interpreter: Add always set default value for version and set it ASAP

Ideally we wouldn't need to have the default dict here and could just
rely on it being set as soon as project is called. There is a corner
case exercised by test case common/35 run program, which is that if a
FeatureNew or FeatureDeprecated is called to generate the meson version
it will be unset, to work around this I've changed the type from a dict
to a default dict with '' as the default value.

A better fix would probably be to store all of the
FeatureNew/FeatureDeprecated checks until the end, then evaluate them,
but for now this results in no loss of functionality, only more
functionality, even if it isn't prefect.

1 files changed, 3 insertions, 1 deletions

diff --git a/mesonbuild/mesonlib.py b/mesonbuild/mesonlib.py
index b901ec9..26fe6eb 100644
--- a/mesonbuild/mesonlib.py
+++ b/mesonbuild/mesonlib.py
@@ -39,8 +39,10 @@ _U = T.TypeVar('_U')
 
 have_fcntl = False
 have_msvcrt = False
+# TODO: this is such a hack, this really should be either in coredata or in the
+# interpreter
 # {subproject: project_meson_version}
-project_meson_versions = {}  # type: T.Dict[str, str]
+project_meson_versions = collections.defaultdict(str)  # type: T.DefaultDict[str, str]
 
 try:
     import fcntl