Fix include_directories test for relative path

- On Windows, it was not detected if include directory was an absolute
  path to source directory, because of the mis of path separators.

- In the edgecase the include directory begins with the exact same
  string as the source directory, but is a different directory, it was
  falsely reported as an error.

Fixes #12217.

1 files changed, 3 insertions, 3 deletions

diff --git a/mesonbuild/interpreter/interpreter.py b/mesonbuild/interpreter/interpreter.py
index 5657b20..d9a260c 100644
--- a/mesonbuild/interpreter/interpreter.py
+++ b/mesonbuild/interpreter/interpreter.py
@@ -25,7 +25,7 @@ from ..wrap import wrap, WrapMode
 from .. import mesonlib
 from ..mesonlib import (EnvironmentVariables, ExecutableSerialisation, MesonBugException, MesonException, HoldableObject,
                         FileMode, MachineChoice, OptionKey, listify,
-                        extract_as_list, has_path_sep, PerMachine)
+                        extract_as_list, has_path_sep, path_is_in_root, PerMachine)
 from ..programs import ExternalProgram, NonExistingExternalProgram
 from ..dependencies import Dependency
 from ..depfile import DepFile
@@ -551,7 +551,7 @@ class Interpreter(InterpreterBase, HoldableObject):
             if f.is_built:
                 return
             f = os.path.normpath(f.relative_name())
-        elif os.path.isfile(f) and not f.startswith('/dev'):
+        elif os.path.isfile(f) and not f.startswith('/dev/'):
             srcdir = Path(self.environment.get_source_dir())
             builddir = Path(self.environment.get_build_dir())
             try:
@@ -2773,7 +2773,7 @@ class Interpreter(InterpreterBase, HoldableObject):
         absbase_build = os.path.join(build_root, self.subdir)
 
         for a in incdir_strings:
-            if a.startswith(src_root):
+            if path_is_in_root(Path(a), Path(src_root)):
                 raise InvalidArguments(textwrap.dedent('''\
                     Tried to form an absolute path to a dir in the source tree.
                     You should not do that but use relative paths instead, for