.name!r}.\nIt is meant only for ' + \
-                    'pre-built object files that are shipped with the\nsource ' + \
-                    'tree. Try adding it in the list of sources.'
-                raise InvalidArguments(msg)
+            elif isinstance(s, (CustomTarget, CustomTargetIndex, GeneratedList)):
+                non_objects = [o for o in s.get_outputs() if not is_object(o)]
+                if non_objects:
+                    raise InvalidArguments(f'Generated file {non_objects[0]} in the \'objects\' kwarg is not an object.')
+                self.generated.append(s)
             else:
                 raise InvalidArguments(f'Bad object of type {type(s).__name__!r} in target {self.name!r}.')
 
diff --git a/test cases/unit/15 prebuilt object/meson.build b/test cases/unit/15 prebuilt object/meson.build
index b542d1c..81aa2ae 100644
--- a/test cases/unit/15 prebuilt object/meson.build
+++ b/test cases/unit/15 prebuilt object/meson.build
@@ -35,6 +35,12 @@ e += executable('exe5', 'main.c', ct[0])
 sl2 = static_library('lib6', sources: ct)
 e += executable('exe6', sources: 'main.c', objects: sl2.extract_all_objects(recursive: true))
 
+e += executable('exe7', sources: 'main.c', objects: ct)
+e += executable('exe8', sources: 'main.c', objects: ct[0])
+
+sl3 = static_library('lib9', objects: ct)
+e += executable('exe9', sources: 'main.c', objects: sl2.extract_all_objects(recursive: true))
+
 foreach i : e
   test(i.name(), i)
 endforeach