ninja backend: generate additional meta-rules for test/benchmarks targets

'meson-test-prereq' now depends on any targets that were formerly added
directly to 'all'. Behavior is not changed -- the all target still
depends on this other meta-rule, and thus indirectly depends on all
targets it used to depend on.

It is now possible to build just the targets needed for the testsuite
and then e.g. run `meson test --no-rebuild`.

mesonbuild/backend/backends.py

@@ -11,6 +11,7 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
+from __future__ import annotations
 
 from collections import OrderedDict
 from dataclasses import dataclass, InitVar
@@ -1244,10 +1245,12 @@ class Backend:
         for name, b in self.build.get_targets().items():
             if b.build_by_default:
                 result[name] = b
-        # Get all targets used as test executables and arguments. These must
-        # also be built by default. XXX: Sometime in the future these should be
-        # built only before running tests.
-        for t in self.build.get_tests():
+        return result
+
+    def get_testlike_targets(self, benchmark: bool = False) -> T.OrderedDict[str, T.Union[build.BuildTarget, build.CustomTarget]]:
+        result: T.OrderedDict[str, T.Union[build.BuildTarget, build.CustomTarget]] = OrderedDict()
+        targets = self.build.get_benchmarks() if benchmark else self.build.get_tests()
+        for t in targets:
             exe = t.exe
             if isinstance(exe, (build.CustomTarget, build.BuildTarget)):
                 result[exe.get_id()] = exe

mesonbuild/backend/ninjabackend.py

@@ -3272,14 +3272,22 @@ https://gcc.gnu.org/bugzilla/show_bug.cgi?id=47485'''))
         self.add_build(elem)
 
     def generate_ending(self):
-        targetlist = []
-        for t in self.get_build_by_default_targets().values():
-            # Add the first output of each target to the 'all' target so that
-            # they are all built
-            targetlist.append(os.path.join(self.get_target_dir(t), t.get_outputs()[0]))
-
-        elem = NinjaBuildElement(self.all_outputs, 'all', 'phony', targetlist)
-        self.add_build(elem)
+        for targ, deps in [
+                ('all', self.get_build_by_default_targets()),
+                ('meson-test-prereq', self.get_testlike_targets()),
+                ('meson-benchmark-prereq', self.get_testlike_targets(True))]:
+            targetlist = []
+            # These must also be built by default.
+            # XXX: Sometime in the future these should be built only before running tests.
+            if targ == 'all':
+                targetlist.extend(['meson-test-prereq', 'meson-benchmark-prereq'])
+            for t in deps.values():
+                # Add the first output of each target to the 'all' target so that
+                # they are all built
+                targetlist.append(os.path.join(self.get_target_dir(t), t.get_outputs()[0]))
+
+            elem = NinjaBuildElement(self.all_outputs, targ, 'phony', targetlist)
+            self.add_build(elem)
 
         elem = self.create_phony_target(self.all_outputs, 'clean', 'CUSTOM_COMMAND', 'PHONY')
         elem.add_item('COMMAND', self.ninja_command + ['-t', 'clean'])

mesonbuild/backend/vs2010backend.py

@@ -358,6 +358,7 @@ class Vs2010Backend(backends.Backend):
 
     def generate_solution(self, sln_filename, projlist):
         default_projlist = self.get_build_by_default_targets()
+        default_projlist.update(self.get_testlike_targets())
         sln_filename_tmp = sln_filename + '~'
         # Note using the utf-8 BOM requires the blank line, otherwise Visual Studio Version Selector fails.
         # Without the BOM, VSVS fails if there is a blank line.