interpreter: Correctly ignore def files in build directory

See https://gitlab.freedesktop.org/gstreamer/gst-build/-/issues/85.

mesonbuild/interpreter.py

@@ -2422,14 +2422,14 @@ class Interpreter(InterpreterBase):
                 return
             f = os.path.normpath(f.relative_name())
         elif os.path.isfile(f) and not f.startswith('/dev'):
-            srcdir = self.environment.get_source_dir()
-            builddir = self.environment.get_build_dir()
-            f = os.path.normpath(f)
-            rel_path = mesonlib.relpath(f, start=srcdir)
-            if not rel_path.startswith('..'):
-                f = rel_path
-            elif not mesonlib.relpath(f, start=builddir).startswith('..'):
+            srcdir = Path(self.environment.get_source_dir())
+            builddir = Path(self.environment.get_build_dir())
+            f = Path(f).resolve()
+            if builddir in f.parents:
                 return
+            if srcdir in f.parents:
+                f = f.relative_to(srcdir)
+            f = str(f)
         else:
             return
         if f not in self.build_def_files:

run_unittests.py

@@ -4562,6 +4562,34 @@ recommended as it is not supported on some platforms''')
         self._run([*self.meson_command, 'compile', '-C', self.builddir, '--clean'])
         self.assertPathDoesNotExist(os.path.join(self.builddir, prog))
 
+    def test_spurious_reconfigure_built_dep_file(self):
+        testdir = os.path.join(self.unit_test_dir, '74 dep files')
+
+        # Regression test: Spurious reconfigure was happening when build
+        # directory is inside source directory.
+        # See https://gitlab.freedesktop.org/gstreamer/gst-build/-/issues/85.
+        srcdir = os.path.join(self.builddir, 'srctree')
+        shutil.copytree(testdir, srcdir)
+        builddir = os.path.join(srcdir, '_build')
+        self.change_builddir(builddir)
+
+        self.init(srcdir)
+        self.build()
+
+        # During first configure the file did not exist so no dependency should
+        # have been set. A rebuild should not trigger a reconfigure.
+        self.clean()
+        out = self.build()
+        self.assertNotIn('Project configured', out)
+
+        self.init(srcdir, extra_args=['--reconfigure'])
+
+        # During the reconfigure the file did exist, but is inside build
+        # directory, so no dependency should have been set. A rebuild should not
+        # trigger a reconfigure.
+        self.clean()
+        out = self.build()
+        self.assertNotIn('Project configured', out)
 
 class FailureTests(BasePlatformTests):
     '''

test cases/unit/74 dep files/meson.build

@@ -0,0 +1,16 @@
+project('test', 'c')
+
+python = import('python').find_installation()
+
+lib = library('foo', 'foo.c')
+
+# The library does not yet exist but we can already use its path during
+# configuration. This should not trigger a reconfigure when the library is
+# rebuilt.
+configure_file(
+  output: 'out.txt',
+  capture: true,
+  command: [python, '-c', 'import sys; print(sys.argv[1])', lib.full_path()],
+)
+
+message('Project configured')