add install_emptydir function

This replaces the absolute hack of using

```
install_subdir('nonexisting', install_dir: 'share')
```

which requires you to make sure you don't accidentally or deliberately
have a completely different directory with the same name in your source
tree that is full of files you don't want installed. It also avoids
splitting the name in two and listing them in the wrong order.

You can also set the install mode of each directory component by listing
them one at a time in order, and in fact create nested structures at
all.

Fixes #1604
Properly fixes #2904

1 files changed, 15 insertions, 0 deletions

diff --git a/mesonbuild/backend/backends.py b/mesonbuild/backend/backends.py
index 6218156..3d8654e 100644
--- a/mesonbuild/backend/backends.py
+++ b/mesonbuild/backend/backends.py
@@ -120,6 +120,7 @@ class InstallData:
         self.targets: T.List[TargetInstallData] = []
         self.headers: T.List[InstallDataBase] = []
         self.man: T.List[InstallDataBase] = []
+        self.emptydir: T.List[InstallEmptyDir] = []
         self.data: T.List[InstallDataBase] = []
         self.install_scripts: T.List[ExecutableSerialisation] = []
         self.install_subdirs: T.List[SubdirInstallData] = []
@@ -147,6 +148,13 @@ class TargetInstallData:
         self.optional = optional
         self.tag = tag
 
+class InstallEmptyDir:
+    def __init__(self, path: str, install_mode: 'FileMode', subproject: str, tag: T.Optional[str] = None):
+        self.path = path
+        self.install_mode = install_mode
+        self.subproject = subproject
+        self.tag = tag
+
 class InstallDataBase:
     def __init__(self, path: str, install_path: str, install_path_name: str,
                  install_mode: 'FileMode', subproject: str, tag: T.Optional[str] = None,
@@ -1470,6 +1478,7 @@ class Backend:
         self.generate_target_install(d)
         self.generate_header_install(d)
         self.generate_man_install(d)
+        self.generate_emptydir_install(d)
         self.generate_data_install(d)
         self.generate_custom_install_script(d)
         self.generate_subdir_install(d)
@@ -1665,6 +1674,12 @@ class Backend:
                 i = InstallDataBase(srcabs, dstabs, dstname, m.get_custom_install_mode(), m.subproject, tag='man')
                 d.man.append(i)
 
+    def generate_emptydir_install(self, d: InstallData) -> None:
+        emptydir: T.List[build.EmptyDir] = self.build.get_emptydir()
+        for e in emptydir:
+            i = InstallEmptyDir(e.path, e.install_mode, e.subproject, e.install_tag)
+            d.emptydir.append(i)
+
     def generate_data_install(self, d: InstallData) -> None:
         data = self.build.get_data()
         srcdir = self.environment.get_source_dir()