introspection: untangle install_plan implemetation, fix a bunch of wrong ones

Generally plumb through the values of get_option() passed to
install_dir, and use this to establish the install plan name. Fixes
several odd cases, such as:

- {datadir} being prepended to "share" or "include"

- dissociating custom install directories and writing them out as
  {prefix}/share/foo or {prefix}/lib/python3.10/site-packages

This is the second half of #9478
Fixes #10601

6 files changed, 53 insertions, 48 deletions

diff --git a/mesonbuild/backend/backends.py b/mesonbuild/backend/backends.py
index 67bc8bf..42f6255 100644
--- a/mesonbuild/backend/backends.py
+++ b/mesonbuild/backend/backends.py
@@ -1534,7 +1534,7 @@ class Backend:
         for t in self.build.get_targets().values():
             if not t.should_install():
                 continue
-            outdirs, default_install_dir_name, custom_install_dir = t.get_install_dir()
+            outdirs, install_dir_names, custom_install_dir = t.get_install_dir()
             # Sanity-check the outputs and install_dirs
             num_outdirs, num_out = len(outdirs), len(t.get_outputs())
             if num_outdirs != 1 and num_outdirs != num_out:
@@ -1544,7 +1544,9 @@ class Backend:
                 raise MesonException(m.format(t.name, num_out, t.get_outputs(), num_outdirs))
             assert len(t.install_tag) == num_out
             install_mode = t.get_custom_install_mode()
-            first_outdir = outdirs[0]  # because mypy get's confused type narrowing in lists
+            # because mypy get's confused type narrowing in lists
+            first_outdir = outdirs[0]
+            first_outdir_name = install_dir_names[0]
 
             # Install the target output(s)
             if isinstance(t, build.BuildTarget):
@@ -1570,7 +1572,7 @@ class Backend:
                     tag = t.install_tag[0] or ('devel' if isinstance(t, build.StaticLibrary) else 'runtime')
                     mappings = t.get_link_deps_mapping(d.prefix)
                     i = TargetInstallData(self.get_target_filename(t), first_outdir,
-                                          default_install_dir_name,
+                                          first_outdir_name,
                                           should_strip, mappings, t.rpath_dirs_to_remove,
                                           t.install_rpath, install_mode, t.subproject,
                                           tag=tag, can_strip=can_strip)
@@ -1595,7 +1597,7 @@ class Backend:
                                 implib_install_dir = self.environment.get_import_lib_dir()
                             # Install the import library; may not exist for shared modules
                             i = TargetInstallData(self.get_target_filename_for_linking(t),
-                                                  implib_install_dir, default_install_dir_name,
+                                                  implib_install_dir, first_outdir_name,
                                                   False, {}, set(), '', install_mode,
                                                   t.subproject, optional=isinstance(t, build.SharedModule),
                                                   tag='devel')
@@ -1604,19 +1606,19 @@ class Backend:
                         if not should_strip and t.get_debug_filename():
                             debug_file = os.path.join(self.get_target_dir(t), t.get_debug_filename())
                             i = TargetInstallData(debug_file, first_outdir,
-                                                  default_install_dir_name,
+                                                  first_outdir_name,
                                                   False, {}, set(), '',
                                                   install_mode, t.subproject,
                                                   optional=True, tag='devel')
                             d.targets.append(i)
                 # Install secondary outputs. Only used for Vala right now.
                 if num_outdirs > 1:
-                    for output, outdir, tag in zip(t.get_outputs()[1:], outdirs[1:], t.install_tag[1:]):
+                    for output, outdir, outdir_name, tag in zip(t.get_outputs()[1:], outdirs[1:], install_dir_names[1:], t.install_tag[1:]):
                         # User requested that we not install this output
                         if outdir is False:
                             continue
                         f = os.path.join(self.get_target_dir(t), output)
-                        i = TargetInstallData(f, outdir, default_install_dir_name, False, {}, set(), None,
+                        i = TargetInstallData(f, outdir, outdir_name, False, {}, set(), None,
                                               install_mode, t.subproject,
                                               tag=tag)
                         d.targets.append(i)
@@ -1635,18 +1637,18 @@ class Backend:
                     if first_outdir is not False:
                         for output, tag in zip(t.get_outputs(), t.install_tag):
                             f = os.path.join(self.get_target_dir(t), output)
-                            i = TargetInstallData(f, first_outdir, default_install_dir_name,
+                            i = TargetInstallData(f, first_outdir, first_outdir_name,
                                                   False, {}, set(), None, install_mode,
                                                   t.subproject, optional=not t.build_by_default,
                                                   tag=tag)
                             d.targets.append(i)
                 else:
-                    for output, outdir, tag in zip(t.get_outputs(), outdirs, t.install_tag):
+                    for output, outdir, outdir_name, tag in zip(t.get_outputs(), outdirs, install_dir_names, t.install_tag):
                         # User requested that we not install this output
                         if outdir is False:
                             continue
                         f = os.path.join(self.get_target_dir(t), output)
-                        i = TargetInstallData(f, outdir, default_install_dir_name,
+                        i = TargetInstallData(f, outdir, outdir_name,
                                               False, {}, set(), None, install_mode,
                                               t.subproject, optional=not t.build_by_default,
                                               tag=tag)
diff --git a/mesonbuild/build.py b/mesonbuild/build.py
index 2729373..c7f5997 100644
--- a/mesonbuild/build.py
+++ b/mesonbuild/build.py
@@ -628,7 +628,7 @@ class Target(HoldableObject):
             # False (which means we want this specific output out of many
             # outputs to not be installed).
             custom_install_dir = True
-            default_install_dir_name = None
+            install_dir_names = [getattr(i, 'optname', None) for i in outdirs]
         else:
             custom_install_dir = False
             # if outdirs is empty we need to set to something, otherwise we set
@@ -637,8 +637,9 @@ class Target(HoldableObject):
                 outdirs[0] = default_install_dir
             else:
                 outdirs = [default_install_dir]
+            install_dir_names = [default_install_dir_name] * len(outdirs)
 
-        return outdirs, default_install_dir_name, custom_install_dir
+        return outdirs, install_dir_names, custom_install_dir
 
     def get_basename(self) -> str:
         return self.name
diff --git a/mesonbuild/interpreter/interpreter.py b/mesonbuild/interpreter/interpreter.py
index 8caf010..131f073 100644
--- a/mesonbuild/interpreter/interpreter.py
+++ b/mesonbuild/interpreter/interpreter.py
@@ -2342,14 +2342,8 @@ class Interpreter(InterpreterBase, HoldableObject):
                     '"rename" and "sources" argument lists must be the same length if "rename" is given. '
                     f'Rename has {len(rename)} elements and sources has {len(sources)}.')
 
-        install_dir_name = kwargs['install_dir']
-        if install_dir_name:
-            if not os.path.isabs(install_dir_name):
-                install_dir_name = os.path.join('{datadir}', install_dir_name)
-        else:
-            install_dir_name = '{datadir}'
         return self.install_data_impl(sources, kwargs['install_dir'], kwargs['install_mode'],
-                                      rename, kwargs['install_tag'], install_dir_name,
+                                      rename, kwargs['install_tag'],
                                       preserve_path=kwargs['preserve_path'])
 
     def install_data_impl(self, sources: T.List[mesonlib.File], install_dir: T.Optional[str],
@@ -2361,7 +2355,9 @@ class Interpreter(InterpreterBase, HoldableObject):
 
         """Just the implementation with no validation."""
         idir = install_dir or ''
-        idir_name = install_dir_name or idir
+        idir_name = install_dir_name or idir or '{datadir}'
+        if isinstance(idir_name, P_OBJ.OptionString):
+            idir_name = idir_name.optname
         dirs = collections.defaultdict(list)
         ret_data = []
         if preserve_path:
@@ -2594,10 +2590,13 @@ class Interpreter(InterpreterBase, HoldableObject):
             if not idir:
                 raise InterpreterException(
                     '"install_dir" must be specified when "install" in a configure_file is true')
+            idir_name = idir
+            if isinstance(idir_name, P_OBJ.OptionString):
+                idir_name = idir_name.optname
             cfile = mesonlib.File.from_built_file(ofile_path, ofile_fname)
             install_mode = kwargs['install_mode']
             install_tag = kwargs['install_tag']
-            self.build.data.append(build.Data([cfile], idir, idir, install_mode, self.subproject,
+            self.build.data.append(build.Data([cfile], idir, idir_name, install_mode, self.subproject,
                                               install_tag=install_tag, data_type='configure'))
         return mesonlib.File.from_built_file(self.subdir, output)
 
diff --git a/mesonbuild/mintro.py b/mesonbuild/mintro.py
index eee2e7c..fd5c16f 100644
--- a/mesonbuild/mintro.py
+++ b/mesonbuild/mintro.py
@@ -143,8 +143,6 @@ def list_install_plan(installdata: backends.InstallData) -> T.Dict[str, T.Dict[s
             install_path_name = data.install_path_name
             if key == 'headers':  # in the headers, install_path_name is the directory
                 install_path_name = os.path.join(install_path_name, os.path.basename(data.path))
-            elif data_type == 'configure':
-                install_path_name = os.path.join('{prefix}', install_path_name)
 
             plan[data_type] = plan.get(data_type, {})
             plan[data_type][data.path] = {
diff --git a/mesonbuild/modules/python.py b/mesonbuild/modules/python.py
index 91443b8..9b50de4 100644
--- a/mesonbuild/modules/python.py
+++ b/mesonbuild/modules/python.py
@@ -30,6 +30,7 @@ from ..dependencies.base import process_method_kw
 from ..dependencies.detect import get_dep_identifier
 from ..environment import detect_cpu_family
 from ..interpreter import ExternalProgramHolder, extract_required_kwarg, permitted_dependency_kwargs
+from ..interpreter import primitives as P_OBJ
 from ..interpreter.type_checking import NoneType, PRESERVE_PATH_KW
 from ..interpreterbase import (
     noPosargs, noKwargs, permittedKwargs, ContainerTypeInfo,
@@ -514,7 +515,7 @@ class PythonInstallation(ExternalProgramHolder):
             if not isinstance(subdir, str):
                 raise InvalidArguments('"subdir" argument must be a string.')
 
-            kwargs['install_dir'] = os.path.join(self.platlib_install_path, subdir)
+            kwargs['install_dir'] = self._get_install_dir_impl(False, subdir)
 
         new_deps = []
         has_pydep = False
@@ -598,11 +599,12 @@ class PythonInstallation(ExternalProgramHolder):
     def install_sources_method(self, args: T.Tuple[T.List[T.Union[str, mesonlib.File]]],
                                kwargs: 'PyInstallKw') -> 'Data':
         tag = kwargs['install_tag'] or 'runtime'
+        install_dir = self._get_install_dir_impl(kwargs['pure'], kwargs['subdir'])
         return self.interpreter.install_data_impl(
             self.interpreter.source_strings_to_files(args[0]),
-            self._get_install_dir_impl(kwargs['pure'], kwargs['subdir']),
+            install_dir,
             mesonlib.FileMode(), rename=None, tag=tag, install_data_type='python',
-            install_dir_name=self._get_install_dir_name_impl(kwargs['pure'], kwargs['subdir']),
+            install_dir_name=install_dir.optname,
             preserve_path=kwargs['preserve_path'])
 
     @noPosargs
@@ -610,12 +612,15 @@ class PythonInstallation(ExternalProgramHolder):
     def get_install_dir_method(self, args: T.List['TYPE_var'], kwargs: 'PyInstallKw') -> str:
         return self._get_install_dir_impl(kwargs['pure'], kwargs['subdir'])
 
-    def _get_install_dir_impl(self, pure: bool, subdir: str) -> str:
-        return os.path.join(
-            self.purelib_install_path if pure else self.platlib_install_path, subdir)
+    def _get_install_dir_impl(self, pure: bool, subdir: str) -> P_OBJ.OptionString:
+        if pure:
+            base = self.purelib_install_path
+            name = '{py_purelib}'
+        else:
+            base = self.platlib_install_path
+            name = '{py_platlib}'
 
-    def _get_install_dir_name_impl(self, pure: bool, subdir: str) -> str:
-        return os.path.join('{py_purelib}' if pure else '{py_platlib}', subdir)
+        return P_OBJ.OptionString(os.path.join(base, subdir), os.path.join(name, subdir))
 
     @noPosargs
     @noKwargs
diff --git a/unittests/allplatformstests.py b/unittests/allplatformstests.py
index 3238a39..824d97b 100644
--- a/unittests/allplatformstests.py
+++ b/unittests/allplatformstests.py
@@ -4145,11 +4145,11 @@ class AllPlatformTests(BasePlatformTests):
         expected = {
             'targets': {
                 f'{self.builddir}/out1-notag.txt': {
-                    'destination': '{prefix}/share/out1-notag.txt',
+                    'destination': '{datadir}/out1-notag.txt',
                     'tag': None,
                 },
                 f'{self.builddir}/out2-notag.txt': {
-                    'destination': '{prefix}/share/out2-notag.txt',
+                    'destination': '{datadir}/out2-notag.txt',
                     'tag': None,
                 },
                 f'{self.builddir}/libstatic.a': {
@@ -4197,67 +4197,67 @@ class AllPlatformTests(BasePlatformTests):
                     'tag': 'devel',
                 },
                 f'{self.builddir}/out1-custom.txt': {
-                    'destination': '{prefix}/share/out1-custom.txt',
+                    'destination': '{datadir}/out1-custom.txt',
                     'tag': 'custom',
                 },
                 f'{self.builddir}/out2-custom.txt': {
-                    'destination': '{prefix}/share/out2-custom.txt',
+                    'destination': '{datadir}/out2-custom.txt',
                     'tag': 'custom',
                 },
                 f'{self.builddir}/out3-custom.txt': {
-                    'destination': '{prefix}/share/out3-custom.txt',
+                    'destination': '{datadir}/out3-custom.txt',
                     'tag': 'custom',
                 },
                 f'{self.builddir}/subdir/out1.txt': {
-                    'destination': '{prefix}/share/out1.txt',
+                    'destination': '{datadir}/out1.txt',
                     'tag': None,
                 },
                 f'{self.builddir}/subdir/out2.txt': {
-                    'destination': '{prefix}/share/out2.txt',
+                    'destination': '{datadir}/out2.txt',
                     'tag': None,
                 },
                 f'{self.builddir}/out-devel.h': {
-                    'destination': '{prefix}/include/out-devel.h',
+                    'destination': '{includedir}/out-devel.h',
                     'tag': 'devel',
                 },
                 f'{self.builddir}/out3-notag.txt': {
-                    'destination': '{prefix}/share/out3-notag.txt',
+                    'destination': '{datadir}/out3-notag.txt',
                     'tag': None,
                 },
             },
             'configure': {
                 f'{self.builddir}/foo-notag.h': {
-                    'destination': '{prefix}/share/foo-notag.h',
+                    'destination': '{datadir}/foo-notag.h',
                     'tag': None,
                 },
                 f'{self.builddir}/foo2-devel.h': {
-                    'destination': '{prefix}/include/foo2-devel.h',
+                    'destination': '{includedir}/foo2-devel.h',
                     'tag': 'devel',
                 },
                 f'{self.builddir}/foo-custom.h': {
-                    'destination': '{prefix}/share/foo-custom.h',
+                    'destination': '{datadir}/foo-custom.h',
                     'tag': 'custom',
                 },
                 f'{self.builddir}/subdir/foo2.h': {
-                    'destination': '{prefix}/share/foo2.h',
+                    'destination': '{datadir}/foo2.h',
                     'tag': None,
                 },
             },
             'data': {
                 f'{testdir}/bar-notag.txt': {
-                    'destination': '{datadir}/share/bar-notag.txt',
+                    'destination': '{datadir}/bar-notag.txt',
                     'tag': None,
                 },
                 f'{testdir}/bar-devel.h': {
-                    'destination': '{datadir}/include/bar-devel.h',
+                    'destination': '{includedir}/bar-devel.h',
                     'tag': 'devel',
                 },
                 f'{testdir}/bar-custom.txt': {
-                    'destination': '{datadir}/share/bar-custom.txt',
+                    'destination': '{datadir}/bar-custom.txt',
                     'tag': 'custom',
                 },
                 f'{testdir}/subdir/bar2-devel.h': {
-                    'destination': '{datadir}/include/bar2-devel.h',
+                    'destination': '{includedir}/bar2-devel.h',
                     'tag': 'devel',
                 },
             },