backends: Use POSIX paths for target paths

This commit completes 5de09cbe8838e8febf1ca3aa83b53cf06972bff3,
ensuring that only POSIX style paths are passed to the compiler
line, and thus fixing UNIX-style tools that treat single
backward slashes as Unicode escaped characters.

Fixes #12191

Completes #12534

Completes #12564

1 files changed, 5 insertions, 5 deletions

diff --git a/mesonbuild/backend/backends.py b/mesonbuild/backend/backends.py
index ed57a4c1b..3aab420e8 100644
--- a/mesonbuild/backend/backends.py
+++ b/mesonbuild/backend/backends.py
@@ -150,7 +150,7 @@ class TargetInstallData:
     def __post_init__(self, outdir_name: T.Optional[str]) -> None:
         if outdir_name is None:
             outdir_name = os.path.join('{prefix}', self.outdir)
-        self.out_name = os.path.join(outdir_name, os.path.basename(self.fname))
+        self.out_name = Path(outdir_name, os.path.basename(self.fname)).as_posix()
 
 @dataclass(eq=False)
 class InstallEmptyDir:
@@ -307,16 +307,16 @@ class Backend:
         else:
             assert isinstance(t, build.BuildTarget), t
             filename = t.get_filename()
-        return os.path.join(self.get_target_dir(t), filename)
+        return Path(self.get_target_dir(t), filename).as_posix()
 
     def get_target_filename_abs(self, target: T.Union[build.Target, build.CustomTargetIndex]) -> str:
-        return os.path.join(self.environment.get_build_dir(), self.get_target_filename(target))
+        return Path(self.environment.get_build_dir(), self.get_target_filename(target)).as_posix()
 
     def get_target_debug_filename(self, target: build.BuildTarget) -> T.Optional[str]:
         assert isinstance(target, build.BuildTarget), target
         if target.get_debug_filename():
             debug_filename = target.get_debug_filename()
-            return os.path.join(self.get_target_dir(target), debug_filename)
+            return Path(self.get_target_dir(target), debug_filename).as_posix()
         else:
             return None
 
@@ -324,7 +324,7 @@ class Backend:
         assert isinstance(target, build.BuildTarget), target
         if not target.get_debug_filename():
             return None
-        return os.path.join(self.environment.get_build_dir(), self.get_target_debug_filename(target))
+        return Path(self.environment.get_build_dir(), self.get_target_debug_filename(target)).as_posix()
 
     def get_source_dir_include_args(self, target: build.BuildTarget, compiler: 'Compiler', *, absolute_path: bool = False) -> T.List[str]:
         curdir = target.get_subdir()