boost: Allow older behavior with a warning

Fixes #2813

mesonbuild/dependencies/misc.py

@@ -71,11 +71,6 @@ class BoostDependency(ExternalDependency):
         self.is_multithreading = threading == "multi"
 
         self.requested_modules = self.get_requested(kwargs)
-        invalid_modules = [c for c in self.requested_modules if 'boost_' + c not in BOOST_LIBS]
-        if invalid_modules:
-            mlog.warning('Invalid Boost modules: ' + ', '.join(invalid_modules))
-            self.log_fail()
-            return
 
         self.boost_root = None
         self.boost_roots = []
@@ -112,6 +107,24 @@ class BoostDependency(ExternalDependency):
             self.log_fail()
             return
 
+        invalid_modules = [c for c in self.requested_modules if 'boost_' + c not in BOOST_LIBS]
+
+        # previous versions of meson allowed include dirs as modules
+        remove = []
+        for m in invalid_modules:
+            if m in os.listdir(os.path.join(self.incdir, 'boost')):
+                mlog.warning('Requested boost library', mlog.bold(m), 'that doesn\'t exist. '
+                             'This will be an error in the future')
+                remove.append(m)
+
+        self.requested_modules = [x for x in self.requested_modules if x not in remove]
+        invalid_modules = [x for x in invalid_modules if x not in remove]
+
+        if invalid_modules:
+            mlog.warning('Invalid Boost modules: ' + ', '.join(invalid_modules))
+            self.log_fail()
+            return
+
         mlog.debug('Boost library root dir is', mlog.bold(self.boost_root))
         mlog.debug('Boost include directory is', mlog.bold(self.incdir))
 

test cases/frameworks/1 boost/meson.build

@@ -9,7 +9,7 @@ add_project_arguments(['-DBOOST_LOG_DYN_LINK'],
 # within one project. The need to be independent of each other.
 # Use one without a library dependency and one with it.
 
-linkdep = dependency('boost', modules : ['thread', 'system'])
+linkdep = dependency('boost', modules : ['thread', 'system', 'test'])
 staticdep = dependency('boost', modules : ['thread', 'system'], static : true)
 testdep = dependency('boost', modules : ['unit_test_framework'])
 nomoddep = dependency('boost')