allow (but lint for) inferring commands on explicit targets

1 files changed, 7 insertions, 1 deletions

diff --git a/yapymake/makefile/__init__.py b/yapymake/makefile/__init__.py
index 0290e9f..4617047 100644
--- a/yapymake/makefile/__init__.py
+++ b/yapymake/makefile/__init__.py
@@ -254,7 +254,9 @@ class Makefile:
 
     def target(self, name: str) -> 'Target':
         # TODO implement .DEFAULT
-        if name not in self._targets:
+        # it's not POSIXful, but GNU make will use inference rules for defined targets with no commands,
+        follow_gnu = True # TODO implement .POSIX and scope it properly
+        if name not in self._targets or (follow_gnu and len(self._targets[name].commands) == 0):
             # > When no target rule is found to update a target, the inference rules shall be checked. The suffix of
             # > the target (.s1) to be built...
             suffix = PurePath(name).suffix
@@ -269,6 +271,10 @@ class Makefile:
                         # > whose prerequisite file ($*.s2) exists.
                         prerequisite_path = PurePath(name).with_suffix(rule.s2)
                         if ImpurePath(prerequisite_path).exists():
+                            if name in self._targets:
+                                # we got here by following GNU
+                                print('warning: non-POSIX use of inference rule', f'{rule.s1}{rule.s2}',
+                                      'on explicit target', name)
                             self._targets[name] = Target(name, [str(prerequisite_path)], rule.commands)
                             break
         if name not in self._targets: