Merge pull request sphinx-doc#6277 from tk0miya/6271_make_clean

Fix sphinx-doc#6271: make clean is catastrophically broken if building into '.'

CHANGES

@@ -70,6 +70,7 @@ Features added
 * #6232: Enable CLI override of Makefile variables
 * #6212 autosummary: Add :confval:`autosummary_imported_members` to display
   imported members on autosummary
+* #6271: ``make clean`` is catastrophically broken if building into '.'
 
 Bugs fixed
 ----------

sphinx/cmd/make_mode.py

@@ -72,11 +72,19 @@ def builddir_join(self, *comps):
 
     def build_clean(self):
         # type: () -> int
+        srcdir = path.abspath(self.srcdir)
+        builddir = path.abspath(self.builddir)
         if not path.exists(self.builddir):
             return 0
         elif not path.isdir(self.builddir):
             print("Error: %r is not a directory!" % self.builddir)
             return 1
+        elif srcdir == builddir:
+            print("Error: %r is same as source directory!" % self.builddir)
+            return 1
+        elif path.commonpath([srcdir, builddir]) == builddir:
+            print("Error: %r directory contains source directory!" % self.builddir)
+            return 1
         print("Removing everything under %r..." % self.builddir)
         for item in os.listdir(self.builddir):
             rmtree(self.builddir_join(item))