Merge pull request #7902 from bonzini/mtest-build-depends-only

mtest: only build what is needed for the tests

4 files changed, 91 insertions, 29 deletions

diff --git a/docs/markdown/snippets/meson_test_depends.md b/docs/markdown/snippets/meson_test_depends.md
new file mode 100644
index 0000000..09d78f1
--- /dev/null
+++ b/docs/markdown/snippets/meson_test_depends.md
@@ -0,0 +1,17 @@
+## `meson test` only rebuilds test dependencies
+
+Until now, `meson test` rebuilt the whole project independent of the
+requested tests and their dependencies.  With this release, `meson test`
+will only rebuild what is needed for the tests or suites that will be run.
+This feature can be used, for example, to speed up bisecting regressions
+using commands like the following:
+
+    git bisect start <broken commit> <working commit>
+    git bisect run meson test <failing test name>
+
+This would find the broken commit automatically while at each step
+rebuilding only those pieces of code needed to run the test.
+
+However, this change could cause failures if dependencies are not
+specified correctly in `meson.build`.
+
diff --git a/mesonbuild/minstall.py b/mesonbuild/minstall.py
index 47bb88b..a8ec8f3 100644
--- a/mesonbuild/minstall.py
+++ b/mesonbuild/minstall.py
@@ -19,7 +19,6 @@ from glob import glob
 from .scripts import depfixer
 from .scripts import destdir_join
 from .mesonlib import is_windows, Popen_safe
-from .mtest import rebuild_all
 from .backend.backends import InstallData
 from .coredata import major_versions_differ, MesonVersionMismatchException
 from .coredata import version as coredata_version
@@ -532,6 +531,23 @@ class Installer:
                     else:
                         raise
 
+def rebuild_all(wd: str) -> bool:
+    if not (Path(wd) / 'build.ninja').is_file():
+        print('Only ninja backend is supported to rebuild the project before installation.')
+        return True
+
+    ninja = environment.detect_ninja()
+    if not ninja:
+        print("Can't find ninja, can't rebuild test.")
+        return False
+
+    ret = subprocess.run(ninja + ['-C', wd]).returncode
+    if ret != 0:
+        print('Could not rebuild {}'.format(wd))
+        return False
+
+    return True
+
 def run(opts):
     datafilename = 'meson-private/install.dat'
     private_dir = os.path.dirname(datafilename)
diff --git a/mesonbuild/mintro.py b/mesonbuild/mintro.py
index d36927f..f6262c3 100644
--- a/mesonbuild/mintro.py
+++ b/mesonbuild/mintro.py
@@ -385,12 +385,25 @@ def print_results(options: argparse.Namespace, results: T.Sequence[T.Tuple[str,
         print(json.dumps(out, indent=indent))
     return 0
 
+def get_infodir(builddir: T.Optional[str] = None) -> str:
+    infodir = 'meson-info'
+    if builddir is not None:
+        infodir = os.path.join(builddir, infodir)
+    return infodir
+
+def get_info_file(infodir: str, kind: T.Optional[str] = None) -> str:
+    return os.path.join(infodir,
+                        'meson-info.json' if not kind else 'intro-{}.json'.format(kind))
+
+def load_info_file(infodir: str, kind: T.Optional[str] = None) -> T.Any:
+    with open(get_info_file(infodir, kind), 'r') as fp:
+        return json.load(fp)
+
 def run(options: argparse.Namespace) -> int:
     datadir = 'meson-private'
-    infodir = 'meson-info'
+    infodir = get_infodir(options.builddir)
     if options.builddir is not None:
         datadir = os.path.join(options.builddir, datadir)
-        infodir = os.path.join(options.builddir, infodir)
     indent = 4 if options.indent else None
     results = []  # type: T.List[T.Tuple[str, T.Union[dict, T.List[T.Any]]]]
     sourcedir = '.' if options.builddir == 'meson.build' else options.builddir[:-11]
@@ -411,17 +424,18 @@ def run(options: argparse.Namespace) -> int:
             results += [(key, val.no_bd(intr))]
         return print_results(options, results, indent)
 
-    infofile = get_meson_info_file(infodir)
-    if not os.path.isdir(datadir) or not os.path.isdir(infodir) or not os.path.isfile(infofile):
-        print('Current directory is not a meson build directory.\n'
-              'Please specify a valid build dir or change the working directory to it.\n'
-              'It is also possible that the build directory was generated with an old\n'
-              'meson version. Please regenerate it in this case.')
-        return 1
-
-    with open(infofile, 'r') as fp:
-        raw = json.load(fp)
+    try:
+        raw = load_info_file(infodir)
         intro_vers = raw.get('introspection', {}).get('version', {}).get('full', '0.0.0')
+    except FileNotFoundError:
+        if not os.path.isdir(datadir) or not os.path.isdir(infodir):
+            print('Current directory is not a meson build directory.\n'
+                  'Please specify a valid build dir or change the working directory to it.')
+        else:
+            print('Introspection file {} does not exist.\n'
+                  'It is also possible that the build directory was generated with an old\n'
+                  'meson version. Please regenerate it in this case.'.format(get_info_file(infodir)))
+        return 1
 
     vers_to_check = get_meson_introspection_required_version()
     for i in vers_to_check:
@@ -437,12 +451,11 @@ def run(options: argparse.Namespace) -> int:
             continue
         if not options.all and not getattr(options, i, False):
             continue
-        curr = os.path.join(infodir, 'intro-{}.json'.format(i))
-        if not os.path.isfile(curr):
-            print('Introspection file {} does not exist.'.format(curr))
+        try:
+            results += [(i, load_info_file(infodir, i))]
+        except FileNotFoundError:
+            print('Introspection file {} does not exist.'.format(get_info_file(infodir, i)))
             return 1
-        with open(curr, 'r') as fp:
-            results += [(i, json.load(fp))]
 
     return print_results(options, results, indent)
 
diff --git a/mesonbuild/mtest.py b/mesonbuild/mtest.py
index a92b5cc..4f687a5 100644
--- a/mesonbuild/mtest.py
+++ b/mesonbuild/mtest.py
@@ -45,6 +45,7 @@ from .coredata import major_versions_differ, MesonVersionMismatchException
 from .coredata import version as coredata_version
 from .dependencies import ExternalProgram
 from .mesonlib import MesonException, get_wine_shortpath, split_args, join_args
+from .mintro import get_infodir, load_info_file
 from .backend.backends import TestProtocol, TestSerialisation
 
 # GNU autotools interprets a return code of 77 from tests it executes to
@@ -1019,13 +1020,21 @@ class TestHarness:
     def total_failure_count(self) -> int:
         return self.fail_count + self.unexpectedpass_count + self.timeout_count
 
-    def doit(self) -> int:
+    def doit(self, options: argparse.Namespace) -> int:
         if self.is_run:
             raise RuntimeError('Test harness object can only be used once.')
         self.is_run = True
         tests = self.get_tests()
         if not tests:
             return 0
+        if not options.no_rebuild and not rebuild_deps(options.wd, tests):
+            # We return 125 here in case the build failed.
+            # The reason is that exit code 125 tells `git bisect run` that the current
+            # commit should be skipped.  Thus users can directly use `meson test` to
+            # bisect without needing to handle the does-not-build case separately in a
+            # wrapper script.
+            sys.exit(125)
+
         self.run_tests(tests)
         return self.total_failure_count()
 
@@ -1272,7 +1281,7 @@ def list_tests(th: TestHarness) -> bool:
         print(th.get_pretty_suite(t))
     return not tests
 
-def rebuild_all(wd: str) -> bool:
+def rebuild_deps(wd: str, tests: T.List[TestSerialisation]) -> bool:
     if not (Path(wd) / 'build.ninja').is_file():
         print('Only ninja backend is supported to rebuild tests before running them.')
         return True
@@ -1282,7 +1291,21 @@ def rebuild_all(wd: str) -> bool:
         print("Can't find ninja, can't rebuild test.")
         return False
 
-    ret = subprocess.run(ninja + ['-C', wd]).returncode
+    depends = set()            # type: T.Set[str]
+    targets = set()            # type: T.Set[str]
+    intro_targets = dict()     # type: T.Dict[str, T.List[str]]
+    for target in load_info_file(get_infodir(wd), kind='targets'):
+        intro_targets[target['id']] = [
+                os.path.relpath(f, wd)
+                for f in target['filename']]
+    for t in tests:
+        for d in t.depends:
+            if d in depends:
+                continue
+            depends.update(d)
+            targets.update(intro_targets[d])
+
+    ret = subprocess.run(ninja + ['-C', wd] + sorted(targets)).returncode
     if ret != 0:
         print('Could not rebuild {}'.format(wd))
         return False
@@ -1318,18 +1341,11 @@ def run(options: argparse.Namespace) -> int:
             print('Could not find requested program: {!r}'.format(check_bin))
             return 1
 
-    if not options.list and not options.no_rebuild:
-        if not rebuild_all(options.wd):
-            # We return 125 here in case the build failed.
-            # The reason is that exit code 125 tells `git bisect run` that the current commit should be skipped.
-            # Thus users can directly use `meson test` to bisect without needing to handle the does-not-build case separately in a wrapper script.
-            return 125
-
     with TestHarness(options) as th:
         try:
             if options.list:
                 return list_tests(th)
-            return th.doit()
+            return th.doit(options)
         except TestException as e:
             print('Meson test encountered an error:\n')
             if os.environ.get('MESON_FORCE_BACKTRACE'):