Track dependencies of subproject option files.

backends.py

@@ -13,7 +13,7 @@
 # limitations under the License.
 
 import os, sys, re, pickle
-import interpreter, nodes
+import nodes
 import environment, mlog
 from meson_install import InstallData
 from build import InvalidArguments
@@ -1023,6 +1023,10 @@ class NinjaBackend(Backend):
         deps.append('meson-private/coredata.dat')
         if os.path.exists(os.path.join(self.environment.get_source_dir(), 'meson_options.txt')):
             deps.append(os.path.join(self.build_to_src, 'meson_options.txt'))
+        for sp in self.build.subprojects.keys():
+            fname = os.path.join(self.environment.get_source_dir(), sp, 'meson_options.txt')
+            if os.path.isfile(fname):
+                deps.append(os.path.join(self.build_to_src, sp, 'meson_options.txt'))
         elem = NinjaBuildElement('build.ninja', 'REGENERATE_BUILD', deps)
         elem.write(outfile)
 

build.py

@@ -40,6 +40,7 @@ class Build:
         self.static_cross_linker = None
         self.configure_files = []
         self.pot = []
+        self.subprojects = {}
 
     def add_compiler(self, compiler):
         if len(self.compilers) == 0:

interpreter.py

@@ -740,7 +740,7 @@ class Interpreter():
             raise InterpreterException('Subprojects must be defined at the root directory.')
         if self.subproject != '':
             raise InterpreterException('Subprojects of subprojects are not yet supported.')
-        if dirname in self.subprojects:
+        if dirname in self.build.subprojects:
             raise InterpreterException('Tried to add the same subproject twice.')
         subdir = os.path.join(self.subproject, self.subdir, dirname)
         abs_subdir = os.path.join(self.build.environment.get_source_dir(), subdir)
@@ -751,6 +751,7 @@ class Interpreter():
         subi = Interpreter(self.build, subdir)
         subi.run()
         mlog.log('\nSubproject finished.\n')
+        self.build.subprojects[dirname] = True
         self.subprojects[dirname] = SubprojectHolder(subi)
         return self.subprojects[dirname]